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comparison clang-tools-extra/clangd/FS.h @ 150:1d019706d866

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LLVM10
author anatofuz
date Thu, 13 Feb 2020 15:10:13 +0900
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147:c2174574ed3a 150:1d019706d866
1 //===--- FS.h - File system related utils ------------------------*- C++-*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
11
12 #include "Path.h"
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 /// Returns a version of \p File that doesn't contain dots and dot dots.
70 /// e.g /a/b/../c -> /a/c
71 /// /a/b/./c -> /a/b/c
72 /// FIXME: We should avoid encountering such paths in clangd internals by
73 /// filtering everything we get over LSP, CDB, etc.
74 Path removeDots(PathRef File);
75
76 } // namespace clangd
77 } // namespace clang
78
79 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H