ProcessCacheLRUTest.php

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<?php

class ProcessCacheLRUTest extends MediaWikiTestCase {

        function assertCacheEmpty( $cache, $msg = 'Cache should be empty' ) {
                $this->assertAttributeEquals( array(), 'cache', $cache, $msg );
        }

        function fillCache( &$cache, $numEntries ) {
                // Fill cache with three values
                for( $i=1; $i<=$numEntries; $i++) {
                        $cache->set( "cache-key-$i", "prop-$i", "value-$i" );
                }
        }

        function getExpectedCache( $cacheMaxEntries, $entryToFill ) {
                $expected = array();

                if( $entryToFill === 0 ) {
                        # The cache is empty!
                        return array();
                } elseif( $entryToFill <= $cacheMaxEntries ) {
                        # Cache is not fully filled
                        $firstKey = 1;
                } else {
                        # Cache overflowed
                        $firstKey = 1 + $entryToFill - $cacheMaxEntries;
                }

                $lastKey  = $entryToFill;

                for( $i=$firstKey; $i<=$lastKey; $i++ ) {
                        $expected["cache-key-$i"] = array( "prop-$i" => "value-$i" );
                }
                return $expected;
        }

        function testPhpUnitArrayEquality() {
                $one = array( 'A' => 1, 'B' => 2 );
                $two = array( 'B' => 2, 'A' => 1 );
                $this->assertEquals( $one, $two );  // ==
                $this->assertNotSame( $one, $two ); // ===
        }

        function testConstructorGivenInvalidValue( $maxSize ) {
                $c = new ProcessCacheLRUTestable( $maxSize );
        }

        public static function provideInvalidConstructorArg() {
                return array(
                        array( null ),
                        array( array() ),
                        array( new stdClass() ),
                        array( 0 ),
                        array( '5' ),
                        array( -1 ),
                );
        }

        function testAddAndGetAKey() {
                $oneCache = new ProcessCacheLRUTestable( 1 );
                $this->assertCacheEmpty( $oneCache );

                // First set just one value
                $oneCache->set( 'cache-key', 'prop1', 'value1' );
                $this->assertEquals( 1, $oneCache->getEntriesCount() );
                $this->assertTrue( $oneCache->has( 'cache-key', 'prop1' ) );
                $this->assertEquals( 'value1', $oneCache->get( 'cache-key', 'prop1' ) );
        }

        function testDeleteOldKey() {
                $oneCache = new ProcessCacheLRUTestable( 1 );
                $this->assertCacheEmpty( $oneCache );

                $oneCache->set( 'cache-key', 'prop1', 'value1' );
                $oneCache->set( 'cache-key', 'prop1', 'value2' );
                $this->assertEquals( 'value2', $oneCache->get( 'cache-key', 'prop1' ) );
        }

        function testFillingCache( $cacheMaxEntries, $entryToFill, $msg = '' ) {
                $cache = new ProcessCacheLRUTestable( $cacheMaxEntries );
                $this->fillCache( $cache, $entryToFill);

                $this->assertSame(
                        $this->getExpectedCache( $cacheMaxEntries, $entryToFill ),
                        $cache->getCache(),
                        "Filling a $cacheMaxEntries entries cache with $entryToFill entries"
                );

        }

        public static function provideCacheFilling() {
                // ($cacheMaxEntries, $entryToFill, $msg='')
                return array(
                        array( 1,  0 ),
                        array( 1,  1 ),
                        array( 1,  2 ), # overflow
                        array( 5, 33 ), # overflow
                );

        }

        function testReplaceExistingKeyShouldBumpEntryToTop() {
                $maxEntries = 3;

                $cache = new ProcessCacheLRUTestable( $maxEntries );
                // Fill cache leaving just one remaining slot
                $this->fillCache( $cache, $maxEntries - 1 );

                // Set an existing cache key
                $cache->set( "cache-key-1", "prop-1", "new-value-for-1" );

                $this->assertSame(
                        array(
                                'cache-key-2' => array( 'prop-2' => 'value-2' ),
                                'cache-key-1' => array( 'prop-1' => 'new-value-for-1' ),
                        ),
                        $cache->getCache()
                );
        }

        function testRecentlyAccessedKeyStickIn() {
                $cache = new ProcessCacheLRUTestable( 2 );
                $cache->set( 'first' , 'prop1', 'value1' );
                $cache->set( 'second', 'prop2', 'value2' );

                // Get first
                $cache->get( 'first', 'prop1' );
                // Cache a third value, should invalidate the least used one
                $cache->set( 'third', 'prop3', 'value3' );

                $this->assertFalse( $cache->has( 'second', 'prop2' ) );
        }

        function testReplaceExistingKeyInAFullCacheShouldBumpToTop() {
                $maxEntries = 3;

                $cache = new ProcessCacheLRUTestable( $maxEntries );
                $this->fillCache( $cache, $maxEntries );

                // Set an existing cache key
                $cache->set( "cache-key-2", "prop-2", "new-value-for-2" );
                $this->assertSame(
                        array(
                                'cache-key-1' => array( 'prop-1' => 'value-1' ),
                                'cache-key-3' => array( 'prop-3' => 'value-3' ),
                                'cache-key-2' => array( 'prop-2' => 'new-value-for-2' ),
                        ),
                        $cache->getCache()
                );
                $this->assertEquals( 'new-value-for-2',
                        $cache->get( 'cache-key-2', 'prop-2' )
                );
        }

        function testBumpExistingKeyToTop() {
                $cache = new ProcessCacheLRUTestable( 3 );
                $this->fillCache( $cache, 3 );

                // Set the very first cache key to a new value
                $cache->set( "cache-key-1", "prop-1", "new value for 1" );
                $this->assertEquals(
                        array(
                                'cache-key-2' => array( 'prop-2' => 'value-2' ),
                                'cache-key-3' => array( 'prop-3' => 'value-3' ),
                                'cache-key-1' => array( 'prop-1' => 'new value for 1' ),
                        ),
                        $cache->getCache()
                );

        }

}

class ProcessCacheLRUTestable extends ProcessCacheLRU {
        public $cache = array();

        public function getCache() {
                return $this->cache;
        }
        public function getEntriesCount() {
                return count( $this->cache );
        }
}