WANObjectCacheTest.php

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<?php

class WANObjectCacheTest extends PHPUnit_Framework_TestCase  {
    private $cache;
    private $internalCache;

    protected function setUp() {
        parent::setUp();

        $this->cache = new WANObjectCache( [
            'cache' => new HashBagOStuff(),
            'pool' => 'testcache-hash',
            'relayer' => new EventRelayerNull( [] )
        ] );

        $wanCache = TestingAccessWrapper::newFromObject( $this->cache );
        $this->internalCache = $wanCache->cache;
    }

    public function testSetAndGet( $value, $ttl ) {
        $curTTL = null;
        $asOf = null;
        $key = $this->cache->makeKey( 'x', wfRandomString() );

        $this->cache->get( $key, $curTTL, [], $asOf );
        $this->assertNull( $curTTL, "Current TTL is null" );
        $this->assertNull( $asOf, "Current as-of-time is infinite" );

        $t = microtime( true );
        $this->cache->set( $key, $value, $ttl );

        $this->assertEquals( $value, $this->cache->get( $key, $curTTL, [], $asOf ) );
        if ( is_infinite( $ttl ) || $ttl == 0 ) {
            $this->assertTrue( is_infinite( $curTTL ), "Current TTL is infinite" );
        } else {
            $this->assertGreaterThan( 0, $curTTL, "Current TTL > 0" );
            $this->assertLessThanOrEqual( $ttl, $curTTL, "Current TTL < nominal TTL" );
        }
        $this->assertGreaterThanOrEqual( $t - 1, $asOf, "As-of-time in range of set() time" );
        $this->assertLessThanOrEqual( $t + 1, $asOf, "As-of-time in range of set() time" );
    }

    public static function provideSetAndGet() {
        return [
            [ 14141, 3 ],
            [ 3535.666, 3 ],
            [ [], 3 ],
            [ null, 3 ],
            [ '0', 3 ],
            [ (object)[ 'meow' ], 3 ],
            [ INF, 3 ],
            [ '', 3 ],
            [ 'pizzacat', INF ],
        ];
    }

    public function testGetNotExists() {
        $key = $this->cache->makeGlobalKey( 'y', wfRandomString(), 'p' );
        $curTTL = null;
        $value = $this->cache->get( $key, $curTTL );

        $this->assertFalse( $value, "Non-existing key has false value" );
        $this->assertNull( $curTTL, "Non-existing key has null current TTL" );
    }

    public function testSetOver() {
        $key = wfRandomString();
        for ( $i = 0; $i < 3; ++$i ) {
            $value = wfRandomString();
            $this->cache->set( $key, $value, 3 );

            $this->assertEquals( $this->cache->get( $key ), $value );
        }
    }

    public function testStaleSet() {
        $key = wfRandomString();
        $value = wfRandomString();
        $this->cache->set( $key, $value, 3, [ 'since' => microtime( true ) - 30 ] );

        $this->assertFalse( $this->cache->get( $key ), "Stale set() value ignored" );
    }

    public function testProcessCache() {
        $hit = 0;
        $callback = function () use ( &$hit ) {
            ++$hit;
            return 42;
        };
        $keys = [ wfRandomString(), wfRandomString(), wfRandomString() ];
        $groups = [ 'thiscache:1', 'thatcache:1', 'somecache:1' ];

        foreach ( $keys as $i => $key ) {
            $this->cache->getWithSetCallback(
                $key, 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 3, $hit );

        foreach ( $keys as $i => $key ) {
            $this->cache->getWithSetCallback(
                $key, 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 3, $hit, "Values cached" );

        foreach ( $keys as $i => $key ) {
            $this->cache->getWithSetCallback(
                "$key-2", 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 6, $hit );

        foreach ( $keys as $i => $key ) {
            $this->cache->getWithSetCallback(
                "$key-2", 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 6, $hit, "New values cached" );

        foreach ( $keys as $i => $key ) {
            $this->cache->delete( $key );
            $this->cache->getWithSetCallback(
                $key, 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 9, $hit, "Values evicted" );

