FileJournal tests
authorAryeh Gregor <ayg@aryeh.name>
Thu, 22 Aug 2019 06:47:54 +0000 (09:47 +0300)
committerDaniel Kinzler <dkinzler@wikimedia.org>
Tue, 3 Sep 2019 10:12:41 +0000 (10:12 +0000)
100% unit test coverage for FileJournal and NullFileJournal. 100%
integration test coverage for DBFileJournal. Unit tests for
DBFileJournal once it supports injection.

I removed FileJournal and NullFileJournal from the list of classes that
FileBackendTest tests. It doesn't actually test them, it just happens to
run code from them without checking its correctness at all.

Depends-On: Ic22075bb5e81b7c2c4c1b8647547aa55306a10a7
Change-Id: I46d10ab7b87c23937aa04d7ec1922abfcf3bd611

includes/filebackend/filejournal/DBFileJournal.php
includes/libs/filebackend/filejournal/FileJournal.php
tests/phpunit/MediaWikiIntegrationTestCase.php
tests/phpunit/includes/filebackend/FileBackendTest.php
tests/phpunit/includes/filebackend/filejournal/DBFileJournalIntegrationTest.php [new file with mode: 0644]
tests/phpunit/unit/includes/libs/filebackend/filejournal/FileJournalTest.php [new file with mode: 0644]
tests/phpunit/unit/includes/libs/filebackend/filejournal/NullFileJournalTest.php [new file with mode: 0644]
tests/phpunit/unit/includes/libs/filebackend/filejournal/TestFileJournal.php [new file with mode: 0644]

index 17cf8f0..7ce2edd 100644 (file)
@@ -24,6 +24,7 @@
 use MediaWiki\MediaWikiServices;
 use Wikimedia\Rdbms\IDatabase;
 use Wikimedia\Rdbms\DBError;
+use Wikimedia\Timestamp\ConvertibleTimestamp;
 
 /**
  * Version of FileJournal that logs to a DB table
@@ -36,12 +37,12 @@ class DBFileJournal extends FileJournal {
        protected $domain;
 
        /**
-        * Construct a new instance from configuration.
+        * Construct a new instance from configuration. Do not call directly, use FileJournal::factory.
         *
         * @param array $config Includes:
         *   domain: database domain ID of the wiki
         */
-       protected function __construct( array $config ) {
+       public function __construct( array $config ) {
                parent::__construct( $config );
 
                $this->domain = $config['domain'] ?? $config['wiki']; // b/c
@@ -64,7 +65,7 @@ class DBFileJournal extends FileJournal {
                        return $status;
                }
 
-               $now = wfTimestamp( TS_UNIX );
+               $now = ConvertibleTimestamp::time();
 
                $data = [];
                foreach ( $entries as $entry ) {
@@ -80,8 +81,11 @@ class DBFileJournal extends FileJournal {
 
                try {
                        $dbw->insert( 'filejournal', $data, __METHOD__ );
+                       // XXX Should we do this deterministically so it's testable? Maybe look at the last two
+                       // digits of a hash of a bunch of the data?
                        if ( mt_rand( 0, 99 ) == 0 ) {
-                               $this->purgeOldLogs(); // occasionally delete old logs
+                               // occasionally delete old logs
+                               $this->purgeOldLogs(); // @codeCoverageIgnore
                        }
                } catch ( DBError $e ) {
                        $status->fatal( 'filejournal-fail-dbquery', $this->backend );
@@ -164,7 +168,7 @@ class DBFileJournal extends FileJournal {
                }
 
                $dbw = $this->getMasterDB();
-               $dbCutoff = $dbw->timestamp( time() - 86400 * $this->ttlDays );
+               $dbCutoff = $dbw->timestamp( ConvertibleTimestamp::time() - 86400 * $this->ttlDays );
 
                $dbw->delete( 'filejournal',
                        [ 'fj_timestamp < ' . $dbw->addQuotes( $dbCutoff ) ],
index e512423..c256d72 100644 (file)
@@ -40,7 +40,7 @@ use Wikimedia\Timestamp\ConvertibleTimestamp;
 abstract class FileJournal {
        /** @var string */
        protected $backend;
-       /** @var int */
+       /** @var int|false */
        protected $ttlDays;
 
