Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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michaelgsharp merged 1 commit into from
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Fix Apply in PrimitiveColumnContainer so it does not change source column #6642

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20 changes: 6 additions & 14 deletions src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
{
for (int b = 0; b < Buffers.Count; b++)
{
ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
long prevLength = checked(Buffers[0].Length * b);
DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
Buffers[b] = mutableBuffer;
Span<T> span = mutableBuffer.Span;
DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
NullBitMapBuffers[b] = mutableNullBitMapBuffer;
Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];

@JakeRadMSFTJakeRadMSFTMay 4, 2023•
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@agocke@jaredpar

Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?

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Maybe it doesn't because it actually does a copy?

https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36

@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:

DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.
Clone, Apply, ApplyElementWise, CloneAs

@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.

And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.

This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.

@JakeRadMSFTJakeRadMSFTMay 5, 2023•
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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!

I might take this up as a pet project in the future :)

@JakeRadMSFTJakeRadMSFTMay 5, 2023•
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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.

https://github.com/dotnet/machinelearning/pull/6656/files

@asmirnov82asmirnov82May 29, 2023•
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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in

public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.

RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).
So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.

ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

for (int i = 0; i < span.Length; i++)
for (int i = 0; i < Buffers[b].Length; i++)
{
long curIndex = i + prevLength;
bool isValid = IsValid(nullBitMapSpan, i);
TResult? value = func(isValid ? span[i] : default(T?));
bool isValid = IsValid(sourceNullBitMap, i);
TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
resultSpan[i] = value.GetValueOrDefault();
SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.
}
}
}
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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 Merged

michaelgsharp
merged 1 commit into

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May 5, 2023
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Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

edited

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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 Merged

michaelgsharp
merged 1 commit into

from

May 5, 2023
 Merged


Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

edited

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
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} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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Fix Apply in PrimitiveColumnContainer so it does not change source column
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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 Merged

michaelgsharp
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May 5, 2023
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Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

edited

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

edited

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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 Merged

michaelgsharp
merged 1 commit into

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May 5, 2023
 Merged


Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

edited

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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 Merged

michaelgsharp
merged 1 commit into

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May 5, 2023
 Merged


Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
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JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
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injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
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Fix Apply in PrimitiveColumnContainer so it does not change source column#6642

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michaelgsharp
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May 5, 2023
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Fix Apply in PrimitiveColumnContainer so it does not change source column
#6642
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20 changes: 6 additions & 14 deletions
src/Microsoft.Data.Analysis/PrimitiveColumnContainer.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -257,31 +257,23 @@ public void Apply<TResult>(Func<T?, TResult?> func, PrimitiveColumnContainer<TRe
 {
 for (int b = 0; b < Buffers.Count; b++)
 {
 ReadOnlyDataFrameBuffer<T> buffer = Buffers[b];
 long prevLength = checked(Buffers[0].Length * b);
 DataFrameBuffer<T> mutableBuffer = DataFrameBuffer<T>.GetMutableBuffer(buffer);
 Buffers[b] = mutableBuffer;
 Span<T> span = mutableBuffer.Span;
 DataFrameBuffer<byte> mutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(NullBitMapBuffers[b]);
 NullBitMapBuffers[b] = mutableNullBitMapBuffer;
 Span<byte> nullBitMapSpan = mutableNullBitMapBuffer.Span;
 ReadOnlyDataFrameBuffer<T> sourceBuffer = Buffers[b];
@JakeRadMSFTJakeRadMSFTMay 4, 2023•

edited

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@agocke@jaredpar
Just for my own learning purposes. Is this something that would be improved with the span changes in .NET? Would we no longer need to do all the GetMutableBuffer stuff?
@JakeRadMSFTJakeRadMSFTMay 4, 2023

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Maybe it doesn't because it actually does a copy?
https://github.com/dotnet/machinelearning/blob/d974a212538884bbffa0d95c82bf85de44a55782/src/Microsoft.Data.Analysis/DataFrameBuffer.cs#LL43C13-L44C36
@JakeRadMSFTJakeRadMSFTMay 5, 2023

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Specifically I'm wondering if there would be a better way to refactor out the code like this:
DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
resultContainer.Buffers[b] = resultMutableBuffer;
Span<TResult> resultSpan = resultMutableBuffer.Span;
DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

It's all over this file in some form.

