objectcache: Remove hacky testMerge_fork() method in BagOStuffTest

This method easily fails due to use of the same resource in each
thread after calling pcntl_fork(). This can cause thread-safety
problems like mysqli errors, which in turn make tests fail.

Change-Id: I4ff3657940c1d1cdad58bafb7449bdd0182cbe56

diff --git a/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php b/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
index e6b277b..4a09a2e 100644 (file)
--- a/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
+++ b/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
@@ -107,77 +107,6 @@ class BagOStuffTest extends MediaWikiTestCase {
                $this->assertEquals( $n, $calls );
        }
 
-       /**
-        * @covers BagOStuff::merge
-        * @dataProvider provideTestMerge_fork
-        */
-       public function testMerge_fork( $exists, $childWins, $resCAS ) {
-               $key = $this->cache->makeKey( self::TEST_KEY );
-               $pCallback = function ( BagOStuff $cache, $key, $oldVal ) {
-                       return ( $oldVal === false ) ? 'init-parent' : $oldVal . '-merged-parent';
-               };
-               $cCallback = function ( BagOStuff $cache, $key, $oldVal ) {
-                       return ( $oldVal === false ) ? 'init-child' : $oldVal . '-merged-child';
-               };
-
-               if ( $exists ) {
-                       $this->cache->set( $key, 'x', 5 );
-               }
-
-               /*
-                * Test concurrent merges by forking this process, if:
-                * - not manually called with --use-bagostuff
-                * - pcntl_fork is supported by the system
-                * - cache type will correctly support calls over forks
-                */
-               $fork = (bool)$this->getCliArg( 'use-bagostuff' );
-               $fork &= function_exists( 'pcntl_fork' );
-               $fork &= !$this->cache instanceof HashBagOStuff;
-               $fork &= !$this->cache instanceof EmptyBagOStuff;
-               $fork &= !$this->cache instanceof MultiWriteBagOStuff;
-               if ( $fork ) {
-                       $pid = null;
-                       // Function to start merge(), run another merge() midway through, then finish
-                       $func = function ( $cache, $key, $cur ) use ( $pCallback, $cCallback, &$pid ) {
-                               $pid = pcntl_fork();
-                               if ( $pid == -1 ) {
-                                       return false;
-                               } elseif ( $pid ) {
-                                       pcntl_wait( $status );
-
-                                       return $pCallback( $cache, $key, $cur );
-                               } else {
-                                       $this->cache->merge( $key, $cCallback, 0, 1 );
-                                       // Bail out of the outer merge() in the child process since it does not
-                                       // need to attempt to write anything. Success is checked by the parent.
-                                       parent::tearDown(); // avoid phpunit notices
-                                       exit;
-                               }
-                       };
-
-                       // attempt a merge - this should fail
-                       $merged = $this->cache->merge( $key, $func, 0, 1 );
-
-                       if ( $pid == -1 ) {
-                               return; // can't fork, ignore this test...
-                       }
-
-                       // merge has failed because child process was merging (and we only attempted once)
-                       $this->assertEquals( !$childWins, $merged );
-                       $this->assertEquals( $this->cache->get( $key ), $resCAS );
-               } else {
-                       $this->markTestSkipped( 'No pcntl methods available' );
-               }
-       }
-
-       function provideTestMerge_fork() {
-               return [
-                       // (already exists, child wins CAS, result of CAS)
-                       [ false, true, 'init-child' ],
-                       [ true, true, 'x-merged-child' ]
-               ];
-       }
-
        /**
         * @covers BagOStuff::changeTTL
         */