        $key = reset( $keys );
        // Get into cache
        $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
        $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
        $this->assertEquals( 10, $hit, "Value cached" );
        $outerCallback = function () use ( &$callback, $key ) {
            $v = $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );

            return 43 + $v;
        };
        $this->cache->getWithSetCallback( $key, 100, $outerCallback );
        $this->assertEquals( 11, $hit, "Nested callback value process cache skipped" );
    }

    public function testGetWithSetCallback( array $extOpts, $versioned ) {
        $cache = $this->cache;

        $key = wfRandomString();
        $value = wfRandomString();
        $cKey1 = wfRandomString();
        $cKey2 = wfRandomString();

        $priorValue = null;
        $priorAsOf = null;
        $wasSet = 0;
        $func = function( $old, &$ttl, &$opts, $asOf )
        use ( &$wasSet, &$priorValue, &$priorAsOf, $value )
        {
            ++$wasSet;
            $priorValue = $old;
            $priorAsOf = $asOf;
            $ttl = 20; // override with another value
            return $value;
        };

        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $func, [ 'lockTSE' => 5 ] + $extOpts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $this->assertFalse( $priorValue, "No prior value" );
        $this->assertNull( $priorAsOf, "No prior value" );

        $curTTL = null;
        $cache->get( $key, $curTTL );
        $this->assertLessThanOrEqual( 20, $curTTL, 'Current TTL between 19-20 (overriden)' );
        $this->assertGreaterThanOrEqual( 19, $curTTL, 'Current TTL between 19-20 (overriden)' );

        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $func, [
                'lowTTL' => 0,
                'lockTSE' => 5,
            ] + $extOpts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 0, $wasSet, "Value not regenerated" );

        $priorTime = microtime( true );
        usleep( 1 );
        $wasSet = 0;
        $v = $cache->getWithSetCallback(
            $key, 30, $func, [ 'checkKeys' => [ $cKey1, $cKey2 ] ] + $extOpts
        );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated due to check keys" );
        $this->assertEquals( $value, $priorValue, "Has prior value" );
        $this->assertInternalType( 'float', $priorAsOf, "Has prior value" );
        $t1 = $cache->getCheckKeyTime( $cKey1 );
        $this->assertGreaterThanOrEqual( $priorTime, $t1, 'Check keys generated on miss' );
        $t2 = $cache->getCheckKeyTime( $cKey2 );
        $this->assertGreaterThanOrEqual( $priorTime, $t2, 'Check keys generated on miss' );

        $priorTime = microtime( true );
        $wasSet = 0;
        $v = $cache->getWithSetCallback(
            $key, 30, $func, [ 'checkKeys' => [ $cKey1, $cKey2 ] ] + $extOpts
        );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated due to still-recent check keys" );
        $t1 = $cache->getCheckKeyTime( $cKey1 );
        $this->assertLessThanOrEqual( $priorTime, $t1, 'Check keys did not change again' );
        $t2 = $cache->getCheckKeyTime( $cKey2 );
        $this->assertLessThanOrEqual( $priorTime, $t2, 'Check keys did not change again' );

        $curTTL = null;
        $v = $cache->get( $key, $curTTL, [ $cKey1, $cKey2 ] );
        if ( $versioned ) {
            $this->assertEquals( $value, $v[$cache::VFLD_DATA], "Value returned" );
        } else {
            $this->assertEquals( $value, $v, "Value returned" );
        }
        $this->assertLessThanOrEqual( 0, $curTTL, "Value has current TTL < 0 due to check keys" );

        $wasSet = 0;
        $key = wfRandomString();
        $v = $cache->getWithSetCallback( $key, 30, $func, [ 'pcTTL' => 5 ] + $extOpts );
        $this->assertEquals( $value, $v, "Value returned" );
        $cache->delete( $key );
        $v = $cache->getWithSetCallback( $key, 30, $func, [ 'pcTTL' => 5 ] + $extOpts );
        $this->assertEquals( $value, $v, "Value still returned after deleted" );
        $this->assertEquals( 1, $wasSet, "Value process cached while deleted" );
    }

    public static function getWithSetCallback_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }

    public function testGetMultiWithSetCallback( array $extOpts, $versioned ) {
        $cache = $this->cache;

