Coverage Report

Created: 2018-09-19 20:53

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/tools/clang/include/clang/Basic/FileSystemStatCache.h
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//===- FileSystemStatCache.h - Caching for 'stat' calls ---------*- C++ -*-===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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/// \file
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/// Defines the FileSystemStatCache interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H
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#define LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H
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#include "clang/Basic/LLVM.h"
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/FileSystem.h"
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#include <cstdint>
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#include <ctime>
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#include <memory>
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#include <string>
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#include <utility>
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namespace clang {
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namespace vfs {
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class File;
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class FileSystem;
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} // namespace vfs
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// FIXME: should probably replace this with vfs::Status
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struct FileData {
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  std::string Name;
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  uint64_t Size = 0;
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  time_t ModTime = 0;
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  llvm::sys::fs::UniqueID UniqueID;
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  bool IsDirectory = false;
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  bool IsNamedPipe = false;
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  bool InPCH = false;
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  // FIXME: remove this when files support multiple names
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  bool IsVFSMapped = false;
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  FileData() = default;
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};
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/// Abstract interface for introducing a FileManager cache for 'stat'
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/// system calls, which is used by precompiled and pretokenized headers to
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/// improve performance.
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class FileSystemStatCache {
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  virtual void anchor();
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protected:
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  std::unique_ptr<FileSystemStatCache> NextStatCache;
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public:
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0
  virtual ~FileSystemStatCache() = default;
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  enum LookupResult {
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    /// We know the file exists and its cached stat data.
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    CacheExists,
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    /// We know that the file doesn't exist.
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    CacheMissing
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  };
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  /// Get the 'stat' information for the specified path, using the cache
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  /// to accelerate it if possible.
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  ///
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  /// \returns \c true if the path does not exist or \c false if it exists.
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  ///
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  /// If isFile is true, then this lookup should only return success for files
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  /// (not directories).  If it is false this lookup should only return
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  /// success for directories (not files).  On a successful file lookup, the
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  /// implementation can optionally fill in \p F with a valid \p File object and
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  /// the client guarantees that it will close it.
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  static bool get(StringRef Path, FileData &Data, bool isFile,
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                  std::unique_ptr<vfs::File> *F, FileSystemStatCache *Cache,
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                  vfs::FileSystem &FS);
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  /// Sets the next stat call cache in the chain of stat caches.
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  /// Takes ownership of the given stat cache.
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  void setNextStatCache(std::unique_ptr<FileSystemStatCache> Cache) {
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    NextStatCache = std::move(Cache);
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  }
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  /// Retrieve the next stat call cache in the chain.
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  FileSystemStatCache *getNextStatCache() { return NextStatCache.get(); }
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  /// Retrieve the next stat call cache in the chain, transferring
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  /// ownership of this cache (and, transitively, all of the remaining caches)
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  /// to the caller.
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  std::unique_ptr<FileSystemStatCache> takeNextStatCache() {
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    return std::move(NextStatCache);
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  }
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protected:
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  // FIXME: The pointer here is a non-owning/optional reference to the
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  // unique_ptr. Optional<unique_ptr<vfs::File>&> might be nicer, but
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  // Optional needs some work to support references so this isn't possible yet.
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  virtual LookupResult getStat(StringRef Path, FileData &Data, bool isFile,
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                               std::unique_ptr<vfs::File> *F,
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                               vfs::FileSystem &FS) = 0;
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  LookupResult statChained(StringRef Path, FileData &Data, bool isFile,
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                           std::unique_ptr<vfs::File> *F, vfs::FileSystem &FS) {
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    if (FileSystemStatCache *Next = getNextStatCache())
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      return Next->getStat(Path, Data, isFile, F, FS);
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    // If we hit the end of the list of stat caches to try, just compute and
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    // return it without a cache.
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    return get(Path, Data, isFile, F, nullptr, FS) ? CacheMissing : CacheExists;
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  }
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};
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/// A stat "cache" that can be used by FileManager to keep
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/// track of the results of stat() calls that occur throughout the
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/// execution of the front end.
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class MemorizeStatCalls : public FileSystemStatCache {
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public:
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  /// The set of stat() calls that have been seen.
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  llvm::StringMap<FileData, llvm::BumpPtrAllocator> StatCalls;
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  using iterator =
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      llvm::StringMap<FileData, llvm::BumpPtrAllocator>::const_iterator;
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  iterator begin() const { return StatCalls.begin(); }
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  iterator end() const { return StatCalls.end(); }
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  LookupResult getStat(StringRef Path, FileData &Data, bool isFile,
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                       std::unique_ptr<vfs::File> *F,
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                       vfs::FileSystem &FS) override;
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};
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} // namespace clang
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#endif // LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H