Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Force GitHub README to respect dark mode (function() { var style = document.createElement('style'); style.textContent = ' .markdown-body { color-scheme: dark light; } .markdown-body pre { background: #161b22 !important; } .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; } .markdown-body table th, .markdown-body table td { border-color: #30363d !important; } .markdown-body img { background: #0d1117; } .markdown-body blockquote { border-left-color: #8b949e; } .markdown-body hr { border-color: #30363d; } '; document.head.appendChild(style); })(); } } catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + ' Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Highlight search terms from Google/DuckDuckGo/Bing referrer (function() { var ref = document.referrer; var terms = []; if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) { var url = new URL(ref); var q = url.searchParams.get('q') || url.searchParams.get('p'); if (q) { terms = q.split(/\s+/).filter(function(t) { return t.length > 2; }); } } if (terms.length === 0) return; var style = document.createElement('style'); style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }'; document.head.appendChild(style); function highlight(node) { if (node.nodeType === 3) { // text node var text = node.textContent; var found = false; terms.forEach(function(term) { var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi'); if (regex.test(text)) { found = true; var frag = document.createDocumentFragment(); var parts = text.split(regex); parts.forEach(function(part, i) { if (i % 2 === 0) { frag.appendChild(document.createTextNode(part)); } else { var span = document.createElement('span'); span.className = 'userscript-highlight'; span.textContent = part; frag.appendChild(span); } }); node.parentNode.replaceChild(frag, node); } }); } else if (node.nodeType === 1 && node.childNodes) { // element var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT']; if (!skipTags.includes(node.tagName)) { Array.from(node.childNodes).forEach(highlight); } } } highlight(document.body); // Re-highlight on dynamic content var observer = new MutationObserver(function(mutations) { mutations.forEach(function(m) { m.addedNodes.forEach(function(node) { if (node.nodeType === 1 || node.nodeType === 3) highlight(node); }); }); }); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + ' Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Strip utm_, fbclid, gclid, etc. from all links on page (function() { var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content', 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid', 'ref', 'ref_src', 'source', 'medium', 'campaign']; function cleanUrl(url) { try { var u = new URL(url, window.location.origin); var changed = false; trackingParams.forEach(function(p) { if (u.searchParams.has(p)) { u.searchParams.delete(p); changed = true; } }); return changed ? u.toString() : url; } catch (e) { return url; } } function cleanLinks() { document.querySelectorAll('a[href]').forEach(function(a) { var clean = cleanUrl(a.href); if (clean !== a.href) a.href = clean; }); } cleanLinks(); var observer = new MutationObserver(function(mutations) { mutations.forEach(function(m) { m.addedNodes.forEach(function(node) { if (node.nodeType === 1) { if (node.tagName === 'A') cleanLinks(); node.querySelectorAll('a[href]').forEach(function(a) { var clean = cleanUrl(a.href); if (clean !== a.href) a.href = clean; }); } }); }); }); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); } })(); (function(){ try { var __m = "youtube.com"; var __re = new RegExp('^' + "youtube\\.com" + ' Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Auto-enable theater mode on YouTube (function() { function tryTheater() { var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]'); if (btn && !btn.classList.contains('activated')) { btn.click(); } } // Try immediately tryTheater(); // Try after navigation (SPA) var lastUrl = location.href; setInterval(function() { if (location.href !== lastUrl) { lastUrl = location.href; setTimeout(tryTheater, 500); } }, 1000); // Also try on player load var observer = new MutationObserver(tryTheater); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + ' Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev
, 'i'); if (__m === '*' || __re.test(location.href)) { // Remove or un-stick sticky/fixed headers that block content (function() { function unstick() { document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) { if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') { el.style.position = 'static'; el.style.top = 'auto'; el.style.zIndex = 'auto'; } }); } unstick(); var observer = new MutationObserver(unstick); observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] }); })(); } } catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); } })(); })(); Allow async events processing without holding `total_consistency_lock` by tnull · Pull Request #2199 · lightningdevkit/rust-lightning · GitHub
Skip to content

Allow async events processing without holding total_consistency_lock - #2199

Merged
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing
Apr 22, 2023
Merged

Allow async events processing without holding total_consistency_lock#2199
TheBlueMatt merged 4 commits into
lightningdevkit:mainfrom
tnull:2023-04-fix-async-event-processing

Conversation

@tnull

Copy link
Copy Markdown
Contributor

Fixes#2003.

