12cac7cca9
With a user-friendly error message which uses both technical and non-technical language, without the irrelevant detail of filebackend URLs. Bug: T283045 Change-Id: I8704f405d38acdffae7bd4ea5b91f3f591fc2ebc
133 lines
4.2 KiB
PHP
133 lines
4.2 KiB
PHP
<?php
|
|
|
|
use Wikimedia\Rdbms\DBError;
|
|
use Wikimedia\Rdbms\IDatabase;
|
|
|
|
/**
|
|
* MySQL version of DBLockManager that supports shared locks.
|
|
*
|
|
* Do NOT use this on connection handles that are also being used for anything
|
|
* else as the transaction isolation will be wrong and all the other changes will
|
|
* get rolled back when the locks release!
|
|
*
|
|
* All lock servers must have the innodb table defined in maintenance/locking/filelocks.sql.
|
|
* All locks are non-blocking, which avoids deadlocks.
|
|
*
|
|
* @ingroup LockManager
|
|
*/
|
|
class MySqlLockManager extends DBLockManager {
|
|
/** @var array Mapping of lock types to the type actually used */
|
|
protected $lockTypeMap = [
|
|
self::LOCK_SH => self::LOCK_SH,
|
|
self::LOCK_UW => self::LOCK_SH,
|
|
self::LOCK_EX => self::LOCK_EX
|
|
];
|
|
|
|
public function __construct( array $config ) {
|
|
parent::__construct( $config );
|
|
|
|
$this->session = substr( $this->session, 0, 31 ); // fit to field
|
|
}
|
|
|
|
protected function initConnection( $lockDb, IDatabase $db ) {
|
|
# Let this transaction see lock rows from other transactions
|
|
$db->query( "SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;", __METHOD__ );
|
|
# Do everything in a transaction as it all gets rolled back eventually
|
|
$db->startAtomic( __CLASS__ );
|
|
}
|
|
|
|
/**
|
|
* Get a connection to a lock DB and acquire locks on $paths.
|
|
* This does not use GET_LOCK() per https://bugs.mysql.com/bug.php?id=1118.
|
|
*
|
|
* @see DBLockManager::getLocksOnServer()
|
|
* @param string $lockSrv
|
|
* @param array $paths
|
|
* @param string $type
|
|
* @return StatusValue
|
|
*/
|
|
protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
|
|
$status = StatusValue::newGood();
|
|
|
|
$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
|
|
|
|
$keys = []; // list of hash keys for the paths
|
|
$data = []; // list of rows to insert
|
|
$checkEXKeys = []; // list of hash keys that this has no EX lock on
|
|
# Build up values for INSERT clause
|
|
foreach ( $paths as $path ) {
|
|
$key = $this->sha1Base36Absolute( $path );
|
|
$keys[] = $key;
|
|
$data[] = [ 'fls_key' => $key, 'fls_session' => $this->session ];
|
|
if ( !isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
|
|
$checkEXKeys[] = $key; // this has no EX lock on $key itself
|
|
}
|
|
}
|
|
|
|
# Block new writers (both EX and SH locks leave entries here)...
|
|
$db->insert( 'filelocks_shared', $data, __METHOD__, [ 'IGNORE' ] );
|
|
# Actually do the locking queries...
|
|
if ( $type == self::LOCK_SH ) { // reader locks
|
|
# Bail if there are any existing writers...
|
|
if ( count( $checkEXKeys ) ) {
|
|
$blocked = (bool)$db->selectField( 'filelocks_exclusive', '1',
|
|
[ 'fle_key' => $checkEXKeys ],
|
|
__METHOD__
|
|
);
|
|
} else {
|
|
$blocked = false;
|
|
}
|
|
# Other prospective writers that haven't yet updated filelocks_exclusive
|
|
# will recheck filelocks_shared after doing so and bail due to this entry.
|
|
} else { // writer locks
|
|
$encSession = $db->addQuotes( $this->session );
|
|
# Bail if there are any existing writers...
|
|
# This may detect readers, but the safe check for them is below.
|
|
# Note: if two writers come at the same time, both bail :)
|
|
$blocked = (bool)$db->selectField( 'filelocks_shared', '1',
|
|
[ 'fls_key' => $keys, "fls_session != $encSession" ],
|
|
__METHOD__
|
|
);
|
|
if ( !$blocked ) {
|
|
# Build up values for INSERT clause
|
|
$data = [];
|
|
foreach ( $keys as $key ) {
|
|
$data[] = [ 'fle_key' => $key ];
|
|
}
|
|
# Block new readers/writers...
|
|
$db->insert( 'filelocks_exclusive', $data, __METHOD__ );
|
|
# Bail if there are any existing readers...
|
|
$blocked = (bool)$db->selectField( 'filelocks_shared', '1',
|
|
[ 'fls_key' => $keys, "fls_session != $encSession" ],
|
|
__METHOD__
|
|
);
|
|
}
|
|
}
|
|
|
|
if ( $blocked ) {
|
|
$status->fatal( 'lockmanager-fail-conflict' );
|
|
}
|
|
|
|
return $status;
|
|
}
|
|
|
|
/**
|
|
* @see QuorumLockManager::releaseAllLocks()
|
|
* @return StatusValue
|
|
*/
|
|
protected function releaseAllLocks() {
|
|
$status = StatusValue::newGood();
|
|
|
|
foreach ( $this->conns as $lockDb => $db ) {
|
|
if ( $db->trxLevel() ) { // in transaction
|
|
try {
|
|
$db->rollback( __METHOD__ ); // finish transaction and kill any rows
|
|
} catch ( DBError $e ) {
|
|
$status->fatal( 'lockmanager-fail-db-release', $lockDb );
|
|
}
|
|
}
|
|
}
|
|
|
|
return $status;
|
|
}
|
|
}
|