$this->trxWriteCallers = [];
// First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
// Get an estimate of the replication lag before any such queries.
+ $this->trxReplicaLag = null; // clear cached value first
$this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
// T147697: make explicitTrxActive() return true until begin() finishes. This way, no
// caller will think its OK to muck around with the transaction just because startAtomic()
}
public function getSessionLagStatus() {
- return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
+ return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
}
/**
* is this lag plus transaction duration. If they don't, it is still
* safe to be pessimistic. This returns null if there is no transaction.
*
+ * This returns null if the lag status for this transaction was not yet recorded.
+ *
* @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
* @since 1.27
*/
- final protected function getTransactionLagStatus() {
- return $this->trxLevel
+ final protected function getRecordedTransactionLagStatus() {
+ return ( $this->trxLevel && $this->trxReplicaLag !== null )
? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
: null;
}