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Use new Dictionary AlternateLookup to avoid allocation in DictionaryJumpTable #58305

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Merged
merged 2 commits into from
Nov 19, 2024
Merged

Use new Dictionary AlternateLookup to avoid allocation in DictionaryJumpTable #58305

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87ac8c0
Use new Dictionary AlternateLookup to avoid allocation in DictionaryJ…
andrewjsaid Oct 8, 2024
a6bafc9
Modify JumpTableMultipleEntryBenchmark to use substring of entire path
andrewjsaid Oct 8, 2024
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6 changes: 4 additions & 2 deletions src/Http/Routing/perf/Microbenchmarks/Matching/JumpTableMultipleEntryBenchmark.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ public void Setup()

for (var i = 0; i < _strings.Length; i++)
{
_segments[i] = new PathSegment(0, _strings[i].Length);
_segments[i] = new PathSegment(1, _strings[i].Length - 2);
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@BrennanConroy BrennanConroy Oct 9, 2024

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Shouldn't this be - 1?

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@andrewjsaid andrewjsaid Oct 9, 2024

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I attempted to trim one from the start and one from the end but I don't suppose it matters too much as long as it's a substring.

}

var samples = new int[Count];
Expand All @@ -39,7 +39,9 @@ public void Setup()
var entries = new List<(string text, int _)>();
for (var i = 0; i < samples.Length; i++)
{
entries.Add((_strings[samples[i]], i));
var sampleIndex = samples[i];
var segment = _segments[sampleIndex];
entries.Add((_strings[sampleIndex].Substring(segment.Start, segment.Length), i));
}

_linearSearch = new LinearSearchJumpTable(0, -1, entries.ToArray());
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6 changes: 4 additions & 2 deletions src/Http/Routing/src/Matching/DictionaryJumpTable.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ internal sealed class DictionaryJumpTable : JumpTable
private readonly int _defaultDestination;
private readonly int _exitDestination;
private readonly FrozenDictionary<string, int> _dictionary;
private readonly FrozenDictionary<string, int>.AlternateLookup<ReadOnlySpan<char>> _lookup;

public DictionaryJumpTable(
int defaultDestination,
Expand All @@ -22,6 +23,7 @@ public DictionaryJumpTable(
_exitDestination = exitDestination;

_dictionary = entries.ToFrozenDictionary(e => e.text, e => e.destination, StringComparer.OrdinalIgnoreCase);
_lookup = _dictionary.GetAlternateLookup<ReadOnlySpan<char>>();
}

public override int GetDestination(string path, PathSegment segment)
Expand All @@ -31,8 +33,8 @@ public override int GetDestination(string path, PathSegment segment)
return _exitDestination;
}

var text = path.Substring(segment.Start, segment.Length);
if (_dictionary.TryGetValue(text, out var destination))
var text = path.AsSpan(segment.Start, segment.Length);
if (_lookup.TryGetValue(text, out var destination))
{
return destination;
}
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