Records status information for files open()ed or stat()ed during preamble build (except for the main file), so we can avoid stat()s on the underlying FS when reusing the preamble. More...

#include <FS.h>

Public Member Functions
	PreambleFileStatusCache (llvm::StringRef MainFilePath)
	`MainFilePath` is the absolute path of the main source file this preamble corresponds to.
void	update (const llvm::vfs::FileSystem &FS, llvm::vfs::Status S, llvm::StringRef File)
std::optional< llvm::vfs::Status >	lookup (llvm::StringRef Path) const
	`Path` is a path stored in preamble.
IntrusiveRefCntPtr< llvm::vfs::FileSystem >	getProducingFS (IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS)
	Returns a VFS that collects file status.
IntrusiveRefCntPtr< llvm::vfs::FileSystem >	getConsumingFS (IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS) const
	Returns a VFS that uses the cache collected.

Detailed Description

Records status information for files open()ed or stat()ed during preamble build (except for the main file), so we can avoid stat()s on the underlying FS when reusing the preamble.

For example, code completion can re-stat files when getting FileID for source locations stored in preamble (e.g. checking whether a location is in the main file).

The cache is keyed by absolute path of file name in cached status, as this is what preamble stores.

The cache is not thread-safe when updates happen, so the use pattern should be:

One FS writes to the cache from one thread (or several but strictly sequenced), e.g. when building preamble.
Sequence point (no writes after this point, no reads before).
Several FSs can read from the cache, e.g. code completions.

Note that the cache is only valid when reusing preamble.

Definition at line 38 of file FS.h.

Constructor & Destructor Documentation

◆ PreambleFileStatusCache()

clang::clangd::PreambleFileStatusCache::PreambleFileStatusCache ( llvm::StringRef MainFilePath )

MainFilePath is the absolute path of the main source file this preamble corresponds to.

The stat for the main file will not be cached.

Definition at line 19 of file FS.cpp.

Referenced by getConsumingFS(), and getProducingFS().

Member Function Documentation

◆ getConsumingFS()

llvm::IntrusiveRefCntPtr< llvm::vfs::FileSystem > clang::clangd::PreambleFileStatusCache::getConsumingFS ( IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS ) const

Returns a VFS that uses the cache collected.

Note that the returned VFS should not outlive the cache.

Definition at line 96 of file FS.cpp.

References PreambleFileStatusCache().

◆ getProducingFS()

llvm::IntrusiveRefCntPtr< llvm::vfs::FileSystem > clang::clangd::PreambleFileStatusCache::getProducingFS ( IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS )

Returns a VFS that collects file status.

Only cache stats for files that exist because 1) we only care about existing files when reusing preamble, unlike building preamble. 2) we use the file name in the Status as the cache key.

Note that the returned VFS should not outlive the cache.

Definition at line 56 of file FS.cpp.

References clang::clangd::File, and PreambleFileStatusCache().