WANObjectCacheTest.php

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<?php
 
use Wikimedia\TestingAccessWrapper;
 
class WANObjectCacheTest extends PHPUnit\Framework\TestCase {
 
    use MediaWikiCoversValidator;
    use PHPUnit4And6Compat;
 
    private $cache;
    private $internalCache;
 
    protected function setUp() {
        parent::setUp();
 
        $this->cache = new WANObjectCache( [
            'cache' => new HashBagOStuff()
        ] );
 
        $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() {
        $mockWallClock = 1549343530.2053;
        $this->cache->setMockTime( $mockWallClock );
 
        $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 ) {
            // Should evict from process cache
            $this->cache->delete( $key );
            $mockWallClock += 0.001; // cached values will be newer than tombstone
            // Get into cache (specific process cache group)
            $this->cache->getWithSetCallback(
                $key, 100, $callback, [ 'pcTTL' => 5, 'pcGroup' => $groups[$i] ] );
        }
        $this->assertEquals( 9, $hit, "Values evicted by delete()" );
 
        // Get into cache (default process cache group)
        $key = reset( $keys );
        $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
        $this->assertEquals( 9, $hit, "Value recently interim-cached" );
 
        $mockWallClock += 0.2; // interim key not brand new
        $this->cache->clearProcessCache();
        $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
        $this->assertEquals( 10, $hit, "Value calculated (interim key not recent and reset)" );
        $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
        $this->assertEquals( 10, $hit, "Value process cached" );
 
        $mockWallClock += 0.2; // interim key not brand new
        $outerCallback = function () use ( &$callback, $key ) {
            $v = $this->cache->getWithSetCallback( $key, 100, $callback, [ 'pcTTL' => 5 ] );
 
            return 43 + $v;
        };
        // Outer key misses and refuses inner key process cache value
        $this->cache->getWithSetCallback( "$key-miss-outer", 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;
        };
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $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" );
 
        $mockWallClock += 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' );
 
        $mockWallClock += 0.2; // interim key is not brand new and check keys have past values
        $priorTime = $mockWallClock; // reference time
        $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" );
 
        $oldValReceived = -1;
        $oldAsOfReceived = -1;
        $checkFunc = function ( $oldVal, &$ttl, array $setOpts, $oldAsOf )
        use ( &$oldValReceived, &$oldAsOfReceived, &$wasSet ) {
            ++$wasSet;
            $oldValReceived = $oldVal;
            $oldAsOfReceived = $oldAsOf;
 
            return 'xxx' . $wasSet;
        };
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
 
        $wasSet = 0;
        $key = wfRandomString();
        $v = $cache->getWithSetCallback(
            $key, 30, $checkFunc, [ 'staleTTL' => 50 ] + $extOpts );
        $this->assertEquals( 'xxx1', $v, "Value returned" );
        $this->assertEquals( false, $oldValReceived, "Callback got no stale value" );
        $this->assertEquals( null, $oldAsOfReceived, "Callback got no stale value" );
 
        $mockWallClock += 40;
        $v = $cache->getWithSetCallback(
            $key, 30, $checkFunc, [ 'staleTTL' => 50 ] + $extOpts );
        $this->assertEquals( 'xxx2', $v, "Value still returned after expired" );
        $this->assertEquals( 2, $wasSet, "Value recalculated while expired" );
        $this->assertEquals( 'xxx1', $oldValReceived, "Callback got stale value" );
        $this->assertNotEquals( null, $oldAsOfReceived, "Callback got stale value" );
 
        $mockWallClock += 260;
        $v = $cache->getWithSetCallback(
            $key, 30, $checkFunc, [ 'staleTTL' => 50 ] + $extOpts );
        $this->assertEquals( 'xxx3', $v, "Value still returned after expired" );
        $this->assertEquals( 3, $wasSet, "Value recalculated while expired" );
        $this->assertEquals( false, $oldValReceived, "Callback got no stale value" );
        $this->assertEquals( null, $oldAsOfReceived, "Callback got no stale value" );
 
        $mockWallClock = ( $priorTime - $cache::HOLDOFF_TTL - 1 );
        $wasSet = 0;
        $key = wfRandomString();
        $checkKey = $cache->makeKey( 'template', 'X' );
        $cache->touchCheckKey( $checkKey ); // init check key
        $mockWallClock = $priorTime;
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'graceTTL' => $cache::TTL_WEEK, 'checkKeys' => [ $checkKey ] ] + $extOpts
        );
        $this->assertEquals( 'xxx1', $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value computed" );
        $this->assertEquals( false, $oldValReceived, "Callback got no stale value" );
        $this->assertEquals( null, $oldAsOfReceived, "Callback got no stale value" );
 
