mirror of https://github.com/microsoft/clang.git
132 lines
4.6 KiB
C++
132 lines
4.6 KiB
C++
//===--- 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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/// \brief 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/Support/FileSystem.h"
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#include <memory>
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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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}
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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;
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time_t ModTime;
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llvm::sys::fs::UniqueID UniqueID;
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bool IsDirectory;
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bool IsNamedPipe;
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bool InPCH;
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bool IsVFSMapped; // FIXME: remove this when files support multiple names
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FileData()
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: Size(0), ModTime(0), IsDirectory(false), IsNamedPipe(false),
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InPCH(false), IsVFSMapped(false) {}
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};
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/// \brief 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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virtual ~FileSystemStatCache() {}
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enum LookupResult {
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CacheExists, ///< We know the file exists and its cached stat data.
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CacheMissing ///< We know that the file doesn't exist.
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};
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/// \brief 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(const char *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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/// \brief 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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/// \brief Retrieve the next stat call cache in the chain.
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FileSystemStatCache *getNextStatCache() { return NextStatCache.get(); }
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/// \brief 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(const char *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(const char *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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/// \brief 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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/// \brief The set of stat() calls that have been seen.
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llvm::StringMap<FileData, llvm::BumpPtrAllocator> StatCalls;
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typedef llvm::StringMap<FileData, llvm::BumpPtrAllocator>::const_iterator
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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(const char *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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} // end namespace clang
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#endif
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