clang  9.0.0svn
FileSystemStatCache.h
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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.
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.
43 
44  /// We know that the file doesn't exist.
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.
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
TypePropertyCache< Private > Cache
Definition: Type.cpp:3573
We know the file exists and its cached stat data.
We know that the file doesn&#39;t exist.
llvm::StringMap< llvm::vfs::Status, llvm::BumpPtrAllocator >::const_iterator iterator
virtual LookupResult getStat(StringRef Path, llvm::vfs::Status &Status, bool isFile, std::unique_ptr< llvm::vfs::File > *F, llvm::vfs::FileSystem &FS)=0
virtual ~FileSystemStatCache()=default
Abstract interface for introducing a FileManager cache for &#39;stat&#39; system calls, which is used by prec...
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
Dataflow Directional Tag Classes.
llvm::StringMap< llvm::vfs::Status, llvm::BumpPtrAllocator > StatCalls
The set of stat() calls that have been seen.
A stat "cache" that can be used by FileManager to keep track of the results of stat() calls that occu...