        /**
@@ -153,7 +153,7 @@ abstract class FileJournal {
         * A starting change ID and/or limit can be specified.
         *
         * @param int|null $start Starting change ID or null
-        * @param int $limit Maximum number of items to return
+        * @param int $limit Maximum number of items to return (0 = unlimited)
         * @param string|null &$next Updated to the ID of the next entry.
         * @return array List of associative arrays, each having:
         *     id         : unique, monotonic, ID for this change
index b1eb9ef..78983f9 100644 (file)
@@ -10,6 +10,7 @@ use Wikimedia\Rdbms\IDatabase;
 use Wikimedia\Rdbms\IMaintainableDatabase;
 use Wikimedia\Rdbms\Database;
 use Wikimedia\TestingAccessWrapper;
+use Wikimedia\Timestamp\ConvertibleTimestamp;
 
 /**
  * @since 1.18
@@ -657,6 +658,9 @@ abstract class MediaWikiIntegrationTestCase extends PHPUnit\Framework\TestCase {
                        $this->fail( $message );
                }
 
+               // If anything faked the time, reset it
+               ConvertibleTimestamp::setFakeTime( false );
+
                parent::tearDown();
        }
 
index 8548fde..bc3696d 100644 (file)
@@ -29,7 +29,6 @@ use Wikimedia\TestingAccessWrapper;
  * @covers FileBackendStoreShardDirIterator
  * @covers FileBackendStoreShardFileIterator
  * @covers FileBackendStoreShardListIterator
- * @covers FileJournal
  * @covers FileOp
  * @covers FileOpBatch
  * @covers HTTPFileStreamer
@@ -37,7 +36,6 @@ use Wikimedia\TestingAccessWrapper;
  * @covers MemoryFileBackend
  * @covers MoveFileOp
  * @covers MySqlLockManager
- * @covers NullFileJournal
  * @covers NullFileOp
  * @covers StoreFileOp
  * @covers TempFSFile
diff --git a/tests/phpunit/includes/filebackend/filejournal/DBFileJournalIntegrationTest.php b/tests/phpunit/includes/filebackend/filejournal/DBFileJournalIntegrationTest.php
new file mode 100644 (file)
index 0000000..9a0ba1c
--- /dev/null
@@ -0,0 +1,237 @@
+<?php
+
+use MediaWiki\MediaWikiServices;
+use Wikimedia\Timestamp\ConvertibleTimestamp;
+
+/**
+ * @coversDefaultClass DBFileJournal
+ * @covers ::__construct
+ * @covers ::getMasterDB
+ * @group Database
+ */
+class DBFileJournalIntegrationTest extends MediaWikiIntegrationTestCase {
+       public function addDBDataOnce() {
+               global $IP;
+               $db = MediaWikiServices::getInstance()->getDBLoadBalancer()->getConnection( DB_MASTER );
+               if ( $db->getType() !== 'mysql' ) {
+                       return;
+               }
+               if ( !$db->tableExists( 'filejournal' ) ) {
+                       $db->sourceFile( "$IP/maintenance/archives/patch-filejournal.sql" );
+               }
+       }
+
+       protected function setUp() {
+               parent::setUp();
+
+               $db = MediaWikiServices::getInstance()->getDBLoadBalancer()->getConnection( DB_MASTER );
+               if ( $db->getType() !== 'mysql' ) {
+                       $this->markTestSkipped( 'No filejournal schema available for this database type' );
+               }
+
+               $this->tablesUsed[] = 'filejournal';
+       }
+
+       private function getJournal( $options = [] ) {
+               return FileJournal::factory(
+                       $options + [ 'class' => DBFileJournal::class, 'domain' => wfWikiID() ],
+                       'local-backend' );
+       }
+
+       /**
+        * @covers ::doLogChangeBatch
+        */
+       public function testDoLogChangeBatch_exceptionDbConnect() {
+               $journal = $this->getJournal( [ 'domain' => 'no-such-domain' ] );
+
+               $this->assertEquals(
+                       StatusValue::newFatal( 'filejournal-fail-dbconnect', 'local-backend' ),
+                       $journal->logChangeBatch( [ [] ], 'batch' ) );
+       }
+
+       /**
+        * @covers ::doLogChangeBatch
+        */
+       public function testDoLogChangeBatch_exceptionDbQuery() {
+               MediaWikiServices::getInstance()->getConfiguredReadOnlyMode()->setReason( 'testing' );
+
+               $journal = $this->getJournal();
+
+               $this->assertEquals(
+                       StatusValue::newFatal( 'filejournal-fail-dbquery', 'local-backend' ),
