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         protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
  82                 $status = Status::newGood();
  83
  84                 $server = $this->lockServers[$lockSrv];
  85                 $conn = $this->redisPool->getConnection( $server );
  86                 if ( !$conn ) {
  87                         foreach ( array_merge( array_values( $pathsByType ) ) as $path ) {
  88                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
  89                         }
  90
  91                         return $status;
  92                 }
  93
  94                 $pathsByKey = array(); // (type:hash => path) map
  95                 foreach ( $pathsByType as $type => $paths ) {
  96                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
  97                         foreach ( $paths as $path ) {
  98                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
  99                         }
 100                 }
 101
 102                 try {
 103                         static $script =
 104 <<<LUA
 105                         local failed = {}
 106                         -- Load input params (e.g. session, ttl, time of request)
 107                         local rSession, rTTL, rTime = unpack(ARGV)
 108                         -- Check that all the locks can be acquired
 109                         for i,requestKey in ipairs(KEYS) do
 110                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 111                                 local keyIsFree = true
 112                                 local currentLocks = redis.call('hKeys',resourceKey)
 113                                 for i,lockKey in ipairs(currentLocks) do
 114                                         -- Get the type and session of this lock
 115                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 116                                         -- Check any locks that are not owned by this session
 117                                         if session ~= rSession then
 118                                                 local lockExpiry = redis.call('hGet',resourceKey,lockKey)
 119                                                 if 1*lockExpiry < 1*rTime then
 120                                                         -- Lock is stale, so just prune it out
 121                                                         redis.call('hDel',resourceKey,lockKey)
 122                                                 elseif rType == 'EX' or type == 'EX' then
 123                                                         keyIsFree = false
 124                                                         break
 125                                                 end
 126                                         end
 127                                 end
 128                                 if not keyIsFree then
 129                                         failed[#failed+1] = requestKey
 130                                 end
 131                         end
 132                         -- If all locks could be acquired, then do so
 133                         if #failed == 0 then
 134                                 for i,requestKey in ipairs(KEYS) do
 135                                         local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 136                                         redis.call('hSet',resourceKey,rType .. ':' .. rSession,rTime + rTTL)
 137                                         -- In addition to invalidation logic, be sure to garbage collect
 138                                         redis.call('expire',resourceKey,rTTL)
 139                                 end
 140                         end
 141                         return failed
 142 LUA;
 143                         $res = $conn->luaEval( $script,
 144                                 array_merge(
 145                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 146                                         array(
 147                                                 $this->session, // ARGV[1]
 148                                                 $this->lockTTL, // ARGV[2]
 149                                                 time() // ARGV[3]
 150                                         )
 151                                 ),
 152                                 count( $pathsByKey ) # number of first argument(s) that are keys
 153                         );
 154                 } catch ( RedisException $e ) {
 155                         $res = false;
 156                         $this->redisPool->handleError( $conn, $e );
 157                 }
 158
 159                 if ( $res === false ) {
 160                         foreach ( array_merge( array_values( $pathsByType ) ) as $path ) {
 161                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 162                         }
 163                 } else {
 164                         foreach ( $res as $key ) {
 165                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 166                         }
 167                 }
 168
 169                 return $status;
 170         }
 171
 172         protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
 173                 $status = Status::newGood();
 174
 175                 $server = $this->lockServers[$lockSrv];
 176                 $conn = $this->redisPool->getConnection( $server );
 177                 if ( !$conn ) {
 178                         foreach ( array_merge( array_values( $pathsByType ) ) as $path ) {
 179                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 180                         }
 181
 182                         return $status;
 183                 }
 184
 185                 $pathsByKey = array(); // (type:hash => path) map
 186                 foreach ( $pathsByType as $type => $paths ) {
 187                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
 188                         foreach ( $paths as $path ) {
 189                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
 190                         }
 191                 }
 192
 193                 try {
 194                         static $script =
 195 <<<LUA
 196                         local failed = {}
 197                         -- Load input params (e.g. session)
 198                         local rSession = unpack(ARGV)
 199                         for i,requestKey in ipairs(KEYS) do
 200                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 201                                 local released = redis.call('hDel',resourceKey,rType .. ':' .. rSession)
 202                                 if released > 0 then
 203                                         -- Remove the whole structure if it is now empty
 204                                         if redis.call('hLen',resourceKey) == 0 then
 205                                                 redis.call('del',resourceKey)
 206                                         end
 207                                 else
 208                                         failed[#failed+1] = requestKey
 209                                 end
 210                         end
 211                         return failed
 212 LUA;
 213                         $res = $conn->luaEval( $script,
 214                                 array_merge(
 215                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 216                                         array(
 217                                                 $this->session, // ARGV[1]
 218                                         )
 219                                 ),
 220                                 count( $pathsByKey ) # number of first argument(s) that are keys
 221                         );
 222                 } catch ( RedisException $e ) {
 223                         $res = false;
 224                         $this->redisPool->handleError( $conn, $e );
 225                 }
 226
 227                 if ( $res === false ) {
 228                         foreach ( array_merge( array_values( $pathsByType ) ) as $path ) {
 229                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 230                         }
 231                 } else {
 232                         foreach ( $res as $key ) {
 233                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 234                         }
 235                 }
 236
 237                 return $status;
 238         }
 239
 240         protected function releaseAllLocks() {
 241                 return Status::newGood(); // not supported
 242         }
 243
 244         protected function isServerUp( $lockSrv ) {
 245                 return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
 246         }
 247
 248         /**
 249          * @param string $path
 250          * @param string $type One of (EX,SH)
 251          * @return string
 252          */
 253         protected function recordKeyForPath( $path, $type ) {
 254                 return implode( ':',
 255                         array( __CLASS__, 'locks', "$type:" . $this->sha1Base36Absolute( $path ) ) );
 256         }
 257
 258         /**
 259          * Make sure remaining locks get cleared for sanity
 260          */
 261         function __destruct() {
 262                 while ( count( $this->locksHeld ) ) {
 263                         $pathsByType = array();
 264                         foreach ( $this->locksHeld as $path => $locks ) {
 265                                 foreach ( $locks as $type => $count ) {
 266                                         $pathsByType[$type][] = $path;
 267                                 }
 268                         }
 269                         $this->unlockByType( $pathsByType );
 270                 }
 271         }
 272 }