Cache API: Introduce wp_cache_get_multi().

Many caching backend have support for multiple gets in a single request. This brings that support to core, with a compatability fallback that will loop over requests if needed.

Fixes: #20875.
Props: nacin, tollmanz, wonderboymusic, ryan, jeremyfelt, spacedmonkey, boonebgorges, dd32, rmccue, ocean90, jipmoors, johnjamesjacoby, tillkruess, donmhico, davidbaumwald, SergeyBiryukov, whyisjake.



git-svn-id: https://develop.svn.wordpress.org/trunk@47938 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/cache.php

@@ -126,6 +126,24 @@ function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
 	return $wp_object_cache->get( $key, $group, $force, $found );
 }
 
+/**
+ * Gets multiple values from cache in one call.
+ *
+ * @since 5.5.0
+ * @see WP_Object_Cache::get_multiple()
+ *
+ * @param array       $keys   Array of keys to get from group.
+ * @param string      $group  Optional. Where the cache contents are grouped. Default empty.
+ * @param bool        $force  Optional. Whether to force an update of the local cache from the persistent
+ *                            cache. Default false.
+ * @return array|bool Array of values.
+ */
+function wp_cache_get_multiple( $keys, $group = '', $force = false ) {
+	global $wp_object_cache;
+
+	return $wp_object_cache->get_multiple( $keys, $group, $force );
+}
+
 /**
  * Increment numeric cache item's value
  *

src/wp-includes/class-wp-object-cache.php

@@ -302,6 +302,27 @@ class WP_Object_Cache {
 		return false;
 	}
 
+	/**
+	 * Retrieves multiple values from the cache.
+	 *
+	 * @since  5.5.0
+	 *
+	 * @param array $keys        Array of keys to fetch.
+	 * @param bool  $force       Optional. Unused. Whether to force a refetch rather than relying on the local
+	 *                           cache. Default false.
+	 *
+	 * @return array Array of values organized into groups.
+	 */
+	public function get_multiple( $keys, $group = 'default', $force = false ) {
+		$values = array();
+
+		foreach ( $keys as $key ) {
+			$values[ $key ] = $this->get( $key, $group, $force );
+		}
+
+		return $values;
+	}
+
 	/**
 	 * Increments numeric cache item's value.
 	 *

src/wp-includes/load.php

@@ -628,6 +628,8 @@ function wp_start_object_cache() {
 		require_once ABSPATH . WPINC . '/cache.php';
 	}
 
+	require_once( ABSPATH . WPINC . '/cache-compat.php' );
+
 	/*
 	 * If cache supports reset, reset instead of init if already
 	 * initialized. Reset signals to the cache that global IDs