Unfortunately, the RAII types used by RwLock are not Send, which is why they can't be held over await boundaries. In order to allow asynchronous events processing in multi-threaded environments, we here allow to process events without holding the total_consistency_lock. We do so by cloning the events and only draining and persisting the queue after they have successfully been processed.

The first commit reverts a prior commit of #2177, as we now want the behavior of the two process_event methods to diverge, i.e., want to avoid cloning in the sync case.

I tried to be minimally invasive as the event processing will receive a general overhaul with #2167 and follow-ups and any more substantial changes would likely only make sense after they have landed.

@tnull

tnull commented Apr 18, 2023

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

@codecov-commenter

codecov-commenter commented Apr 18, 2023

Copy link
Copy Markdown

Codecov Report

Patch coverage: 94.11% and project coverage change: +1.04 🎉

Comparison is base (2ebbe6f) 91.34% compared to head (a5358d0) 92.38%.

❗ Current head a5358d0 differs from pull request most recent head f2453b7. Consider uploading reports for the commit f2453b7 to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files
@@ Coverage Diff @@## main #2199 +/- ##
==========================================
+ Coverage 91.34% 92.38% +1.04% 
==========================================
Files 102 104 +2 Lines 50470 61358 +10888 Branches 50470 61358 +10888 ==========================================
+ Hits 46103 56688 +10585 - Misses 4367 4670 +303 
Impacted FilesCoverage Δ
lightning/src/ln/channelmanager.rs91.65% <75.00%> (+2.48%)⬆️
lightning-background-processor/src/lib.rs83.51% <100.00%> (+6.40%)⬆️
lightning-net-tokio/src/lib.rs78.41% <100.00%> (ø)

... and 64 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch 3 times, most recently from 9d6077b to 5467f97CompareApril 18, 2023 14:36
@tnull

Copy link
Copy Markdown
ContributorAuthor

Currently fails due to a previously-silent panic in BP tests that, due to the behavior of the tokio runtime, wasn't surfaced and caught before. Looking into that.

Correction: after fixing the CI script, this should now really fail until we fix the bug..

Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs Outdated
Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMattTheBlueMatt added this to the 0.0.115 milestone Apr 18, 2023
tnull added 2 commits April 19, 2023 10:25
Just two trivial compiler warnings that are unrelated to the changes
made here.
Currently the BP `futures` tests rely on `std`. In order to actually
have them run, we should enable `std`, i.e., remove
`--no-default-features`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from 5467f97 to c9cfd20CompareApril 19, 2023 09:13

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from c9cfd20 to dd48d55CompareApril 20, 2023 10:43
@tnull

Copy link
Copy Markdown
ContributorAuthor

Sorry can you not break out the macro? Not because it's wrong here but because there's a lot more complexity coming in a followup PR in there and we'll just have to add it again.

Alright, dropped the revert commit and now also cloning in the sync case.

@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from dd48d55 to d7de357CompareApril 20, 2023 10:46
Comment threadlightning/src/ln/channelmanager.rs
Comment threadlightning/src/ln/channelmanager.rs Outdated

@TheBlueMattTheBlueMatt left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM.

Comment threadlightning/src/ln/channelmanager.rs Outdated
let mut pending_events = $self.pending_events.lock().unwrap();
pending_events.drain(..num_events);
processed_all_events = pending_events.is_empty();
$self.pending_events_processor.store(false, Ordering::Release);

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should this only happen if !processed_all_events? Not a big deal either way, I think.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You mean if we processed all events? Yeah, I think I'd leave it as is.

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, no, I mean literally just move the setter here into a check for if we're about to go around again.

