%PDF-
%PDF-
Mini Shell
Mini Shell
<?php
/**
* Generator and manager of database load balancing objects
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Database
*/
namespace Wikimedia\Rdbms;
use Psr\Log\LoggerInterface;
use Wikimedia\ScopedCallback;
use BagOStuff;
use EmptyBagOStuff;
use WANObjectCache;
use Exception;
use RuntimeException;
use LogicException;
/**
* An interface for generating database load balancers
* @ingroup Database
*/
abstract class LBFactory implements ILBFactory {
/** @var ChronologyProtector */
private $chronProt;
/** @var object|string Class name or object With profileIn/profileOut methods */
private $profiler;
/** @var TransactionProfiler */
private $trxProfiler;
/** @var LoggerInterface */
private $replLogger;
/** @var LoggerInterface */
private $connLogger;
/** @var LoggerInterface */
private $queryLogger;
/** @var LoggerInterface */
private $perfLogger;
/** @var callable Error logger */
private $errorLogger;
/** @var callable Deprecation logger */
private $deprecationLogger;
/** @var BagOStuff */
protected $srvCache;
/** @var BagOStuff */
protected $memStash;
/** @var WANObjectCache */
protected $wanCache;
/** @var DatabaseDomain Local domain */
protected $localDomain;
/** @var string Local hostname of the app server */
private $hostname;
/** @var array Web request information about the client */
private $requestInfo;
/** @var bool Whether this PHP instance is for a CLI script */
private $cliMode;
/** @var string Agent name for query profiling */
private $agent;
/** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
private $tableAliases = [];
/** @var string[] Map of (index alias => index) */
private $indexAliases = [];
/** @var callable[] */
private $replicationWaitCallbacks = [];
/** @var mixed */
private $ticket;
/** @var string|bool String if a requested DBO_TRX transaction round is active */
private $trxRoundId = false;
/** @var string One of the ROUND_* class constants */
private $trxRoundStage = self::ROUND_CURSORY;
/** @var string|bool Reason all LBs are read-only or false if not */
protected $readOnlyReason = false;
/** @var string|null */
private $defaultGroup = null;
const ROUND_CURSORY = 'cursory';
const ROUND_BEGINNING = 'within-begin';
const ROUND_COMMITTING = 'within-commit';
const ROUND_ROLLING_BACK = 'within-rollback';
const ROUND_COMMIT_CALLBACKS = 'within-commit-callbacks';
const ROUND_ROLLBACK_CALLBACKS = 'within-rollback-callbacks';
private static $loggerFields =
[ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
public function __construct( array $conf ) {
$this->localDomain = isset( $conf['localDomain'] )
? DatabaseDomain::newFromId( $conf['localDomain'] )
: DatabaseDomain::newUnspecified();
if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
$this->readOnlyReason = $conf['readOnlyReason'];
}
$this->srvCache = $conf['srvCache'] ?? new EmptyBagOStuff();
$this->memStash = $conf['memStash'] ?? new EmptyBagOStuff();
$this->wanCache = $conf['wanCache'] ?? WANObjectCache::newEmpty();
foreach ( self::$loggerFields as $key ) {
$this->$key = $conf[$key] ?? new \Psr\Log\NullLogger();
}
$this->errorLogger = $conf['errorLogger'] ?? function ( Exception $e ) {
trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
};
$this->deprecationLogger = $conf['deprecationLogger'] ?? function ( $msg ) {
trigger_error( $msg, E_USER_DEPRECATED );
};
$this->profiler = $conf['profiler'] ?? null;
$this->trxProfiler = $conf['trxProfiler'] ?? new TransactionProfiler();
$this->requestInfo = [
'IPAddress' => $_SERVER[ 'REMOTE_ADDR' ] ?? '',
'UserAgent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
// Headers application can inject via LBFactory::setRequestInfo()
'ChronologyProtection' => null,
'ChronologyClientId' => null, // prior $cpClientId value from LBFactory::shutdown()
'ChronologyPositionIndex' => null // prior $cpIndex value from LBFactory::shutdown()
];
$this->cliMode = $conf['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
$this->hostname = $conf['hostname'] ?? gethostname();
$this->agent = $conf['agent'] ?? '';
$this->defaultGroup = $conf['defaultGroup'] ?? null;
$this->ticket = mt_rand();
}
public function destroy() {
$this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
$this->forEachLBCallMethod( 'disable' );
}
public function getLocalDomainID() {
return $this->localDomain->getId();
}
public function resolveDomainID( $domain ) {
return ( $domain !== false ) ? (string)$domain : $this->getLocalDomainID();
}
