[PATCH] D51539: [clangd] Add symbol slab size to index memory consumption estimates

[Eric Liu via Phabricator via cfe-commits]

ioeric added inline comments.


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Comment at: clang-tools-extra/clangd/index/FileIndex.cpp:144
+size_t FileIndex::estimateMemoryUsage() const {
+  return FSymbols.estimateMemoryUsage();
+}
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This can be a bit tricky. Generally, the size of a `FileIndex` is the size of FSymbols plus the overhead of the underlying index, but there can be multiple snapshots of symbols in `SwapIndex`. I think we can treat them as burst and only consider the size of the latest snapshot. 

`FSymbols` and the index have shared ownership to the symbol corpus. We can make either of them bookkeep the size, but I think it might be more straightforward to let the index "own" the size. You could set the payload size when creating the index, and you wouldn't need to expose `estimateMemoryUsage` from `FSymbols`.


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Comment at: clang-tools-extra/clangd/index/dex/DexIndex.h:44
+  DexIndex(Range &&Symbols, llvm::ArrayRef<std::string> URISchemes,
+           size_t BackingMemory = 0)
+      : BackingMemory(BackingMemory), URISchemes(URISchemes) {
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For this constructor, the index doesn't own the backing data. We should probably not include it in the estimation?

(same for MemIndex)


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Comment at: clang-tools-extra/clangd/index/dex/DexIndex.h:53
   DexIndex(Range &&Symbols, Payload &&BackingData,
-           llvm::ArrayRef<std::string> URISchemes)
-      : DexIndex(std::forward<Range>(Symbols), URISchemes) {
+           llvm::ArrayRef<std::string> URISchemes, size_t BackingMemory = 0)
+      : DexIndex(std::forward<Range>(Symbols), URISchemes, BackingMemory) {
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nit: maybe call `BackingDataSize`? `BackingMemory` sounds like the actual memory. Maybe also put the parameter right after `BackingData`, as they are closely related?

(same for MemIndex)


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Comment at: clang-tools-extra/clangd/index/dex/DexIndex.h:100
+  /// Slab.
+  size_t BackingMemory;
 
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nit: `=0`?


https://reviews.llvm.org/D51539