        $mockWallClock += $cache::TTL_HOUR; // some time passes
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'graceTTL' => $cache::TTL_WEEK, 'checkKeys' => [ $checkKey ] ] + $extOpts
        );
        $this->assertEquals( 'xxx1', $v, "Cached value returned" );
        $this->assertEquals( 1, $wasSet, "Cached value returned" );
 
        $cache->touchCheckKey( $checkKey ); // make key stale
        $mockWallClock += 0.01; // ~1 week left of grace (barely stale to avoid refreshes)
 
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'graceTTL' => $cache::TTL_WEEK, 'checkKeys' => [ $checkKey ] ] + $extOpts
        );
        $this->assertEquals( 'xxx1', $v, "Value still returned after expired (in grace)" );
        $this->assertEquals( 1, $wasSet, "Value still returned after expired (in grace)" );
 
        // Chance of refresh increase to unity as staleness approaches graceTTL
        $mockWallClock += $cache::TTL_WEEK; // 8 days of being stale
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'graceTTL' => $cache::TTL_WEEK, 'checkKeys' => [ $checkKey ] ] + $extOpts
        );
        $this->assertEquals( 'xxx2', $v, "Value was recomputed (past grace)" );
        $this->assertEquals( 2, $wasSet, "Value was recomputed (past grace)" );
        $this->assertEquals( 'xxx1', $oldValReceived, "Callback got post-grace stale value" );
        $this->assertNotEquals( null, $oldAsOfReceived, "Callback got post-grace stale value" );
    }
 
    function testGetWithSetcallback_touched( array $extOpts, $versioned ) {
        $cache = $this->cache;
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $checkFunc = function ( $oldVal, &$ttl, array $setOpts, $oldAsOf )
        use ( &$wasSet ) {
            ++$wasSet;
 
            return 'xxx' . $wasSet;
        };
 
        $key = wfRandomString();
        $wasSet = 0;
        $touched = null;
        $touchedCallback = function () use ( &$touched ) {
            return $touched;
        };
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'touchedCallback' => $touchedCallback ] + $extOpts
        );
        $mockWallClock += 60;
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'touchedCallback' => $touchedCallback ] + $extOpts
        );
        $this->assertEquals( 'xxx1', $v, "Value was computed once" );
        $this->assertEquals( 1, $wasSet, "Value was computed once" );
 
        $touched = $mockWallClock - 10;
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'touchedCallback' => $touchedCallback ] + $extOpts
        );
        $v = $cache->getWithSetCallback(
            $key,
            $cache::TTL_INDEFINITE,
            $checkFunc,
            [ 'touchedCallback' => $touchedCallback ] + $extOpts
        );
        $this->assertEquals( 'xxx2', $v, "Value was recomputed once" );
        $this->assertEquals( 2, $wasSet, "Value was recomputed once" );
    }
 
    public static function getWithSetCallback_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }
 
    public function testPreemtiveRefresh() {
        $value = 'KatCafe';
        $wasSet = 0;
        $func = function ( $old, &$ttl, &$opts, $asOf ) use ( &$wasSet, &$value )
        {
            ++$wasSet;
            return $value;
        };
 
        $cache = new NearExpiringWANObjectCache( [ 'cache' => new HashBagOStuff() ] );
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $wasSet = 0;
        $key = wfRandomString();
        $opts = [ 'lowTTL' => 30 ];
        $v = $cache->getWithSetCallback( $key, 20, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value calculated" );
 
        $mockWallClock += 0.2; // interim key is not brand new
        $v = $cache->getWithSetCallback( $key, 20, $func, $opts );
        $this->assertEquals( 2, $wasSet, "Value re-calculated" );
 
        $wasSet = 0;
        $key = wfRandomString();
        $opts = [ 'lowTTL' => 1 ];
        $v = $cache->getWithSetCallback( $key, 30, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value calculated" );
        $v = $cache->getWithSetCallback( $key, 30, $func, $opts );
        $this->assertEquals( 1, $wasSet, "Value cached" );
 
        $asycList = [];
        $asyncHandler = function ( $callback ) use ( &$asycList ) {
            $asycList[] = $callback;
        };
        $cache = new NearExpiringWANObjectCache( [
            'cache'        => new HashBagOStuff(),
            'asyncHandler' => $asyncHandler
        ] );
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $wasSet = 0;
        $key = wfRandomString();
        $opts = [ 'lowTTL' => 100 ];
        $v = $cache->getWithSetCallback( $key, 300, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value calculated" );
        $v = $cache->getWithSetCallback( $key, 300, $func, $opts );
        $this->assertEquals( 1, $wasSet, "Cached value used" );
        $this->assertEquals( $v, $value, "Value cached" );
 