public function shutdown(
$mode = self::SHUTDOWN_CHRONPROT_SYNC,
callable $workCallback = null,
&$cpIndex = null,
&$cpClientId = null
) {
$chronProt = $this->getChronologyProtector();
if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
$this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
} elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
$this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
}
$cpClientId = $chronProt->getClientId();
$this->commitMasterChanges( __METHOD__ ); // sanity
}
/**
* @see ILBFactory::newMainLB()
* @param bool $domain
* @return ILoadBalancer
*/
abstract public function newMainLB( $domain = false );
/**
* @see ILBFactory::getMainLB()
* @param bool $domain
* @return ILoadBalancer
*/
abstract public function getMainLB( $domain = false );
/**
* @see ILBFactory::newExternalLB()
* @param string $cluster
* @return ILoadBalancer
*/
abstract public function newExternalLB( $cluster );
/**
* @see ILBFactory::getExternalLB()
* @param string $cluster
* @return ILoadBalancer
*/
abstract public function getExternalLB( $cluster );
/**
* Call a method of each tracked load balancer
*
* @param string $methodName
* @param array $args
*/
protected function forEachLBCallMethod( $methodName, array $args = [] ) {
$this->forEachLB(
function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
$loadBalancer->$methodName( ...$args );
},
[ $methodName, $args ]
);
}
public function flushReplicaSnapshots( $fname = __METHOD__ ) {
$this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
}
final public function commitAll( $fname = __METHOD__, array $options = [] ) {
$this->commitMasterChanges( $fname, $options );
$this->forEachLBCallMethod( 'flushMasterSnapshots', [ $fname ] );
$this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
}
final public function beginMasterChanges( $fname = __METHOD__ ) {
$this->assertTransactionRoundStage( self::ROUND_CURSORY );
$this->trxRoundStage = self::ROUND_BEGINNING;
if ( $this->trxRoundId !== false ) {
throw new DBTransactionError(
null,
"$fname: transaction round '{$this->trxRoundId}' already started."
);
}
$this->trxRoundId = $fname;
// Set DBO_TRX flags on all appropriate DBs
$this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
$this->trxRoundStage = self::ROUND_CURSORY;
}
final public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
$this->assertTransactionRoundStage( self::ROUND_CURSORY );
$this->trxRoundStage = self::ROUND_COMMITTING;
if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
throw new DBTransactionError(
null,
"$fname: transaction round '{$this->trxRoundId}' still running."
);
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
// Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
do {
$count = 0; // number of callbacks executed this iteration
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count ) {
$count += $lb->finalizeMasterChanges();
} );
} while ( $count > 0 );
$this->trxRoundId = false;
// Perform pre-commit checks, aborting on failure
$this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
// Log the DBs and methods involved in multi-DB transactions
$this->logIfMultiDbTransaction();
// Actually perform the commit on all master DB connections and revert DBO_TRX
$this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
// Run all post-commit callbacks in a separate step
$this->trxRoundStage = self::ROUND_COMMIT_CALLBACKS;
$e = $this->executePostTransactionCallbacks();
$this->trxRoundStage = self::ROUND_CURSORY;
// Throw any last post-commit callback error
if ( $e instanceof Exception ) {
throw $e;
}
}
final public function rollbackMasterChanges( $fname = __METHOD__ ) {
$this->trxRoundStage = self::ROUND_ROLLING_BACK;
$this->trxRoundId = false;
// Actually perform the rollback on all master DB connections and revert DBO_TRX
$this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
// Run all post-commit callbacks in a separate step
$this->trxRoundStage = self::ROUND_ROLLBACK_CALLBACKS;
$this->executePostTransactionCallbacks();
$this->trxRoundStage = self::ROUND_CURSORY;
}
/**
* @return Exception|null
*/
private function executePostTransactionCallbacks() {
// Run all post-commit callbacks until new ones stop getting added
$e = null; // first callback exception
do {
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
$ex = $lb->runMasterTransactionIdleCallbacks();
$e = $e ?: $ex;
} );
} while ( $this->hasMasterChanges() );
// Run all listener callbacks once
