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#ifndef _sys_LockFile_h
#define _sys_LockFile_h
/*
*
* Copyright (c) 2008 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <string>
#include "IntegerTypes.h"
namespace qpid {
namespace sys {
class LockFilePrivate;
/**
* @class LockFile
*
* LockFile represents a locked file suitable for a coarse-grain system
* lock. For example, the broker uses this to ensure that only one broker
* runs. A common usage idiom is to store the current "owner" process ID
* in the lock file - if the lock file exists, but the stored process ID
* doesn't, the old owner has probably died without cleaning up the lock
* file.
*/
class LockFile : private boost::noncopyable
{
boost::shared_ptr<LockFilePrivate> impl;
std::string path;
bool created;
public:
LockFile(const std::string& path_, bool create);
~LockFile();
/**
* Read the process ID from the lock file. This method assumes that
* if there is a process ID in the file, it was written there by
* writePid(); thus, it's at the start of the file.
*
* Throws an exception if there is an error reading the file.
*
* @returns The stored process ID. No validity check is done on it.
*/
pid_t readPid(void) const;
/**
* Write the current process's ID to the lock file. It's written at
* the start of the file and will overwrite any other content that
* may be in the file.
*
* Throws an exception if the write fails.
*/
void writePid(void);
};
}} /* namespace qpid::sys */
#endif /*!_sys_LockFile_h*/
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