/** How long before it is worth doing a dummy query to test the connection */
const PING_TTL = 1.0;
+ const PING_QUERY = 'SELECT 1 AS ping';
+
+ const TINY_WRITE_SEC = .010;
+ const SLOW_WRITE_SEC = .500;
+ const SMALL_WRITE_ROWS = 100;
/** @var string SQL query */
protected $mLastQuery = '';
* @var int
*/
protected $mTrxLevel = 0;
-
/**
* Either a short hexidecimal string if a transaction is active or ""
*
* @see DatabaseBase::mTrxLevel
*/
protected $mTrxShortId = '';
-
/**
* The UNIX time that the transaction started. Callers can assume that if
* snapshot isolation is used, then the data is *at least* up to date to that
* @see DatabaseBase::mTrxLevel
*/
private $mTrxTimestamp = null;
-
/** @var float Lag estimate at the time of BEGIN */
private $mTrxSlaveLag = null;
-
/**
* Remembers the function name given for starting the most recent transaction via begin().
* Used to provide additional context for error reporting.
* @see DatabaseBase::mTrxLevel
*/
private $mTrxFname = null;
-
/**
* Record if possible write queries were done in the last transaction started
*
* @see DatabaseBase::mTrxLevel
*/
private $mTrxDoneWrites = false;
-
/**
* Record if the current transaction was started implicitly due to DBO_TRX being set.
*
* @see DatabaseBase::mTrxLevel
*/
private $mTrxAutomatic = false;
-
/**
* Array of levels of atomicity within transactions
*
* @var array
*/
private $mTrxAtomicLevels = [];
-
/**
* Record if the current transaction was started implicitly by DatabaseBase::startAtomic
*
* @var bool
*/
private $mTrxAutomaticAtomic = false;
-
/**
* Track the write query callers of the current transaction
*
* @var string[]
*/
private $mTrxWriteCallers = [];
-
/**
- * Track the seconds spent in write queries for the current transaction
- *
- * @var float
+ * @var float Seconds spent in write queries for the current transaction
*/
private $mTrxWriteDuration = 0.0;
+ /**
+ * @var integer Number of write queries for the current transaction
+ */
+ private $mTrxWriteQueryCount = 0;
+ /**
+ * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
+ */
+ private $mTrxWriteAdjDuration = 0.0;
+ /**
+ * @var integer Number of write queries counted in mTrxWriteAdjDuration
+ */
+ private $mTrxWriteAdjQueryCount = 0;
+ /**
+ * @var float RTT time estimate
+ */
+ private $mRTTEstimate = 0.0;
/** @var array Map of (name => 1) for locks obtained via lock() */
private $mNamedLocksHeld = [];
/** @var int[] Prior mFlags values */
private $priorFlags = [];
+ /** @var Profiler */
+ protected $profiler;
/** @var TransactionProfiler */
protected $trxProfiler;
* @return TransactionProfiler
*/
protected function getTransactionProfiler() {
- if ( !$this->trxProfiler ) {
- $this->trxProfiler = new TransactionProfiler();
- }
-
return $this->trxProfiler;
}
);
}
- public function pendingWriteQueryDuration() {
- return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
+ public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
+ if ( !$this->mTrxLevel ) {
+ return false;
+ } elseif ( !$this->mTrxDoneWrites ) {
+ return 0.0;
+ }
+
+ switch ( $type ) {
+ case self::ESTIMATE_DB_APPLY:
+ $this->ping( $rtt );
+ $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
+ $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
+ // For omitted queries, make them count as something at least
+ $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
+ $applyTime += self::TINY_WRITE_SEC * $omitted;
+
+ return $applyTime;
+ default: // everything
+ return $this->mTrxWriteDuration;
+ }
}
public function pendingWriteCallers() {
$this->mForeign = $foreign;
- if ( isset( $params['trxProfiler'] ) ) {
- $this->trxProfiler = $params['trxProfiler']; // override
- }
+ $this->profiler = isset( $params['profiler'] )
+ ? $params['profiler']
+ : Profiler::instance(); // @TODO: remove global state
+ $this->trxProfiler = isset( $params['trxProfiler'] )
+ ? $params['trxProfiler']
+ : new TransactionProfiler();
if ( $user ) {
$this->open( $server, $user, $password, $dbName );
}
+
}
/**
* @return bool
*/
protected function isWriteQuery( $sql ) {
- return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
+ return !preg_match(
