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Temporarily work around GetLineMap CPU usage #1368

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Jul 8, 2025
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Temporarily work around GetLineMap CPU usage #1368

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9 changes: 8 additions & 1 deletion internal/project/project.go
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ type snapshot struct {
project *Project
positionEncoding lsproto.PositionEncodingKind
program *compiler.Program
lineMaps collections.SyncMap[*ast.SourceFile, *ls.LineMap]
}

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Copilot AI Jul 7, 2025

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[nitpick] The lineMaps cache is unbounded and may retain entries even after files are closed or snapshots are discarded. Consider implementing eviction logic or clearing entries when files are removed to prevent potential memory growth.

Suggested change
// RemoveLineMap removes the line map for a given source file from the cache.
func (s *snapshot) RemoveLineMap(file *ast.SourceFile) {
s.lineMaps.Delete(file)
}

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No, these snapshots are request-scoped

// GetLineMap implements ls.Host.
Expand All @@ -51,7 +52,13 @@ func (s *snapshot) GetLineMap(fileName string) *ls.LineMap {
if s.project.getFileVersion(file) == scriptInfo.Version() {
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I still don't really understand why we're doing this at all; it seems to me that we should not cache line maps on script infos at all, instead do it per-source-file, and then just always use that. But I seem to remember someone saying that was wrong for some reason, so, this hack seems better than nothing?

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I recall a conversation around line maps differing between LS and CLI

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That's a different thing but yeah they do.

return scriptInfo.LineMap()
}
return ls.ComputeLineStarts(file.Text())
// The version changed; recompute the line map.
// !!! This shouldn't happen so often, but does. Probably removable once snapshotting is finished.
if cached, ok := s.lineMaps.Load(file); ok {
return cached
}
lineMap, _ := s.lineMaps.LoadOrStore(file, ls.ComputeLineStarts(file.Text()))
return lineMap
}

// GetPositionEncoding implements ls.Host.
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