+                       $journal->logChangeBatch(
+                               [ [ 'op' => null, 'path' => '', 'newSha1' => false ] ], 'batch' ) );
+       }
+
+       /**
+        * @covers ::doLogChangeBatch
+        * @covers ::doGetCurrentPosition
+        */
+       public function testDoGetCurrentPosition() {
+               $journal = $this->getJournal();
+
+               $this->assertNull( $journal->getCurrentPosition() );
+
+               $journal->logChangeBatch(
+                       [ [ 'op' => 'create', 'path' => '/path', 'newSha1' => false ] ], 'batch1' );
+
+               $this->assertSame( '1', $journal->getCurrentPosition() );
+
+               $journal->logChangeBatch(
+                       [ [ 'op' => 'create', 'path' => '/path', 'newSha1' => false ] ], 'batch2' );
+
+               $this->assertSame( '2', $journal->getCurrentPosition() );
+       }
+
+       /**
+        * @covers ::doLogChangeBatch
+        * @covers ::doGetPositionAtTime
+        */
+       public function testDoGetPositionAtTime() {
+               $journal = $this->getJournal();
+
+               $now = time();
+
+               $this->assertFalse( $journal->getPositionAtTime( $now ) );
+
+               ConvertibleTimestamp::setFakeTime( $now - 86400 );
+
+               $journal->logChangeBatch(
+                       [ [ 'op' => 'create', 'path' => '/path', 'newSha1' => false ] ], 'batch1' );
+
+               ConvertibleTimestamp::setFakeTime( $now - 3600 );
+
+               $journal->logChangeBatch(
+                       [ [ 'op' => 'create', 'path' => '/path', 'newSha1' => false ] ], 'batch2' );
+
+               $this->assertFalse( $journal->getPositionAtTime( $now - 86401 ) );
+               $this->assertSame( '1', $journal->getPositionAtTime( $now - 86400 ) );
+               $this->assertSame( '1', $journal->getPositionAtTime( $now - 3601 ) );
+               $this->assertSame( '2', $journal->getPositionAtTime( $now - 3600 ) );
+       }
+
+       /**
+        * @param int $expectedStart First index expected to be returned (0-based)
+        * @param int|null $expectedCount Number of entries expected to be returned (null for all)
+        * @param string|null|false $expectedNext Expected value of $next, or false not to pass
+        * @param array $args If any third argument is present, $next will also be tested
+        * @dataProvider provideDoGetChangeEntries
+        * @covers ::doLogChangeBatch
+        * @covers ::doGetChangeEntries
+        */
+       public function testDoGetChangeEntries(
+               $expectedStart, $expectedCount, $expectedNext, array $args
+       ) {
+               $journal = $this->getJournal();
+
+               $i = 0;
+               $makeExpectedEntry = function ( $op, $path, $newSha1, $batch, $time ) use ( &$i ) {
+                       $i++;
+                       return [
+                               'id' => (string)$i,
+                               'batch_uuid' => $batch,
+                               'backend' => 'local-backend',
+                               'path' => $path,
+                               'op' => $op ?? '',
+                               'new_sha1' => $newSha1 !== false ? $newSha1 : '0',
+                               'timestamp' => ConvertibleTimestamp::convert( TS_MW, $time ),
+                       ];
+               };
+
+               $expectedEntries = [];
+
+               $now = time();
+
+               ConvertibleTimestamp::setFakeTime( $now - 3600 );
+               $changes = [
+                       [ 'op' => 'create', 'path' => '/path1',
+                               'newSha1' => base_convert( sha1( 'a' ), 16, 36 ) ],
+                       [ 'op' => 'delete', 'path' => '/path2', 'newSha1' => false ],
+                       [ 'op' => 'null', 'path' => '', 'newSha1' => false ],
+               ];
+               $this->assertEquals( StatusValue::newGood(),
+                       $journal->logChangeBatch( $changes, 'batch1' ) );
+               foreach ( $changes as $change ) {
+                       $expectedEntries[] = $makeExpectedEntry(
+                               ...array_merge( array_values( $change ), [ 'batch1', $now - 3600 ] ) );