        $keyA = wfRandomString();
        $keyB = wfRandomString();
        $keyC = wfRandomString();
        $cKey1 = wfRandomString();
        $cKey2 = wfRandomString();

        $priorValue = null;
        $priorAsOf = null;
        $wasSet = 0;
        $genFunc = function ( $id, $old, &$ttl, &$opts, $asOf ) use (
            &$wasSet, &$priorValue, &$priorAsOf
        ) {
            ++$wasSet;
            $priorValue = $old;
            $priorAsOf = $asOf;
            $ttl = 20; // override with another value
            return "@$id$";
        };

        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyA => 3353 ] );
        $value = "@3353$";
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'lockTSE' => 5 ] + $extOpts );
        $this->assertEquals( $value, $v[$keyA], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $this->assertFalse( $priorValue, "No prior value" );
        $this->assertNull( $priorAsOf, "No prior value" );

        $curTTL = null;
        $cache->get( $keyA, $curTTL );
        $this->assertLessThanOrEqual( 20, $curTTL, 'Current TTL between 19-20 (overriden)' );
        $this->assertGreaterThanOrEqual( 19, $curTTL, 'Current TTL between 19-20 (overriden)' );

        $wasSet = 0;
        $value = "@efef$";
        $keyedIds = new ArrayIterator( [ $keyB => 'efef' ] );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'lowTTL' => 0, 'lockTSE' => 5, ] + $extOpts );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'lowTTL' => 0, 'lockTSE' => 5, ] + $extOpts );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value not regenerated" );

        $priorTime = microtime( true );
        usleep( 1 );
        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyB => 'efef' ] );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'checkKeys' => [ $cKey1, $cKey2 ] ] + $extOpts
        );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated due to check keys" );
        $this->assertEquals( $value, $priorValue, "Has prior value" );
        $this->assertInternalType( 'float', $priorAsOf, "Has prior value" );
        $t1 = $cache->getCheckKeyTime( $cKey1 );
        $this->assertGreaterThanOrEqual( $priorTime, $t1, 'Check keys generated on miss' );
        $t2 = $cache->getCheckKeyTime( $cKey2 );
        $this->assertGreaterThanOrEqual( $priorTime, $t2, 'Check keys generated on miss' );

        $priorTime = microtime( true );
        $value = "@43636$";
        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyC => 43636 ] );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'checkKeys' => [ $cKey1, $cKey2 ] ] + $extOpts
        );
        $this->assertEquals( $value, $v[$keyC], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated due to still-recent check keys" );
        $t1 = $cache->getCheckKeyTime( $cKey1 );
        $this->assertLessThanOrEqual( $priorTime, $t1, 'Check keys did not change again' );
        $t2 = $cache->getCheckKeyTime( $cKey2 );
        $this->assertLessThanOrEqual( $priorTime, $t2, 'Check keys did not change again' );

        $curTTL = null;
        $v = $cache->get( $keyC, $curTTL, [ $cKey1, $cKey2 ] );
        if ( $versioned ) {
            $this->assertEquals( $value, $v[$cache::VFLD_DATA], "Value returned" );
        } else {
            $this->assertEquals( $value, $v, "Value returned" );
        }
        $this->assertLessThanOrEqual( 0, $curTTL, "Value has current TTL < 0 due to check keys" );

        $wasSet = 0;
        $key = wfRandomString();
        $keyedIds = new ArrayIterator( [ $key => 242424 ] );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'pcTTL' => 5 ] + $extOpts );
        $this->assertEquals( "@{$keyedIds[$key]}$", $v[$key], "Value returned" );
        $cache->delete( $key );
        $keyedIds = new ArrayIterator( [ $key => 242424 ] );
        $v = $cache->getMultiWithSetCallback(
            $keyedIds, 30, $genFunc, [ 'pcTTL' => 5 ] + $extOpts );
        $this->assertEquals( "@{$keyedIds[$key]}$", $v[$key], "Value still returned after deleted" );
        $this->assertEquals( 1, $wasSet, "Value process cached while deleted" );

