| 1 | //===- FileSystemStatCache.h - Caching for 'stat' calls ---------*- 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 | /// \file |
| 10 | /// Defines the FileSystemStatCache interface. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #ifndef LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H |
| 15 | #define LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H |
| 16 | |
| 17 | #include "clang/Basic/LLVM.h" |
| 18 | #include "llvm/ADT/StringMap.h" |
| 19 | #include "llvm/ADT/StringRef.h" |
| 20 | #include "llvm/Support/Allocator.h" |
| 21 | #include "llvm/Support/FileSystem.h" |
| 22 | #include "llvm/Support/VirtualFileSystem.h" |
| 23 | #include <cstdint> |
| 24 | #include <ctime> |
| 25 | #include <memory> |
| 26 | #include <string> |
| 27 | #include <utility> |
| 28 | |
| 29 | namespace clang { |
| 30 | |
| 31 | /// Abstract interface for introducing a FileManager cache for 'stat' |
| 32 | /// system calls, which is used by precompiled and pretokenized headers to |
| 33 | /// improve performance. |
| 34 | class FileSystemStatCache { |
| 35 | virtual void anchor(); |
| 36 | |
| 37 | public: |
| 38 | virtual ~FileSystemStatCache() = default; |
| 39 | |
| 40 | enum LookupResult { |
| 41 | /// We know the file exists and its cached stat data. |
| 42 | CacheExists, |
| 43 | |
| 44 | /// We know that the file doesn't exist. |
| 45 | CacheMissing |
| 46 | }; |
| 47 | |
| 48 | /// Get the 'stat' information for the specified path, using the cache |
| 49 | /// to accelerate it if possible. |
| 50 | /// |
| 51 | /// \returns \c true if the path does not exist or \c false if it exists. |
| 52 | /// |
| 53 | /// If isFile is true, then this lookup should only return success for files |
| 54 | /// (not directories). If it is false this lookup should only return |
| 55 | /// success for directories (not files). On a successful file lookup, the |
| 56 | /// implementation can optionally fill in \p F with a valid \p File object and |
| 57 | /// the client guarantees that it will close it. |
| 58 | static bool get(StringRef Path, llvm::vfs::Status &Status, bool isFile, |
| 59 | std::unique_ptr<llvm::vfs::File> *F, |
| 60 | FileSystemStatCache *Cache, llvm::vfs::FileSystem &FS); |
| 61 | |
| 62 | protected: |
| 63 | // FIXME: The pointer here is a non-owning/optional reference to the |
| 64 | // unique_ptr. Optional<unique_ptr<vfs::File>&> might be nicer, but |
| 65 | // Optional needs some work to support references so this isn't possible yet. |
| 66 | virtual LookupResult getStat(StringRef Path, llvm::vfs::Status &Status, |
| 67 | bool isFile, |
| 68 | std::unique_ptr<llvm::vfs::File> *F, |
| 69 | llvm::vfs::FileSystem &FS) = 0; |
| 70 | }; |
| 71 | |
| 72 | /// A stat "cache" that can be used by FileManager to keep |
| 73 | /// track of the results of stat() calls that occur throughout the |
| 74 | /// execution of the front end. |
| 75 | class MemorizeStatCalls : public FileSystemStatCache { |
| 76 | public: |
| 77 | /// The set of stat() calls that have been seen. |
| 78 | llvm::StringMap<llvm::vfs::Status, llvm::BumpPtrAllocator> StatCalls; |
| 79 | |
| 80 | using iterator = |
| 81 | llvm::StringMap<llvm::vfs::Status, |
| 82 | llvm::BumpPtrAllocator>::const_iterator; |
| 83 | |
| 84 | iterator begin() const { return StatCalls.begin(); } |
| 85 | iterator end() const { return StatCalls.end(); } |
| 86 | |
| 87 | LookupResult getStat(StringRef Path, llvm::vfs::Status &Status, bool isFile, |
| 88 | std::unique_ptr<llvm::vfs::File> *F, |
| 89 | llvm::vfs::FileSystem &FS) override; |
| 90 | }; |
| 91 | |
| 92 | } // namespace clang |
| 93 | |
| 94 | #endif // LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H |
| 95 |