includes/filebackend/lockmanager/RedisLockManager.php

   1 <?php
   2 /**
   3  * Version of LockManager based on using redis servers.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup LockManager
  22  */
  23
  24 /**
  25  * Manage locks using redis servers.
  26  *
  27  * Version of LockManager based on using redis servers.
  28  * This is meant for multi-wiki systems that may share files.
  29  * All locks are non-blocking, which avoids deadlocks.
  30  *
  31  * All lock requests for a resource, identified by a hash string, will map to one
  32  * bucket. Each bucket maps to one or several peer servers, each running redis.
  33  * A majority of peers must agree for a lock to be acquired.
  34  *
  35  * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
  36  *
  37  * @ingroup LockManager
  38  * @since 1.22
  39  */
  40 class RedisLockManager extends QuorumLockManager {
  41         /** @var Array Mapping of lock types to the type actually used */
  42         protected $lockTypeMap = array(
  43                 self::LOCK_SH => self::LOCK_SH,
  44                 self::LOCK_UW => self::LOCK_SH,
  45                 self::LOCK_EX => self::LOCK_EX
  46         );
  47
  48         /** @var RedisConnectionPool */
  49         protected $redisPool;
  50         /** @var Array Map server names to hostname/IP and port numbers */
  51         protected $lockServers = array();
  52
  53         protected $session = ''; // string; random UUID
  54
  55         /**
  56          * Construct a new instance from configuration.
  57          *
  58          * $config paramaters include:
  59          *   - lockServers  : Associative array of server names to "<IP>:<port>" strings.
  60          *   - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
  61          *                    each having an odd-numbered list of server names (peers) as values.
  62          *   - redisConfig  : Configuration for RedisConnectionPool::__construct().
  63          *
  64          * @param Array $config
  65          * @throws MWException
  66          */
  67         public function __construct( array $config ) {
  68                 parent::__construct( $config );
  69
  70                 $this->lockServers = $config['lockServers'];
  71                 // Sanitize srvsByBucket config to prevent PHP errors
  72                 $this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
  73                 $this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
  74
  75                 $config['redisConfig']['serializer'] = 'none';
  76                 $this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] );
  77
  78                 $this->session = wfRandomString( 32 );
  79         }
  80
  81         protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
  82                 $status = Status::newGood();
  83
  84                 $server = $this->lockServers[$lockSrv];
  85                 $conn = $this->redisPool->getConnection( $server );
  86                 if ( !$conn ) {
  87                         foreach ( $paths as $path ) {
  88                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
  89                         }
  90                         return $status;
  91                 }
  92
  93                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
  94
  95                 try {
  96                         static $script =
  97 <<<LUA
  98                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
  99                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 100                         end
 101                         local failed = {}
 102                         -- Check that all the locks can be acquired
 103                         for i,resourceKey in ipairs(KEYS) do
 104                                 local keyIsFree = true
 105                                 local currentLocks = redis.call('hKeys',resourceKey)
 106                                 for i,lockKey in ipairs(currentLocks) do
 107                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 108                                         -- Check any locks that are not owned by this session
 109                                         if session ~= ARGV[2] then
 110                                                 local lockTimestamp = redis.call('hGet',resourceKey,lockKey)
 111                                                 if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then
 112                                                         -- Lock is stale, so just prune it out
 113                                                         redis.call('hDel',resourceKey,lockKey)
 114                                                 elseif ARGV[1] == 'EX' or type == 'EX' then
 115                                                         keyIsFree = false
 116                                                         break
 117                                                 end
 118                                         end
 119                                 end
 120                                 if not keyIsFree then
 121                                         failed[#failed+1] = resourceKey
 122                                 end
 123                         end
 124                         -- If all locks could be acquired, then do so
 125                         if #failed == 0 then
 126                                 for i,resourceKey in ipairs(KEYS) do
 127                                         redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4])
 128                                         -- In addition to invalidation logic, be sure to garbage collect
 129                                         redis.call('expire',resourceKey,ARGV[3])
 130                                 end
 131                         end
 132                         return failed
 133 LUA;
 134                         $res = $conn->luaEval( $script,
 135                                 array_merge(
 136                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 137                                         array(
 138                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 139                                                 $this->session, // ARGV[2]
 140                                                 $this->lockTTL, // ARGV[3]
 141                                                 time() // ARGV[4]
 142                                         )
 143                                 ),
 144                                 count( $keys ) # number of first argument(s) that are keys
 145                         );
 146                 } catch ( RedisException $e ) {
 147                         $res = false;
 148                         $this->redisPool->handleException( $server, $conn, $e );
 149                 }
 150
 151                 if ( $res === false ) {
 152                         foreach ( $paths as $path ) {
 153                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 154                         }
 155                 } else {
 156                         $pathsByKey = array_combine( $keys, $paths );
 157                         foreach ( $res as $key ) {
 158                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 159                         }
 160                 }
 161
 162                 return $status;
 163         }
 164
 165         protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
 166                 $status = Status::newGood();
 167
 168                 $server = $this->lockServers[$lockSrv];
 169                 $conn = $this->redisPool->getConnection( $server );
 170                 if ( !$conn ) {
 171                         foreach ( $paths as $path ) {
 172                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 173                         }
 174                         return $status;
 175                 }
 176
 177                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
 178
 179                 try {
 180                         static $script =
 181 <<<LUA
 182                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
 183                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 184                         end
 185                         local failed = {}
 186                         for i,resourceKey in ipairs(KEYS) do
 187                                 local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2])
 188                                 if released > 0 then
 189                                         -- Remove the whole structure if it is now empty
 190                                         if redis.call('hLen',resourceKey) == 0 then
 191                                                 redis.call('del',resourceKey)
 192                                         end
 193                                 else
 194                                         failed[#failed+1] = resourceKey
 195                                 end
 196                         end
 197                         return failed
 198 LUA;
 199                         $res = $conn->luaEval( $script,
 200                                 array_merge(
 201                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 202                                         array(
 203                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 204                                                 $this->session // ARGV[2]
 205                                         )
 206                                 ),
 207                                 count( $keys ) # number of first argument(s) that are keys
 208                         );
 209                 } catch ( RedisException $e ) {
 210                         $res = false;
 211                         $this->redisPool->handleException( $server, $conn, $e );
 212                 }
 213
 214                 if ( $res === false ) {
 215                         foreach ( $paths as $path ) {
 216                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 217                         }
 218                 } else {
 219                         $pathsByKey = array_combine( $keys, $paths );
 220                         foreach ( $res as $key ) {
 221                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 222                         }
 223                 }
 224
 225                 return $status;
 226         }
 227
 228         protected function releaseAllLocks() {
 229                 return Status::newGood(); // not supported
 230         }
 231
 232         protected function isServerUp( $lockSrv ) {
 233                 return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
 234         }
 235
 236         /**
 237          * @param $path string
 238          * @return string
 239          */
 240         protected function recordKeyForPath( $path ) {
 241                 return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
 242         }
 243
 244         /**
 245          * Make sure remaining locks get cleared for sanity
 246          */
 247         function __destruct() {
 248                 while ( count( $this->locksHeld ) ) {
 249                         foreach ( $this->locksHeld as $path => $locks ) {
 250                                 $this->doUnlock( array( $path ), self::LOCK_EX );
 251                                 $this->doUnlock( array( $path ), self::LOCK_SH );
 252                         }
 253                 }
 254         }
 255 }