| //===- FileSystemStatCache.cpp - Caching for 'stat' calls -----------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the FileSystemStatCache interface. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Basic/FileSystemStatCache.h" |
| #include "llvm/Support/Chrono.h" |
| #include "llvm/Support/ErrorOr.h" |
| #include "llvm/Support/Path.h" |
| #include "llvm/Support/VirtualFileSystem.h" |
| #include <utility> |
| |
| using namespace clang; |
| |
| 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 isFile is true, then this lookup should only return success for files |
| /// (not directories). If it is false 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. |
| std::error_code |
| FileSystemStatCache::get(StringRef Path, llvm::vfs::Status &Status, |
| bool isFile, std::unique_ptr<llvm::vfs::File> *F, |
| FileSystemStatCache *Cache, |
| llvm::vfs::FileSystem &FS) { |
| bool isForDir = !isFile; |
| std::error_code RetCode; |
| |
| // If we have a cache, use it to resolve the stat query. |
| if (Cache) |
| RetCode = Cache->getStat(Path, Status, isFile, F, FS); |
| else if (isForDir || !F) { |
| // If this is a directory or a file descriptor is not needed and we have |
| // no cache, just go to the file system. |
| llvm::ErrorOr<llvm::vfs::Status> StatusOrErr = FS.status(Path); |
| if (!StatusOrErr) { |
| RetCode = StatusOrErr.getError(); |
| } else { |
| Status = *StatusOrErr; |
| } |
| } 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. |
| auto OwnedFile = FS.openFileForRead(Path); |
| |
| if (!OwnedFile) { |
| // If the open fails, our "stat" fails. |
| RetCode = OwnedFile.getError(); |
| } 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. |
| llvm::ErrorOr<llvm::vfs::Status> StatusOrErr = (*OwnedFile)->status(); |
| if (StatusOrErr) { |
| Status = *StatusOrErr; |
| *F = std::move(*OwnedFile); |
| } else { |
| // fstat rarely fails. If it does, claim the initial open didn't |
| // succeed. |
| *F = nullptr; |
| RetCode = StatusOrErr.getError(); |
| } |
| } |
| } |
| |
| // If the path doesn't exist, return failure. |
| if (RetCode) |
| return RetCode; |
| |
| // If the path exists, make sure that its "directoryness" matches the clients |
| // demands. |
| if (Status.isDirectory() != isForDir) { |
| // If not, close the file if opened. |
| if (F) |
| *F = nullptr; |
| return std::make_error_code( |
| Status.isDirectory() ? |
| std::errc::is_a_directory : std::errc::not_a_directory); |
| } |
| |
| return std::error_code(); |
| } |
| |
| std::error_code |
| MemorizeStatCalls::getStat(StringRef Path, llvm::vfs::Status &Status, |
| bool isFile, |
| std::unique_ptr<llvm::vfs::File> *F, |
| llvm::vfs::FileSystem &FS) { |
| auto err = get(Path, Status, isFile, F, nullptr, FS); |
| if (err) { |
| // 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). |
| return err; |
| } |
| |
| // Cache file 'stat' results and directories with absolutely paths. |
| if (!Status.isDirectory() || llvm::sys::path::is_absolute(Path)) |
| StatCalls[Path] = Status; |
| |
| return std::error_code(); |
| } |