Version 1

[yaffs-website] / web / core / lib / Drupal / Core / Cache / BackendChain.php

diff --git a/web/core/lib/Drupal/Core/Cache/BackendChain.php b/web/core/lib/Drupal/Core/Cache/BackendChain.php
new file mode 100644 (file)
index 0000000..a8cef19
--- /dev/null
+++ b/web/core/lib/Drupal/Core/Cache/BackendChain.php
@@ -0,0 +1,222 @@
+<?php
+
+namespace Drupal\Core\Cache;
+/**
+ * Defines a chained cache implementation for combining multiple cache backends.
+ *
+ * Can be used to combine two or more backends together to behave as if they
+ * were a single backend.
+ *
+ * For example a slower, persistent storage engine could be combined with a
+ * faster, volatile storage engine. When retrieving items from cache, they will
+ * be fetched from the volatile backend first, only falling back to the
+ * persistent backend if an item is not available. An item not present in the
+ * volatile backend but found in the persistent one will be propagated back up
+ * to ensure fast retrieval on the next request. On cache sets and deletes, both
+ * backends will be invoked to ensure consistency.
+ *
+ * @see \Drupal\Core\Cache\ChainedFastBackend
+ *
+ * @ingroup cache
+ */
+class BackendChain implements CacheBackendInterface, CacheTagsInvalidatorInterface {
+
+  /**
+   * Ordered list of CacheBackendInterface instances.
+   *
+   * @var array
+   */
+  protected $backends = [];
+
+  /**
+   * Constructs a DatabaseBackend object.
+   *
+   * @param string $bin
+   *   The cache bin for which the object is created.
+   */
+  public function __construct($bin) {
+  }
+
+  /**
+   * Appends a cache backend to the cache chain.
+   *
+   * @param CacheBackendInterface $backend
+   *   The cache backend to be appended to the cache chain.
+   *
+   * @return \Drupal\Core\Cache\BackendChain
+   *   The called object.
+   */
+  public function appendBackend(CacheBackendInterface $backend) {
+    $this->backends[] = $backend;
+
+    return $this;
+  }
+
+  /**
+   * Prepends a cache backend to the cache chain.
+   *
+   * @param CacheBackendInterface $backend
+   *   The backend to be prepended to the cache chain.
+   *
+   * @return \Drupal\Core\Cache\BackendChain
+   *   The called object.
+   */
+  public function prependBackend(CacheBackendInterface $backend) {
+    array_unshift($this->backends, $backend);
+
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function get($cid, $allow_invalid = FALSE) {
+    foreach ($this->backends as $index => $backend) {
+      if (($return = $backend->get($cid, $allow_invalid)) !== FALSE) {
+        // We found a result, propagate it to all missed backends.
+        if ($index > 0) {
+          for ($i = ($index - 1); 0 <= $i; --$i) {
+            $this->backends[$i]->set($cid, $return->data, $return->expire, $return->tags);
+          }
+        }
+
+        return $return;
+      }
+    }
+
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
+    $return = [];
+
+    foreach ($this->backends as $index => $backend) {
+      $items = $backend->getMultiple($cids, $allow_invalid);
+
+      // Propagate the values that could be retrieved from the current cache
+      // backend to all missed backends.
+      if ($index > 0 && !empty($items)) {
+        for ($i = ($index - 1); 0 <= $i; --$i) {
+          foreach ($items as $cached) {
+            $this->backends[$i]->set($cached->cid, $cached->data, $cached->expire, $cached->tags);
+          }
+        }
+      }
+
+      // Append the values to the previously retrieved ones.
+      $return += $items;
+
+      if (empty($cids)) {
+        // No need to go further if we don't have any cid to fetch left.
+        break;
+      }
+    }
+
+    return $return;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
+    foreach ($this->backends as $backend) {
+      $backend->set($cid, $data, $expire, $tags);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setMultiple(array $items) {
+    foreach ($this->backends as $backend) {
+      $backend->setMultiple($items);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function delete($cid) {
+    foreach ($this->backends as $backend) {
+      $backend->delete($cid);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteMultiple(array $cids) {
+    foreach ($this->backends as $backend) {
+      $backend->deleteMultiple($cids);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteAll() {
+    foreach ($this->backends as $backend) {
+      $backend->deleteAll();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidate($cid) {
+    foreach ($this->backends as $backend) {
+      $backend->invalidate($cid);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateMultiple(array $cids) {
+    foreach ($this->backends as $backend) {
+      $backend->invalidateMultiple($cids);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateTags(array $tags) {
+    foreach ($this->backends as $backend) {
+      if ($backend instanceof CacheTagsInvalidatorInterface) {
+        $backend->invalidateTags($tags);
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateAll() {
+    foreach ($this->backends as $backend) {
+      $backend->invalidateAll();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function garbageCollection() {
+    foreach ($this->backends as $backend) {
+      $backend->garbageCollection();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function removeBin() {
+    foreach ($this->backends as $backend) {
+      $backend->removeBin();
+    }
+  }
+
+}