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/**
* Copyright (C) 2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
#include "mongo/platform/basic.h"
#include "mongo/db/storage/storage_engine_lock_file.h"
#include <boost/filesystem.hpp>
#include <fcntl.h>
#include <ostream>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <sstream>
#include "mongo/db/storage/paths.h"
#include "mongo/platform/process_id.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
namespace {
const std::string kLockFileBasename = "mongod.lock";
} // namespace
class StorageEngineLockFile::LockFileHandle {
public:
static const int kInvalidFd = -1;
LockFileHandle() : _fd(kInvalidFd) {}
bool isValid() const {
return _fd != kInvalidFd;
}
void clear() {
_fd = kInvalidFd;
}
int _fd;
};
StorageEngineLockFile::StorageEngineLockFile(const std::string& dbpath)
: _dbpath(dbpath),
_filespec((boost::filesystem::path(_dbpath) / kLockFileBasename).string()),
_uncleanShutdown(boost::filesystem::exists(_filespec) &&
boost::filesystem::file_size(_filespec) > 0),
_lockFileHandle(new LockFileHandle()) {}
StorageEngineLockFile::~StorageEngineLockFile() {}
std::string StorageEngineLockFile::getFilespec() const {
return _filespec;
}
bool StorageEngineLockFile::createdByUncleanShutdown() const {
return _uncleanShutdown;
}
Status StorageEngineLockFile::open() {
try {
if (!boost::filesystem::exists(_dbpath)) {
return Status(ErrorCodes::NonExistentPath,
str::stream() << "Data directory " << _dbpath << " not found.");
}
} catch (const std::exception& ex) {
return Status(ErrorCodes::UnknownError,
str::stream() << "Unable to check existence of data directory " << _dbpath
<< ": " << ex.what());
}
// Use file permissions 644
int lockFile =
::open(_filespec.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (lockFile < 0) {
int errorcode = errno;
return Status(ErrorCodes::DBPathInUse,
str::stream() << "Unable to create/open lock file: " << _filespec << ' '
<< errnoWithDescription(errorcode)
<< " Is a mongod instance already running?");
}
#if !defined(__sun)
int ret = ::flock(lockFile, LOCK_EX | LOCK_NB);
#else
struct flock fileLockInfo = {0};
fileLockInfo.l_type = F_WRLCK;
fileLockInfo.l_whence = SEEK_SET;
int ret = ::fcntl(lockFile, F_SETLK, &fileLockInfo);
#endif // !defined(__sun)
if (ret != 0) {
int errorcode = errno;
::close(lockFile);
return Status(ErrorCodes::DBPathInUse,
str::stream() << "Unable to lock file: " << _filespec << ' '
<< errnoWithDescription(errorcode)
<< ". Is a mongod instance already running?");
}
_lockFileHandle->_fd = lockFile;
return Status::OK();
}
void StorageEngineLockFile::close() {
if (!_lockFileHandle->isValid()) {
return;
}
::close(_lockFileHandle->_fd);
_lockFileHandle->clear();
}
Status StorageEngineLockFile::writePid() {
if (!_lockFileHandle->isValid()) {
return Status(ErrorCodes::FileNotOpen,
str::stream() << "Unable to write process ID to " << _filespec
<< " because file has not been opened.");
}
if (::ftruncate(_lockFileHandle->_fd, 0)) {
int errorcode = errno;
return Status(ErrorCodes::FileStreamFailed,
str::stream() << "Unable to write process id to file (ftruncate failed): "
<< _filespec << ' ' << errnoWithDescription(errorcode));
}
ProcessId pid = ProcessId::getCurrent();
std::stringstream ss;
ss << pid << std::endl;
std::string pidStr = ss.str();
int bytesWritten = ::write(_lockFileHandle->_fd, pidStr.c_str(), pidStr.size());
if (bytesWritten < 0) {
int errorcode = errno;
return Status(ErrorCodes::FileStreamFailed,
str::stream() << "Unable to write process id " << pid.toString()
<< " to file: " << _filespec << ' '
<< errnoWithDescription(errorcode));
} else if (bytesWritten == 0) {
return Status(ErrorCodes::FileStreamFailed,
str::stream() << "Unable to write process id " << pid.toString()
<< " to file: " << _filespec << " no data written.");
}
if (::fsync(_lockFileHandle->_fd)) {
int errorcode = errno;
return Status(ErrorCodes::FileStreamFailed,
str::stream() << "Unable to write process id " << pid.toString()
<< " to file (fsync failed): " << _filespec << ' '
<< errnoWithDescription(errorcode));
}
flushMyDirectory(_filespec);
return Status::OK();
}
void StorageEngineLockFile::clearPidAndUnlock() {
if (!_lockFileHandle->isValid()) {
return;
}
log() << "shutdown: removing fs lock...";
// This ought to be an unlink(), but Eliot says the last
// time that was attempted, there was a race condition
// with acquirePathLock().
if (::ftruncate(_lockFileHandle->_fd, 0)) {
int errorcode = errno;
log() << "couldn't remove fs lock " << errnoWithDescription(errorcode);
}
#if !defined(__sun)
::flock(_lockFileHandle->_fd, LOCK_UN);
#else
struct flock fileLockInfo = {0};
fileLockInfo.l_type = F_UNLCK;
fileLockInfo.l_whence = SEEK_SET;
::fcntl(_lockFileHandle->_fd, F_SETLK, &fileLockInfo);
#endif // !defined(__sun)
}
} // namespace mongo
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