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mediawiki_ynh/sources/mediawiki/includes/filebackend/lockmanager/RedisLockManager.php

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8.6 KiB
PHP

<?php
/**
* Version of LockManager based on using redis 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 redis servers.
*
* Version of LockManager based on using redis 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 redis.
* A majority of peers must agree for a lock to be acquired.
*
* This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
*
* @ingroup LockManager
* @since 1.22
*/
class RedisLockManager 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 RedisConnectionPool */
protected $redisPool;
/** @var Array Map server names to hostname/IP and port numbers */
protected $lockServers = array();
protected $session = ''; // string; random UUID
/**
* 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.
* - redisConfig : Configuration for RedisConnectionPool::__construct().
*
* @param Array $config
* @throws MWException
*/
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
$config['redisConfig']['serializer'] = 'none';
$this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] );
$this->session = wfRandomString( 32 );
}
// @TODO: change this code to work in one batch
protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
$status = Status::newGood();
$lockedPaths = array();
foreach ( $pathsByType as $type => $paths ) {
$status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
if ( $status->isOK() ) {
$lockedPaths[$type] = isset( $lockedPaths[$type] )
? array_merge( $lockedPaths[$type], $paths )
: $paths;
} else {
foreach ( $lockedPaths as $type => $paths ) {
$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
}
break;
}
}
return $status;
}
// @TODO: change this code to work in one batch
protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
$status = Status::newGood();
foreach ( $pathsByType as $type => $paths ) {
$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
}
return $status;
}
protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
$status = Status::newGood();
$server = $this->lockServers[$lockSrv];
$conn = $this->redisPool->getConnection( $server );
if ( !$conn ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-acquirelock', $path );
}
return $status;
}
$keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
try {
static $script =
<<<LUA
if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
end
local failed = {}
-- Check that all the locks can be acquired
for i,resourceKey in ipairs(KEYS) do
local keyIsFree = true
local currentLocks = redis.call('hKeys',resourceKey)
for i,lockKey in ipairs(currentLocks) do
local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
-- Check any locks that are not owned by this session
if session ~= ARGV[2] then
local lockTimestamp = redis.call('hGet',resourceKey,lockKey)
if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then
-- Lock is stale, so just prune it out
redis.call('hDel',resourceKey,lockKey)
elseif ARGV[1] == 'EX' or type == 'EX' then
keyIsFree = false
break
end
end
end
if not keyIsFree then
failed[#failed+1] = resourceKey
end
end
-- If all locks could be acquired, then do so
if #failed == 0 then
for i,resourceKey in ipairs(KEYS) do
redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4])
-- In addition to invalidation logic, be sure to garbage collect
redis.call('expire',resourceKey,ARGV[3])
end
end
return failed
LUA;
$res = $conn->luaEval( $script,
array_merge(
$keys, // KEYS[0], KEYS[1],...KEYS[N]
array(
$type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
$this->session, // ARGV[2]
$this->lockTTL, // ARGV[3]
time() // ARGV[4]
)
),
count( $keys ) # number of first argument(s) that are keys
);
} catch ( RedisException $e ) {
$res = false;
$this->redisPool->handleException( $server, $conn, $e );
}
if ( $res === false ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-acquirelock', $path );
}
} else {
$pathsByKey = array_combine( $keys, $paths );
foreach ( $res as $key ) {
$status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
}
}
return $status;
}
protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) {
$status = Status::newGood();
$server = $this->lockServers[$lockSrv];
$conn = $this->redisPool->getConnection( $server );
if ( !$conn ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-releaselock', $path );
}
return $status;
}
$keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
try {
static $script =
<<<LUA
if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
end
local failed = {}
for i,resourceKey in ipairs(KEYS) do
local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2])
if released > 0 then
-- Remove the whole structure if it is now empty
if redis.call('hLen',resourceKey) == 0 then
redis.call('del',resourceKey)
end
else
failed[#failed+1] = resourceKey
end
end
return failed
LUA;
$res = $conn->luaEval( $script,
array_merge(
$keys, // KEYS[0], KEYS[1],...KEYS[N]
array(
$type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
$this->session // ARGV[2]
)
),
count( $keys ) # number of first argument(s) that are keys
);
} catch ( RedisException $e ) {
$res = false;
$this->redisPool->handleException( $server, $conn, $e );
}
if ( $res === false ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-releaselock', $path );
}
} else {
$pathsByKey = array_combine( $keys, $paths );
foreach ( $res as $key ) {
$status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
}
}
return $status;
}
protected function releaseAllLocks() {
return Status::newGood(); // not supported
}
protected function isServerUp( $lockSrv ) {
return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
}
/**
* @param $path string
* @return string
*/
protected function recordKeyForPath( $path ) {
return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
}
/**
* 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 );
}
}
}
}