rdbms: allow cancelation of dangling nested atomic sections

[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 5b259bd..452b4f8 100644 (file)
--- a/includes/libs/rdbms/database/Database.php
+++ b/includes/libs/rdbms/database/Database.php
@@ -212,7 +212,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
        /**
         * Array of levels of atomicity within transactions
         *
-        * @var array
+        * @var array List of (name, unique ID, savepoint ID)
         */
        private $trxAtomicLevels = [];
        /**
@@ -1293,7 +1293,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
                if ( $this->trxStatus < self::STATUS_TRX_OK ) {
                        throw new DBTransactionStateError(
                                $this,
-                               "Cannot execute query from $fname while transaction status is ERROR. ",
+                               "Cannot execute query from $fname while transaction status is ERROR.",
                                [],
                                $this->trxStatusCause
                        );
@@ -3453,58 +3453,104 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
                        $this->doSavepoint( $savepointId, $fname );
                }
 
-               $this->trxAtomicLevels[] = [ $fname, $savepointId ];
+               $sectionId = new AtomicSectionIdentifier;
+               $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
+
+               return $sectionId;
        }
 
        final public function endAtomic( $fname = __METHOD__ ) {
-               if ( !$this->trxLevel ) {
-                       throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
+               if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
+                       throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
                }
 
-               list( $savedFname, $savepointId ) = $this->trxAtomicLevels
-                       ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
+               // Check if the current section matches $fname
+               $pos = count( $this->trxAtomicLevels ) - 1;
+               list( $savedFname, , $savepointId ) = $this->trxAtomicLevels[$pos];
+
                if ( $savedFname !== $fname ) {
-                       throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
+                       throw new DBUnexpectedError(
+                               $this,
+                               "Invalid atomic section ended (got $fname but expected $savedFname)."
+                       );
                }
 
+               // Remove the last section and re-index the array
+               $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos );
+
                if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
                        $this->commit( $fname, self::FLUSHING_INTERNAL );
-               } elseif ( $savepointId && $savepointId !== 'n/a' ) {
+               } elseif ( $savepointId !== null && $savepointId !== 'n/a' ) {
                        $this->doReleaseSavepoint( $savepointId, $fname );
                }
        }
 
-       final public function cancelAtomic( $fname = __METHOD__ ) {
-               if ( !$this->trxLevel ) {
-                       throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
+       final public function cancelAtomic(
+               $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
+       ) {
+               if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
+                       throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
                }
 
-               list( $savedFname, $savepointId ) = $this->trxAtomicLevels
-                       ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
-               if ( $savedFname !== $fname ) {
-                       throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
+               if ( $sectionId !== null ) {
+                       // Find the (last) section with the given $sectionId
+                       $pos = -1;
+                       foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
+                               if ( $asId === $sectionId ) {
+                                       $pos = $i;
+                               }
+                       }
+                       if ( $pos < 0 ) {
+                               throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
+                       }
+                       // Remove all descendant sections and re-index the array
+                       $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
                }
-               if ( !$savepointId ) {
-                       throw new DBUnexpectedError( $this, "Uncancelable atomic section canceled (got $fname)." );
+
+               // Check if the current section matches $fname
+               $pos = count( $this->trxAtomicLevels ) - 1;
+               list( $savedFname, , $savepointId ) = $this->trxAtomicLevels[$pos];
+
+               if ( $savedFname !== $fname ) {
+                       throw new DBUnexpectedError(
+                               $this,
+                               "Invalid atomic section ended (got $fname but expected $savedFname)."
+                       );
                }
 
-               if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
-                       $this->rollback( $fname, self::FLUSHING_INTERNAL );
-               } elseif ( $savepointId !== 'n/a' ) {
-                       $this->doRollbackToSavepoint( $savepointId, $fname );
-                       $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
-                       $this->trxStatusIgnoredCause = null;
+               // Remove the last section and re-index the array
+               $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos );
+
+               if ( $savepointId !== null ) {
+                       // Rollback the transaction to the state just before this atomic section
+                       if ( $savepointId === 'n/a' ) {
+                               $this->rollback( $fname, self::FLUSHING_INTERNAL );
+                       } else {
+                               $this->doRollbackToSavepoint( $savepointId, $fname );
+                               $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
+                               $this->trxStatusIgnoredCause = null;
+                       }
+               } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
+                       // Put the transaction into an error state if it's not already in one
+                       $this->trxStatus = self::STATUS_TRX_ERROR;
+                       $this->trxStatusCause = new DBUnexpectedError(
+                               $this,
+                               "Uncancelable atomic section canceled (got $fname)."
+                       );
                }
 
                $this->affectedRowCount = 0; // for the sake of consistency
        }
 
-       final public function doAtomicSection( $fname, callable $callback ) {
-               $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
+       final public function doAtomicSection(
+               $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
+       ) {
+               $sectionId = $this->startAtomic( $fname, $cancelable );
                try {
                        $res = call_user_func_array( $callback, [ $this, $fname ] );
                } catch ( Exception $e ) {
-                       $this->cancelAtomic( $fname );
+                       $this->cancelAtomic( $fname, $sectionId );
+
                        throw $e;
                }
                $this->endAtomic( $fname );