Coverage Report

Created: 2020-02-15 09:57

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
Line
Count
Source
1
//===- DependencyScanningFilesystem.h - clang-scan-deps fs ===---*- 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_TOOLING_DEPENDENCY_SCANNING_FILESYSTEM_H
10
#define LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_FILESYSTEM_H
11
12
#include "clang/Basic/LLVM.h"
13
#include "clang/Lex/PreprocessorExcludedConditionalDirectiveSkipMapping.h"
14
#include "llvm/ADT/StringMap.h"
15
#include "llvm/ADT/StringSet.h"
16
#include "llvm/Support/Allocator.h"
17
#include "llvm/Support/ErrorOr.h"
18
#include "llvm/Support/VirtualFileSystem.h"
19
#include <mutex>
20
21
namespace clang {
22
namespace tooling {
23
namespace dependencies {
24
25
/// An in-memory representation of a file system entity that is of interest to
26
/// the dependency scanning filesystem.
27
///
28
/// It represents one of the following:
29
/// - an opened source file with minimized contents and a stat value.
30
/// - an opened source file with original contents and a stat value.
31
/// - a directory entry with its stat value.
32
/// - an error value to represent a file system error.
33
/// - a placeholder with an invalid stat indicating a not yet initialized entry.
34
class CachedFileSystemEntry {
35
public:
36
  /// Default constructor creates an entry with an invalid stat.
37
599
  CachedFileSystemEntry() : MaybeStat(llvm::vfs::Status()) {}
38
39
21
  CachedFileSystemEntry(std::error_code Error) : MaybeStat(std::move(Error)) {}
40
41
  /// Create an entry that represents an opened source file with minimized or
42
  /// original contents.
43
  ///
44
  /// The filesystem opens the file even for `stat` calls open to avoid the
45
  /// issues with stat + open of minimized files that might lead to a
46
  /// mismatching size of the file. If file is not minimized, the full file is
47
  /// read and copied into memory to ensure that it's not memory mapped to avoid
48
  /// running out of file descriptors.
49
  static CachedFileSystemEntry createFileEntry(StringRef Filename,
50
                                               llvm::vfs::FileSystem &FS,
51
                                               bool Minimize = true);
52
53
  /// Create an entry that represents a directory on the filesystem.
54
  static CachedFileSystemEntry createDirectoryEntry(llvm::vfs::Status &&Stat);
55
56
  /// \returns True if the entry is valid.
57
1.19k
  bool isValid() const { return !MaybeStat || 
MaybeStat->isStatusKnown()1.18k
; }
58
59
  /// \returns True if the current entry points to a directory.
60
181
  bool isDirectory() const { return MaybeStat && 
MaybeStat->isDirectory()152
; }
61
62
  /// \returns The error or the file's contents.
63
179
  llvm::ErrorOr<StringRef> getContents() const {
64
179
    if (!MaybeStat)
65
29
      return MaybeStat.getError();
66
150
    assert(!MaybeStat->isDirectory() && "not a file");
67
150
    assert(isValid() && "not initialized");
68
150
    return StringRef(Contents);
69
150
  }
70
71
  /// \returns The error or the status of the entry.
72
359
  llvm::ErrorOr<llvm::vfs::Status> getStatus() const {
73
359
    assert(isValid() && "not initialized");
74
359
    return MaybeStat;
75
359
  }
76
77
  /// \returns the name of the file.
78
149
  StringRef getName() const {
79
149
    assert(isValid() && "not initialized");
80
149
    return MaybeStat->getName();
81
149
  }
82
83
  /// Return the mapping between location -> distance that is used to speed up
84
  /// the block skipping in the preprocessor.
85
189
  const PreprocessorSkippedRangeMapping &getPPSkippedRangeMapping() const {
86
189
    return PPSkippedRangeMapping;
87
189
  }
88
89
66
  CachedFileSystemEntry(CachedFileSystemEntry &&) = default;
90
234
  CachedFileSystemEntry &operator=(CachedFileSystemEntry &&) = default;
91
92
  CachedFileSystemEntry(const CachedFileSystemEntry &) = delete;
93
  CachedFileSystemEntry &operator=(const CachedFileSystemEntry &) = delete;
94
95
private:
96
  llvm::ErrorOr<llvm::vfs::Status> MaybeStat;
97
  // Store the contents in a small string to allow a
98
  // move from the small string for the minimized contents.
