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 "support/Path.h"
13#include "clang/Basic/LLVM.h"
14#include "llvm/ADT/StringMap.h"
15#include "llvm/Support/VirtualFileSystem.h"
16#include <optional>
17
18namespace clang {
19namespace clangd {
20
21/// Records status information for files open()ed or stat()ed during preamble
22/// build (except for the main file), so we can avoid stat()s on the underlying
23/// FS when reusing the preamble. For example, code completion can re-stat files
24/// when getting FileID for source locations stored in preamble (e.g. checking
25/// whether a location is in the main file).
26///
27/// The cache is keyed by absolute path of file name in cached status, as this
28/// is what preamble stores.
29///
30/// The cache is not thread-safe when updates happen, so the use pattern should
31/// be:
32/// - One FS writes to the cache from one thread (or several but strictly
33/// sequenced), e.g. when building preamble.
34/// - Sequence point (no writes after this point, no reads before).
35/// - Several FSs can read from the cache, e.g. code completions.
36///
37/// Note that the cache is only valid when reusing preamble.
38class PreambleFileStatusCache {
39public:
40 /// \p MainFilePath is the absolute path of the main source file this preamble
41 /// corresponds to. The stat for the main file will not be cached.
42 PreambleFileStatusCache(llvm::StringRef MainFilePath);
43
44 void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S,
45 llvm::StringRef File);
46
47 /// \p Path is a path stored in preamble.
48 std::optional<llvm::vfs::Status> lookup(llvm::StringRef Path) const;
49
50 /// Returns a VFS that collects file status.
51 /// Only cache stats for files that exist because
52 /// 1) we only care about existing files when reusing preamble, unlike
53 /// building preamble.
54 /// 2) we use the file name in the Status as the cache key.
55 ///
56 /// Note that the returned VFS should not outlive the cache.
57 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
58 getProducingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
59
60 /// Returns a VFS that uses the cache collected.
61 ///
62 /// Note that the returned VFS should not outlive the cache.
63 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
64 getConsumingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) const;
65
66private:
67 std::string MainFilePath;
68 llvm::StringMap<llvm::vfs::Status> StatCache;
69};
70
71/// Returns a version of \p File that doesn't contain dots and dot dots.
72/// e.g /a/b/../c -> /a/c
73/// /a/b/./c -> /a/b/c
74/// FIXME: We should avoid encountering such paths in clangd internals by
75/// filtering everything we get over LSP, CDB, etc.
76Path removeDots(PathRef File);
77
78} // namespace clangd
79} // namespace clang
80
81#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
82

source code of clang-tools-extra/clangd/FS.h