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