/** @var string Storage key name */
protected $key;
- /** @var array Map of (ip: <IP>, agent: <user-agent>) */
- protected $client;
+ /** @var string Hash of client parameters */
+ protected $clientId;
+ /** @var float|null Minimum UNIX timestamp of 1+ expected startup positions */
+ protected $waitForPosTime;
+ /** @var int Max seconds to wait on positions to appear */
+ protected $waitForPosTimeout = self::POS_WAIT_TIMEOUT;
/** @var bool Whether to no-op all method calls */
protected $enabled = true;
/** @var bool Whether to check and wait on positions */
protected $startupPositions = [];
/** @var DBMasterPos[] Map of (DB master name => position) */
protected $shutdownPositions = [];
+ /** @var float[] Map of (DB master name => 1) */
+ protected $shutdownTouchDBs = [];
+
+ /** @var integer Seconds to store positions */
+ const POSITION_TTL = 60;
+ /** @var integer Max time to wait for positions to appear */
+ const POS_WAIT_TIMEOUT = 5;
/**
* @param BagOStuff $store
* @param array $client Map of (ip: <IP>, agent: <user-agent>)
+ * @param float $posTime UNIX timestamp
* @since 1.27
*/
- public function __construct( BagOStuff $store, array $client ) {
+ public function __construct( BagOStuff $store, array $client, $posTime = null ) {
$this->store = $store;
- $this->client = $client;
- $this->key = $store->makeGlobalKey(
- 'ChronologyProtector',
- md5( $client['ip'] . "\n" . $client['agent'] )
- );
+ $this->clientId = md5( $client['ip'] . "\n" . $client['agent'] );
+ $this->key = $store->makeGlobalKey( __CLASS__, $this->clientId );
+ $this->waitForPosTime = $posTime;
}
/**
* Initialise a LoadBalancer to give it appropriate chronology protection.
*
* If the stash has a previous master position recorded, this will try to
- * make sure that the next query to a slave of that master will see changes up
+ * make sure that the next query to a replica DB of that master will see changes up
* to that position by delaying execution. The delay may timeout and allow stale
- * data if no non-lagged slaves are available.
+ * data if no non-lagged replica DBs are available.
*
* @param LoadBalancer $lb
* @return void
$masterName = $lb->getServerName( $lb->getWriterIndex() );
if ( !empty( $this->startupPositions[$masterName] ) ) {
- $info = $lb->parentInfo();
$pos = $this->startupPositions[$masterName];
- wfDebugLog( 'replication', __METHOD__ .
- ": LB '" . $info['id'] . "' waiting for master pos $pos\n" );
+ wfDebugLog( 'replication', __METHOD__ . ": LB for '$masterName' set to pos $pos\n" );
$lb->waitFor( $pos );
}
}
* @return void
*/
public function shutdownLB( LoadBalancer $lb ) {
- if ( !$this->enabled || $lb->getServerCount() <= 1 ) {
- return; // non-replicated setup or disabled
+ if ( !$this->enabled ) {
+ return; // not enabled
+ } elseif ( !$lb->hasOrMadeRecentMasterChanges( INF ) ) {
+ // Only save the position if writes have been done on the connection
+ return;
}
- $info = $lb->parentInfo();
$masterName = $lb->getServerName( $lb->getWriterIndex() );
-
- // Only save the position if writes have been done on the connection
- $db = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
- if ( !$db || !$db->doneWrites() ) {
- wfDebugLog( 'replication', __METHOD__ . ": LB {$info['id']}, no writes done\n" );
-
- return; // nothing to do
+ if ( $lb->getServerCount() > 1 ) {
+ $pos = $lb->getMasterPos();
+ wfDebugLog( 'replication', __METHOD__ . ": LB for '$masterName' has pos $pos\n" );
+ $this->shutdownPositions[$masterName] = $pos;
+ } else {
+ wfDebugLog( 'replication', __METHOD__ . ": DB '$masterName' touched\n" );
}
-
- $pos = $db->getMasterPos();
- wfDebugLog( 'replication', __METHOD__ . ": LB {$info['id']} has master pos $pos\n" );
- $this->shutdownPositions[$masterName] = $pos;
+ $this->shutdownTouchDBs[$masterName] = 1;
}
/**
* Notify the ChronologyProtector that the LBFactory is done calling shutdownLB() for now.
* May commit chronology data to persistent storage.
*
- * @return array Empty on success; returns the (db name => position) map on failure
+ * @param callable|null $workCallback Work to do instead of waiting on syncing positions
+ * @param string $mode One of (sync, async); whether to wait on remote datacenters
+ * @return DBMasterPos[] Empty on success; returns the (db name => position) map on failure
*/
- public function shutdown() {
- if ( !$this->enabled || !count( $this->shutdownPositions ) ) {
- return true; // nothing to save
+ public function shutdown( callable $workCallback = null, $mode = 'sync' ) {
+ if ( !$this->enabled ) {
+ return [];
+ }
+
+ $store = $this->store;
+ // Some callers might want to know if a user recently touched a DB.
+ // These writes do not need to block on all datacenters receiving them.
