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//===--- FileSystemStatCache.h - Caching for 'stat' calls -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the FileSystemStatCache interface.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_FILESYSTEMSTATCACHE_H
#define LLVM_CLANG_FILESYSTEMSTATCACHE_H
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/StringMap.h"
#include <sys/types.h>
#include <sys/stat.h>
namespace clang {
/// \brief Abstract interface for introducing a FileManager cache for 'stat'
/// system calls, which is used by precompiled and pretokenized headers to
/// improve performance.
class FileSystemStatCache {
protected:
llvm::OwningPtr<FileSystemStatCache> NextStatCache;
public:
virtual ~FileSystemStatCache() {}
enum LookupResult {
CacheHitExists, //< We know the file exists and its cached stat data.
CacheHitMissing, //< We know that the file doesn't exist.
CacheMiss //< We don't know anything about the file.
};
virtual LookupResult getStat(const char *Path, struct stat &StatBuf) = 0;
/// \brief Sets the next stat call cache in the chain of stat caches.
/// Takes ownership of the given stat cache.
void setNextStatCache(FileSystemStatCache *Cache) {
NextStatCache.reset(Cache);
}
/// \brief Retrieve the next stat call cache in the chain.
FileSystemStatCache *getNextStatCache() { return NextStatCache.get(); }
/// \brief Retrieve the next stat call cache in the chain, transferring
/// ownership of this cache (and, transitively, all of the remaining caches)
/// to the caller.
FileSystemStatCache *takeNextStatCache() { return NextStatCache.take(); }
protected:
LookupResult statChained(const char *Path, struct stat &StatBuf) {
if (FileSystemStatCache *Next = getNextStatCache())
return Next->getStat(Path, StatBuf);
return CacheMiss;
}
};
/// \brief A stat "cache" that can be used by FileManager to keep
/// track of the results of stat() calls that occur throughout the
/// execution of the front end.
class MemorizeStatCalls : public FileSystemStatCache {
public:
/// \brief The result of a stat() call.
///
/// The first member is the result of calling stat(). If stat()
/// found something, the second member is a copy of the stat
/// structure.
typedef std::pair<int, struct stat> StatResult;
/// \brief The set of stat() calls that have been
llvm::StringMap<StatResult, llvm::BumpPtrAllocator> StatCalls;
typedef llvm::StringMap<StatResult, llvm::BumpPtrAllocator>::const_iterator
iterator;
iterator begin() const { return StatCalls.begin(); }
iterator end() const { return StatCalls.end(); }
virtual LookupResult getStat(const char *Path, struct stat &StatBuf);
};
} // end namespace clang
#endif
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