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
  51         /** @var array Map server names to hostname/IP and port numbers */
  52         protected $lockServers = array();
  53
  54         /** @var string random UUID */
  55         protected $session = '';
  56
  57         /**
  58          * Construct a new instance from configuration.
  59          *
  60          * @param array $config Parameters include:
  61          *   - lockServers  : Associative array of server names to "<IP>:<port>" strings.
  62          *   - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
  63          *                    each having an odd-numbered list of server names (peers) as values.
  64          *   - redisConfig  : Configuration for RedisConnectionPool::__construct().
  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         // @TODO: change this code to work in one batch
  82         protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
  83                 $status = Status::newGood();
  84
  85                 $lockedPaths = array();
  86                 foreach ( $pathsByType as $type => $paths ) {
  87                         $status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
  88                         if ( $status->isOK() ) {
  89                                 $lockedPaths[$type] = isset( $lockedPaths[$type] )
  90                                         ? array_merge( $lockedPaths[$type], $paths )
  91                                         : $paths;
  92                         } else {
  93                                 foreach ( $lockedPaths as $lType => $lPaths ) {
  94                                         $status->merge( $this->doFreeLocksOnServer( $lockSrv, $lPaths, $lType ) );
  95                                 }
  96                                 break;
  97                         }
  98                 }
  99
 100                 return $status;
 101         }
 102
 103         // @todo Change this code to work in one batch
 104         protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
 105                 $status = Status::newGood();
 106
 107                 foreach ( $pathsByType as $type => $paths ) {
 108                         $status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
 109                 }
 110
 111                 return $status;
 112         }
 113
 114         protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
 115                 $status = Status::newGood();
 116
 117                 $server = $this->lockServers[$lockSrv];
 118                 $conn = $this->redisPool->getConnection( $server );
 119                 if ( !$conn ) {
 120                         foreach ( $paths as $path ) {
 121                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 122                         }
 123
 124                         return $status;
 125                 }
 126
 127                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
 128
 129                 try {
 130                         static $script =
 131 <<<LUA
 132                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
 133                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 134                         end
 135                         local failed = {}
 136                         -- Check that all the locks can be acquired
 137                         for i,resourceKey in ipairs(KEYS) do
 138                                 local keyIsFree = true
 139                                 local currentLocks = redis.call('hKeys',resourceKey)
 140                                 for i,lockKey in ipairs(currentLocks) do
 141                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 142                                         -- Check any locks that are not owned by this session
 143                                         if session ~= ARGV[2] then
 144                                                 local lockTimestamp = redis.call('hGet',resourceKey,lockKey)
 145                                                 if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then
 146                                                         -- Lock is stale, so just prune it out
 147                                                         redis.call('hDel',resourceKey,lockKey)
 148                                                 elseif ARGV[1] == 'EX' or type == 'EX' then
 149                                                         keyIsFree = false
 150                                                         break
 151                                                 end
 152                                         end
 153                                 end
 154                                 if not keyIsFree then
 155                                         failed[#failed+1] = resourceKey
 156                                 end
 157                         end
 158                         -- If all locks could be acquired, then do so
 159                         if #failed == 0 then
 160                                 for i,resourceKey in ipairs(KEYS) do
 161                                         redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4])
 162                                         -- In addition to invalidation logic, be sure to garbage collect
 163                                         redis.call('expire',resourceKey,ARGV[3])
 164                                 end
 165                         end
 166                         return failed
 167 LUA;
 168                         $res = $conn->luaEval( $script,
 169                                 array_merge(
 170                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 171                                         array(
 172                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 173                                                 $this->session, // ARGV[2]
 174                                                 $this->lockTTL, // ARGV[3]
 175                                                 time() // ARGV[4]
 176                                         )
 177                                 ),
 178                                 count( $keys ) # number of first argument(s) that are keys
 179                         );
 180                 } catch ( RedisException $e ) {
 181                         $res = false;
 182                         $this->redisPool->handleException( $server, $conn, $e );
 183                 }
 184
 185                 if ( $res === false ) {
 186                         foreach ( $paths as $path ) {
 187                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 188                         }
 189                 } else {
 190                         $pathsByKey = array_combine( $keys, $paths );
 191                         foreach ( $res as $key ) {
 192                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 193                         }
 194                 }
 195
 196                 return $status;
 197         }
 198
 199         protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) {
 200                 $status = Status::newGood();
 201
 202                 $server = $this->lockServers[$lockSrv];
 203                 $conn = $this->redisPool->getConnection( $server );
 204                 if ( !$conn ) {
 205                         foreach ( $paths as $path ) {
 206                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 207                         }
 208
 209                         return $status;
 210                 }
 211
 212                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
 213
 214                 try {
 215                         static $script =
 216 <<<LUA
 217                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
 218                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 219                         end
 220                         local failed = {}
 221                         for i,resourceKey in ipairs(KEYS) do
 222                                 local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2])
 223                                 if released > 0 then
 224                                         -- Remove the whole structure if it is now empty
 225                                         if redis.call('hLen',resourceKey) == 0 then
 226                                                 redis.call('del',resourceKey)
 227                                         end
 228                                 else
 229                                         failed[#failed+1] = resourceKey
 230                                 end
 231                         end
 232                         return failed
 233 LUA;
 234                         $res = $conn->luaEval( $script,
 235                                 array_merge(
 236                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 237                                         array(
 238                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 239                                                 $this->session // ARGV[2]
 240                                         )
 241                                 ),
 242                                 count( $keys ) # number of first argument(s) that are keys
 243                         );
 244                 } catch ( RedisException $e ) {
 245                         $res = false;
 246                         $this->redisPool->handleException( $server, $conn, $e );
 247                 }
 248
 249                 if ( $res === false ) {
 250                         foreach ( $paths as $path ) {
 251                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 252                         }
 253                 } else {
 254                         $pathsByKey = array_combine( $keys, $paths );
 255                         foreach ( $res as $key ) {
 256                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 257                         }
 258                 }
 259
 260                 return $status;
 261         }
 262
 263         protected function releaseAllLocks() {
 264                 return Status::newGood(); // not supported
 265         }
 266
 267         protected function isServerUp( $lockSrv ) {
 268                 return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
 269         }
 270
 271         /**
 272          * @param string $path
 273          * @return string
 274          */
 275         protected function recordKeyForPath( $path ) {
 276                 return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
 277         }
 278
 279         /**
 280          * Make sure remaining locks get cleared for sanity
 281          */
 282         function __destruct() {
 283                 while ( count( $this->locksHeld ) ) {
 284                         foreach ( $this->locksHeld as $path => $locks ) {
 285                                 $this->doUnlock( array( $path ), self::LOCK_EX );
 286                                 $this->doUnlock( array( $path ), self::LOCK_SH );
 287                         }
 288                 }
 289         }
 290 }