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
$ex = $lb->runMasterTransactionListenerCallbacks();
$e = $e ?: $ex;
} );
return $e;
}
public function hasTransactionRound() {
return ( $this->trxRoundId !== false );
}
public function isReadyForRoundOperations() {
return ( $this->trxRoundStage === self::ROUND_CURSORY );
}
/**
* Log query info if multi DB transactions are going to be committed now
*/
private function logIfMultiDbTransaction() {
$callersByDB = [];
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
$masterName = $lb->getServerName( $lb->getWriterIndex() );
$callers = $lb->pendingMasterChangeCallers();
if ( $callers ) {
$callersByDB[$masterName] = $callers;
}
} );
if ( count( $callersByDB ) >= 2 ) {
$dbs = implode( ', ', array_keys( $callersByDB ) );
$msg = "Multi-DB transaction [{$dbs}]:\n";
foreach ( $callersByDB as $db => $callers ) {
$msg .= "$db: " . implode( '; ', $callers ) . "\n";
}
$this->queryLogger->info( $msg );
}
}
public function hasMasterChanges() {
$ret = false;
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
$ret = $ret || $lb->hasMasterChanges();
} );
return $ret;
}
public function laggedReplicaUsed() {
$ret = false;
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
$ret = $ret || $lb->laggedReplicaUsed();
} );
return $ret;
}
public function hasOrMadeRecentMasterChanges( $age = null ) {
$ret = false;
$this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
$ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
} );
return $ret;
}
public function waitForReplication( array $opts = [] ) {
$opts += [
'domain' => false,
'cluster' => false,
'timeout' => $this->cliMode ? 60 : 1,
'ifWritesSince' => null
];
if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
$opts['domain'] = $opts['wiki']; // b/c
}
// Figure out which clusters need to be checked
/** @var ILoadBalancer[] $lbs */
$lbs = [];
if ( $opts['cluster'] !== false ) {
$lbs[] = $this->getExternalLB( $opts['cluster'] );
} elseif ( $opts['domain'] !== false ) {
$lbs[] = $this->getMainLB( $opts['domain'] );
} else {
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
$lbs[] = $lb;
} );
if ( !$lbs ) {
return; // nothing actually used
}
}
// Get all the master positions of applicable DBs right now.
// This can be faster since waiting on one cluster reduces the
// time needed to wait on the next clusters.
$masterPositions = array_fill( 0, count( $lbs ), false );
foreach ( $lbs as $i => $lb ) {
if ( $lb->getServerCount() <= 1 ) {
// T29975 - Don't try to wait for replica DBs if there are none
// Prevents permission error when getting master position
continue;
} elseif ( $opts['ifWritesSince']
&& $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
) {
continue; // no writes since the last wait
}
$masterPositions[$i] = $lb->getMasterPos();
}
// Run any listener callbacks *after* getting the DB positions. The more
// time spent in the callbacks, the less time is spent in waitForAll().
foreach ( $this->replicationWaitCallbacks as $callback ) {
$callback();
}
$failed = [];
foreach ( $lbs as $i => $lb ) {
if ( $masterPositions[$i] ) {
// The RDBMS may not support getMasterPos()
if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
$failed[] = $lb->getServerName( $lb->getWriterIndex() );
}
}
}
return !$failed;
}
public function setWaitForReplicationListener( $name, callable $callback = null ) {
if ( $callback ) {
$this->replicationWaitCallbacks[$name] = $callback;
} else {
unset( $this->replicationWaitCallbacks[$name] );
}
}
public function getEmptyTransactionTicket( $fname ) {
if ( $this->hasMasterChanges() ) {
$this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
( new RuntimeException() )->getTraceAsString() );
return null;
}
return $this->ticket;
}
final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
if ( $ticket !== $this->ticket ) {
$this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
( new RuntimeException() )->getTraceAsString() );
return;
}
// The transaction owner and any caller with the empty transaction ticket can commit
// so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
$this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
$fnameEffective = $this->trxRoundId;
} else {
$fnameEffective = $fname;
}
$this->commitMasterChanges( $fnameEffective );
$waitSucceeded = $this->waitForReplication( $opts );
// If a nested caller committed on behalf of $fname, start another empty $fname
// transaction, leaving the caller with the same empty transaction state as before.
