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/*
* Copyright (C) 2015 by Multi-Tech Systems
*
* This file is part of libmts-io.
*
* libmts-io is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* libmts-io is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with libmts-io. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*!
\file MTS_IO_LockFile.cpp
\brief A brief description
\date Oct 8, 2014
\author sgodinez
A more elaborate description
*/
#include <mts/MTS_IO_LockFile.h>
#include <mts/MTS_Timer.h>
#include <sys/file.h>
#include <unistd.h>
using namespace MTS::IO;
LockFile::LockFile(const std::string& sFile)
: m_sFile(sFile)
, m_iLockFd(-1)
, m_iLockErr(-1)
{
}
LockFile::~LockFile()
{
unlock();
}
bool LockFile::lock(uint32_t attemptMillis)
{
if (isLocked()) {
return true;
}
m_iLockFd = ::open(m_sFile.c_str(), O_CREAT | O_RDWR, 0644);
if (m_iLockFd >= 0) {
MTS::Timer timer;
timer.start();
while (timer.getMillis() < attemptMillis) {
m_iLockErr = ::flock(m_iLockFd, LOCK_EX | LOCK_NB);
if (m_iLockErr == 0) {
return true;
} else if (errno != EWOULDBLOCK) {
break;
}
::usleep(((rand() % 10) + 1) * 100000); //Sleep from 100ms to 1 Second
}
::close(m_iLockFd);
}
m_iLockFd = -1;
return false;
}
void LockFile::unlock()
{
::flock(m_iLockFd, LOCK_UN);
::close(m_iLockFd);
m_iLockFd = -1;
m_iLockErr = -1;
}
bool LockFile::isLocked()
{
return m_iLockErr == 0;
}
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