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah, yes, had understood as much, but we def. need to reset in the case we leave the method. We could have moved the compare_exchange out of the loop and only reset the flag on exit, but given that it's a rare edge case anyways I thought it made sense to leave as is.

Unfortunately, the RAII types used by `RwLock` are not `Send`, which is
why they can't be held over `await` boundaries. In order to allow
asynchronous events processing in multi-threaded environments, we here
allow to process events without holding the `total_consistency_lock`.
@tnull
tnullforce-pushed the 2023-04-fix-async-event-processing branch from a5358d0 to f2453b7CompareApril 21, 2023 16:05
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wait, why?

@tnulltnullApr 21, 2023

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we're shutting the other task down after the first send. However, we also persist again on shutdown, which triggers a second send, which would panic as the receiver is already gone at that point.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

@alecchendevalecchendev left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM I think! Making sure I'm getting this right, do types need to implement Send across await boundaries because in a multi-threaded environments, a task waiting on a future to complete may be moved to execute on another thread?

// we can be sure no other persists happen while processing events.
let _read_guard = $self.total_consistency_lock.read().unwrap();
let mut processed_all_events = false;
while !processed_all_events {

@alecchendevalecchendevApr 21, 2023

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How come this is all run in a while loop? IIUC there may be other events added to pending_events by other async tasks while handling the events, which is how we end up not having processed all events, but why do we keep processing until pending_events is empty as opposed to just processing the events that were present when we first call this function? I guess does it make much of a difference or is it more just that we might as well do it while we're here

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because we no longer allow multiple processors to run at the same time - if one process_events call starts, and makes some progress, then an event is generated, causing a second process_events call to happen, the second call might return early, but there's some events there the user expects to have processed. Thus, we need to make sure the first process_events goes around again and processes the remaining events.

Comment threadlightning-background-processor/src/lib.rs
sender.send(()).unwrap();
match sender.send(()) {
Ok(()) => {},
Err(std::sync::mpsc::SendError(())) => println!("Persister failed to notify as receiver went away."),

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think a comment for why this is ok would be helpful