+ '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
+ }
+
+ /**
+ * @param $sql
+ * @return string|null
+ */
+ protected function getQueryVerb( $sql ) {
+ return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
}
/**
* @return bool
*/
protected function isTransactableQuery( $sql ) {
- $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
- return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ] );
+ $verb = $this->getQueryVerb( $sql );
+ return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
}
public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
# Include query transaction state
$queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
- $profiler = Profiler::instance();
- if ( !( $profiler instanceof ProfilerStub ) ) {
- $queryProfSection = $profiler->scopedProfileIn( $queryProf );
- }
-
$startTime = microtime( true );
+ $this->profiler->profileIn( $queryProf );
$ret = $this->doQuery( $commentedSql );
- $queryRuntime = microtime( true ) - $startTime;
+ $this->profiler->profileOut( $queryProf );
+ $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
unset( $queryProfSection ); // profile out (if set)
if ( $ret !== false ) {
$this->lastPing = $startTime;
if ( $isWrite && $this->mTrxLevel ) {
- $this->mTrxWriteDuration += $queryRuntime;
+ $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
$this->mTrxWriteCallers[] = $fname;
}
}
+ if ( $sql === self::PING_QUERY ) {
+ $this->mRTTEstimate = $queryRuntime;
+ }
+
$this->getTransactionProfiler()->recordQueryCompletion(
$queryProf, $startTime, $isWrite, $this->affectedRows()
);
return $ret;
}
+ /**
+ * Update the estimated run-time of a query, not counting large row lock times
+ *
+ * LoadBalancer can be set to rollback transactions that will create huge replication
+ * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
+ * queries, like inserting a row can take a long time due to row locking. This method
+ * uses some simple heuristics to discount those cases.
+ *
+ * @param string $sql
+ * @param float $runtime Total runtime, including RTT
+ */
+ private function updateTrxWriteQueryTime( $sql, $runtime ) {
+ $indicativeOfSlaveRuntime = true;
+ if ( $runtime > self::SLOW_WRITE_SEC ) {
+ $verb = $this->getQueryVerb( $sql );
+ // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
+ if ( $verb === 'INSERT' ) {
+ $indicativeOfSlaveRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
+ } elseif ( $verb === 'REPLACE' ) {
+ $indicativeOfSlaveRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
+ }
+ }
+
+ $this->mTrxWriteDuration += $runtime;
+ $this->mTrxWriteQueryCount += 1;
+ if ( $indicativeOfSlaveRuntime ) {
+ $this->mTrxWriteAdjDuration += $runtime;
+ $this->mTrxWriteAdjQueryCount += 1;
+ }
+ }
+
private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
# Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
# Dropped connections also mean that named locks are automatically released.
$this->mTrxAtomicLevels = [];
$this->mTrxShortId = wfRandomString( 12 );
$this->mTrxWriteDuration = 0.0;
+ $this->mTrxWriteQueryCount = 0;
+ $this->mTrxWriteAdjDuration = 0.0;
+ $this->mTrxWriteAdjQueryCount = 0;
$this->mTrxWriteCallers = [];
// First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
// Get an estimate of the slave lag before then, treating estimate staleness
}
}
- public function ping() {
+ public function ping( &$rtt = null ) {
+ // Avoid hitting the server if it was hit recently
if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
- return true;
+ if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
+ $rtt = $this->mRTTEstimate;
+ return true; // don't care about $rtt
+ }
}
- $ignoreErrors = true;
- $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
// This will reconnect if possible or return false if not
- $ok = (bool)$this->query( "SELECT 1 AS ping", __METHOD__, $ignoreErrors );
+ $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
+ $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
$this->restoreFlags( self::RESTORE_PRIOR );
+ if ( $ok ) {
+ $rtt = $this->mRTTEstimate;
+ }
+
return $ok;
}
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