scoped_flock.h revision 833a48501d560c9fa7fc78ef619888138c2d374f
1d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath/* 2d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * Copyright (C) 2011 The Android Open Source Project 3d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * 4d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * Licensed under the Apache License, Version 2.0 (the "License"); 5d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * you may not use this file except in compliance with the License. 6d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * You may obtain a copy of the License at 7d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * 8d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * http://www.apache.org/licenses/LICENSE-2.0 9d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * 10d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * Unless required by applicable law or agreed to in writing, software 11d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * distributed under the License is distributed on an "AS IS" BASIS, 12d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * See the License for the specific language governing permissions and 14d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath * limitations under the License. 15d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath */ 16d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 17d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#ifndef ART_RUNTIME_BASE_SCOPED_FLOCK_H_ 18d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#define ART_RUNTIME_BASE_SCOPED_FLOCK_H_ 19d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 20d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#include <memory> 21d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#include <string> 22d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 23d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#include "base/macros.h" 24d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#include "os.h" 25d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 26d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamathnamespace art { 27d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 28d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamathclass ScopedFlock { 29d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath public: 30d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath ScopedFlock(); 31d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 32d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // Attempts to acquire an exclusive file lock (see flock(2)) on the file 33d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // at filename, and blocks until it can do so. 34d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // 35d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // Returns true if the lock could be acquired, or false if an error 36d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // occurred. It is an error if the file does not exist, or if its inode 37d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // changed (usually due to a new file being created at the same path) 38d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // between attempts to lock it. 39d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath bool Init(const char* filename, std::string* error_msg); 40d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 41d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // Returns the (locked) file associated with this instance. 42d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath File* GetFile(); 43833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe 44833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe // Returns whether a file is held. 45833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe bool HasFile(); 46833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe 47d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath ~ScopedFlock(); 48d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath private: 49d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath std::unique_ptr<File> file_; 50d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath DISALLOW_COPY_AND_ASSIGN(ScopedFlock); 51d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath}; 52d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 53d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath} // namespace art 54d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 55d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#endif // ART_RUNTIME_BASE_SCOPED_FLOCK_H_ 56