Clone, Apply, ApplyElementWise, CloneAs
@agockeagockeMay 5, 2023

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There's a lot of very questionable stuff going on here. The code is going to great lengths to copy the original buffer to get a mutable version... and then passing the span to IsValid or calling the indexer, which both accept ReadOnlySpan.
And then there's the ReadOnlyDataFrameBuffer<T> type which takes a T : struct, but should be T : unmanaged.
This code could likely be simplified by extracting some helper methods, but I think the above issues indicate that someone should review the actual intent and ensure that the code reflects it.
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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That's sort of what it felt like but I appreciate having some expert eyes on it! Thanks @agocke!
I might take this up as a pet project in the future :)
@JakeRadMSFTJakeRadMSFTMay 5, 2023•

edited

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@agocke - I'm not sure it's 100% of the way there but I did a pass and opened a different PR.
https://github.com/dotnet/machinelearning/pull/6656/files
@asmirnov82asmirnov82May 29, 2023•

edited

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I see that PR already closed, but I have some comments regarding this GetMutableBuffer staff. It looks it's used for working with readonly memory, when column is created from the Apache Arrow RecordBatch in
public static DataFrame FromArrowRecordBatch(RecordBatch recordBatch)
{
DataFrame ret = new DataFrame();
Apache.Arrow.Schema arrowSchema = recordBatch.Schema;
int fieldIndex = 0;
IEnumerable<IArrowArray> arrowArrays = recordBatch.Arrays;
foreach (IArrowArray arrowArray in arrowArrays)
{
Field field = arrowSchema.GetFieldByIndex(fieldIndex);
AppendDataFrameColumnFromArrowArray(field, arrowArray, ret);
fieldIndex++;
}
return ret;
}

However, this implementation looks very suspicious.
RecordBatch is a disposable object. Apache Arrow by default uses NativeMemoryAllocator to allocate unmanaged memory (for example, this default allocator is used in Spark.Net to create RecorBatch and pass it to DataFrame.FromArrowRecordBatch factory method).

So it's up to a DataFrame to hold the link to the RecordBatch and correctly Dispose it. Or we have to copy the unmanaged readonly memory from the RecordBatch into managed buffers (that exactly what is happening in GetMutableBuffer on attempt to edit data), but in this case we can avoid using ReadOnlyBuffers at all.
 ReadOnlySpan<byte> sourceNullBitMap = NullBitMapBuffers[b].ReadOnlySpan;

 ReadOnlyDataFrameBuffer<TResult> resultBuffer = resultContainer.Buffers[b];
 long resultPrevLength = checked(resultContainer.Buffers[0].Length * b);
 DataFrameBuffer<TResult> resultMutableBuffer = DataFrameBuffer<TResult>.GetMutableBuffer(resultBuffer);
 resultContainer.Buffers[b] = resultMutableBuffer;
 Span<TResult> resultSpan = resultMutableBuffer.Span;
 DataFrameBuffer<byte> resultMutableNullBitMapBuffer = DataFrameBuffer<byte>.GetMutableBuffer(resultContainer.NullBitMapBuffers[b]);
 resultContainer.NullBitMapBuffers[b] = resultMutableNullBitMapBuffer;
 Span<byte> resultNullBitMapSpan = resultMutableNullBitMapBuffer.Span;

 for (int i = 0; i < span.Length; i++)
 for (int i = 0; i < Buffers[b].Length; i++)
 {
 long curIndex = i + prevLength;
 bool isValid = IsValid(nullBitMapSpan, i);
 TResult? value = func(isValid ? span[i] : default(T?));
 bool isValid = IsValid(sourceNullBitMap, i);
 TResult? value = func(isValid ? sourceBuffer[i] : default(T?));
 resultSpan[i] = value.GetValueOrDefault();
 SetValidityBit(resultNullBitMapSpan, i, value != null);
resultContainer.SetValidityBit(resultNullBitMapSpan, i, value != null);
Comment thread
JakeRadMSFT marked this conversation as resolved.

 }
 }
 }
Expand Down