if ( $fnameEffective !== $fname ) {
$this->beginMasterChanges( $fnameEffective );
}
return $waitSucceeded;
}
public function getChronologyProtectorTouched( $dbName ) {
return $this->getChronologyProtector()->getTouched( $dbName );
}
public function disableChronologyProtection() {
$this->getChronologyProtector()->setEnabled( false );
}
/**
* @return ChronologyProtector
*/
protected function getChronologyProtector() {
if ( $this->chronProt ) {
return $this->chronProt;
}
$this->chronProt = new ChronologyProtector(
$this->memStash,
[
'ip' => $this->requestInfo['IPAddress'],
'agent' => $this->requestInfo['UserAgent'],
'clientId' => $this->requestInfo['ChronologyClientId']
],
$this->requestInfo['ChronologyPositionIndex']
);
$this->chronProt->setLogger( $this->replLogger );
if ( $this->cliMode ) {
$this->chronProt->setEnabled( false );
} elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
// Request opted out of using position wait logic. This is useful for requests
// done by the job queue or background ETL that do not have a meaningful session.
$this->chronProt->setWaitEnabled( false );
} elseif ( $this->memStash instanceof EmptyBagOStuff ) {
// No where to store any DB positions and wait for them to appear
$this->chronProt->setEnabled( false );
$this->replLogger->info( 'Cannot use ChronologyProtector with EmptyBagOStuff.' );
}
$this->replLogger->debug( __METHOD__ . ': using request info ' .
json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
return $this->chronProt;
}
/**
* Get and record all of the staged DB positions into persistent memory storage
*
* @param ChronologyProtector $cp
* @param callable|null $workCallback Work to do instead of waiting on syncing positions
* @param string $mode One of (sync, async); whether to wait on remote datacenters
* @param int|null &$cpIndex DB position key write counter; incremented on update
*/
protected function shutdownChronologyProtector(
ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
) {
// Record all the master positions needed
$this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
$cp->shutdownLB( $lb );
} );
// Write them to the persistent stash. Try to do something useful by running $work
// while ChronologyProtector waits for the stash write to replicate to all DCs.
$unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
if ( $unsavedPositions && $workCallback ) {
// Invoke callback in case it did not cache the result yet
$workCallback(); // work now to block for less time in waitForAll()
}
// If the positions failed to write to the stash, at least wait on local datacenter
// replica DBs to catch up before responding. Even if there are several DCs, this increases
// the chance that the user will see their own changes immediately afterwards. As long
// as the sticky DC cookie applies (same domain), this is not even an issue.
