When trying to switch to async background processing/event handling in LDK Node, I stumbled across the fact that tokio won't let me spawn a task for the process_events_async, as the we currently try to hold the total_consistency_lock over .await boundaries:
| let _read_guard = self.total_consistency_lock.read().unwrap(); |
| |
| letmut result = NotifyOption::SkipPersist; |
| |
| // TODO: This behavior should be documented. It's unintuitive that we query |
| // ChannelMonitors when clearing other events. |
| ifself.process_pending_monitor_events(){ |
| result = NotifyOption::DoPersist; |
| } |
| |
| let pending_events = mem::replace(&mut*self.pending_events.lock().unwrap(),vec![]); |
| if !pending_events.is_empty(){ |
| result = NotifyOption::DoPersist; |
| } |
| |
| for event in pending_events { |
| handler(event).await; |
| } |
This is an issue since RwLockReadGuard is not Send:
= help: within `impl futures::Future<Output = ()>`, the trait `std::marker::Send` is not implementedfor `std::sync::RwLockReadGuard<'_,()>`
note: future is not `Send` as this value is used across an await
--> /Users/ero/.cargo/git/checkouts/rust-lightning-da94c153801dff32/17eafed/lightning/src/ln/channelmanager.rs:5258:18
|
5242 | let _read_guard = self.total_consistency_lock.read().unwrap();
| ----------- has type `std::sync::RwLockReadGuard<'_,()>` which is not `Send`
...
5258 | handler(event).await;
| ^^^^^^ await occurs here, with `_read_guard` maybe used later
...
5264 | }
| - `_read_guard` is later dropped here
note: required by a bound in `tokio::runtime::Runtime::spawn`
--> /Users/ero/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.23.0/src/runtime/runtime.rs:192:21
|
192 | F:Future + Send + 'static,
| ^^^^ required by this bound in `tokio::runtime::Runtime::spawn`
In order to fix this, we need to explore options for replacing the RwLock of total_consistency_lock. One option might be taking a suitable dependency such as parking_lot, another approach would be to implement our own RwLock variant that meets the requirements.
When trying to switch to async background processing/event handling in LDK Node, I stumbled across the fact that tokio won't let me spawn a task for the
process_events_async, as the we currently try to hold thetotal_consistency_lockover.awaitboundaries:rust-lightning/lightning/src/ln/channelmanager.rs
Lines 5242 to 5259 in e1208bf
This is an issue since
RwLockReadGuardis notSend:In order to fix this, we need to explore options for replacing the
RwLockoftotal_consistency_lock. One option might be taking a suitable dependency such asparking_lot, another approach would be to implement our ownRwLockvariant that meets the requirements.