Unverified Commit 4332e36a authored by Alex Pott's avatar Alex Pott
Browse files

fix: #3584324 Make the chained fast backend self-heal when last_write_timestamp is missing 

By: catch
By: smustgrave
By: dries
By: kristiaanvandeneynde
(cherry picked from commit c3a6c1a5)
parent 75f04581

core/lib/Drupal/Core/Cache/ChainedFastBackend.php

+8 −0
Original line number Diff line number Diff line
@@ -121,6 +121,14 @@ public function getMultiple(&$cids, $allow_invalid = FALSE) { 
    // from there.

    $last_write_timestamp = $this->getLastWriteTimestamp();



    // If the last write timestamp is not set, set it with a fresh value so that

    // items written to the fast backend from this point onwards are treated as

    // valid immediately. This avoids having to wait for an explicit cache set

    // before the fast backend can be used.

    if ($last_write_timestamp === 0) {

      $this->markAsOutdated();

    }



    // Don't bother to either read from or write to the fast backend if the last

    // write timestamp is in the future - it is always set with an additional

    // grace period for this reason. This reduces the likelihood of a cache

core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php

+52 −0
Original line number Diff line number Diff line
@@ -54,6 +54,8 @@ public function testGetDoesNotHitConsistentBackend(): void { 
      ->willReturn($timestamp_item);

    $consistent_cache->expects($this->never())

      ->method('getMultiple');

    $consistent_cache->expects($this->never())

      ->method('set');



    $fast_cache = new MemoryBackend(new Time());

    $fast_cache->set('foo', 'baz');
@@ -240,4 +242,54 @@ public function testFallThroughToConsistentCache(): void { 
    $this->assertEquals('baz', $chained_fast_backend->get('foo')->data);

  }



  /**

   * Tests last_write_timestamp missing from the consistent backend.

   */

  public function testLastWriteTimestampMissing(): void {

    $timestamp_cid = ChainedFastBackend::LAST_WRITE_TIMESTAMP_PREFIX . 'cache_foo';

    $cache_item = (object) [

      'cid' => 'foo',

      'data' => 'baz',

      'created' => time(),

      'expire' => time() + 3600,

      'tags' => ['tag'],

    ];



    $consistent_cache = $this->createMock(CacheBackendInterface::class);

    $fast_cache = $this->createMock(CacheBackendInterface::class);



    // Simulate the last_write_timestamp being unset on the consistent backend.

    $consistent_cache->expects($this->once())

      ->method('get')

      ->with($timestamp_cid)

      ->willReturn(NULL);



    // Because the last_write_timestamp was missing, it will be newly set on the

    // consistent backend.

    $consistent_cache->expects($this->once())

      ->method('set')

      ->with($timestamp_cid);



    $consistent_cache->expects($this->once())

      ->method('getMultiple')

      ->with([$cache_item->cid])

      ->willReturn([$cache_item->cid => $cache_item]);



    // We should not get a call for the cache item on the fast backend but

    // because the last_write_timestamp is now in place, the item from the

    // consistent backend should be written back.

    $fast_cache->expects($this->never())

      ->method('getMultiple');

    $fast_cache->expects($this->once())

      ->method('set')

      ->with($cache_item->cid);



    $chained_fast_backend = new ChainedFastBackend(

      $consistent_cache,

      $fast_cache,

      'foo'

    );

    $this->assertEquals('baz', $chained_fast_backend->get('foo')->data);

  }



}