+               }
+
+               ConvertibleTimestamp::setFakeTime( $now - 60 );
+               $change = [ 'op' => 'update', 'path' => '/path1',
+                       'newSha1' => base_convert( sha1( 'b' ), 16, 36 ) ];
+               $this->assertEquals(
+                  StatusValue::newGood(), $journal->logChangeBatch( [ $change ], 'batch2' ) );
+               $expectedEntries[] = $makeExpectedEntry(
+                       ...array_merge( array_values( $change ), [ 'batch2', $now - 60 ] ) );
+
+               if ( $expectedNext === false ) {
+                       $this->assertSame(
+                               array_slice( $expectedEntries, $expectedStart, $expectedCount ),
+                               $journal->getChangeEntries( ...$args )
+                       );
+               } else {
+                       $next = false;
+                       $this->assertSame(
+                               array_slice( $expectedEntries, $expectedStart, $expectedCount ),
+                               $journal->getChangeEntries( $args[0], $args[1], $next )
+                       );
+                       $this->assertSame( $expectedNext, $next );
+               }
+       }
+
+       public static function provideDoGetChangeEntries() {
+               return [
+                       'No args' => [ 0, 4, false, [] ],
+                       'null' => [ 0, 4, false, [ null ] ],
+                       '1' => [ 0, 4, false, [ 1 ] ],
+                       '2' => [ 1, 3, false, [ 2 ] ],
+                       '4' => [ 3, 1, false, [ 4 ] ],
+                       '5' => [ 0, 0, false, [ 5 ] ],
+                       'null, 0' => [ 0, 4, null, [ null, 0 ] ],
+                       '1, 0' => [ 0, 4, null, [ 1, 0 ] ],
+                       '2, 0' => [ 1, 3, null, [ 2, 0 ] ],
+                       '4, 0' => [ 3, 1, null, [ 4, 0 ] ],
+                       '5, 0' => [ 0, 0, null, [ 5, 0 ] ],
+                       '1, 1' => [ 0, 1, '2', [ 1, 1 ] ],
+                       '1, 2' => [ 0, 2, '3', [ 1, 2 ] ],
+                       '1, 4' => [ 0, 4, null, [ 1, 4 ] ],
+                       '1, 5' => [ 0, 4, null, [ 1, 5 ] ],
+                       '2, 2' => [ 1, 2, '4', [ 2, 2 ] ],
+                       '1, 2 with no $next' => [ 0, 2, false, [ 1, 2 ] ],
+               ];
+       }
+
+       /**
+        * @covers ::doPurgeOldLogs
+        */
+       public function testDoPurgeOldLogs_noop() {
+               // If we tried to access the database, it would throw, because the domain doesn't exist
+               $journal = $this->getJournal( [ 'domain' => 'no-such-domain' ] );
+               $this->assertEquals( StatusValue::newGood(), $journal->purgeOldLogs() );
+       }
+
+       /**
+        * @covers ::doPurgeOldLogs
+        * @covers ::doLogChangeBatch
+        * @covers ::doGetChangeEntries
+        */
+       public function testDoPurgeOldLogs() {
+               $journal = $this->getJournal( [ 'ttlDays' => 1 ] );
+               $now = time();
+
+               // One day and one second ago
+               ConvertibleTimestamp::setFakeTime( $now - 86401 );
+               $this->assertEquals( StatusValue::newGood(), $journal->logChangeBatch(
+                       [ [ 'op' => 'null', 'path' => '', 'newSha1' => false ] ], 'batch1' ) );
+
+               // One day ago exactly, won't get purged
+               ConvertibleTimestamp::setFakeTime( $now - 86400 );
+               $this->assertEquals( StatusValue::newGood(), $journal->logChangeBatch(
+                       [ [ 'op' => 'null', 'path' => '', 'newSha1' => false ] ], 'batch2' ) );
+
+               ConvertibleTimestamp::setFakeTime( $now );
+               $this->assertCount( 2, $journal->getChangeEntries() );
+               $journal->purgeOldLogs();
+               $this->assertCount( 1, $journal->getChangeEntries() );
+       }
+}
diff --git a/tests/phpunit/unit/includes/libs/filebackend/filejournal/FileJournalTest.php b/tests/phpunit/unit/includes/libs/filebackend/filejournal/FileJournalTest.php
new file mode 100644 (file)
index 0000000..10eef7e
--- /dev/null
@@ -0,0 +1,153 @@
+<?php
+
+require_once __DIR__ . '/TestFileJournal.php';
+
