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         // @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 $type => $paths ) {
  94                                         $status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
  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                         return $status;
 124                 }
 125
 126                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
 127
 128                 try {
 129                         static $script =
 130 <<<LUA
 131                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
 132                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 133                         end
 134                         local failed = {}
 135                         -- Check that all the locks can be acquired
 136                         for i,resourceKey in ipairs(KEYS) do
 137                                 local keyIsFree = true
 138                                 local currentLocks = redis.call('hKeys',resourceKey)
 139                                 for i,lockKey in ipairs(currentLocks) do
 140                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 141                                         -- Check any locks that are not owned by this session
 142                                         if session ~= ARGV[2] then
 143                                                 local lockTimestamp = redis.call('hGet',resourceKey,lockKey)
 144                                                 if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then
 145                                                         -- Lock is stale, so just prune it out
 146                                                         redis.call('hDel',resourceKey,lockKey)
 147                                                 elseif ARGV[1] == 'EX' or type == 'EX' then
 148                                                         keyIsFree = false
 149                                                         break
 150                                                 end
 151                                         end
 152                                 end
 153                                 if not keyIsFree then
 154                                         failed[#failed+1] = resourceKey
 155                                 end
 156                         end
 157                         -- If all locks could be acquired, then do so
 158                         if #failed == 0 then
 159                                 for i,resourceKey in ipairs(KEYS) do
 160                                         redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4])
 161                                         -- In addition to invalidation logic, be sure to garbage collect
 162                                         redis.call('expire',resourceKey,ARGV[3])
 163                                 end
 164                         end
 165                         return failed
 166 LUA;
 167                         $res = $conn->luaEval( $script,
 168                                 array_merge(
 169                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 170                                         array(
 171                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 172                                                 $this->session, // ARGV[2]
 173                                                 $this->lockTTL, // ARGV[3]
 174                                                 time() // ARGV[4]
 175                                         )
 176                                 ),
 177                                 count( $keys ) # number of first argument(s) that are keys
 178                         );
 179                 } catch ( RedisException $e ) {
 180                         $res = false;
 181                         $this->redisPool->handleException( $server, $conn, $e );
 182                 }
 183
 184                 if ( $res === false ) {
 185                         foreach ( $paths as $path ) {
 186                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 187                         }
 188                 } else {
 189                         $pathsByKey = array_combine( $keys, $paths );
 190                         foreach ( $res as $key ) {
 191                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 192                         }
 193                 }
 194
 195                 return $status;
 196         }
 197
 198         protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) {
 199                 $status = Status::newGood();
 200
 201                 $server = $this->lockServers[$lockSrv];
 202                 $conn = $this->redisPool->getConnection( $server );
 203                 if ( !$conn ) {
 204                         foreach ( $paths as $path ) {
 205                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 206                         }
 207                         return $status;
 208                 }
 209
 210                 $keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
 211
 212                 try {
 213                         static $script =
 214 <<<LUA
 215                         if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
 216                                 return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
 217                         end
 218                         local failed = {}
 219                         for i,resourceKey in ipairs(KEYS) do
 220                                 local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2])
 221                                 if released > 0 then
 222                                         -- Remove the whole structure if it is now empty
 223                                         if redis.call('hLen',resourceKey) == 0 then
 224                                                 redis.call('del',resourceKey)
 225                                         end
 226                                 else
 227                                         failed[#failed+1] = resourceKey
 228                                 end
 229                         end
 230                         return failed
 231 LUA;
 232                         $res = $conn->luaEval( $script,
 233                                 array_merge(
 234                                         $keys, // KEYS[0], KEYS[1],...KEYS[N]
 235                                         array(
 236                                                 $type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
 237                                                 $this->session // ARGV[2]
 238                                         )
 239                                 ),
 240                                 count( $keys ) # number of first argument(s) that are keys
 241                         );
 242                 } catch ( RedisException $e ) {
 243                         $res = false;
 244                         $this->redisPool->handleException( $server, $conn, $e );
 245                 }
 246
 247                 if ( $res === false ) {
 248                         foreach ( $paths as $path ) {
 249                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 250                         }
 251                 } else {
 252                         $pathsByKey = array_combine( $keys, $paths );
 253                         foreach ( $res as $key ) {
 254                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 255                         }
 256                 }
 257
 258                 return $status;
 259         }
 260
 261         protected function releaseAllLocks() {
 262                 return Status::newGood(); // not supported
 263         }
 264
 265         protected function isServerUp( $lockSrv ) {
 266                 return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
 267         }
 268
 269         /**
 270          * @param $path string
 271          * @return string
 272          */
 273         protected function recordKeyForPath( $path ) {
 274                 return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
 275         }
 276
 277         /**
 278          * Make sure remaining locks get cleared for sanity
 279          */
 280         function __destruct() {
 281                 while ( count( $this->locksHeld ) ) {
 282                         foreach ( $this->locksHeld as $path => $locks ) {
 283                                 $this->doUnlock( array( $path ), self::LOCK_EX );
 284                                 $this->doUnlock( array( $path ), self::LOCK_SH );
 285                         }
 286                 }
 287         }
 288 }