1 //===--- FileSystemStatCache.h - Caching for 'stat' calls -------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 /// 10 /// \file 11 /// \brief Defines the FileSystemStatCache interface. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_CLANG_FILESYSTEMSTATCACHE_H 16 #define LLVM_CLANG_FILESYSTEMSTATCACHE_H 17 18 #include "clang/Basic/LLVM.h" 19 #include "llvm/ADT/OwningPtr.h" 20 #include "llvm/ADT/StringMap.h" 21 #include "llvm/Support/FileSystem.h" 22 #include <sys/stat.h> 23 #include <sys/types.h> 24 25 namespace clang { 26 27 struct FileData { 28 uint64_t Size; 29 time_t ModTime; 30 llvm::sys::fs::UniqueID UniqueID; 31 bool IsDirectory; 32 bool IsNamedPipe; 33 bool InPCH; 34 }; 35 36 /// \brief Abstract interface for introducing a FileManager cache for 'stat' 37 /// system calls, which is used by precompiled and pretokenized headers to 38 /// improve performance. 39 class FileSystemStatCache { 40 virtual void anchor(); 41 protected: 42 OwningPtr<FileSystemStatCache> NextStatCache; 43 44 public: 45 virtual ~FileSystemStatCache() {} 46 47 enum LookupResult { 48 CacheExists, ///< We know the file exists and its cached stat data. 49 CacheMissing ///< We know that the file doesn't exist. 50 }; 51 52 /// \brief Get the 'stat' information for the specified path, using the cache 53 /// to accelerate it if possible. 54 /// 55 /// \returns \c true if the path does not exist or \c false if it exists. 56 /// 57 /// If isFile is true, then this lookup should only return success for files 58 /// (not directories). If it is false this lookup should only return 59 /// success for directories (not files). On a successful file lookup, the 60 /// implementation can optionally fill in FileDescriptor with a valid 61 /// descriptor and the client guarantees that it will close it. 62 static bool get(const char *Path, FileData &Data, bool isFile, 63 int *FileDescriptor, FileSystemStatCache *Cache); 64 65 /// \brief Sets the next stat call cache in the chain of stat caches. 66 /// Takes ownership of the given stat cache. 67 void setNextStatCache(FileSystemStatCache *Cache) { 68 NextStatCache.reset(Cache); 69 } 70 71 /// \brief Retrieve the next stat call cache in the chain. 72 FileSystemStatCache *getNextStatCache() { return NextStatCache.get(); } 73 74 /// \brief Retrieve the next stat call cache in the chain, transferring 75 /// ownership of this cache (and, transitively, all of the remaining caches) 76 /// to the caller. 77 FileSystemStatCache *takeNextStatCache() { return NextStatCache.take(); } 78 79 protected: 80 virtual LookupResult getStat(const char *Path, FileData &Data, bool isFile, 81 int *FileDescriptor) = 0; 82 83 LookupResult statChained(const char *Path, FileData &Data, bool isFile, 84 int *FileDescriptor) { 85 if (FileSystemStatCache *Next = getNextStatCache()) 86 return Next->getStat(Path, Data, isFile, FileDescriptor); 87 88 // If we hit the end of the list of stat caches to try, just compute and 89 // return it without a cache. 90 return get(Path, Data, isFile, FileDescriptor, 0) ? CacheMissing 91 : CacheExists; 92 } 93 }; 94 95 /// \brief A stat "cache" that can be used by FileManager to keep 96 /// track of the results of stat() calls that occur throughout the 97 /// execution of the front end. 98 class MemorizeStatCalls : public FileSystemStatCache { 99 public: 100 /// \brief The set of stat() calls that have been seen. 101 llvm::StringMap<FileData, llvm::BumpPtrAllocator> StatCalls; 102 103 typedef llvm::StringMap<FileData, llvm::BumpPtrAllocator>::const_iterator 104 iterator; 105 106 iterator begin() const { return StatCalls.begin(); } 107 iterator end() const { return StatCalls.end(); } 108 109 virtual LookupResult getStat(const char *Path, FileData &Data, bool isFile, 110 int *FileDescriptor); 111 }; 112 113 } // end namespace clang 114 115 #endif 116