+use Wikimedia\Timestamp\ConvertibleTimestamp;
+
+/**
+ * @coversDefaultClass FileJournal
+ */
+class FileJournalTest extends MediaWikiUnitTestCase {
+       private function newObj( $options = [], $backend = '' ) {
+               return FileJournal::factory(
+                       $options + [ 'class' => TestFileJournal::class ],
+                       $backend
+               );
+       }
+
+       /**
+        * @covers ::factory
+        */
+       public function testConstructor_backend() {
+               $this->assertSame( 'some_backend', $this->newObj( [], 'some_backend' )->getBackend() );
+       }
+
+       /**
+        * @covers ::__construct
+        * @covers ::factory
+        */
+       public function testConstructor_ttlDays() {
+               $this->assertSame( 42, $this->newObj( [ 'ttlDays' => 42 ] )->getTtlDays() );
+       }
+
+       /**
+        * @covers ::__construct
+        * @covers ::factory
+        */
+       public function testConstructor_noTtlDays() {
+               $this->assertSame( false, $this->newObj()->getTtlDays() );
+       }
+
+       /**
+        * @covers ::__construct
+        * @covers ::factory
+        */
+       public function testConstructor_nullTtlDays() {
+               $this->assertSame( false, $this->newObj( [ 'ttlDays' => null ] )->getTtlDays() );
+       }
+
+       /**
+        * @covers ::factory
+        */
+       public function testFactory_invalidClass() {
+               $this->setExpectedException( UnexpectedValueException::class,
+                       'Expected instance of FileJournal, got stdClass' );
+
+               FileJournal::factory( [ 'class' => 'stdclass' ], '' );
+       }
+
+       /**
+        * @covers ::getTimestampedUUID
+        */
+       public function testGetTimestampedUUID() {
+               $obj = FileJournal::factory( [ 'class' => 'NullFileJournal' ], '' );
+               $uuids = [];
+               for ( $i = 0; $i < 10; $i++ ) {
+                       $time1 = time();
+                       $uuid = $obj->getTimestampedUUID();
+                       $time2 = time();
+                       $this->assertRegexp( '/^[0-9a-z]{31}$/', $uuid );
+                       $this->assertArrayNotHasKey( $uuid, $uuids );
+                       $uuids[$uuid] = true;
+
+                       // Now test that the timestamp portion is as expected.
+                       $time = ConvertibleTimestamp::convert( TS_UNIX, Wikimedia\base_convert(
+                               substr( $uuid, 0, 9 ), 36, 10 ) );
+
+                       $this->assertGreaterThanOrEqual( $time1, $time );
+                       $this->assertLessThanOrEqual( $time2, $time );
+               }
+       }
+
+       /**
+        * @covers ::logChangeBatch
+        */
+       public function testLogChangeBatch() {
+               $this->assertEquals(
+                       StatusValue::newGood( 'Logged' ), $this->newObj()->logChangeBatch( [ 1 ], '' ) );
+       }
+
+       /**
+        * @covers ::logChangeBatch
+        */
+       public function testLogChangeBatch_empty() {
+               $this->assertEquals( StatusValue::newGood(), $this->newObj()->logChangeBatch( [], '' ) );
+       }
+
+       /**
+        * @covers ::getCurrentPosition
+        */
+       public function testGetCurrentPosition() {
+               $this->assertEquals( 613, $this->newObj()->getCurrentPosition() );
+       }
+
+       /**
+        * @covers ::getPositionAtTime
+        */
+       public function testGetPositionAtTime() {
+               $this->assertEquals( 248, $this->newObj()->getPositionAtTime( 0 ) );
+       }
+
+       /**
+        * @dataProvider provideGetChangeEntries
+        * @covers ::getChangeEntries
+        * @param int|null $start
+        * @param int $limit
+        * @param string|null $expectedNext
+        * @param string[] $expectedReturn Expected id's of returned values
+        */
+       public function testGetChangeEntries( $start, $limit, $expectedNext, array $expectedReturn ) {
+               $expectedReturn = array_map(
+                       function ( $val ) {
+                               return [ 'id' => $val ];
+                       }, $expectedReturn
