Issue #2900947: Implement initial RedisCluster client integration

src/Cache/PhpRedisCluster.php

+<?php
+
+namespace Drupal\redis\Cache;
+
+use Drupal\Component\Serialization\SerializationInterface;
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Cache\CacheTagsChecksumInterface;
+
+/**
+ * PhpRedisCluster cache backend.
+ */
+class PhpRedisCluster extends CacheBase {
+
+  /**
+   * The client.
+   *
+   * @var \RedisCluster
+   */
+  protected $client;
+
+  /**
+   * Creates a PhpRedisCluster cache backend.
+   *
+   * @param string $bin
+   *   The cache bin for which the object is created.
+   * @param \RedisCluster $client
+   *   The cluster client.
+   * @param \Drupal\Core\Cache\CacheTagsChecksumInterface $checksum_provider
+   *   The cluster checksum.
+   * @param \Drupal\Component\Serialization\SerializationInterface $serializer
+   *   The serialization class to use.
+   */
+  public function __construct($bin, \RedisCluster $client, CacheTagsChecksumInterface $checksum_provider, SerializationInterface $serializer) {
+    parent::__construct($bin, $serializer);
+    $this->client = $client;
+    $this->checksumProvider = $checksum_provider;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
+    // Avoid an error when there are no cache ids.
+    if (empty($cids)) {
+      return [];
+    }
+
+    $return = [];
+
+    // Build the list of keys to fetch.
+    foreach (array_map([$this, 'getKey'], $cids) as $key) {
+      $result[] = $this->client->hGetAll($key);
+    }
+
+    // Loop over the cid values to ensure numeric indexes.
+    foreach (array_values($cids) as $index => $key) {
+      // Check if a valid result was returned from Redis.
+      if (isset($result[$index]) && is_array($result[$index])) {
+        // Check expiration and invalidation and convert into an object.
+        $item = $this->expandEntry($result[$index], $allow_invalid);
+        if ($item) {
+          $return[$item->cid] = $item;
+        }
+      }
+    }
+
+    // Remove fetched cids from the list.
+    $cids = array_diff($cids, array_keys($return));
+
+    return $return;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
+
+    $ttl = $this->getExpiration($expire);
+
+    $key = $this->getKey($cid);
+
+    // If the item is already expired, delete it.
+    if ($ttl <= 0) {
+      $this->delete($key);
+    }
+
+    // Build the cache item and save it as a hash array.
+    $entry = $this->createEntryHash($cid, $data, $expire, $tags);
+    $this->client->hMset($key, $entry);
+    $this->client->expire($key, $ttl);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doDeleteMultiple(array $cids) {
+    $keys = array_map([$this, 'getKey'], $cids);
+    $this->client->del($keys);
+  }
+
+}