function DatabaseBackendTest::testGarbageCollection

Tests the row count limiting of cache bin database tables.

File

core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTest.php, line 78

Class

DatabaseBackendTest

Unit test of the database backend using the generic cache unit test base.

Namespace

Code

public function testGarbageCollection() : void {
    $backend = $this->getCacheBackend();
    $max_rows = static::$maxRows;
    $this->assertSame(0, (int) $this->getNumRows());
    // Fill to just the limit.
    for ($i = 0; $i < $max_rows; $i++) {
        // Ensure that each cache item created happens in a different millisecond,
        // by waiting 1 ms (1000 microseconds). The garbage collection might
        // otherwise keep less than exactly 100 records (which is acceptable for
        // real-world cases, but not for this test).
        usleep(1000);
        $backend->set("test{$i}", $i);
    }
    $this->assertSame($max_rows, $this->getNumRows());
    // Garbage collection has no effect.
    $backend->garbageCollection();
    $this->assertSame($max_rows, $this->getNumRows());
    // Go one row beyond the limit.
    $backend->set('test' . ($max_rows + 1), $max_rows + 1);
    $this->assertSame($max_rows + 1, $this->getNumRows());
    // Garbage collection removes one row: the oldest.
    $backend->garbageCollection();
    $this->assertSame($max_rows, $this->getNumRows());
    $this->assertFalse($backend->get('test0'));
}