        $calls = 0;
        $ids = [ 1, 2, 3, 4, 5, 6 ];
        $keyFunc = function ( $id, WANObjectCache $wanCache ) {
            return $wanCache->makeKey( 'test', $id );
        };
        $keyedIds = $cache->makeMultiKeys( $ids, $keyFunc );
        $genFunc = function ( $id, $oldValue, &$ttl, array &$setops ) use ( &$calls ) {
            ++$calls;

            return "val-{$id}";
        };
        $values = $cache->getMultiWithSetCallback( $keyedIds, 10, $genFunc );

        $this->assertEquals(
            [ "val-1", "val-2", "val-3", "val-4", "val-5", "val-6" ],
            array_values( $values ),
            "Correct values in correct order"
        );
        $this->assertEquals(
            array_map( $keyFunc, $ids, array_fill( 0, count( $ids ), $this->cache ) ),
            array_keys( $values ),
            "Correct keys in correct order"
        );
        $this->assertEquals( count( $ids ), $calls );

        $cache->getMultiWithSetCallback( $keyedIds, 10, $genFunc );
        $this->assertEquals( count( $ids ), $calls, "Values cached" );
    }

    public static function getMultiWithSetCallback_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }

    public function testLockTSE() {
        $cache = $this->cache;
        $key = wfRandomString();
        $value = wfRandomString();

        $calls = 0;
        $func = function() use ( &$calls, $value, $cache, $key ) {
            ++$calls;
            // Immediately kill any mutex rather than waiting a second
            $cache->delete( $cache::MUTEX_KEY_PREFIX . $key );
            return $value;
        };

        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Value was populated' );

        // Acquire a lock to verify that getWithSetCallback uses lockTSE properly
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );

        $checkKeys = [ wfRandomString() ]; // new check keys => force misses
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'lockTSE' => 5, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Old value used' );
        $this->assertEquals( 1, $calls, 'Callback was not used' );

        $cache->delete( $key );
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'lockTSE' => 5, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Callback was used; interim saved' );
        $this->assertEquals( 2, $calls, 'Callback was used; interim saved' );

        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'lockTSE' => 5, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Callback was not used; used interim' );
        $this->assertEquals( 2, $calls, 'Callback was not used; used interim' );
    }

    public function testLockTSESlow() {
        $cache = $this->cache;
        $key = wfRandomString();
        $value = wfRandomString();

        $calls = 0;
        $func = function( $oldValue, &$ttl, &$setOpts ) use ( &$calls, $value, $cache, $key ) {
            ++$calls;
            $setOpts['since'] = microtime( true ) - 10;
            // Immediately kill any mutex rather than waiting a second
            $cache->delete( $cache::MUTEX_KEY_PREFIX . $key );
            return $value;
        };

        // Value should be marked as stale due to snapshot lag
        $curTTL = null;
        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( $value, $cache->get( $key, $curTTL ), 'Value was populated' );
        $this->assertLessThan( 0, $curTTL, 'Value has negative curTTL' );
        $this->assertEquals( 1, $calls, 'Value was generated' );

        // Acquire a lock to verify that getWithSetCallback uses lockTSE properly
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Callback was not used' );
    }

    public function testBusyValue() {
        $cache = $this->cache;
        $key = wfRandomString();
        $value = wfRandomString();
        $busyValue = wfRandomString();

        $calls = 0;
        $func = function() use ( &$calls, $value, $cache, $key ) {
            ++$calls;
            // Immediately kill any mutex rather than waiting a second
            $cache->delete( $cache::MUTEX_KEY_PREFIX . $key );
            return $value;
        };

        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'busyValue' => $busyValue ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Value was populated' );

        // Acquire a lock to verify that getWithSetCallback uses busyValue properly
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );

        $checkKeys = [ wfRandomString() ]; // new check keys => force misses
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'busyValue' => $busyValue, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Callback used' );
        $this->assertEquals( 2, $calls, 'Callback used' );

        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'lockTSE' => 30, 'busyValue' => $busyValue, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Old value used' );
        $this->assertEquals( 2, $calls, 'Callback was not used' );

        $cache->delete( $key ); // no value at all anymore and still locked
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'busyValue' => $busyValue, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $busyValue, $ret, 'Callback was not used; used busy value' );
        $this->assertEquals( 2, $calls, 'Callback was not used; used busy value' );

