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 = [
  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         /** @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 Exception
  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                 $pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
  85
  86                 $server = $this->lockServers[$lockSrv];
  87                 $conn = $this->redisPool->getConnection( $server );
  88                 if ( !$conn ) {
  89                         foreach ( $pathList as $path ) {
  90                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
  91                         }
  92
  93                         return $status;
  94                 }
  95
  96                 $pathsByKey = []; // (type:hash => path) map
  97                 foreach ( $pathsByType as $type => $paths ) {
  98                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
  99                         foreach ( $paths as $path ) {
 100                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
 101                         }
 102                 }
 103
 104                 try {
 105                         static $script =
 106 <<<LUA
 107                         local failed = {}
 108                         -- Load input params (e.g. session, ttl, time of request)
 109                         local rSession, rTTL, rTime = unpack(ARGV)
 110                         -- Check that all the locks can be acquired
 111                         for i,requestKey in ipairs(KEYS) do
 112                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 113                                 local keyIsFree = true
 114                                 local currentLocks = redis.call('hKeys',resourceKey)
 115                                 for i,lockKey in ipairs(currentLocks) do
 116                                         -- Get the type and session of this lock
 117                                         local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
 118                                         -- Check any locks that are not owned by this session
 119                                         if session ~= rSession then
 120                                                 local lockExpiry = redis.call('hGet',resourceKey,lockKey)
 121                                                 if 1*lockExpiry < 1*rTime then
 122                                                         -- Lock is stale, so just prune it out
 123                                                         redis.call('hDel',resourceKey,lockKey)
 124                                                 elseif rType == 'EX' or type == 'EX' then
 125                                                         keyIsFree = false
 126                                                         break
 127                                                 end
 128                                         end
 129                                 end
 130                                 if not keyIsFree then
 131                                         failed[#failed+1] = requestKey
 132                                 end
 133                         end
 134                         -- If all locks could be acquired, then do so
 135                         if #failed == 0 then
 136                                 for i,requestKey in ipairs(KEYS) do
 137                                         local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 138                                         redis.call('hSet',resourceKey,rType .. ':' .. rSession,rTime + rTTL)
 139                                         -- In addition to invalidation logic, be sure to garbage collect
 140                                         redis.call('expire',resourceKey,rTTL)
 141                                 end
 142                         end
 143                         return failed
 144 LUA;
 145                         $res = $conn->luaEval( $script,
 146                                 array_merge(
 147                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 148                                         [
 149                                                 $this->session, // ARGV[1]
 150                                                 $this->lockTTL, // ARGV[2]
 151                                                 time() // ARGV[3]
 152                                         ]
 153                                 ),
 154                                 count( $pathsByKey ) # number of first argument(s) that are keys
 155                         );
 156                 } catch ( RedisException $e ) {
 157                         $res = false;
 158                         $this->redisPool->handleError( $conn, $e );
 159                 }
 160
 161                 if ( $res === false ) {
 162                         foreach ( $pathList as $path ) {
 163                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
 164                         }
 165                 } else {
 166                         foreach ( $res as $key ) {
 167                                 $status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
 168                         }
 169                 }
 170
 171                 return $status;
 172         }
 173
 174         protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
 175                 $status = Status::newGood();
 176
 177                 $pathList = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
 178
 179                 $server = $this->lockServers[$lockSrv];
 180                 $conn = $this->redisPool->getConnection( $server );
 181                 if ( !$conn ) {
 182                         foreach ( $pathList as $path ) {
 183                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 184                         }
 185
 186                         return $status;
 187                 }
 188
 189                 $pathsByKey = []; // (type:hash => path) map
 190                 foreach ( $pathsByType as $type => $paths ) {
 191                         $typeString = ( $type == LockManager::LOCK_SH ) ? 'SH' : 'EX';
 192                         foreach ( $paths as $path ) {
 193                                 $pathsByKey[$this->recordKeyForPath( $path, $typeString )] = $path;
 194                         }
 195                 }
 196
 197                 try {
 198                         static $script =
 199 <<<LUA
 200                         local failed = {}
 201                         -- Load input params (e.g. session)
 202                         local rSession = unpack(ARGV)
 203                         for i,requestKey in ipairs(KEYS) do
 204                                 local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
 205                                 local released = redis.call('hDel',resourceKey,rType .. ':' .. rSession)
 206                                 if released > 0 then
 207                                         -- Remove the whole structure if it is now empty
 208                                         if redis.call('hLen',resourceKey) == 0 then
 209                                                 redis.call('del',resourceKey)
 210                                         end
 211                                 else
 212                                         failed[#failed+1] = requestKey
 213                                 end
 214                         end
 215                         return failed
 216 LUA;
 217                         $res = $conn->luaEval( $script,
 218                                 array_merge(
 219                                         array_keys( $pathsByKey ), // KEYS[0], KEYS[1],...,KEYS[N]
 220                                         [
 221                                                 $this->session, // ARGV[1]
 222                                         ]
 223                                 ),
 224                                 count( $pathsByKey ) # number of first argument(s) that are keys
 225                         );
 226                 } catch ( RedisException $e ) {
 227                         $res = false;
 228                         $this->redisPool->handleError( $conn, $e );
 229                 }
 230
 231                 if ( $res === false ) {
 232                         foreach ( $pathList as $path ) {
 233                                 $status->fatal( 'lockmanager-fail-releaselock', $path );
 234                         }
 235                 } else {
 236                         foreach ( $res as $key ) {
 237                                 $status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
 238                         }
 239                 }
 240
 241                 return $status;
 242         }
 243
 244         protected function releaseAllLocks() {
 245                 return Status::newGood(); // not supported
 246         }
 247
 248         protected function isServerUp( $lockSrv ) {
 249                 return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
 250         }
 251
 252         /**
 253          * @param string $path
 254          * @param string $type One of (EX,SH)
 255          * @return string
 256          */
 257         protected function recordKeyForPath( $path, $type ) {
 258                 return implode( ':',
 259                         [ __CLASS__, 'locks', "$type:" . $this->sha1Base36Absolute( $path ) ] );
 260         }
 261
 262         /**
 263          * Make sure remaining locks get cleared for sanity
 264          */
 265         function __destruct() {
 266                 while ( count( $this->locksHeld ) ) {
 267                         $pathsByType = [];
 268                         foreach ( $this->locksHeld as $path => $locks ) {
 269                                 foreach ( $locks as $type => $count ) {
 270                                         $pathsByType[$type][] = $path;
 271                                 }
 272                         }
 273                         $this->unlockByType( $pathsByType );
 274                 }
 275         }
 276 }