        $mockWallClock += 250;
        $v = $cache->getWithSetCallback( $key, 300, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Stale value used" );
        $this->assertEquals( 1, count( $asycList ), "Refresh deferred." );
        $value = 'NewCatsInTown'; // change callback return value
        $asycList[0](); // run the refresh callback
        $asycList = [];
        $this->assertEquals( 2, $wasSet, "Value calculated at later time" );
        $this->assertEquals( 0, count( $asycList ), "No deferred refreshes added." );
        $v = $cache->getWithSetCallback( $key, 300, $func, $opts );
        $this->assertEquals( $value, $v, "New value stored" );
 
        $cache = new PopularityRefreshingWANObjectCache( [
            'cache'   => new HashBagOStuff()
        ] );
 
        $mockWallClock = $priorTime;
        $cache->setMockTime( $mockWallClock );
 
        $wasSet = 0;
        $key = wfRandomString();
        $opts = [ 'hotTTR' => 900 ];
        $v = $cache->getWithSetCallback( $key, 60, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value calculated" );
 
        $mockWallClock += 30;
 
        $v = $cache->getWithSetCallback( $key, 60, $func, $opts );
        $this->assertEquals( 1, $wasSet, "Value cached" );
 
        $mockWallClock = $priorTime;
        $wasSet = 0;
        $key = wfRandomString();
        $opts = [ 'hotTTR' => 10 ];
        $v = $cache->getWithSetCallback( $key, 60, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value calculated" );
 
        $mockWallClock += 30;
 
        $v = $cache->getWithSetCallback( $key, 60, $func, $opts );
        $this->assertEquals( $value, $v, "Value returned" );
        $this->assertEquals( 2, $wasSet, "Value re-calculated" );
    }
 
    public function testGetWithSetCallback_invalidCallback() {
        $this->setExpectedException( InvalidArgumentException::class );
        $this->cache->getWithSetCallback( 'key', 30, 'invalid callback' );
    }
 
    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$";
        };
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $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" );
        $this->assertEquals( 0, $cache->getWarmupKeyMisses(), "Keys warmed yet in process cache" );
        $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" );
        $this->assertEquals( 0, $cache->getWarmupKeyMisses(), "Keys warmed in process cache" );
 
        $mockWallClock += 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' );
 
        $mockWallClock += 0.01;
        $priorTime = $mockWallClock;
        $value = "@43636$";
        $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" );
 
        // Mock the BagOStuff to assure only one getMulti() call given process caching
        $localBag = $this->getMockBuilder( HashBagOStuff::class )
            ->setMethods( [ 'getMulti' ] )->getMock();
        $localBag->expects( $this->exactly( 1 ) )->method( 'getMulti' )->willReturn( [
            WANObjectCache::VALUE_KEY_PREFIX . 'k1' => 'val-id1',
            WANObjectCache::VALUE_KEY_PREFIX . 'k2' => 'val-id2'
        ] );
        $wanCache = new WANObjectCache( [ 'cache' => $localBag ] );
 
        // Warm the process cache
        $keyedIds = new ArrayIterator( [ 'k1' => 'id1', 'k2' => 'id2' ] );
        $this->assertEquals(
            [ 'k1' => 'val-id1', 'k2' => 'val-id2' ],
            $wanCache->getMultiWithSetCallback( $keyedIds, 10, $genFunc, [ 'pcTTL' => 5 ] )
        );
        // Use the process cache
        $this->assertEquals(
            [ 'k1' => 'val-id1', 'k2' => 'val-id2' ],
            $wanCache->getMultiWithSetCallback( $keyedIds, 10, $genFunc, [ 'pcTTL' => 5 ] )
        );
    }
 
    public static function getMultiWithSetCallback_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }
 
    public function testGetMultiWithUnionSetCallback( array $extOpts, $versioned ) {
        $cache = $this->cache;
 
        $keyA = wfRandomString();
        $keyB = wfRandomString();
        $keyC = wfRandomString();
        $cKey1 = wfRandomString();
        $cKey2 = wfRandomString();
 
        $wasSet = 0;
        $genFunc = function ( array $ids, array &$ttls, array &$setOpts ) use (
            &$wasSet, &$priorValue, &$priorAsOf
        ) {
            $newValues = [];
            foreach ( $ids as $id ) {
                ++$wasSet;
                $newValues[$id] = "@$id$";
                $ttls[$id] = 20; // override with another value
            }
 
            return $newValues;
        };
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyA => 3353 ] );
        $value = "@3353$";
        $v = $cache->getMultiWithUnionSetCallback(
            $keyedIds, 30, $genFunc, $extOpts );
        $this->assertEquals( $value, $v[$keyA], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
 
