Merge "Move DB errors to Rdbms namespace"

diff --combined includes/libs/rdbms/loadbalancer/ILoadBalancer.php
index dbf653d,98b94fe..ceb8d07
--- 1/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
--- 2/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
@@@ -23,10 -23,6 +23,6 @@@
   */
  namespace Wikimedia\Rdbms;
  
- use DBError;
- use DBAccessError;
- use DBTransactionError;
- use DBExpectedError;
  use Exception;
  use InvalidArgumentException;
  
@@@ -135,10 -131,6 +131,10 @@@ interface ILoadBalancer 
         * If a DB_REPLICA connection has been opened already, then wait immediately.
         * Otherwise sets a variable telling it to wait if such a connection is opened.
         *
 +       * This only applies to connections to the generic replica DB for this request.
 +       * If a timeout happens when waiting, then getLaggedReplicaMode()/laggedReplicaUsed()
 +       * will return true.
 +       *
         * @param DBMasterPos|bool $pos Master position or false
         */
        public function waitFor( $pos );
@@@ -444,17 -436,13 +440,17 @@@
        /**
         * @note This method will trigger a DB connection if not yet done
         * @param string|bool $domain Domain ID, or false for the current domain
 -       * @return bool Whether the generic connection for reads is highly "lagged"
 +       * @return bool Whether the database for generic connections this request is highly "lagged"
         */
        public function getLaggedReplicaMode( $domain = false );
  
        /**
 +       * Checks whether the database for generic connections this request was both:
 +       *   - a) Already choosen due to a prior connection attempt
 +       *   - b) Considered highly "lagged"
 +       *
         * @note This method will never cause a new DB connection
 -       * @return bool Whether any generic connection used for reads was highly "lagged"
 +       * @return bool
         */
        public function laggedReplicaUsed();
  

diff --combined includes/libs/rdbms/loadbalancer/LoadBalancer.php
index e8069c0,0e07fac..c1b8a0f
--- 1/includes/libs/rdbms/loadbalancer/LoadBalancer.php
--- 2/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@@ -29,13 -29,6 +29,6 @@@ use BagOStuff
  use EmptyBagOStuff;
  use WANObjectCache;
  use ArrayUtils;
- use DBError;
- use DBAccessError;
- use DBExpectedError;
- use DBUnexpectedError;
- use DBTransactionError;
- use DBTransactionSizeError;
- use DBConnectionError;
  use InvalidArgumentException;
  use RuntimeException;
  use Exception;
@@@ -411,11 -404,7 +404,11 @@@ class LoadBalancer implements ILoadBala
                        # Replica DB connection successful.
                        # Wait for the session master pos for a short time.
                        if ( $this->mWaitForPos && $i > 0 ) {
 -                              $this->doWait( $i );
 +                              # When LoadBalancer::waitFor() set mWaitForPos, the wait will happen here.
 +                              # Be sure to update laggedReplicaMode accordingly for consistency.
 +                              if ( !$this->doWait( $i ) ) {
 +                                      $laggedReplicaMode = true;
 +                              }
                        }
                        if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
                                $this->mReadIndex = $i;
@@@ -444,7 -433,7 +437,7 @@@
                                }
                        }
                } finally {
 -                      // Restore the older position if it was higher
 +                      // Restore the older position if it was higher since this is used for lag-protection
                        $this->setWaitForPositionIfHigher( $oldPos );
                }
        }
@@@ -469,8 -458,8 +462,8 @@@
                                $ok = true; // no applicable loads
                        }
                } finally {
 -                      // Restore the older position if it was higher
 -                      $this->setWaitForPositionIfHigher( $oldPos );
 +                      # Restore the old position, as this is not used for lag-protection but for throttling
 +                      $this->mWaitForPos = $oldPos;
                }
  
                return $ok;
@@@ -489,8 -478,8 +482,8 @@@
                                }
                        }
                } finally {
 -                      // Restore the older position if it was higher
 -                      $this->setWaitForPositionIfHigher( $oldPos );
 +                      # Restore the old position, as this is not used for lag-protection but for throttling
 +                      $this->mWaitForPos = $oldPos;
                }
  
                return $ok;