99
  // Note: small size of 1 allows us to store an empty string with an implicit
100
  // null terminator without any allocations.
101
  llvm::SmallString<1> Contents;
102
  PreprocessorSkippedRangeMapping PPSkippedRangeMapping;
103
};
104
105
/// This class is a shared cache, that caches the 'stat' and 'open' calls to the
106
/// underlying real file system.
107
///
108
/// It is sharded based on the hash of the key to reduce the lock contention for
109
/// the worker threads.
110
class DependencyScanningFilesystemSharedCache {
111
public:
112
  struct SharedFileSystemEntry {
113
    std::mutex ValueLock;
114
    CachedFileSystemEntry Value;
115
  };
116
117
  DependencyScanningFilesystemSharedCache();
118
119
  /// Returns a cache entry for the corresponding key.
120
  ///
121
  /// A new cache entry is created if the key is not in the cache. This is a
122
  /// thread safe call.
123
  SharedFileSystemEntry &get(StringRef Key);
124
125
private:
126
  struct CacheShard {
127
    std::mutex CacheLock;
128
    llvm::StringMap<SharedFileSystemEntry, llvm::BumpPtrAllocator> Cache;
129
  };
130
  std::unique_ptr<CacheShard[]> CacheShards;
131
  unsigned NumShards;
132
};
133
134
/// A virtual file system optimized for the dependency discovery.
135
///
136
/// It is primarily designed to work with source files whose contents was was
137
/// preprocessed to remove any tokens that are unlikely to affect the dependency
138
/// computation.
139
///
140
/// This is not a thread safe VFS. A single instance is meant to be used only in
141
/// one thread. Multiple instances are allowed to service multiple threads
142
/// running in parallel.
143
class DependencyScanningWorkerFilesystem : public llvm::vfs::ProxyFileSystem {
144
public:
145
  DependencyScanningWorkerFilesystem(
146
      DependencyScanningFilesystemSharedCache &SharedCache,
147
      IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
148
      ExcludedPreprocessorDirectiveSkipMapping *PPSkipMappings)
149
      : ProxyFileSystem(std::move(FS)), SharedCache(SharedCache),
150
43
        PPSkipMappings(PPSkipMappings) {}
151
152
  llvm::ErrorOr<llvm::vfs::Status> status(const Twine &Path) override;
153
  llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
154
  openFileForRead(const Twine &Path) override;
155
156
  /// The set of files that should not be minimized.
157
  llvm::StringSet<> IgnoredFiles;
158
159
private:
160
302
  void setCachedEntry(StringRef Filename, const CachedFileSystemEntry *Entry) {
161
302
    bool IsInserted = Cache.try_emplace(Filename, Entry).second;
162
302
    (void)IsInserted;
163
302
    assert(IsInserted && "local cache is updated more than once");
164
302
  }
165
166
628
  const CachedFileSystemEntry *getCachedEntry(StringRef Filename) {
167
628
    auto It = Cache.find(Filename);
168
628
    return It == Cache.end() ? 
nullptr539
:
It->getValue()89
;
169
628
  }
170
171
  llvm::ErrorOr<const CachedFileSystemEntry *>
172
  getOrCreateFileSystemEntry(const StringRef Filename);
173
174
  DependencyScanningFilesystemSharedCache &SharedCache;
175
  /// The local cache is used by the worker thread to cache file system queries
176
  /// locally instead of querying the global cache every time.
177
  llvm::StringMap<const CachedFileSystemEntry *, llvm::BumpPtrAllocator> Cache;
178
  /// The optional mapping structure which records information about the
179
  /// excluded conditional directive skip mappings that are used by the
180
  /// currently active preprocessor.
181
  ExcludedPreprocessorDirectiveSkipMapping *PPSkipMappings;
182
};
183
184
} // end namespace dependencies
185
} // end namespace tooling
186
} // end namespace clang
187
188
#endif // LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_FILESYSTEM_H