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 // 35877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // Returns true if the lock could be acquired, or false if an error occurred. 36877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // It is an error if its inode changed (usually due to a new file being 37877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // created at the same path) between attempts to lock it. In blocking mode, 38877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // locking will be retried if the file changed. In non-blocking mode, false 39877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // is returned and no attempt is made to re-acquire the lock. 40877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // 41877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // The file is opened with the provided flags. 42877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle bool Init(const char* filename, int flags, bool block, std::string* error_msg); 43877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle // Calls Init(filename, O_CREAT | O_RDWR, true, errror_msg) 44d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath bool Init(const char* filename, std::string* error_msg); 45a59dd80f9f48cb750d329d4d4af2d99d72b484d1Alex Light // Attempt to acquire an exclusive file lock (see flock(2)) on 'file'. 46a59dd80f9f48cb750d329d4d4af2d99d72b484d1Alex Light // Returns true if the lock could be acquired or false if an error 47a59dd80f9f48cb750d329d4d4af2d99d72b484d1Alex Light // occured. 48a59dd80f9f48cb750d329d4d4af2d99d72b484d1Alex Light bool Init(File* file, std::string* error_msg); 49d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 50d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath // Returns the (locked) file associated with this instance. 51877fd963548a3175665bfef25b0d24bc0e5a0135Calin Juravle File* GetFile() const; 52833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe 53833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe // Returns whether a file is held. 54833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe bool HasFile(); 55833a48501d560c9fa7fc78ef619888138c2d374fAndreas Gampe 56d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath ~ScopedFlock(); 57a59dd80f9f48cb750d329d4d4af2d99d72b484d1Alex Light 58d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath private: 59d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath std::unique_ptr<File> file_; 60d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath DISALLOW_COPY_AND_ASSIGN(ScopedFlock); 61d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath}; 62d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 63d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath} // namespace art 64d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath 65d1c606f280797be81e2592c483869a6ec836a9f3Narayan Kamath#endif // ART_RUNTIME_BASE_SCOPED_FLOCK_H_ 66