diff options
Diffstat (limited to 'contrib/llvm/tools/clang/lib/Basic/FileSystemStatCache.cpp')
-rw-r--r-- | contrib/llvm/tools/clang/lib/Basic/FileSystemStatCache.cpp | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/Basic/FileSystemStatCache.cpp b/contrib/llvm/tools/clang/lib/Basic/FileSystemStatCache.cpp new file mode 100644 index 0000000..875d397 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/Basic/FileSystemStatCache.cpp @@ -0,0 +1,122 @@ +//===--- FileSystemStatCache.cpp - Caching for 'stat' calls ---------------===// +// +// 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. +// +//===----------------------------------------------------------------------===// + +#include "clang/Basic/FileSystemStatCache.h" +#include "llvm/Support/Path.h" +#include <fcntl.h> + +// FIXME: This is terrible, we need this for ::close. +#if !defined(_MSC_VER) && !defined(__MINGW32__) +#include <unistd.h> +#include <sys/uio.h> +#else +#include <io.h> +#endif +using namespace clang; + +#if defined(_MSC_VER) +#define S_ISDIR(s) ((_S_IFDIR & s) !=0) +#endif + +void FileSystemStatCache::anchor() { } + +/// FileSystemStatCache::get - Get the 'stat' information for the specified +/// path, using the cache to accelerate it if possible. This returns true if +/// the path does not exist or false if it exists. +/// +/// If FileDescriptor is non-null, then this lookup should only return success +/// for files (not directories). If it is null this lookup should only return +/// success for directories (not files). On a successful file lookup, the +/// implementation can optionally fill in FileDescriptor with a valid +/// descriptor and the client guarantees that it will close it. +bool FileSystemStatCache::get(const char *Path, struct stat &StatBuf, + int *FileDescriptor, FileSystemStatCache *Cache) { + LookupResult R; + bool isForDir = FileDescriptor == 0; + + // If we have a cache, use it to resolve the stat query. + if (Cache) + R = Cache->getStat(Path, StatBuf, FileDescriptor); + else if (isForDir) { + // If this is a directory and we have no cache, just go to the file system. + R = ::stat(Path, &StatBuf) != 0 ? CacheMissing : CacheExists; + } else { + // Otherwise, we have to go to the filesystem. We can always just use + // 'stat' here, but (for files) the client is asking whether the file exists + // because it wants to turn around and *open* it. It is more efficient to + // do "open+fstat" on success than it is to do "stat+open". + // + // Because of this, check to see if the file exists with 'open'. If the + // open succeeds, use fstat to get the stat info. + int OpenFlags = O_RDONLY; +#ifdef O_BINARY + OpenFlags |= O_BINARY; // Open input file in binary mode on win32. +#endif + *FileDescriptor = ::open(Path, OpenFlags); + + if (*FileDescriptor == -1) { + // If the open fails, our "stat" fails. + R = CacheMissing; + } else { + // Otherwise, the open succeeded. Do an fstat to get the information + // about the file. We'll end up returning the open file descriptor to the + // client to do what they please with it. + if (::fstat(*FileDescriptor, &StatBuf) == 0) + R = CacheExists; + else { + // fstat rarely fails. If it does, claim the initial open didn't + // succeed. + R = CacheMissing; + ::close(*FileDescriptor); + *FileDescriptor = -1; + } + } + } + + // If the path doesn't exist, return failure. + if (R == CacheMissing) return true; + + // If the path exists, make sure that its "directoryness" matches the clients + // demands. + if (S_ISDIR(StatBuf.st_mode) != isForDir) { + // If not, close the file if opened. + if (FileDescriptor && *FileDescriptor != -1) { + ::close(*FileDescriptor); + *FileDescriptor = -1; + } + + return true; + } + + return false; +} + + +MemorizeStatCalls::LookupResult +MemorizeStatCalls::getStat(const char *Path, struct stat &StatBuf, + int *FileDescriptor) { + LookupResult Result = statChained(Path, StatBuf, FileDescriptor); + + // Do not cache failed stats, it is easy to construct common inconsistent + // situations if we do, and they are not important for PCH performance (which + // currently only needs the stats to construct the initial FileManager + // entries). + if (Result == CacheMissing) + return Result; + + // Cache file 'stat' results and directories with absolutely paths. + if (!S_ISDIR(StatBuf.st_mode) || llvm::sys::path::is_absolute(Path)) + StatCalls[Path] = StatBuf; + + return Result; +} |