--- /dev/null
+<?php
+/**
+ * Version of LockManager based on using memcached 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 memcached servers.
+ *
+ * Version of LockManager based on using memcached 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 memcached.
+ * A majority of peers must agree for a lock to be acquired.
+ *
+ * @ingroup LockManager
+ * @since 1.20
+ */
+class MemcLockManager 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 server names to MemcachedBagOStuff objects */
+ protected $bagOStuffs = array();
+ /** @var Array */
+ protected $serversUp = array(); // (server name => bool)
+
+ protected $lockExpiry; // integer; maximum time locks can be held
+ protected $session = ''; // string; random SHA-1 UUID
+ protected $wikiId = ''; // string
+
+ /**
+ * Construct a new instance from configuration.
+ *
+ * $config paramaters include:
+ * 'lockServers' : Associative array of server names to <IP>:<port> strings.
+ * 'srvsByBucket' : Array of 1-16 consecutive integer keys, starting from 0,
+ * each having an odd-numbered list of server names (peers) as values.
+ * 'memcConfig' : Configuration array for ObjectCache::newFromParams. [optional]
+ * If set, this must use one of the memcached classes.
+ * 'wikiId' : Wiki ID string that all resources are relative to. [optional]
+ *
+ * @param Array $config
+ */
+ public function __construct( array $config ) {
+ parent::__construct( $config );
+
+ // Sanitize srvsByBucket config to prevent PHP errors
+ $this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
+ $this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
+
+ $memcConfig = isset( $config['memcConfig'] )
+ ? $config['memcConfig']
+ : array( 'class' => 'MemcachedPhpBagOStuff' );
+
+ foreach ( $config['lockServers'] as $name => $address ) {
+ $params = array( 'servers' => array( $address ) ) + $memcConfig;
+ $cache = ObjectCache::newFromParams( $params );
+ if ( $cache instanceof MemcachedBagOStuff ) {
+ $this->bagOStuffs[$name] = $cache;
+ } else {
+ throw new MWException(
+ 'Only MemcachedBagOStuff classes are supported by MemcLockManager.' );
+ }
+ }
+
+ $this->wikiId = isset( $config['wikiId'] ) ? $config['wikiId'] : wfWikiID();
+
+ $met = ini_get( 'max_execution_time' ); // this is 0 in CLI mode
+ $this->lockExpiry = $met ? 2*(int)$met : 2*3600;
+
+ $this->session = wfRandomString( 31 );
+ }
+
+ /**
+ * @see QuorumLockManager::getLocksOnServer()
+ * @return Status
+ */
+ protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+ $status = Status::newGood();
+
+ $memc = $this->getCache( $lockSrv );
+ $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
+
+ // Lock all of the active lock record keys...
+ if ( !$this->acquireMutexes( $memc, $keys ) ) {
+ foreach ( $paths as $path ) {
+ $status->fatal( 'lockmanager-fail-acquirelock', $path );
+ }
+ return;
+ }
+
+ // Fetch all the existing lock records...
+ $lockRecords = $memc->getMulti( $keys );
+
+ $now = time();
+ // Check if the requested locks conflict with existing ones...
+ foreach ( $paths as $path ) {
+ $locksKey = $this->recordKeyForPath( $path );
+ $locksHeld = isset( $lockRecords[$locksKey] )
+ ? $lockRecords[$locksKey]
+ : array( self::LOCK_SH => array(), self::LOCK_EX => array() ); // init
+ foreach ( $locksHeld[self::LOCK_EX] as $session => $expiry ) {
+ if ( $expiry < $now ) { // stale?
+ unset( $locksHeld[self::LOCK_EX][$session] );
+ } elseif ( $session !== $this->session ) {
+ $status->fatal( 'lockmanager-fail-acquirelock', $path );
+ }
+ }
+ if ( $type === self::LOCK_EX ) {
+ foreach ( $locksHeld[self::LOCK_SH] as $session => $expiry ) {
+ if ( $expiry < $now ) { // stale?
+ unset( $locksHeld[self::LOCK_SH][$session] );
+ } elseif ( $session !== $this->session ) {
+ $status->fatal( 'lockmanager-fail-acquirelock', $path );
+ }
+ }
+ }
+ if ( $status->isOK() ) {
+ // Register the session in the lock record array
+ $locksHeld[$type][$this->session] = $now + $this->lockExpiry;
+ // We will update this record if none of the other locks conflict
+ $lockRecords[$locksKey] = $locksHeld;
+ }
+ }
+
+ // If there were no lock conflicts, update all the lock records...
+ if ( $status->isOK() ) {
+ foreach ( $lockRecords as $locksKey => $locksHeld ) {
+ $memc->set( $locksKey, $locksHeld );
+ wfDebug( __METHOD__ . ": acquired lock on key $locksKey.\n" );
+ }
+ }
+
+ // Unlock all of the active lock record keys...
