139 lines
4.8 KiB
C++
139 lines
4.8 KiB
C++
//===--- FileSystemStatCache.cpp - Caching for 'stat' calls ---------------===//
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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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// This file defines the FileSystemStatCache interface.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Basic/FileSystemStatCache.h"
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#include "clang/Basic/VirtualFileSystem.h"
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#include "llvm/Support/Path.h"
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// FIXME: This is terrible, we need this for ::close.
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#if !defined(_MSC_VER) && !defined(__MINGW32__)
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#include <unistd.h>
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#include <sys/uio.h>
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#else
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#include <io.h>
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#endif
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using namespace clang;
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#if defined(_MSC_VER)
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#define S_ISDIR(s) ((_S_IFDIR & s) !=0)
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#endif
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void FileSystemStatCache::anchor() { }
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static void copyStatusToFileData(const vfs::Status &Status,
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FileData &Data) {
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Data.Name = Status.getName();
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Data.Size = Status.getSize();
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Data.ModTime = Status.getLastModificationTime().toEpochTime();
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Data.UniqueID = Status.getUniqueID();
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Data.IsDirectory = Status.isDirectory();
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Data.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
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Data.InPCH = false;
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Data.IsVFSMapped = Status.IsVFSMapped;
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}
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/// FileSystemStatCache::get - Get the 'stat' information for the specified
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/// path, using the cache to accelerate it if possible. This returns true if
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/// the path does not exist or 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 FileDescriptor with a valid
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/// descriptor and the client guarantees that it will close it.
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bool FileSystemStatCache::get(const char *Path, FileData &Data, bool isFile,
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std::unique_ptr<vfs::File> *F,
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FileSystemStatCache *Cache, vfs::FileSystem &FS) {
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LookupResult R;
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bool isForDir = !isFile;
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// If we have a cache, use it to resolve the stat query.
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if (Cache)
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R = Cache->getStat(Path, Data, isFile, F, FS);
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else if (isForDir || !F) {
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// If this is a directory or a file descriptor is not needed and we have
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// no cache, just go to the file system.
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llvm::ErrorOr<vfs::Status> Status = FS.status(Path);
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if (!Status) {
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R = CacheMissing;
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} else {
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R = CacheExists;
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copyStatusToFileData(*Status, Data);
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}
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} else {
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// Otherwise, we have to go to the filesystem. We can always just use
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// 'stat' here, but (for files) the client is asking whether the file exists
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// because it wants to turn around and *open* it. It is more efficient to
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// do "open+fstat" on success than it is to do "stat+open".
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//
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// Because of this, check to see if the file exists with 'open'. If the
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// open succeeds, use fstat to get the stat info.
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std::unique_ptr<vfs::File> OwnedFile;
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std::error_code EC = FS.openFileForRead(Path, OwnedFile);
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if (EC) {
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// If the open fails, our "stat" fails.
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R = CacheMissing;
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} else {
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// Otherwise, the open succeeded. Do an fstat to get the information
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// about the file. We'll end up returning the open file descriptor to the
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// client to do what they please with it.
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llvm::ErrorOr<vfs::Status> Status = OwnedFile->status();
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if (Status) {
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R = CacheExists;
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copyStatusToFileData(*Status, Data);
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*F = std::move(OwnedFile);
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} else {
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// fstat rarely fails. If it does, claim the initial open didn't
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// succeed.
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R = CacheMissing;
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*F = nullptr;
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}
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}
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}
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// If the path doesn't exist, return failure.
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if (R == CacheMissing) return true;
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// If the path exists, make sure that its "directoryness" matches the clients
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// demands.
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if (Data.IsDirectory != isForDir) {
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// If not, close the file if opened.
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if (F)
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*F = nullptr;
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return true;
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}
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return false;
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}
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MemorizeStatCalls::LookupResult
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MemorizeStatCalls::getStat(const char *Path, FileData &Data, bool isFile,
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std::unique_ptr<vfs::File> *F, vfs::FileSystem &FS) {
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LookupResult Result = statChained(Path, Data, isFile, F, FS);
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// Do not cache failed stats, it is easy to construct common inconsistent
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// situations if we do, and they are not important for PCH performance (which
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// currently only needs the stats to construct the initial FileManager
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// entries).
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if (Result == CacheMissing)
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return Result;
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// Cache file 'stat' results and directories with absolutely paths.
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if (!Data.IsDirectory || llvm::sys::path::is_absolute(Path))
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StatCalls[Path] = Data;
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return Result;
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}
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