$this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
$masterName = $lb->getServerName( $lb->getWriterIndex() );
if ( isset( $unsavedPositions[$masterName] ) ) {
$lb->waitForAll( $unsavedPositions[$masterName] );
}
} );
}
/**
* Base parameters to ILoadBalancer::__construct()
* @return array
*/
final protected function baseLoadBalancerParams() {
if ( $this->trxRoundStage === self::ROUND_COMMIT_CALLBACKS ) {
$initStage = ILoadBalancer::STAGE_POSTCOMMIT_CALLBACKS;
} elseif ( $this->trxRoundStage === self::ROUND_ROLLBACK_CALLBACKS ) {
$initStage = ILoadBalancer::STAGE_POSTROLLBACK_CALLBACKS;
} else {
$initStage = null;
}
return [
'localDomain' => $this->localDomain,
'readOnlyReason' => $this->readOnlyReason,
'srvCache' => $this->srvCache,
'wanCache' => $this->wanCache,
'profiler' => $this->profiler,
'trxProfiler' => $this->trxProfiler,
'queryLogger' => $this->queryLogger,
'connLogger' => $this->connLogger,
'replLogger' => $this->replLogger,
'errorLogger' => $this->errorLogger,
'deprecationLogger' => $this->deprecationLogger,
'hostname' => $this->hostname,
'cliMode' => $this->cliMode,
'agent' => $this->agent,
'defaultGroup' => $this->defaultGroup,
'chronologyCallback' => function ( ILoadBalancer $lb ) {
// Defer ChronologyProtector construction in case setRequestInfo() ends up
// being called later (but before the first connection attempt) (T192611)
$this->getChronologyProtector()->initLB( $lb );
},
'roundStage' => $initStage
];
}
/**
* @param ILoadBalancer $lb
*/
protected function initLoadBalancer( ILoadBalancer $lb ) {
if ( $this->trxRoundId !== false ) {
$lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
}
$lb->setTableAliases( $this->tableAliases );
$lb->setIndexAliases( $this->indexAliases );
}
public function setTableAliases( array $aliases ) {
$this->tableAliases = $aliases;
}
public function setIndexAliases( array $aliases ) {
$this->indexAliases = $aliases;
}
public function setDomainPrefix( $prefix ) {
$this->localDomain = new DatabaseDomain(
$this->localDomain->getDatabase(),
null,
$prefix
);
$this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
$lb->setDomainPrefix( $prefix );
} );
}
public function closeAll() {
$this->forEachLBCallMethod( 'closeAll', [] );
}
public function setAgentName( $agent ) {
$this->agent = $agent;
}
public function appendShutdownCPIndexAsQuery( $url, $index ) {
$usedCluster = 0;
$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
$usedCluster |= ( $lb->getServerCount() > 1 );
} );
if ( !$usedCluster ) {
return $url; // no master/replica clusters touched
}
return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
}
/**
* @param int $index Write index
* @param int $time UNIX timestamp; can be used to detect stale cookies (T190082)
* @param string $clientId Agent ID hash from ILBFactory::shutdown()
* @return string Timestamp-qualified write index of the form "<index>@<timestamp>#<hash>"
* @since 1.32
*/
public static function makeCookieValueFromCPIndex( $index, $time, $clientId ) {
return "$index@$time#$clientId";
}
/**
* @param string $value Possible result of LBFactory::makeCookieValueFromCPIndex()
* @param int $minTimestamp Lowest UNIX timestamp that a non-expired value can have
* @return array (index: int or null, clientId: string or null)
* @since 1.32
*/
public static function getCPInfoFromCookieValue( $value, $minTimestamp ) {
static $placeholder = [ 'index' => null, 'clientId' => null ];
if ( !preg_match( '/^(\d+)@(\d+)#([0-9a-f]{32})$/', $value, $m ) ) {
return $placeholder; // invalid
}
$index = (int)$m[1];
if ( $index <= 0 ) {
return $placeholder; // invalid
} elseif ( isset( $m[2] ) && $m[2] !== '' && (int)$m[2] < $minTimestamp ) {
return $placeholder; // expired
}
$clientId = ( isset( $m[3] ) && $m[3] !== '' ) ? $m[3] : null;
return [ 'index' => $index, 'clientId' => $clientId ];
}
public function setRequestInfo( array $info ) {
if ( $this->chronProt ) {
throw new LogicException( 'ChronologyProtector already initialized.' );
}
$this->requestInfo = $info + $this->requestInfo;
}
/**
* @param string $stage
*/
private function assertTransactionRoundStage( $stage ) {
if ( $this->trxRoundStage !== $stage ) {
throw new DBTransactionError(
null,
"Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
);
}
}
/**
* Make PHP ignore user aborts/disconnects until the returned
* value leaves scope. This returns null and does nothing in CLI mode.
*
* @return ScopedCallback|null
*/
final protected function getScopedPHPBehaviorForCommit() {
if ( PHP_SAPI != 'cli' ) { // https://bugs.php.net/bug.php?id=47540
$old = ignore_user_abort( true ); // avoid half-finished operations
return new ScopedCallback( function () use ( $old ) {
ignore_user_abort( $old );
} );
}
return null;
}
function __destruct() {
$this->destroy();
}
}
Zerion Mini Shell 1.0