+ $this->releaseMutexes( $memc, $keys );
+
+ return $status;
+ }
+
+ /**
+ * @see QuorumLockManager::freeLocksOnServer()
+ * @return Status
+ */
+ protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
+ $status = Status::newGood();
+
+ $memc = $this->getCache( $lockSrv );
+ $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
+
+ // Lock all of the active lock record keys...
+ if ( !$this->acquireMutexes( $memc, $keys ) ) {
+ foreach ( $paths as $path ) {
+ $status->fatal( 'lockmanager-fail-releaselock', $path );
+ }
+ return;
+ }
+
+ // Fetch all the existing lock records...
+ $lockRecords = $memc->getMulti( $keys );
+
+ // Remove the requested locks from all records...
+ foreach ( $paths as $path ) {
+ $locksKey = $this->recordKeyForPath( $path ); // lock record
+ if ( !isset( $lockRecords[$locksKey] ) ) {
+ continue; // nothing to do
+ }
+ $locksHeld = $lockRecords[$locksKey];
+ if ( is_array( $locksHeld ) && isset( $locksHeld[$type] ) ) {
+ unset( $locksHeld[$type][$this->session] );
+ $ok = $memc->set( $locksKey, $locksHeld );
+ } else {
+ $ok = true;
+ }
+ if ( !$ok ) {
+ $status->fatal( 'lockmanager-fail-releaselock', $path );
+ }
+ wfDebug( __METHOD__ . ": released lock on key $locksKey.\n" );
+ }
+
+ // Unlock all of the active lock record keys...
+ $this->releaseMutexes( $memc, $keys );
+
+ return $status;
+ }
+
+ /**
+ * @see QuorumLockManager::releaseAllLocks()
+ * @return Status
+ */
+ protected function releaseAllLocks() {
+ return Status::newGood(); // not supported
+ }
+
+ /**
+ * @see QuorumLockManager::isServerUp()
+ * @return bool
+ */
+ protected function isServerUp( $lockSrv ) {
+ return (bool)$this->getCache( $lockSrv );
+ }
+
+ /**
+ * Get the MemcachedBagOStuff object for a $lockSrv
+ *
+ * @param $lockSrv string Server name
+ * @return MemcachedBagOStuff|null
+ */
+ protected function getCache( $lockSrv ) {
+ $memc = null;
+ if ( isset( $this->bagOStuffs[$lockSrv] ) ) {
+ $memc = $this->bagOStuffs[$lockSrv];
+ if ( !isset( $this->serversUp[$lockSrv] ) ) {
+ $this->serversUp[$lockSrv] = $memc->set( 'MemcLockManager:ping', 1, 1 );
+ if ( !$this->serversUp[$lockSrv] ) {
+ trigger_error( __METHOD__ . ": Could not contact $lockSrv.", E_USER_WARNING );
+ }
+ }
+ if ( !$this->serversUp[$lockSrv] ) {
+ return null; // server appears to be down
+ }
+ }
+ return $memc;
+ }
+
+ /**
+ * @param $path string
+ * @return string
+ */
+ protected function recordKeyForPath( $path ) {
+ $hash = LockManager::sha1Base36( $path );
+ list( $db, $prefix ) = wfSplitWikiID( $this->wikiId );
+ return wfForeignMemcKey( $db, $prefix, __CLASS__, 'locks', $hash );
+ }
+
+ /**
+ * @param $memc MemcachedBagOStuff
+ * @param $keys Array List of keys to acquire
+ * @return bool
+ */
+ protected function acquireMutexes( MemcachedBagOStuff $memc, array $keys ) {
+ $lockedKeys = array();
+
+ $start = microtime( true );
+ do {
+ foreach ( array_diff( $keys, $lockedKeys ) as $key ) {
+ if ( $memc->add( "$key:mutex", 1, 180 ) ) { // lock record
+ $lockedKeys[] = $key;
+ }
+ }
+ } while ( count( $lockedKeys ) < count( $keys ) && ( microtime( true ) - $start ) <= 6 );
+
+ if ( count( $lockedKeys ) != count( $keys ) ) {
+ $this->releaseMutexes( $lockedKeys ); // failed; release what was locked
+ return false;
+ }
+
+ return true;
+ }
+
+ /**
+ * @param $memc MemcachedBagOStuff
+ * @param $keys Array List of acquired keys
+ * @return void
+ */
+ protected function releaseMutexes( MemcachedBagOStuff $memc, array $keys ) {
+ foreach ( $keys as $key ) {
+ $memc->delete( "$key:mutex" );
+ }
+ }
+
+ /**
+ * Make sure remaining locks get cleared for sanity
+ */
+ function __destruct() {
+ while ( count( $this->locksHeld ) ) {
+ foreach ( $this->locksHeld as $path => $locks ) {
+ $this->doUnlock( array( $path ), self::LOCK_EX );
+ $this->doUnlock( array( $path ), self::LOCK_SH );
+ }
+ }
+ }
+}
dépôts / lhc / web / wiklou.git / commitdiff