includes/libs/lockmanager/PostgreSqlLockManager.php

   1 <?php
   2 /**
   3  * PostgreSQL version of DBLockManager that supports shared locks.
   4  * All locks are non-blocking, which avoids deadlocks.
   5  *
   6  * @ingroup LockManager
   7  */
   8 class PostgreSqlLockManager extends DBLockManager {
   9         /** @var array Mapping of lock types to the type actually used */
  10         protected $lockTypeMap = [
  11                 self::LOCK_SH => self::LOCK_SH,
  12                 self::LOCK_UW => self::LOCK_SH,
  13                 self::LOCK_EX => self::LOCK_EX
  14         ];
  15
  16         protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
  17                 $status = StatusValue::newGood();
  18                 if ( !count( $paths ) ) {
  19                         return $status; // nothing to lock
  20                 }
  21
  22                 $db = $this->getConnection( $lockSrv ); // checked in isServerUp()
  23                 $bigints = array_unique( array_map(
  24                         function ( $key ) {
  25                                 return Wikimedia\base_convert( substr( $key, 0, 15 ), 16, 10 );
  26                         },
  27                         array_map( [ $this, 'sha1Base16Absolute' ], $paths )
  28                 ) );
  29
  30                 // Try to acquire all the locks...
  31                 $fields = [];
  32                 foreach ( $bigints as $bigint ) {
  33                         $fields[] = ( $type == self::LOCK_SH )
  34                                 ? "pg_try_advisory_lock_shared({$db->addQuotes( $bigint )}) AS K$bigint"
  35                                 : "pg_try_advisory_lock({$db->addQuotes( $bigint )}) AS K$bigint";
  36                 }
  37                 $res = $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
  38                 $row = $res->fetchRow();
  39
  40                 if ( in_array( 'f', $row ) ) {
  41                         // Release any acquired locks if some could not be acquired...
  42                         $fields = [];
  43                         foreach ( $row as $kbigint => $ok ) {
  44                                 if ( $ok === 't' ) { // locked
  45                                         $bigint = substr( $kbigint, 1 ); // strip off the "K"
  46                                         $fields[] = ( $type == self::LOCK_SH )
  47                                                 ? "pg_advisory_unlock_shared({$db->addQuotes( $bigint )})"
  48                                                 : "pg_advisory_unlock({$db->addQuotes( $bigint )})";
  49                                 }
  50                         }
  51                         if ( count( $fields ) ) {
  52                                 $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
  53                         }
  54                         foreach ( $paths as $path ) {
  55                                 $status->fatal( 'lockmanager-fail-acquirelock', $path );
  56                         }
  57                 }
  58
  59                 return $status;
  60         }
  61
  62         /**
  63          * @see QuorumLockManager::releaseAllLocks()
  64          * @return StatusValue
  65          */
  66         protected function releaseAllLocks() {
  67                 $status = StatusValue::newGood();
  68
  69                 foreach ( $this->conns as $lockDb => $db ) {
  70                         try {
  71                                 $db->query( "SELECT pg_advisory_unlock_all()", __METHOD__ );
  72                         } catch ( DBError $e ) {
  73                                 $status->fatal( 'lockmanager-fail-db-release', $lockDb );
  74                         }
  75                 }
  76
  77                 return $status;
  78         }
  79 }