        $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->getMultiWithUnionSetCallback(
            $keyedIds, 30, $genFunc, [ 'lowTTL' => 0 ] + $extOpts );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $this->assertEquals( 0, $cache->getWarmupKeyMisses(), "Keys warmed yet in process cache" );
        $v = $cache->getMultiWithUnionSetCallback(
            $keyedIds, 30, $genFunc, [ 'lowTTL' => 0 ] + $extOpts );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value not regenerated" );
        $this->assertEquals( 0, $cache->getWarmupKeyMisses(), "Keys warmed in process cache" );
 
        $mockWallClock += 1;
 
        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyB => 'efef' ] );
        $v = $cache->getMultiWithUnionSetCallback(
            $keyedIds, 30, $genFunc, [ 'checkKeys' => [ $cKey1, $cKey2 ] ] + $extOpts
        );
        $this->assertEquals( $value, $v[$keyB], "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated due to check keys" );
        $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' );
 
        $mockWallClock += 0.01;
        $priorTime = $mockWallClock;
        $value = "@43636$";
        $wasSet = 0;
        $keyedIds = new ArrayIterator( [ $keyC => 43636 ] );
        $v = $cache->getMultiWithUnionSetCallback(
            $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->getMultiWithUnionSetCallback(
            $keyedIds, 30, $genFunc, [ 'pcTTL' => 5 ] + $extOpts );
        $this->assertEquals( "@{$keyedIds[$key]}$", $v[$key], "Value returned" );
        $cache->delete( $key );
        $keyedIds = new ArrayIterator( [ $key => 242424 ] );
        $v = $cache->getMultiWithUnionSetCallback(
            $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 ( array $ids, array &$ttls, array &$setOpts ) use ( &$calls ) {
            $newValues = [];
            foreach ( $ids as $id ) {
                ++$calls;
                $newValues[$id] = "val-{$id}";
            }
 
            return $newValues;
        };
        $values = $cache->getMultiWithUnionSetCallback( $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->getMultiWithUnionSetCallback( $keyedIds, 10, $genFunc );
        $this->assertEquals( count( $ids ), $calls, "Values cached" );
    }
 
    public static function getMultiWithUnionSetCallback_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }
 
    public function testLockTSE() {
        $cache = $this->cache;
        $key = wfRandomString();
        $value = wfRandomString();
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $calls = 0;
        $func = function () use ( &$calls, $value, $cache, $key ) {
            ++$calls;
            return $value;
        };
 
        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Value was populated' );
 
        // Acquire the mutex 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 );
        $mockWallClock += 0.001; // cached values will be newer than tombstone
        $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 (mutex failed)' );
        $this->assertEquals( 2, $calls, 'Callback was not used; used interim (mutex failed)' );
    }
 
    public function testLockTSESlow() {
        $cache = $this->cache;
        $key = wfRandomString();
        $key2 = wfRandomString();
        $value = wfRandomString();
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $calls = 0;
        $func = function ( $oldValue, &$ttl, &$setOpts ) use ( &$calls, $value, &$mockWallClock ) {
            ++$calls;
            $setOpts['since'] = $mockWallClock - 10;
            return $value;
        };
 
        // Value should be given a low logical TTL due to snapshot lag
        $curTTL = null;
        $ret = $cache->getWithSetCallback( $key, 300, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( $value, $cache->get( $key, $curTTL ), 'Value was populated' );
        $this->assertEquals( 1, $curTTL, 'Value has reduced logical TTL', 0.01 );
        $this->assertEquals( 1, $calls, 'Value was generated' );
 
        $mockWallClock += 2; // low logical TTL expired
 
        $ret = $cache->getWithSetCallback( $key, 300, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 2, $calls, 'Callback used (mutex acquired)' );
 
        $ret = $cache->getWithSetCallback( $key, 300, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 2, $calls, 'Callback was not used (interim value used)' );
 
        $mockWallClock += 2; // low logical TTL expired
        // Acquire a lock to verify that getWithSetCallback uses lockTSE properly
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
 
        $ret = $cache->getWithSetCallback( $key, 300, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 2, $calls, 'Callback was not used (mutex not acquired)' );
 
        $mockWallClock += 301; // physical TTL expired
        // Acquire a lock to verify that getWithSetCallback uses lockTSE properly
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
 
        $ret = $cache->getWithSetCallback( $key, 300, $func, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 3, $calls, 'Callback was used (mutex not acquired, not in cache)' );
 
        $calls = 0;
        $func2 = function ( $oldValue, &$ttl, &$setOpts ) use ( &$calls, $value ) {
            ++$calls;
            $setOpts['lag'] = 15;
            return $value;
        };
 
