rdbms: rename and clarify getTransactionLagStatus method regarding begin()

[lhc/web/wiklou.git] / includes / libs / rdbms / database / Database.php

diff --git a/includes/libs/rdbms/database/Database.php b/includes/libs/rdbms/database/Database.php
index 699fee7..8739cbf 100644 (file)
--- a/includes/libs/rdbms/database/Database.php
+++ b/includes/libs/rdbms/database/Database.php
@@ -3393,6 +3393,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
                $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()
@@ -3666,7 +3667,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
        }
 
        public function getSessionLagStatus() {
-               return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
+               return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
        }
 
        /**
@@ -3677,11 +3678,13 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
         * 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;
        }