Comment threadlightning/src/ln/channelmanager.rs
@TheBlueMatt
TheBlueMatt merged commit 5f96d13 into lightningdevkit:mainApr 22, 2023
PXplod pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
0.0.115 - Apr 24, 2023 - "Rebroadcast the Bugfixes"
API Updates
===========
* The MSRV of the main LDK crates has been increased to 1.48 (lightningdevkit#2107).
* Attempting to claim an un-expired payment on a channel which has closed no
longer fails. The expiry time of payments is exposed via
`PaymentClaimable::claim_deadline` (lightningdevkit#2148).
* `payment_metadata` is now supported in `Invoice` deserialization, sending,
and receiving (via a new `RecipientOnionFields` struct) (lightningdevkit#2139, lightningdevkit#2127).
* `Event::PaymentFailed` now exposes a failure reason (lightningdevkit#2142).
* BOLT12 messages now support stateless generation and validation (lightningdevkit#1989).
* The `NetworkGraph` is now pruned of stale data after RGS processing (lightningdevkit#2161).
* Max inbound HTLCs in-flight can be changed in the handshake config (lightningdevkit#2138).
* `lightning-transaction-sync` feature `esplora-async-https` was added (lightningdevkit#2085).
* A `ChannelPending` event is now emitted after the initial handshake (lightningdevkit#2098).
* `PaymentForwarded::outbound_amount_forwarded_msat` was added (lightningdevkit#2136).
* `ChannelManager::list_channels_by_counterparty` was added (lightningdevkit#2079).
* `ChannelDetails::feerate_sat_per_1000_weight` was added (lightningdevkit#2094).
* `Invoice::fallback_addresses` was added to fetch `bitcoin` types (lightningdevkit#2023).
* The offer/refund description is now exposed in `Invoice{,Request}` (lightningdevkit#2206).
Backwards Compatibility
=======================
* Payments sent with the legacy `*_with_route` methods on LDK 0.0.115+ will no
longer be retryable via the LDK 0.0.114- `retry_payment` method (lightningdevkit#2139).
* `Event::PaymentPathFailed::retry` was removed and will always be `None` for
payments initiated on 0.0.115 which fail on an earlier version (lightningdevkit#2063).
* `Route`s and `PaymentParameters` with blinded path information will not be
readable on prior versions of LDK. Such objects are not currently constructed
by LDK, but may be when processing BOLT12 data in a coming release (lightningdevkit#2146).
* Providing `ChannelMonitorUpdate`s generated by LDK 0.0.115 to a
`ChannelMonitor` on 0.0.114 or before may panic (lightningdevkit#2059). Note that this is
in general unsupported, and included here only for completeness.
Bug Fixes
=========
* Fixed a case where `process_events_async` may `poll` a `Future` which has
already completed (lightningdevkit#2081).
* Fixed deserialization of `u16` arrays. This bug may have previously corrupted
the historical buckets in a `ProbabilisticScorer`. Users relying on the
historical buckets may wish to wipe their scorer on upgrade to remove corrupt
data rather than waiting on it to decay (lightningdevkit#2191).
* The `process_events_async` task is now `Send` and can thus be polled on a
multi-threaded runtime (lightningdevkit#2199).
* Fixed a missing macro export causing
`impl_writeable_tlv_based_enum{,_upgradable}` calls to not compile (lightningdevkit#2091).
* Fixed compilation of `lightning-invoice` with both `no-std` and serde (lightningdevkit#2187)
* Fix an issue where the `background-processor` would not wake when a
`ChannelMonitorUpdate` completed asynchronously, causing delays (lightningdevkit#2090).
* Fix an issue where `process_events_async` would exit immediately (lightningdevkit#2145).
* `Router` calls from the `ChannelManager` now call `find_route_with_id` rather
than `find_route`, as was intended and described in the API (lightningdevkit#2092).
* Ensure `process_events_async` always exits if any sleep future returns true,
not just if all sleep futures repeatedly return true (lightningdevkit#2145).
* `channel_update` messages no longer set the disable bit unless the peer has
been disconnected for some time. This should resolve cases where channels are
disabled for extended periods of time (lightningdevkit#2198).
* We no longer remove CLN nodes from the network graph for violating the BOLT
spec in some cases after failing to pay through them (lightningdevkit#2220).
* Fixed a debug assertion which may panic under heavy load (lightningdevkit#2172).
* `CounterpartyForceClosed::peer_msg` is now wrapped in UntrustedString (lightningdevkit#2114)
* Fixed a potential deadlock in `funding_transaction_generated` (lightningdevkit#2158).
Security
========
* Transaction re-broadcasting is now substantially more aggressive, including a
new regular rebroadcast feature called on a timer from the
`background-processor` or from `ChainMonitor::rebroadcast_pending_claims`.
This should substantially increase transaction confirmation reliability
without relying on downstream `TransactionBroadcaster` implementations for
rebroadcasting (lightningdevkit#2203, lightningdevkit#2205, lightningdevkit#2208).
* Implemented the changes from BOLT PRs lightningdevkit#1031, lightningdevkit#1032, and lightningdevkit#1040 which resolve a
privacy vulnerability which allows an intermediate node on the path to
discover the final destination for a payment (lightningdevkit#2062).
In total, this release features 110 files changed, 11928 insertions, 6368
deletions in 215 commits from 21 authors, in alphabetical order:
* Advait
* Alan Cohen
* Alec Chen
* Allan Douglas R. de Oliveira
* Arik Sosman
* Elias Rohrer
* Evan Feenstra
* Jeffrey Czyz
* John Cantrell
* Lucas Soriano del Pino
* Marc Tyndel
* Matt Corallo
* Paul Miller
* Steven
* Steven Williamson
* Steven Zhao
* Tony Giorgio
* Valentine Wallace
* Wilmer Paulino
* benthecarman
* munjesi
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Switch total_consistency_lock to a SendRwLock variant

6 participants

@tnull@codecov-commenter@TheBlueMatt@wpaulino@valentinewallace@alecchendev