[PATCH] D64475: [clangd] Duplicate lines of semantic highlightings sent removed.

[Haojian Wu via Phabricator via cfe-commits]

hokein added inline comments.


================
Comment at: clang-tools-extra/clangd/ClangdLSPServer.cpp:1125
+    Old = std::move(FileToHighlightings[File]);
+    FileToHighlightings[File] = Highlightings;
+  }
----------------
ilya-biryukov wrote:
> NIT: avoid copying (from `Highlightings` into the map) under a lock, make the copy outside the lock instead
I think we can even avoid copy, since we only use the `Highlightings` for calculating the diff.

Maybe just 

```
{
    std::lock_guard<std::mutex> Lock(HighlightingsMutex);
    Old = std::move(FileToHighlightings[File]);
}
// calculate the diff.
{  
     std::lock_guard<std::mutex> Lock(HighlightingsMutex);
     FileToHighlightings[File] = std::move(Highlightings);
}
```


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D64475/new/

https://reviews.llvm.org/D64475