        // Value should be given a low logical TTL due to replication lag
        $curTTL = null;
        $ret = $cache->getWithSetCallback( $key2, 300, $func2, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( $value, $cache->get( $key2, $curTTL ), 'Value was populated' );
        $this->assertEquals( 30, $curTTL, 'Value has reduced logical TTL', 0.01 );
        $this->assertEquals( 1, $calls, 'Value was generated' );
 
        $ret = $cache->getWithSetCallback( $key2, 300, $func2, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Callback was used (not expired)' );
 
        $mockWallClock += 31;
 
        $ret = $cache->getWithSetCallback( $key2, 300, $func2, [ 'lockTSE' => 5 ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 2, $calls, 'Callback was used (mutex acquired)' );
    }
 
    public function testBusyValue() {
        $cache = $this->cache;
        $key = wfRandomString();
        $value = wfRandomString();
        $busyValue = wfRandomString();
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $calls = 0;
        $func = function () use ( &$calls, $value, $cache, $key ) {
            ++$calls;
            return $value;
        };
 
        $ret = $cache->getWithSetCallback( $key, 30, $func, [ 'busyValue' => $busyValue ] );
        $this->assertEquals( $value, $ret );
        $this->assertEquals( 1, $calls, 'Value was populated' );
 
        $mockWallClock += 0.2; // interim keys not brand new
 
        // 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 );
        $mockWallClock += 0.001; // cached values will be newer than tombstone
        $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();
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $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();
 
        $mockWallClock += 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' );
 
        $mockWallClock += 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();
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        // 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 );
        }
 
        $mockWallClock += 0.100;
 
        $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' );
 
        $mockWallClock += 0.100;
        $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();
        $valueV1 = wfRandomString();
        $valueV2 = [ wfRandomString() ];
 
        $wasSet = 0;
        $funcV1 = function () use ( &$wasSet, $valueV1 ) {
            ++$wasSet;
 
            return $valueV1;
        };
 
        $priorValue = false;
        $priorAsOf = null;
        $funcV2 = function ( $oldValue, &$ttl, $setOpts, $oldAsOf )
        use ( &$wasSet, $valueV2, &$priorValue, &$priorAsOf ) {
            $priorValue = $oldValue;
            $priorAsOf = $oldAsOf;
            ++$wasSet;
 
            return $valueV2; // new array format
        };
 
        // Set the main key (version N if versioned)
        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $funcV1, $extOpts );
        $this->assertEquals( $valueV1, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $cache->getWithSetCallback( $key, 30, $funcV1, $extOpts );
        $this->assertEquals( 1, $wasSet, "Value not regenerated" );
        $this->assertEquals( $valueV1, $v, "Value not regenerated" );
 
        if ( $versioned ) {
            // Set the key for version N+1 format
            $verOpts = [ 'version' => $extOpts['version'] + 1 ];
        } else {
            // Start versioning now with the unversioned key still there
            $verOpts = [ 'version' => 1 ];
        }
 
        // Value goes to secondary key since V1 already used $key
        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $funcV2, $verOpts + $extOpts );
        $this->assertEquals( $valueV2, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
        $this->assertEquals( false, $priorValue, "Old value not given due to old format" );
        $this->assertEquals( null, $priorAsOf, "Old value not given due to old format" );
 
        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $funcV2, $verOpts + $extOpts );
        $this->assertEquals( $valueV2, $v, "Value not regenerated (secondary key)" );
        $this->assertEquals( 0, $wasSet, "Value not regenerated (secondary key)" );
 
        // Clear out the older or unversioned key
        $cache->delete( $key, 0 );
 
        // Set the key for next/first versioned format
        $wasSet = 0;
        $v = $cache->getWithSetCallback( $key, 30, $funcV2, $verOpts + $extOpts );
        $this->assertEquals( $valueV2, $v, "Value returned" );
        $this->assertEquals( 1, $wasSet, "Value regenerated" );
 
        $v = $cache->getWithSetCallback( $key, 30, $funcV2, $verOpts + $extOpts );
        $this->assertEquals( $valueV2, $v, "Value not regenerated (main key)" );
        $this->assertEquals( 1, $wasSet, "Value not regenerated (main key)" );
    }
 
    public static function getWithSetCallback_versions_provider() {
        return [
            [ [], false ],
            [ [ 'version' => 1 ], true ]
        ];
    }
 
    public function testInterimHoldOffCaching() {
        $cache = $this->cache;
 
        $mockWallClock = 1549343530.2053;
        $cache->setMockTime( $mockWallClock );
 
