Support: Have directory_iterator::status() return FindFirstFileEx/FindNextFile results on Windows.

This allows clients to avoid an unnecessary fs::status() call on each
directory entry. Because the information returned by FindFirstFileEx
is a subset of the information returned by a regular status() call,
I needed to extract a base class from file_status that contains only
that information.

On my machine, this reduces the time required to enumerate a ThinLTO
cache directory containing 520k files from almost 4 minutes to less
than 2 seconds.

Differential Revision: https://reviews.llvm.org/D38716

llvm-svn: 315378

1 files changed, 8 insertions, 14 deletions

diff --git a/llvm/lib/Support/CachePruning.cpp b/llvm/lib/Support/CachePruning.cpp
index 60d0964f276..5a9580cf440 100644
--- a/llvm/lib/Support/CachePruning.cpp
+++ b/llvm/lib/Support/CachePruning.cpp
@@ -182,19 +182,9 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
   bool ShouldComputeSize =
       (Policy.MaxSizePercentageOfAvailableSpace > 0 || Policy.MaxSizeBytes > 0);
 
-  // Keep track of space
+  // Keep track of space. Needs to be kept ordered by size for determinism.
   std::set<std::pair<uint64_t, std::string>> FileSizes;
   uint64_t TotalSize = 0;
-  // Helper to add a path to the set of files to consider for size-based
-  // pruning, sorted by size.
-  auto AddToFileListForSizePruning =
-      [&](StringRef Path) {
-        if (!ShouldComputeSize)
-          return;
-        TotalSize += FileStatus.getSize();
-        FileSizes.insert(
-            std::make_pair(FileStatus.getSize(), std::string(Path)));
-      };
 
   // Walk the entire directory cache, looking for unused files.
   std::error_code EC;
@@ -212,13 +202,14 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
 
     // Look at this file. If we can't stat it, there's nothing interesting
     // there.
-    if (sys::fs::status(File->path(), FileStatus)) {
+    ErrorOr<sys::fs::basic_file_status> StatusOrErr = File->status();
+    if (!StatusOrErr) {
       DEBUG(dbgs() << "Ignore " << File->path() << " (can't stat)\n");
       continue;
     }
 
     // If the file hasn't been used recently enough, delete it
-    const auto FileAccessTime = FileStatus.getLastAccessedTime();
+    const auto FileAccessTime = StatusOrErr->getLastAccessedTime();
     auto FileAge = CurrentTime - FileAccessTime;
     if (FileAge > Policy.Expiration) {
       DEBUG(dbgs() << "Remove " << File->path() << " ("
@@ -228,7 +219,10 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
     }
 
     // Leave it here for now, but add it to the list of size-based pruning.
-    AddToFileListForSizePruning(File->path());
+    if (!ShouldComputeSize)
+      continue;
+    TotalSize += StatusOrErr->getSize();
+    FileSizes.insert({StatusOrErr->getSize(), std::string(File->path())});
   }
 
   // Prune for size now if needed