        $this->internalCache->delete( $cache::MUTEX_KEY_PREFIX . $key );
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'lockTSE' => 30, 'busyValue' => $busyValue, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Callback was used; saved interim' );
        $this->assertEquals( 3, $calls, 'Callback was used; saved interim' );

        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
        $ret = $cache->getWithSetCallback( $key, 30, $func,
            [ 'busyValue' => $busyValue, 'checkKeys' => $checkKeys ] );
        $this->assertEquals( $value, $ret, 'Callback was not used; used interim' );
        $this->assertEquals( 3, $calls, 'Callback was not used; used interim' );
    }

    public function testGetMulti() {
        $cache = $this->cache;

        $value1 = [ 'this' => 'is', 'a' => 'test' ];
        $value2 = [ 'this' => 'is', 'another' => 'test' ];

        $key1 = wfRandomString();
        $key2 = wfRandomString();
        $key3 = wfRandomString();

        $cache->set( $key1, $value1, 5 );
        $cache->set( $key2, $value2, 10 );

        $curTTLs = [];
        $this->assertEquals(
            [ $key1 => $value1, $key2 => $value2 ],
            $cache->getMulti( [ $key1, $key2, $key3 ], $curTTLs ),
            'Result array populated'
        );

        $this->assertEquals( 2, count( $curTTLs ), "Two current TTLs in array" );
        $this->assertGreaterThan( 0, $curTTLs[$key1], "Key 1 has current TTL > 0" );
        $this->assertGreaterThan( 0, $curTTLs[$key2], "Key 2 has current TTL > 0" );

        $cKey1 = wfRandomString();
        $cKey2 = wfRandomString();

        $priorTime = microtime( true );
        usleep( 1 );
        $curTTLs = [];
        $this->assertEquals(
            [ $key1 => $value1, $key2 => $value2 ],
            $cache->getMulti( [ $key1, $key2, $key3 ], $curTTLs, [ $cKey1, $cKey2 ] ),
            "Result array populated even with new check keys"
        );
        $t1 = $cache->getCheckKeyTime( $cKey1 );
        $this->assertGreaterThanOrEqual( $priorTime, $t1, 'Check key 1 generated on miss' );
        $t2 = $cache->getCheckKeyTime( $cKey2 );
        $this->assertGreaterThanOrEqual( $priorTime, $t2, 'Check key 2 generated on miss' );
        $this->assertEquals( 2, count( $curTTLs ), "Current TTLs array set" );
        $this->assertLessThanOrEqual( 0, $curTTLs[$key1], 'Key 1 has current TTL <= 0' );
        $this->assertLessThanOrEqual( 0, $curTTLs[$key2], 'Key 2 has current TTL <= 0' );

        usleep( 1 );
        $curTTLs = [];
        $this->assertEquals(
            [ $key1 => $value1, $key2 => $value2 ],
            $cache->getMulti( [ $key1, $key2, $key3 ], $curTTLs, [ $cKey1, $cKey2 ] ),
            "Result array still populated even with new check keys"
        );
        $this->assertEquals( 2, count( $curTTLs ), "Current TTLs still array set" );
        $this->assertLessThan( 0, $curTTLs[$key1], 'Key 1 has negative current TTL' );
        $this->assertLessThan( 0, $curTTLs[$key2], 'Key 2 has negative current TTL' );
    }

    public function testGetMultiCheckKeys() {
        $cache = $this->cache;

        $checkAll = wfRandomString();
        $check1 = wfRandomString();
        $check2 = wfRandomString();
        $check3 = wfRandomString();
        $value1 = wfRandomString();
        $value2 = wfRandomString();

        // Fake initial check key to be set in the past. Otherwise we'd have to sleep for
        // several seconds during the test to assert the behaviour.
        foreach ( [ $checkAll, $check1, $check2 ] as $checkKey ) {
            $cache->touchCheckKey( $checkKey, WANObjectCache::HOLDOFF_NONE );
        }
        usleep( 100 );

        $cache->set( 'key1', $value1, 10 );
        $cache->set( 'key2', $value2, 10 );