        $value = 'CRL-40-940';
        $wasCalled = 0;
        $func = function () use ( &$wasCalled, $value ) {
            $wasCalled++;
 
            return $value;
        };
 
        $cache->useInterimHoldOffCaching( true );
 
        $key = wfRandomString( 32 );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 1, $wasCalled, 'Value cached' );
 
        $cache->delete( $key );
        $mockWallClock += 0.001; // cached values will be newer than tombstone
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 2, $wasCalled, 'Value regenerated (got mutex)' ); // sets interim
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 2, $wasCalled, 'Value interim cached' ); // reuses interim
 
        $mockWallClock += 0.2; // interim key not brand new
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 3, $wasCalled, 'Value regenerated (got mutex)' ); // sets interim
        // Lock up the mutex so interim cache is used
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 3, $wasCalled, 'Value interim cached (failed mutex)' );
        $this->internalCache->delete( $cache::MUTEX_KEY_PREFIX . $key );
 
        $cache->useInterimHoldOffCaching( false );
 
        $wasCalled = 0;
        $key = wfRandomString( 32 );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 1, $wasCalled, 'Value cached' );
        $cache->delete( $key );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 2, $wasCalled, 'Value regenerated (got mutex)' );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 3, $wasCalled, 'Value still regenerated (got mutex)' );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 4, $wasCalled, 'Value still regenerated (got mutex)' );
        // Lock up the mutex so interim cache is used
        $this->internalCache->add( $cache::MUTEX_KEY_PREFIX . $key, 1, 0 );
        $v = $cache->getWithSetCallback( $key, 60, $func );
        $this->assertEquals( 5, $wasCalled, 'Value still regenerated (failed mutex)' );
    }
 
    public function testTouchKeys() {
        $cache = $this->cache;
        $key = wfRandomString();
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $cache->setMockTime( $mockWallClock );
 
        $mockWallClock += 0.100;
        $t0 = $cache->getCheckKeyTime( $key );
        $this->assertGreaterThanOrEqual( $priorTime, $t0, 'Check key auto-created' );
 
        $priorTime = $mockWallClock;
        $mockWallClock += 0.100;
        $cache->touchCheckKey( $key );
        $t1 = $cache->getCheckKeyTime( $key );
        $this->assertGreaterThanOrEqual( $priorTime, $t1, 'Check key created' );
 
        $t2 = $cache->getCheckKeyTime( $key );
        $this->assertEquals( $t1, $t2, 'Check key time did not change' );
 
        $mockWallClock += 0.100;
        $cache->touchCheckKey( $key );
        $t3 = $cache->getCheckKeyTime( $key );
        $this->assertGreaterThan( $t2, $t3, 'Check key time increased' );
 
        $t4 = $cache->getCheckKeyTime( $key );
        $this->assertEquals( $t3, $t4, 'Check key time did not change' );
 
        $mockWallClock += 0.100;
        $cache->resetCheckKey( $key );
        $t5 = $cache->getCheckKeyTime( $key );
        $this->assertGreaterThan( $t4, $t5, 'Check key time increased' );
 
        $t6 = $cache->getCheckKeyTime( $key );
        $this->assertEquals( $t5, $t6, 'Check key time did not change' );
    }
 
    public function testGetWithSeveralCheckKeys() {
        $key = wfRandomString();
        $tKey1 = wfRandomString();
        $tKey2 = wfRandomString();
        $value = 'meow';
 
        $mockWallClock = 1549343530.2053;
        $priorTime = $mockWallClock; // reference time
        $this->cache->setMockTime( $mockWallClock );
 
        // 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 . ( $priorTime - 3 )
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey2,
            WANObjectCache::PURGE_VAL_PREFIX . ( $priorTime - 5 )
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey1,
            WANObjectCache::PURGE_VAL_PREFIX . ( $priorTime - 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 testReap() {
        $vKey1 = wfRandomString();
        $vKey2 = wfRandomString();
        $tKey1 = wfRandomString();
        $tKey2 = wfRandomString();
        $value = 'moo';
 
        $knownPurge = time() - 60;
        $goodTime = microtime( true ) - 5;
        $badTime = microtime( true ) - 300;
 
        $this->internalCache->set(
            WANObjectCache::VALUE_KEY_PREFIX . $vKey1,
            [
                WANObjectCache::FLD_VERSION => WANObjectCache::VERSION,
                WANObjectCache::FLD_VALUE => $value,
                WANObjectCache::FLD_TTL => 3600,
                WANObjectCache::FLD_TIME => $goodTime
            ]
        );
        $this->internalCache->set(
            WANObjectCache::VALUE_KEY_PREFIX . $vKey2,
            [
                WANObjectCache::FLD_VERSION => WANObjectCache::VERSION,
                WANObjectCache::FLD_VALUE => $value,
                WANObjectCache::FLD_TTL => 3600,
                WANObjectCache::FLD_TIME => $badTime
            ]
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey1,
            WANObjectCache::PURGE_VAL_PREFIX . $goodTime
        );
        $this->internalCache->set(
            WANObjectCache::TIME_KEY_PREFIX . $tKey2,
            WANObjectCache::PURGE_VAL_PREFIX . $badTime
        );
 
