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