clang-tools 8.0.0

FS.h
Go to the documentation of this file.
1 //===--- FS.h - File system related utils ------------------------*- C++-*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
11 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
12
13 #include "clang/Basic/LLVM.h"
14 #include "llvm/ADT/Optional.h"
15 #include "llvm/Support/VirtualFileSystem.h"
16
17 namespace clang {
18 namespace clangd {
19
20 /// Records status information for files open()ed or stat()ed during preamble
21 /// build (except for the main file), so we can avoid stat()s on the underlying
22 /// FS when reusing the preamble. For example, code completion can re-stat files
23 /// when getting FileID for source locations stored in preamble (e.g. checking
24 /// whether a location is in the main file).
25 ///
26 /// The cache is keyed by absolute path of file name in cached status, as this
27 /// is what preamble stores.
28 ///
29 /// The cache is not thread-safe when updates happen, so the use pattern should
30 /// be:
31 /// - One FS writes to the cache from one thread (or several but strictly
32 /// sequenced), e.g. when building preamble.
33 /// - Sequence point (no writes after this point, no reads before).
34 /// - Several FSs can read from the cache, e.g. code completions.
35 ///
36 /// Note that the cache is only valid when reusing preamble.
37 class PreambleFileStatusCache {
38 public:
39 /// \p MainFilePath is the absolute path of the main source file this preamble
40 /// corresponds to. The stat for the main file will not be cached.
41 PreambleFileStatusCache(llvm::StringRef MainFilePath);
42
43 void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S);
44
45 /// \p Path is a path stored in preamble.
46 llvm::Optional<llvm::vfs::Status> lookup(llvm::StringRef Path) const;
47
48 /// Returns a VFS that collects file status.
49 /// Only cache stats for files that exist because
50 /// 1) we only care about existing files when reusing preamble, unlike
51 /// building preamble.
52 /// 2) we use the file name in the Status as the cache key.
53 ///
54 /// Note that the returned VFS should not outlive the cache.
55 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
56 getProducingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
57
58 /// Returns a VFS that uses the cache collected.
59 ///
60 /// Note that the returned VFS should not outlive the cache.
61 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
62 getConsumingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) const;
63
64 private:
65 std::string MainFilePath;
66 llvm::StringMap<llvm::vfs::Status> StatCache;
67 };
68
69 } // namespace clangd
70 } // namespace clang
71
72 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
clang::clangd::PreambleFileStatusCache::update
void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S)
Definition: FS.cpp:23
clang::clangd::PreambleFileStatusCache::lookup
llvm::Optional< llvm::vfs::Status > lookup(llvm::StringRef Path) const
Path is a path stored in preamble.
Definition: FS.cpp:36
clang::clangd::PreambleFileStatusCache::PreambleFileStatusCache
PreambleFileStatusCache(llvm::StringRef MainFilePath)
MainFilePath is the absolute path of the main source file this preamble corresponds to...
Definition: FS.cpp:18
clang::clangd::PreambleFileStatusCache::getConsumingFS
IntrusiveRefCntPtr< llvm::vfs::FileSystem > getConsumingFS(IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS) const
Returns a VFS that uses the cache collected.
Definition: FS.cpp:84
clang::clangd::PreambleFileStatusCache::getProducingFS
IntrusiveRefCntPtr< llvm::vfs::FileSystem > getProducingFS(IntrusiveRefCntPtr< llvm::vfs::FileSystem > FS)
Returns a VFS that collects file status.
Definition: FS.cpp:44
clang::clangd::Path
std::string Path
A typedef to represent a file path.
Definition: Path.h:21
clang::clangd::PreambleFileStatusCache
Records status information for files open()ed or stat()ed during preamble build (except for the main ...
Definition: FS.h:37
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ChangeNamespace.cpp:18