        $this->assertEquals( $value, $this->cache->get( $vKey1 ) );
        $this->assertEquals( $value, $this->cache->get( $vKey2 ) );
        $this->cache->reap( $vKey1, $knownPurge, $bad1 );
        $this->cache->reap( $vKey2, $knownPurge, $bad2 );
 
        $this->assertFalse( $bad1 );
        $this->assertTrue( $bad2 );
 
        $this->cache->reapCheckKey( $tKey1, $knownPurge, $tBad1 );
        $this->cache->reapCheckKey( $tKey2, $knownPurge, $tBad2 );
        $this->assertFalse( $tBad1 );
        $this->assertTrue( $tBad2 );
    }
 
    public function testReap_fail() {
        $backend = $this->getMockBuilder( EmptyBagOStuff::class )
            ->setMethods( [ 'get', 'changeTTL' ] )->getMock();
        $backend->expects( $this->once() )->method( 'get' )
            ->willReturn( [
                WANObjectCache::FLD_VERSION => WANObjectCache::VERSION,
                WANObjectCache::FLD_VALUE => 'value',
                WANObjectCache::FLD_TTL => 3600,
                WANObjectCache::FLD_TIME => 300,
            ] );
        $backend->expects( $this->once() )->method( 'changeTTL' )
            ->willReturn( false );
 
        $wanCache = new WANObjectCache( [
            'cache' => $backend
        ] );
 
        $isStale = null;
        $ret = $wanCache->reap( 'key', 360, $isStale );
        $this->assertTrue( $isStale, 'value was stale' );
        $this->assertFalse( $ret, 'changeTTL failed' );
    }
 
    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->getMockBuilder( EmptyBagOStuff::class )
            ->setMethods( [ 'set', 'delete' ] )->getMock();
        $localBag->expects( $this->never() )->method( 'set' );
        $localBag->expects( $this->never() )->method( 'delete' );
        $wanCache = new WANObjectCache( [
            'cache' => $localBag,
            'mcrouterAware' => true,
            'region' => 'pmtpa',
            'cluster' => 'mw-wan'
        ] );
        $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' );
        $wanCache->reap( 'x', time() - 300 );
        $wanCache->reap( 'zzz', time() - 300 );
    }
 
    public function testMcRouterSupportBroadcastDelete() {
        $localBag = $this->getMockBuilder( EmptyBagOStuff::class )
            ->setMethods( [ 'set' ] )->getMock();
        $wanCache = new WANObjectCache( [
            'cache' => $localBag,
            'mcrouterAware' => true,
            'region' => 'pmtpa',
            'cluster' => 'mw-wan'
        ] );
 
        $localBag->expects( $this->once() )->method( 'set' )
            ->with( "/*/mw-wan/" . $wanCache::VALUE_KEY_PREFIX . "test" );
 
        $wanCache->delete( 'test' );
    }
 
    public function testMcRouterSupportBroadcastTouchCK() {
        $localBag = $this->getMockBuilder( EmptyBagOStuff::class )
            ->setMethods( [ 'set' ] )->getMock();
        $wanCache = new WANObjectCache( [
            'cache' => $localBag,
            'mcrouterAware' => true,
            'region' => 'pmtpa',
            'cluster' => 'mw-wan'
        ] );
 
        $localBag->expects( $this->once() )->method( 'set' )
            ->with( "/*/mw-wan/" . $wanCache::TIME_KEY_PREFIX . "test" );
 
        $wanCache->touchCheckKey( 'test' );
    }
 
    public function testMcRouterSupportBroadcastResetCK() {
        $localBag = $this->getMockBuilder( EmptyBagOStuff::class )
            ->setMethods( [ 'delete' ] )->getMock();
        $wanCache = new WANObjectCache( [
            'cache' => $localBag,
            'mcrouterAware' => true,
            'region' => 'pmtpa',
            'cluster' => 'mw-wan'
        ] );
 
        $localBag->expects( $this->once() )->method( 'delete' )
            ->with( "/*/mw-wan/" . $wanCache::TIME_KEY_PREFIX . "test" );
 
