Differential D55455 Diff 179323 cfe/trunk/include/clang/Basic/FileSystemStatCache.h

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cfe/trunk/include/clang/Basic/FileSystemStatCache.h

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55	};	55	};
56		56
57	/// Abstract interface for introducing a FileManager cache for 'stat'	57	/// Abstract interface for introducing a FileManager cache for 'stat'
58	/// system calls, which is used by precompiled and pretokenized headers to	58	/// system calls, which is used by precompiled and pretokenized headers to
59	/// improve performance.	59	/// improve performance.
60	class FileSystemStatCache {	60	class FileSystemStatCache {
61	virtual void anchor();	61	virtual void anchor();
62		62
63	protected:
64	std::unique_ptr<FileSystemStatCache> NextStatCache;
65
66	public:	63	public:
67	virtual ~FileSystemStatCache() = default;	64	virtual ~FileSystemStatCache() = default;
68		65
69	enum LookupResult {	66	enum LookupResult {
70	/// We know the file exists and its cached stat data.	67	/// We know the file exists and its cached stat data.
71	CacheExists,	68	CacheExists,
72		69
73	/// We know that the file doesn't exist.	70	/// We know that the file doesn't exist.
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83	/// (not directories). If it is false this lookup should only return	80	/// (not directories). If it is false this lookup should only return
84	/// success for directories (not files). On a successful file lookup, the	81	/// success for directories (not files). On a successful file lookup, the
85	/// implementation can optionally fill in \p F with a valid \p File object and	82	/// implementation can optionally fill in \p F with a valid \p File object and
86	/// the client guarantees that it will close it.	83	/// the client guarantees that it will close it.
87	static bool get(StringRef Path, FileData &Data, bool isFile,	84	static bool get(StringRef Path, FileData &Data, bool isFile,
88	std::unique_ptr<llvm::vfs::File> *F,	85	std::unique_ptr<llvm::vfs::File> *F,
89	FileSystemStatCache *Cache, llvm::vfs::FileSystem &FS);	86	FileSystemStatCache *Cache, llvm::vfs::FileSystem &FS);
90		87
91	/// Sets the next stat call cache in the chain of stat caches.
92	/// Takes ownership of the given stat cache.
93	void setNextStatCache(std::unique_ptr<FileSystemStatCache> Cache) {
94	NextStatCache = std::move(Cache);
95	}
96
97	/// Retrieve the next stat call cache in the chain.
98	FileSystemStatCache *getNextStatCache() { return NextStatCache.get(); }
99
100	/// Retrieve the next stat call cache in the chain, transferring
101	/// ownership of this cache (and, transitively, all of the remaining caches)
102	/// to the caller.
103	std::unique_ptr<FileSystemStatCache> takeNextStatCache() {
104	return std::move(NextStatCache);
105	}
106
107	protected:	88	protected:
108	// FIXME: The pointer here is a non-owning/optional reference to the	89	// FIXME: The pointer here is a non-owning/optional reference to the
109	// unique_ptr. Optional<unique_ptr<vfs::File>&> might be nicer, but	90	// unique_ptr. Optional<unique_ptr<vfs::File>&> might be nicer, but
110	// Optional needs some work to support references so this isn't possible yet.	91	// Optional needs some work to support references so this isn't possible yet.
111	virtual LookupResult getStat(StringRef Path, FileData &Data, bool isFile,	92	virtual LookupResult getStat(StringRef Path, FileData &Data, bool isFile,
112	std::unique_ptr<llvm::vfs::File> *F,	93	std::unique_ptr<llvm::vfs::File> *F,
113	llvm::vfs::FileSystem &FS) = 0;	94	llvm::vfs::FileSystem &FS) = 0;
114
115	LookupResult statChained(StringRef Path, FileData &Data, bool isFile,
116	std::unique_ptr<llvm::vfs::File> *F,
117	llvm::vfs::FileSystem &FS) {
118	if (FileSystemStatCache *Next = getNextStatCache())
119	return Next->getStat(Path, Data, isFile, F, FS);
120
121	// If we hit the end of the list of stat caches to try, just compute and
122	// return it without a cache.
123	return get(Path, Data, isFile, F, nullptr, FS) ? CacheMissing : CacheExists;
124	}
125	};	95	};
126		96
127	/// A stat "cache" that can be used by FileManager to keep	97	/// A stat "cache" that can be used by FileManager to keep
128	/// track of the results of stat() calls that occur throughout the	98	/// track of the results of stat() calls that occur throughout the
129	/// execution of the front end.	99	/// execution of the front end.
130	class MemorizeStatCalls : public FileSystemStatCache {	100	class MemorizeStatCalls : public FileSystemStatCache {
131	public:	101	public:
132	/// The set of stat() calls that have been seen.	102	/// The set of stat() calls that have been seen.
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