+ foreach ( $this->shutdownTouchDBs as $dbName => $unused ) {
+ $store->set(
+ $this->getTouchedKey( $this->store, $dbName ),
+ microtime( true ),
+ $store::TTL_DAY
+ );
+ }
+
+ if ( !count( $this->shutdownPositions ) ) {
+ return []; // nothing to save
}
wfDebugLog( 'replication',
// CP-protected writes should overwhemingly go to the master datacenter, so get DC-local
// lock to merge the values. Use a DC-local get() and a synchronous all-DC set(). This
// makes it possible for the BagOStuff class to write in parallel to all DCs with one RTT.
- if ( $this->store->lock( $this->key, 3 ) ) {
- $ok = $this->store->set(
+ if ( $store->lock( $this->key, 3 ) ) {
+ if ( $workCallback ) {
+ // Let the store run the work before blocking on a replication sync barrier. By the
+ // time it's done with the work, the barrier should be fast if replication caught up.
+ $store->addBusyCallback( $workCallback );
+ }
+ $ok = $store->set(
$this->key,
- self::mergePositions( $this->store->get( $this->key ), $this->shutdownPositions ),
- BagOStuff::TTL_MINUTE,
- BagOStuff::WRITE_SYNC
+ self::mergePositions( $store->get( $this->key ), $this->shutdownPositions ),
+ self::POSITION_TTL,
+ ( $mode === 'sync' ) ? $store::WRITE_SYNC : 0
);
- $this->store->unlock( $this->key );
+ $store->unlock( $this->key );
} else {
$ok = false;
}
if ( !$ok ) {
+ $bouncedPositions = $this->shutdownPositions;
// Raced out too many times or stash is down
wfDebugLog( 'replication',
__METHOD__ . ": failed to save master pos for " .
implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
);
-
- return $this->shutdownPositions;
+ } elseif ( $mode === 'sync' &&
+ $store->getQoS( $store::ATTR_SYNCWRITES ) < $store::QOS_SYNCWRITES_BE
+ ) {
+ // Positions may not be in all datacenters, force LBFactory to play it safe
+ wfDebugLog( 'replication',
+ __METHOD__ . ": store does not report ability to sync replicas. " );
+ $bouncedPositions = $this->shutdownPositions;
+ } else {
+ $bouncedPositions = [];
}
- return [];
+ return $bouncedPositions;
+ }
+
+ /**
+ * @param string $dbName DB master name (e.g. "db1052")
+ * @return float|bool UNIX timestamp when client last touched the DB; false if not on record
+ * @since 1.28
+ */
+ public function getTouched( $dbName ) {
+ return $this->store->get( $this->getTouchedKey( $this->store, $dbName ) );
+ }
+
+ /**
+ * @param BagOStuff $store
+ * @param string $dbName
+ * @return string
+ */
+ private function getTouchedKey( BagOStuff $store, $dbName ) {
+ return $store->makeGlobalKey( __CLASS__, 'mtime', $this->clientId, $dbName );
}
/**
$this->initialized = true;
if ( $this->wait ) {
- $data = $this->store->get( $this->key );
- $this->startupPositions = $data ? $data['positions'] : [];
+ // If there is an expectation to see master positions with a certain min
+ // timestamp, then block until they appear, or until a timeout is reached.
+ if ( $this->waitForPosTime ) {
+ $data = null;
+ $loop = new WaitConditionLoop(
+ function () use ( &$data ) {
+ $data = $this->store->get( $this->key );
+
+ return ( self::minPosTime( $data ) >= $this->waitForPosTime )
+ ? WaitConditionLoop::CONDITION_REACHED
+ : WaitConditionLoop::CONDITION_CONTINUE;
+ },
+ $this->waitForPosTimeout
+ );
+ $result = $loop->invoke();
+ $waitedMs = $loop->getLastWaitTime() * 1e3;
+
+ if ( $result == $loop::CONDITION_REACHED ) {
+ $msg = "expected and found pos time {$this->waitForPosTime} ({$waitedMs}ms)";
+ } else {
+ $msg = "expected but missed pos time {$this->waitForPosTime} ({$waitedMs}ms)";
+ }
+ wfDebugLog( 'replication', $msg );
+ } else {
+ $data = $this->store->get( $this->key );
+ }
+ $this->startupPositions = $data ? $data['positions'] : [];
wfDebugLog( 'replication', __METHOD__ . ": key is {$this->key} (read)\n" );
} else {
$this->startupPositions = [];
-
wfDebugLog( 'replication', __METHOD__ . ": key is {$this->key} (unread)\n" );
}
}
+ /**
+ * @param array|bool $data
+ * @return float|null
+ */
+ private static function minPosTime( $data ) {
+ if ( !isset( $data['positions'] ) ) {
+ return null;
+ }
+
+ $min = null;
+ foreach ( $data['positions'] as $pos ) {
+ /** @var DBMasterPos $pos */
+ $min = $min ? min( $pos->asOfTime(), $min ) : $pos->asOfTime();
+ }
+
+ return $min;
+ }
+
/**
* @param array|bool $curValue
* @param DBMasterPos[] $shutdownPositions
dépôts / lhc / web / wiklou.git / blobdiff