        $wanCache->resetCheckKey( 'test' );
    }
 
    public function testEpoch() {
        $bag = new HashBagOStuff();
        $cache = new WANObjectCache( [ 'cache' => $bag ] );
        $key = $cache->makeGlobalKey( 'The whole of the Law' );
 
        $now = microtime( true );
        $cache->setMockTime( $now );
 
        $cache->set( $key, 'Do what thou Wilt' );
        $cache->touchCheckKey( $key );
 
        $then = $now;
        $now += 30;
        $this->assertEquals( 'Do what thou Wilt', $cache->get( $key ) );
        $this->assertEquals( $then, $cache->getCheckKeyTime( $key ), 'Check key init', 0.01 );
 
        $cache = new WANObjectCache( [
            'cache' => $bag,
            'epoch' => $now - 3600
        ] );
        $cache->setMockTime( $now );
 
        $this->assertEquals( 'Do what thou Wilt', $cache->get( $key ) );
        $this->assertEquals( $then, $cache->getCheckKeyTime( $key ), 'Check key kept', 0.01 );
 
        $now += 30;
        $cache = new WANObjectCache( [
            'cache' => $bag,
            'epoch' => $now + 3600
        ] );
        $cache->setMockTime( $now );
 
        $this->assertFalse( $cache->get( $key ), 'Key rejected due to epoch' );
        $this->assertEquals( $now, $cache->getCheckKeyTime( $key ), 'Check key reset', 0.01 );
    }
 
    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, 0.2, 720 ],
            [ 3600, 500, 30, 0.2, 500 ],
            [ 3600, 86400, 800, 0.2, 800 ],
            [ false, 86400, 800, 0.2, 800 ],
            [ null, 86400, 800, 0.2, 800 ]
        ];
    }
 
    public function testNewEmpty() {
        $this->assertInstanceOf(
            WANObjectCache::class,
            WANObjectCache::newEmpty()
        );
    }
 
    public function testSetLogger() {
        $this->assertSame( null, $this->cache->setLogger( new Psr\Log\NullLogger ) );
    }
 
    public function testGetQoS() {
        $backend = $this->getMockBuilder( HashBagOStuff::class )
            ->setMethods( [ 'getQoS' ] )->getMock();
        $backend->expects( $this->once() )->method( 'getQoS' )
            ->willReturn( BagOStuff::QOS_UNKNOWN );
        $wanCache = new WANObjectCache( [ 'cache' => $backend ] );
 
        $this->assertSame(
            $wanCache::QOS_UNKNOWN,
            $wanCache->getQoS( $wanCache::ATTR_EMULATION )
        );
    }
 
    public function testMakeKey() {
        $backend = $this->getMockBuilder( HashBagOStuff::class )
            ->setMethods( [ 'makeKey' ] )->getMock();
        $backend->expects( $this->once() )->method( 'makeKey' )
            ->willReturn( 'special' );
 
        $wanCache = new WANObjectCache( [
            'cache' => $backend
        ] );
 
        $this->assertSame( 'special', $wanCache->makeKey( 'a', 'b' ) );
    }
 
    public function testMakeGlobalKey() {
        $backend = $this->getMockBuilder( HashBagOStuff::class )
            ->setMethods( [ 'makeGlobalKey' ] )->getMock();
        $backend->expects( $this->once() )->method( 'makeGlobalKey' )
            ->willReturn( 'special' );
 
        $wanCache = new WANObjectCache( [
            'cache' => $backend
        ] );
 
        $this->assertSame( 'special', $wanCache->makeGlobalKey( 'a', 'b' ) );
    }
 
    public static function statsKeyProvider() {
        return [
            [ 'domain:page:5', 'page' ],
            [ 'domain:main-key', 'main-key' ],
            [ 'domain:page:history', 'page' ],
            [ 'missingdomainkey', 'missingdomainkey' ]
        ];
    }
 
    public function testStatsKeyClass( $key, $class ) {
        $wanCache = TestingAccessWrapper::newFromObject( new WANObjectCache( [
            'cache' => new HashBagOStuff
        ] ) );
 
        $this->assertEquals( $class, $wanCache->determineKeyClassForStats( $key ) );
    }
}
 
class NearExpiringWANObjectCache extends WANObjectCache {
    const CLOCK_SKEW = 1;
 
    protected function worthRefreshExpiring( $curTTL, $lowTTL ) {
        return ( $curTTL > 0 && ( $curTTL + self::CLOCK_SKEW ) < $lowTTL );
    }
}
 
class PopularityRefreshingWANObjectCache extends WANObjectCache {
    protected function worthRefreshPopular( $asOf, $ageNew, $timeTillRefresh, $now ) {
        return ( ( $now - $asOf ) > $timeTillRefresh );
    }
}