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 18 namespace clang { 19 namespace 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. 38 class PreambleFileStatusCache { 39 public: 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 66 private: 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. 76 Path removeDots(PathRef File); 77 78 } // namespace clangd 79 } // namespace clang 80 81 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H 82