        $curTTLs = [];
        $result = $cache->getMulti( [ 'key1', 'key2', 'key3' ], $curTTLs, [
            'key1' => $check1,
            $checkAll,
            'key2' => $check2,
            'key3' => $check3,
        ] );
        $this->assertEquals(
            [ 'key1' => $value1, 'key2' => $value2 ],
            $result,
            'Initial values'
        );
        $this->assertGreaterThanOrEqual( 9.5, $curTTLs['key1'], 'Initial ttls' );
        $this->assertLessThanOrEqual( 10.5, $curTTLs['key1'], 'Initial ttls' );
        $this->assertGreaterThanOrEqual( 9.5, $curTTLs['key2'], 'Initial ttls' );
        $this->assertLessThanOrEqual( 10.5, $curTTLs['key2'], 'Initial ttls' );

        $cache->touchCheckKey( $check1 );

        $curTTLs = [];
        $result = $cache->getMulti( [ 'key1', 'key2', 'key3' ], $curTTLs, [
            'key1' => $check1,
            $checkAll,
            'key2' => $check2,
            'key3' => $check3,
        ] );
        $this->assertEquals(
            [ 'key1' => $value1, 'key2' => $value2 ],
            $result,
            'key1 expired by check1, but value still provided'
        );
        $this->assertLessThan( 0, $curTTLs['key1'], 'key1 TTL expired' );
        $this->assertGreaterThan( 0, $curTTLs['key2'], 'key2 still valid' );

        $cache->touchCheckKey( $checkAll );

        $curTTLs = [];
        $result = $cache->getMulti( [ 'key1', 'key2', 'key3' ], $curTTLs, [
            'key1' => $check1,
            $checkAll,
            'key2' => $check2,
            'key3' => $check3,
        ] );
        $this->assertEquals(
            [ 'key1' => $value1, 'key2' => $value2 ],
            $result,
            'All keys expired by checkAll, but value still provided'
        );
        $this->assertLessThan( 0, $curTTLs['key1'], 'key1 expired by checkAll' );
        $this->assertLessThan( 0, $curTTLs['key2'], 'key2 expired by checkAll' );
    }

    public function testCheckKeyInitHoldoff() {
        $cache = $this->cache;

        for ( $i = 0; $i < 500; ++$i ) {
            $key = wfRandomString();
            $checkKey = wfRandomString();
            // miss, set, hit
            $cache->get( $key, $curTTL, [ $checkKey ] );
            $cache->set( $key, 'val', 10 );
            $curTTL = null;
            $v = $cache->get( $key, $curTTL, [ $checkKey ] );

            $this->assertEquals( 'val', $v );
            $this->assertLessThan( 0, $curTTL, "Step $i: CTL < 0 (miss/set/hit)" );
        }

        for ( $i = 0; $i < 500; ++$i ) {
            $key = wfRandomString();
            $checkKey = wfRandomString();
            // set, hit
            $cache->set( $key, 'val', 10 );
            $curTTL = null;
            $v = $cache->get( $key, $curTTL, [ $checkKey ] );

            $this->assertEquals( 'val', $v );
            $this->assertLessThan( 0, $curTTL, "Step $i: CTL < 0 (set/hit)" );
        }
    }

    public function testDelete() {
        $key = wfRandomString();
        $value = wfRandomString();
        $this->cache->set( $key, $value );

        $curTTL = null;
        $v = $this->cache->get( $key, $curTTL );
        $this->assertEquals( $value, $v, "Key was created with value" );
        $this->assertGreaterThan( 0, $curTTL, "Existing key has current TTL > 0" );

        $this->cache->delete( $key );

        $curTTL = null;
        $v = $this->cache->get( $key, $curTTL );
        $this->assertFalse( $v, "Deleted key has false value" );
        $this->assertLessThan( 0, $curTTL, "Deleted key has current TTL < 0" );

        $this->cache->set( $key, $value . 'more' );
        $v = $this->cache->get( $key, $curTTL );
        $this->assertFalse( $v, "Deleted key is tombstoned and has false value" );
        $this->assertLessThan( 0, $curTTL, "Deleted key is tombstoned and has current TTL < 0" );

