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<?php
/**
* Version of LockManager based on using lock daemon servers.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup LockManager
*/
/**
* Manage locks using a lock daemon server.
*
* Version of LockManager based on using lock daemon servers.
* This is meant for multi-wiki systems that may share files.
* All locks are non-blocking, which avoids deadlocks.
*
* All lock requests for a resource, identified by a hash string, will map
* to one bucket. Each bucket maps to one or several peer servers, each
* running LockServerDaemon.php, listening on a designated TCP port.
* A majority of peers must agree for a lock to be acquired.
*
* @ingroup LockManager
* @since 1.19
*/
class LSLockManager extends QuorumLockManager {
/** @var Array Mapping of lock types to the type actually used */
protected $lockTypeMap = array(
self::LOCK_SH => self::LOCK_SH,
self::LOCK_UW => self::LOCK_SH,
self::LOCK_EX => self::LOCK_EX
);
/** @var Array Map of server names to server config */
protected $lockServers; // (server name => server config array)
/** @var Array Map Server connections (server name => resource) */
protected $conns = array();
protected $connTimeout; // float number of seconds
protected $session = ''; // random SHA-1 string
/**
* Construct a new instance from configuration.
*
* $config paramaters include:
* - lockServers : Associative array of server names to configuration.
* Configuration is an associative array that includes:
* - host : IP address/hostname
* - port : TCP port
* - authKey : Secret string the lock server uses
* - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
* each having an odd-numbered list of server names (peers) as values.
* - connTimeout : Lock server connection attempt timeout. [optional]
*
* @param Array $config
*/
public function __construct( array $config ) {
parent::__construct( $config );
$this->lockServers = $config['lockServers'];
// Sanitize srvsByBucket config to prevent PHP errors
$this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
$this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
if ( isset( $config['connTimeout'] ) ) {
$this->connTimeout = $config['connTimeout'];
} else {
$this->connTimeout = 3; // use some sane amount
}
$this->session = wfRandomString( 32 ); // 128 bits
}
/**
* @see QuorumLockManager::getLocksOnServer()
* @return Status
*/
protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
$status = Status::newGood();
// Send out the command and get the response...
$type = ( $type == self::LOCK_SH ) ? 'SH' : 'EX';
$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
$response = $this->sendCommand( $lockSrv, 'ACQUIRE', $type, $keys );
if ( $response !== 'ACQUIRED' ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-acquirelock', $path );
}
}
return $status;
}
/**
* @see QuorumLockManager::freeLocksOnServer()
* @return Status
*/
protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
$status = Status::newGood();
// Send out the command and get the response...
$type = ( $type == self::LOCK_SH ) ? 'SH' : 'EX';
$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
$response = $this->sendCommand( $lockSrv, 'RELEASE', $type, $keys );
if ( $response !== 'RELEASED' ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-releaselock', $path );
}
}
return $status;
}
/**
* @see QuorumLockManager::releaseAllLocks()
* @return Status
*/
protected function releaseAllLocks() {
$status = Status::newGood();
foreach ( $this->conns as $lockSrv => $conn ) {
$response = $this->sendCommand( $lockSrv, 'RELEASE_ALL', '', array() );
if ( $response !== 'RELEASED_ALL' ) {
$status->fatal( 'lockmanager-fail-svr-release', $lockSrv );
}
}
return $status;
}
/**
* @see QuorumLockManager::isServerUp()
* @return bool
*/
protected function isServerUp( $lockSrv ) {
return (bool)$this->getConnection( $lockSrv );
}
/**
* Send a command and get back the response
*
* @param $lockSrv string
* @param $action string
* @param $type string
* @param $values Array
* @return string|bool
*/
protected function sendCommand( $lockSrv, $action, $type, $values ) {
$conn = $this->getConnection( $lockSrv );
if ( !$conn ) {
return false; // no connection
}
$authKey = $this->lockServers[$lockSrv]['authKey'];
// Build of the command as a flat string...
$values = implode( '|', $values );
$key = sha1( $this->session . $action . $type . $values . $authKey );
// Send out the command...
if ( fwrite( $conn, "{$this->session}:$key:$action:$type:$values\n" ) === false ) {
return false;
}
// Get the response...
$response = fgets( $conn );
if ( $response === false ) {
return false;
}
return trim( $response );
}
/**
* Get (or reuse) a connection to a lock server
*
* @param $lockSrv string
* @return resource
*/
protected function getConnection( $lockSrv ) {
if ( !isset( $this->conns[$lockSrv] ) ) {
$cfg = $this->lockServers[$lockSrv];
wfSuppressWarnings();
$errno = $errstr = '';
$conn = fsockopen( $cfg['host'], $cfg['port'], $errno, $errstr, $this->connTimeout );
wfRestoreWarnings();
if ( $conn === false ) {
return null;
}
$sec = floor( $this->connTimeout );
$usec = floor( ( $this->connTimeout - floor( $this->connTimeout ) ) * 1e6 );
stream_set_timeout( $conn, $sec, $usec );
$this->conns[$lockSrv] = $conn;
}
return $this->conns[$lockSrv];
}
/**
* Make sure remaining locks get cleared for sanity
*/
function __destruct() {
$this->releaseAllLocks();
foreach ( $this->conns as $conn ) {
fclose( $conn );
}
}
}
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