[PATCH] D151185: [clangd] Store paths as requested in PreambleStatCache

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet created this revision.
kadircet added a reviewer: hokein.
Herald added a subscriber: arphaman.
Herald added a project: All.
kadircet requested review of this revision.
Herald added subscribers: cfe-commits, MaskRay, ilya-biryukov.
Herald added a project: clang-tools-extra.

Underlying FS can store different file names inside the stat response
(e.g. symlinks resolved, absolute paths, dots removed). But we store path names
as requested inside the preamble,
https://github.com/llvm/llvm-project/blob/main/clang/lib/Serialization/ASTWriter.cpp#L1635.

This improves cache hit rates from ~30% to 90% in a build system that uses
symlinks.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D151185

Files:
  clang-tools-extra/clangd/FS.cpp
  clang-tools-extra/clangd/FS.h
  clang-tools-extra/clangd/unittests/FSTests.cpp


Index: clang-tools-extra/clangd/unittests/FSTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/FSTests.cpp
+++ clang-tools-extra/clangd/unittests/FSTests.cpp
@@ -37,18 +37,19 @@
                       std::chrono::system_clock::now(), 0, 0, 1024,
                       llvm::sys::fs::file_type::regular_file,
                       llvm::sys::fs::all_all);
-  StatCache.update(*FS, S);
+  StatCache.update(*FS, S, "real");
   auto ConsumeFS = StatCache.getConsumingFS(FS);
-  auto Cached = ConsumeFS->status(testPath("fake"));
+  EXPECT_FALSE(ConsumeFS->status(testPath("fake")));
+  auto Cached = ConsumeFS->status(testPath("real"));
   EXPECT_TRUE(Cached);
-  EXPECT_EQ(Cached->getName(), testPath("fake"));
+  EXPECT_EQ(Cached->getName(), testPath("real"));
   EXPECT_EQ(Cached->getUniqueID(), S.getUniqueID());
 
-  // fake and temp/../fake should hit the same cache entry.
+  // real and temp/../real should hit the same cache entry.
   // However, the Status returned reflects the actual path requested.
-  auto CachedDotDot = ConsumeFS->status(testPath("temp/../fake"));
+  auto CachedDotDot = ConsumeFS->status(testPath("temp/../real"));
   EXPECT_TRUE(CachedDotDot);
-  EXPECT_EQ(CachedDotDot->getName(), testPath("temp/../fake"));
+  EXPECT_EQ(CachedDotDot->getName(), testPath("temp/../real"));
   EXPECT_EQ(CachedDotDot->getUniqueID(), S.getUniqueID());
 }
 
Index: clang-tools-extra/clangd/FS.h
===================================================================
--- clang-tools-extra/clangd/FS.h
+++ clang-tools-extra/clangd/FS.h
@@ -41,7 +41,8 @@
   /// corresponds to. The stat for the main file will not be cached.
   PreambleFileStatusCache(llvm::StringRef MainFilePath);
 
-  void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S);
+  void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S,
+              llvm::StringRef File);
 
   /// \p Path is a path stored in preamble.
   std::optional<llvm::vfs::Status> lookup(llvm::StringRef Path) const;
Index: clang-tools-extra/clangd/FS.cpp
===================================================================
--- clang-tools-extra/clangd/FS.cpp
+++ clang-tools-extra/clangd/FS.cpp
@@ -11,6 +11,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <optional>
+#include <utility>
 
 namespace clang {
 namespace clangd {
@@ -23,9 +24,10 @@
 }
 
 void PreambleFileStatusCache::update(const llvm::vfs::FileSystem &FS,
-                                     llvm::vfs::Status S) {
+                                     llvm::vfs::Status S,
+                                     llvm::StringRef File) {
   // Canonicalize path for later lookup, which is usually by absolute path.
-  llvm::SmallString<32> PathStore(S.getName());
+  llvm::SmallString<32> PathStore(File);
   if (FS.makeAbsolute(PathStore))
     return;
   llvm::sys::path::remove_dots(PathStore, /*remove_dot_dot=*/true);
@@ -72,14 +74,14 @@
       // many times (e.g. code completion) and the repeated status call is
       // likely to be cached in the underlying file system anyway.
       if (auto S = File->get()->status())
-        StatCache.update(getUnderlyingFS(), std::move(*S));
+        StatCache.update(getUnderlyingFS(), std::move(*S), Path.str());
       return File;
     }
 
     llvm::ErrorOr<llvm::vfs::Status> status(const llvm::Twine &Path) override {
       auto S = getUnderlyingFS().status(Path);
       if (S)
-        StatCache.update(getUnderlyingFS(), *S);
+        StatCache.update(getUnderlyingFS(), *S, Path.str());
       return S;
     }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D151185.524592.patch
Type: text/x-patch
Size: 3624 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20230523/b468dbee/attachment.bin>