        $this->cache->set( $key, $value );
        $this->cache->delete( $key, WANObjectCache::HOLDOFF_NONE );

        $curTTL = null;
        $v = $this->cache->get( $key, $curTTL );
        $this->assertFalse( $v, "Deleted key has false value" );
        $this->assertNull( $curTTL, "Deleted key has null current TTL" );

        $this->cache->set( $key, $value );
        $v = $this->cache->get( $key, $curTTL );
        $this->assertEquals( $value, $v, "Key was created with value" );
        $this->assertGreaterThan( 0, $curTTL, "Existing key has current TTL > 0" );
    }

    public function testGetWithSetCallback_versions( array $extOpts, $versioned ) {
        $cache = $this->cache;

        $key = wfRandomString();
        $value = wfRandomString();

        $wasSet = 0;
        $func = function( $old, &$ttl ) use ( &$wasSet, $value ) {
            ++$wasSet;
            return $value;
        };

        // Set the main key (version N if versioned)
        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $func, $extOpts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $cache->getWithSetCallback( $key, 30, $func, $extOpts );
        $this->assertEquals( 1, $wasSet, "Value not regenerated" );
        // Set the key for version N+1 (if versioned)
        if ( $versioned ) {
            $verOpts = [ 'version' => $extOpts['version'] + 1 ];

            $wasSet = 0;
            $v = $cache->getWithSetCallback( $key, 30, $func, $verOpts + $extOpts );
            $this->assertEquals( $value, $v, "Value returned" );
            $this->assertEquals( 1, $wasSet, "Value regenerated" );

            $wasSet = 0;
            $v = $cache->getWithSetCallback( $key, 30, $func, $verOpts + $extOpts );
            $this->assertEquals( $value, $v, "Value returned" );
            $this->assertEquals( 0, $wasSet, "Value not regenerated" );
        }

        $wasSet = 0;
        $cache->getWithSetCallback( $key, 30, $func, $extOpts );
        $this->assertEquals( 0, $wasSet, "Value not regenerated" );

        $wasSet = 0;
        $cache->delete( $key );
        $v = $cache->getWithSetCallback( $key, 30, $func, $extOpts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );

        if ( $versioned ) {
            $wasSet = 0;
            $verOpts = [ 'version' => $extOpts['version'] + 1 ];
            $v = $cache->getWithSetCallback( $key, 30, $func, $verOpts + $extOpts );
            $this->assertEquals( $value, $v, "Value returned" );
            $this->assertEquals( 1, $wasSet, "Value regenerated" );
        }
    }

    public static function getWithSetCallback_versions_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }

    public function testTouchKeys() {
        $key = wfRandomString();

        $priorTime = microtime( true );
        usleep( 100 );
        $t0 = $this->cache->getCheckKeyTime( $key );
        $this->assertGreaterThanOrEqual( $priorTime, $t0, 'Check key auto-created' );

        $priorTime = microtime( true );
        usleep( 100 );
        $this->cache->touchCheckKey( $key );
        $t1 = $this->cache->getCheckKeyTime( $key );
        $this->assertGreaterThanOrEqual( $priorTime, $t1, 'Check key created' );

        $t2 = $this->cache->getCheckKeyTime( $key );
        $this->assertEquals( $t1, $t2, 'Check key time did not change' );

        usleep( 100 );
        $this->cache->touchCheckKey( $key );
        $t3 = $this->cache->getCheckKeyTime( $key );
        $this->assertGreaterThan( $t2, $t3, 'Check key time increased' );

        $t4 = $this->cache->getCheckKeyTime( $key );
        $this->assertEquals( $t3, $t4, 'Check key time did not change' );

        usleep( 100 );
        $this->cache->resetCheckKey( $key );
        $t5 = $this->cache->getCheckKeyTime( $key );
        $this->assertGreaterThan( $t4, $t5, 'Check key time increased' );

        $t6 = $this->cache->getCheckKeyTime( $key );
        $this->assertEquals( $t5, $t6, 'Check key time did not change' );
    }

    public function testGetWithSeveralCheckKeys() {
        $key = wfRandomString();
        $tKey1 = wfRandomString();
        $tKey2 = wfRandomString();
        $value = 'meow';

