includes/libs/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 = [
  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 = [];
  53
  54         /**
  55          * Construct a new instance from configuration.
  56          *
  57          * @param array $config Parameters include:
  58          *   - lockServers  : Associative array of server names to "<IP>:<port>" strings.
  59          *   - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
  60          *                    each having an odd-numbered list of server names (peers) as values.
  61          *   - redisConfig  : Configuration for RedisConnectionPool::__construct().
  62          * @throws Exception
  63          */
  64         public function __construct( array $config ) {
  65                 parent::__construct( $config );
  66
  67                 $this->lockServers = $config['lockServers'];
  68                 // Sanitize srvsByBucket config to prevent PHP errors
  69                 $this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
  70                 $this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
  71
  72                 $config['redisConfig']['serializer'] = 'none';
  73                 $this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] );
  74         }
  75
  76         protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
  77                 $status = StatusValue::newGood();
  78
  79                 $pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
  80
  81                 $server = $this->lockServers[$lockSrv];
  82                 $conn = $this->redisPool->getConnection( $server, $this->logger );
  83                 if ( !$conn ) {
  84                         foreach ( $pathList as $path ) {
  85                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
  86                         }
  87
  88                         return $status;
  89                 }
  90
  91                 $pathsByKey = []; // (type:hash => path) map
  92                 foreach ( $pathsByType as $type => $paths ) {
  93                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
  94                         foreach ( $paths as $path ) {
  95                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
  96                         }
  97                 }
  98
  99                 try {
 100                         static $script =
 101 <<<LUA
 102                         local failed = {}
 103                         -- Load input params (e.g. session, ttl, time of request)
 104                         local rSession, rTTL, rTime = unpack(ARGV)
 105                         -- Check that all the locks can be acquired
 106                         for i,requestKey in ipairs(KEYS) do
 107                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 108                                 local keyIsFree = true
 109                                 local currentLocks = redis.call('hKeys',resourceKey)
 110                                 for i,lockKey in ipairs(currentLocks) do
 111                                         -- Get the type and session of this lock
 112                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 113                                         -- Check any locks that are not owned by this session
 114                                         if session ~= rSession then
 115                                                 local lockExpiry = redis.call('hGet',resourceKey,lockKey)
 116                                                 if 1*lockExpiry < 1*rTime then
 117                                                         -- Lock is stale, so just prune it out
 118                                                         redis.call('hDel',resourceKey,lockKey)
 119                                                 elseif rType == 'EX' or type == 'EX' then
 120                                                         keyIsFree = false
 121                                                         break
 122                                                 end
 123                                         end
 124                                 end
 125                                 if not keyIsFree then
 126                                         failed[#failed+1] = requestKey
 127                                 end
 128                         end
 129                         -- If all locks could be acquired, then do so
 130                         if #failed == 0 then
 131                                 for i,requestKey in ipairs(KEYS) do
 132                                         local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 133                                         redis.call('hSet',resourceKey,rType .. ':' .. rSession,rTime + rTTL)
 134                                         -- In addition to invalidation logic, be sure to garbage collect
 135                                         redis.call('expire',resourceKey,rTTL)
 136                                 end
 137                         end
 138                         return failed
 139 LUA;
 140                         $res = $conn->luaEval( $script,
 141                                 array_merge(
 142                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 143                                         [
 144                                                 $this->session, // ARGV[1]
 145                                                 $this->lockTTL, // ARGV[2]
 146                                                 time() // ARGV[3]
 147                                         ]
 148                                 ),
 149                                 count( $pathsByKey ) # number of first argument(s) that are keys
 150                         );
 151                 } catch ( RedisException $e ) {
 152                         $res = false;
 153                         $this->redisPool->handleError( $conn, $e );
 154                 }
 155
 156                 if ( $res === false ) {
 157                         foreach ( $pathList as $path ) {
 158                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 159                         }
 160                 } else {
 161                         foreach ( $res as $key ) {
 162                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 163                         }
 164                 }
 165
 166                 return $status;
 167         }
 168
 169         protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
 170                 $status = StatusValue::newGood();
 171
 172                 $pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
 173
 174                 $server = $this->lockServers[$lockSrv];
 175                 $conn = $this->redisPool->getConnection( $server, $this->logger );
 176                 if ( !$conn ) {
 177                         foreach ( $pathList as $path ) {
 178                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 179                         }
 180
 181                         return $status;
 182                 }
 183
 184                 $pathsByKey = []; // (type:hash => path) map
 185                 foreach ( $pathsByType as $type => $paths ) {
 186                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
 187                         foreach ( $paths as $path ) {
 188                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
 189                         }
 190                 }
 191
 192                 try {
 193                         static $script =
 194 <<<LUA
 195                         local failed = {}
 196                         -- Load input params (e.g. session)
 197                         local rSession = unpack(ARGV)
 198                         for i,requestKey in ipairs(KEYS) do
 199                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 200                                 local released = redis.call('hDel',resourceKey,rType .. ':' .. rSession)
 201                                 if released > 0 then
 202                                         -- Remove the whole structure if it is now empty
 203                                         if redis.call('hLen',resourceKey) == 0 then
 204                                                 redis.call('del',resourceKey)
 205                                         end
 206                                 else
 207                                         failed[#failed+1] = requestKey
 208                                 end
 209                         end
 210                         return failed
 211 LUA;
 212                         $res = $conn->luaEval( $script,
 213                                 array_merge(
 214                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 215                                         [
 216                                                 $this->session, // ARGV[1]
 217                                         ]
 218                                 ),
 219                                 count( $pathsByKey ) # number of first argument(s) that are keys
 220                         );
 221                 } catch ( RedisException $e ) {
 222                         $res = false;
 223                         $this->redisPool->handleError( $conn, $e );
 224                 }
 225
 226                 if ( $res === false ) {
 227                         foreach ( $pathList as $path ) {
 228                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 229                         }
 230                 } else {
 231                         foreach ( $res as $key ) {
 232                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 233                         }
 234                 }
 235
 236                 return $status;
 237         }
 238
 239         protected function releaseAllLocks() {
 240                 return StatusValue::newGood(); // not supported
 241         }
 242
 243         protected function isServerUp( $lockSrv ) {
 244                 $conn = $this->redisPool->getConnection( $this->lockServers[$lockSrv], $this->logger );
 245
 246                 return (bool)$conn;
 247         }
 248
 249         /**
 250          * @param string $path
 251          * @param string $type One of (EX,SH)
 252          * @return string
 253          */
 254         protected function recordKeyForPath( $path, $type ) {
 255                 return implode( ':',
 256                         [ __CLASS__, 'locks', "$type:" . $this->sha1Base36Absolute( $path ) ] );
 257         }
 258
 259         /**
 260          * Make sure remaining locks get cleared for sanity
 261          */
 262         function __destruct() {
 263                 while ( count( $this->locksHeld ) ) {
 264                         $pathsByType = [];
 265                         foreach ( $this->locksHeld as $path => $locks ) {
 266                                 foreach ( $locks as $type => $count ) {
 267                                         $pathsByType[$type][] = $path;
 268                                 }
 269                         }
 270                         $this->unlockByType( $pathsByType );
 271                 }
 272         }
 273 }