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Reduce allocations during typing #75351

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merged 2 commits into from
Oct 3, 2024
Merged

Reduce allocations during typing #75351

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d124a73
Reduce allocations during typing
ToddGrun Oct 2, 2024
867116e
Switch to FixedSizeArrayBuilder
ToddGrun Oct 2, 2024
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9 changes: 5 additions & 4 deletions src/Compilers/Core/Portable/Text/TextChangeRangeExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,17 +6,16 @@
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Text;

namespace Roslyn.Utilities
{
internal static class TextChangeRangeExtensions
{
public static TextChangeRange? Accumulate(this TextChangeRange? accumulatedTextChangeSoFar, IEnumerable<TextChangeRange> changesInNextVersion)
public static TextChangeRange? Accumulate(this TextChangeRange? accumulatedTextChangeSoFar, IReadOnlyList<TextChangeRange> changesInNextVersion)
{
if (!changesInNextVersion.Any())
if (changesInNextVersion.Count == 0)
{
return accumulatedTextChangeSoFar;
}
Expand All @@ -25,7 +24,9 @@ internal static class TextChangeRangeExtensions
// we could apply each one individually like we do in SyntaxDiff::ComputeSpansInNew by calculating delta
// between each change in changesInNextVersion which is already sorted in its textual position ascending order.
// but end result will be same as just applying it once with encompassed text change range.
var newChange = TextChangeRange.Collapse(changesInNextVersion);
var newChange = changesInNextVersion.Count == 1
? changesInNextVersion[0]
: TextChangeRange.Collapse(changesInNextVersion);
Comment on lines +27 to +29
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Should this optimization be moved inside TextChangeRange.Collapse itself?

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I considered that, but that method has several usages in which the caller only has an IEnumerable. I instead chose to limit the changes to the caller that was showing up in the performance profile I was looking at.


// no previous accumulated change, return the new value.
if (accumulatedTextChangeSoFar == null)
Expand Down
38 changes: 29 additions & 9 deletions src/EditorFeatures/Text/ITextImageHelpers.cs
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Expand Up @@ -7,6 +7,7 @@
using System.Collections.Immutable;
using System.Linq;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.VisualStudio.Text;
using Roslyn.Utilities;

Expand Down Expand Up @@ -51,35 +52,54 @@ public static IReadOnlyList<TextChangeRange> GetChangeRanges(ITextImageVersion o
}

if (changes == null)
{
return [];
}
else

var builder = ArrayBuilder<TextChangeRange>.GetInstance(changes.Count);
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for (var i = 0; i < changes.Count; i++)
{
return ImmutableArray.CreateRange(changes.Select(forward ? s_forwardTextChangeRange : s_backwardTextChangeRange));
var change = changes[i];
builder.Add(forward ? s_forwardTextChangeRange(change) : s_backwardTextChangeRange(change));
}

return builder.ToImmutableAndFree();
}

private static TextChangeRange GetChangeRanges(ITextImageVersion oldVersion, ITextImageVersion newVersion, bool forward)
{
TextChangeRange? range = null;
var iterator = GetMultipleVersionTextChanges(oldVersion, newVersion, forward);
foreach (var changes in forward ? iterator : iterator.Reverse())
using var _ = ArrayBuilder<ArrayBuilder<TextChangeRange>>.GetInstance(out var builder);

GetMultipleVersionTextChanges(oldVersion, newVersion, forward, builder);
foreach (var changes in builder)
{
range = range.Accumulate(changes);
changes.Free();
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}

RoslynDebug.Assert(range.HasValue);
return range.Value;
}

private static IEnumerable<IEnumerable<TextChangeRange>> GetMultipleVersionTextChanges(
ITextImageVersion oldVersion, ITextImageVersion newVersion, bool forward)
private static void GetMultipleVersionTextChanges(
ITextImageVersion oldVersion,
ITextImageVersion newVersion,
bool forward,
ArrayBuilder<ArrayBuilder<TextChangeRange>> builder)
{
for (var version = oldVersion; version != newVersion; version = version.Next)
{
yield return version.Changes.Select(forward ? s_forwardTextChangeRange : s_backwardTextChangeRange);
var changes = ArrayBuilder<TextChangeRange>.GetInstance(version.Changes.Count);
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for (var i = 0; i < version.Changes.Count; i++)
{
var change = version.Changes[i];
changes.Add(forward ? s_forwardTextChangeRange(change) : s_backwardTextChangeRange(change));
}

builder.Add(changes);
}

if (!forward)
builder.ReverseContents();
}

private static TextChangeRange CreateTextChangeRange(ITextChange change, bool forward)
Expand Down