        // Two check keys are newer (given hold-off) than $key, another is older
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey2,
            WANObjectCache::PURGE_VAL_PREFIX . ( microtime( true ) - 3 )
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey2,
            WANObjectCache::PURGE_VAL_PREFIX . ( microtime( true ) - 5 )
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey1,
            WANObjectCache::PURGE_VAL_PREFIX . ( microtime( true ) - 30 )
        );
        $this->cache->set( $key, $value, 30 );

        $curTTL = null;
        $v = $this->cache->get( $key, $curTTL, [ $tKey1, $tKey2 ] );
        $this->assertEquals( $value, $v, "Value matches" );
        $this->assertLessThan( -4.9, $curTTL, "Correct CTL" );
        $this->assertGreaterThan( -5.1, $curTTL, "Correct CTL" );
    }

    public function testSetWithLag() {
        $value = 1;

        $key = wfRandomString();
        $opts = [ 'lag' => 300, 'since' => microtime( true ) ];
        $this->cache->set( $key, $value, 30, $opts );
        $this->assertEquals( $value, $this->cache->get( $key ), "Rep-lagged value written." );

        $key = wfRandomString();
        $opts = [ 'lag' => 0, 'since' => microtime( true ) - 300 ];
        $this->cache->set( $key, $value, 30, $opts );
        $this->assertEquals( false, $this->cache->get( $key ), "Trx-lagged value not written." );

        $key = wfRandomString();
        $opts = [ 'lag' => 5, 'since' => microtime( true ) - 5 ];
        $this->cache->set( $key, $value, 30, $opts );
        $this->assertEquals( false, $this->cache->get( $key ), "Lagged value not written." );
    }

    public function testWritePending() {
        $value = 1;

        $key = wfRandomString();
        $opts = [ 'pending' => true ];
        $this->cache->set( $key, $value, 30, $opts );
        $this->assertEquals( false, $this->cache->get( $key ), "Pending value not written." );
    }

    public function testMcRouterSupport() {
        $localBag = $this->getMock( 'EmptyBagOStuff', [ 'set', 'delete' ] );
        $localBag->expects( $this->never() )->method( 'set' );
        $localBag->expects( $this->never() )->method( 'delete' );
        $wanCache = new WANObjectCache( [
            'cache' => $localBag,
            'pool' => 'testcache-hash',
            'relayer' => new EventRelayerNull( [] )
        ] );
        $valFunc = function () {
            return 1;
        };

        // None of these should use broadcasting commands (e.g. SET, DELETE)
        $wanCache->get( 'x' );
        $wanCache->get( 'x', $ctl, [ 'check1' ] );
        $wanCache->getMulti( [ 'x', 'y' ] );
        $wanCache->getMulti( [ 'x', 'y' ], $ctls, [ 'check2' ] );
        $wanCache->getWithSetCallback( 'p', 30, $valFunc );
        $wanCache->getCheckKeyTime( 'zzz' );
    }

    public function testAdaptiveTTL( $ago, $maxTTL, $minTTL, $factor, $adaptiveTTL ) {
        $mtime = $ago ? time() - $ago : $ago;
        $margin = 5;
        $ttl = $this->cache->adaptiveTTL( $mtime, $maxTTL, $minTTL, $factor );

        $this->assertGreaterThanOrEqual( $adaptiveTTL - $margin, $ttl );
        $this->assertLessThanOrEqual( $adaptiveTTL + $margin, $ttl );

        $ttl = $this->cache->adaptiveTTL( (string)$mtime, $maxTTL, $minTTL, $factor );

        $this->assertGreaterThanOrEqual( $adaptiveTTL - $margin, $ttl );
        $this->assertLessThanOrEqual( $adaptiveTTL + $margin, $ttl );
    }

    public static function provideAdaptiveTTL() {
        return [
            [ 3600, 900, 30, .2, 720 ],
            [ 3600, 500, 30, .2, 500 ],
            [ 3600, 86400, 800, .2, 800 ],
            [ false, 86400, 800, .2, 800 ],
            [ null, 86400, 800, .2, 800 ]
        ];
    }
}