+               );
+               $next = "Different from $expectedNext";
+               $ret = $this->newObj()->getChangeEntries( $start, $limit, $next );
+               $this->assertSame( $expectedNext, $next );
+               $this->assertSame( $expectedReturn, $ret );
+       }
+
+       public static function provideGetChangeEntries() {
+               return [
+                       [ null, 0, null, [ 1, 2, 3 ] ],
+                       [ null, 1, 2, [ 1 ] ],
+                       [ null, 2, 3, [ 1, 2 ] ],
+                       [ null, 3, null, [ 1, 2, 3 ] ],
+                       [ 1, 0, null, [ 1, 2, 3 ] ],
+                       [ 1, 2, 3, [ 1, 2 ] ],
+                       [ 1, 1, 2, [ 1 ] ],
+                       [ 2, 2, null, [ 2, 3 ] ],
+               ];
+       }
+
+       /**
+        * @covers ::purgeOldLogs
+        */
+       public function testPurgeOldLogs() {
+               $obj = $this->newObj();
+               $this->assertFalse( $obj->getPurged() );
+               $obj->purgeOldLogs();
+               $this->assertTrue( $obj->getPurged() );
+       }
+}
diff --git a/tests/phpunit/unit/includes/libs/filebackend/filejournal/NullFileJournalTest.php b/tests/phpunit/unit/includes/libs/filebackend/filejournal/NullFileJournalTest.php
new file mode 100644 (file)
index 0000000..c0b782b
--- /dev/null
@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * @coversDefaultClass NullFileJournal
+ */
+class NullFileJournalTest extends MediaWikiUnitTestCase {
+       public function newObj() : NullFileJournal {
+               return FileJournal::factory( [ 'class' => NullFileJournal::class ], '' );
+       }
+
+       /**
+        * @covers ::doLogChangeBatch
+        */
+       public function testLogChangeBatch() {
+               $this->assertEquals( StatusValue::newGood(), $this->newObj()->logChangeBatch( [ 1 ], '' ) );
+       }
+
+       /**
+        * @covers ::doGetCurrentPosition
+        */
+       public function testGetCurrentPosition() {
+               $this->assertFalse( $this->newObj()->getCurrentPosition() );
+       }
+
+       /**
+        * @covers ::doGetPositionAtTime
+        */
+       public function testGetPositionAtTime() {
+               $this->assertFalse( $this->newObj()->getPositionAtTime( 2 ) );
+       }
+
+       /**
+        * @covers ::doGetChangeEntries
+        */
+       public function testGetChangeEntries() {
+               $next = 1;
+               $entries = $this->newObj()->getChangeEntries( null, 0, $next );
+               $this->assertSame( [], $entries );
+               $this->assertNull( $next );
+       }
+
+       /**
+        * @covers ::doPurgeOldLogs
+        */
+       public function testPurgeOldLogs() {
+               $this->assertEquals( StatusValue::newGood(), $this->newObj()->purgeOldLogs() );
+       }
+}
diff --git a/tests/phpunit/unit/includes/libs/filebackend/filejournal/TestFileJournal.php b/tests/phpunit/unit/includes/libs/filebackend/filejournal/TestFileJournal.php
new file mode 100644 (file)
index 0000000..c115925
--- /dev/null
@@ -0,0 +1,42 @@
+<?php
+
+class TestFileJournal extends NullFileJournal {
+       /** @var bool */
+       private $purged = false;
+
+       public function getTtlDays() {
+               return $this->ttlDays;
+       }
+
+       public function getBackend() {
+               return $this->backend;
+       }
+
+       protected function doLogChangeBatch( array $entries, $batchId ) {
+               return StatusValue::newGood( 'Logged' );
+       }
+
+       protected function doGetCurrentPosition() {
+               return 613;
+       }
+
+       protected function doGetPositionAtTime( $time ) {
+               return 248;
+       }
+
+       protected function doGetChangeEntries( $start, $limit ) {
+               return array_slice( [
+                       [ 'id' => 1 ],
+                       [ 'id' => 2 ],
+                       [ 'id' => 3 ],
+               ], $start === null ? 0 : $start - 1, $limit ? $limit : null );
+       }
+
+       protected function doPurgeOldLogs() {
+               $this->purged = true;
+       }
+
+       public function getPurged() {
+               return $this->purged;
+       }
+}