Delete Cache by Group

src/wp-includes/cache-compat.php

@@ -141,3 +141,30 @@ function wp_cache_flush_runtime() {
 		return wp_using_ext_object_cache() ? false : wp_cache_flush();
 	}
 endif;
+
+if ( ! function_exists( 'wp_cache_flush_group' ) ) :
+	/**
+	 * Removes all cache items in a group, if the object cache implementation supports it.
+	 * Before calling this method, always check for group flushing support using the
+	 * `WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH` constant.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @see WP_Object_Cache::flush_group()
+	 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
+	 *
+	 * @param string|array $group name(s) of group to remove from cache.
+	 * @return bool|array|WP_Error Bool or array of bool if array passed, WP_Error if not supported.
+	 */
+	function wp_cache_flush_group( $group ) {
+		if ( ! defined( 'WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH' ) || ! WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH ) {
+            $error = new WP_Error( 'unsupported', __( 'Your object cache implementation does not support flushing individual groups.' ) );
+
+		    _doing_it_wrong( __FUNCTION__, $error->get_error_message(), '6.0.0' );
+
+		    return $error;			
+		}
+
+		return $wp_object_cache->flush_group( $group );
+	}
+endif;

src/wp-includes/cache.php

@@ -11,6 +11,11 @@
 /** WP_Object_Cache class */
 require_once ABSPATH . WPINC . '/class-wp-object-cache.php';
 
+/**
+  * Indicate that this object cache implementation supports group flushing.
+  */
+define( 'WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH', true );
+
 /**
  * Sets up Object Cache Global and assigns it.
  *
@@ -132,6 +137,30 @@ function wp_cache_set_multiple( array $data, $group = '', $expire = 0 ) {
 	return $wp_object_cache->set_multiple( $data, $group, $expire );
 }
 
+/**
+ * Removes all cache items in a group, if the object cache implementation supports it.
+ * Before calling this method, always check for group flushing support using the
+ * `WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH` constant.
+ *
+ * @since 6.0.0
+ *
+ * @see WP_Object_Cache::flush_group()
+ * @global WP_Object_Cache $wp_object_cache Object cache global instance.
+ *
+ * @param string|array $group name(s) of group to remove from cache.
+ * @return bool|array|WP_Error Bool or array of bool if array passed, WP_Error if not supported.
+ */
+function wp_cache_flush_group( $group ) {
+	global $wp_object_cache;
+
+	// if group is an array loop and call each key in the array
+	if ( is_array( $group ) ) {
+		return array_map( 'wp_cache_flush_group', array_values( $group ) );
+	}
+
+	return $wp_object_cache->flush_group( $group );
+}
+
 /**
  * Retrieves the cache contents from the cache by key and group.
  *

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

@@ -290,6 +290,18 @@ public function set_multiple( array $data, $group = '', $expire = 0 ) {
 		return $values;
 	}
 
+	/**
+	 * Removes all cache items in a group.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @return true Always returns true.
+	 */
+	public function flush_group( $group ) {
+		unset( $this->cache[ $group ] );
+
+		return true;
+	}
 	/**
 	 * Retrieves the cache contents, if it exists.
 	 *

tests/phpunit/includes/object-cache.php

@@ -1,4 +1,8 @@
 <?php
+/**
+ * Indicate that this object cache implementation does not support group flushing.
+ */
+define( 'WP_OBJECT_CACHE_SUPPORTS_GROUP_FLUSH', false );
 /**
  * Adds a value to cache.
  *

tests/phpunit/tests/cache.php

@@ -415,4 +415,58 @@ public function test_wp_cache_delete_multiple() {
 
 		$this->assertSame( $expected, $found );
 	}
+
+	/**
+	 * @ticket 4476
+	 * @ticket 9773
+	 *
+	 * test wp_cache_flush_group
+	 *
+	 * @covers ::wp_cache_flush_group
+	 */
+	public function test_wp_cache_flush_group() {
+		$key = 'my-key';
+		$val = 'my-val';
+
+		wp_cache_set( $key, $val, 'group-test' );
+		wp_cache_set( $key, $val, 'group-kept' );
+		$this->assertSame( $val, wp_cache_get( $key, 'group-test' ), 'test_wp_cache_flush_group: group-test should contain my-val' );
+
+		$results = wp_cache_flush_group( 'group-test' );
+		$this->assertTrue( $results );
+		$this->assertFalse( wp_cache_get( $key, 'group-test' ), 'test_wp_cache_flush_group: group-test should return false' );
+		$this->assertSame( $val, wp_cache_get( $key, 'group-kept' ), 'test_wp_cache_flush_group: group-kept should still contain my-val' );
+	}
+
+	/**
+	 * @ticket 4476
+	 * @ticket 9773
+	 *
+	 * test wp_cache_flush_group with an array of groups
+	 *
+	 * @covers ::wp_cache_flush_groups
+	 */
+	public function test_wp_cache_flush_groups() {
+		$key = 'my-key';
+		$val = 'my-val';
+
+		wp_cache_set( $key, $val, 'group-test' );
+		wp_cache_set( $key, $val, 'group-test2' );
+		wp_cache_set( $key, $val, 'group-kept' );
+		$this->assertSame( $val, wp_cache_get( $key, 'group-test' ), 'test_wp_cache_flush_groups: group-test should contain my-val' );
+		$this->assertSame( $val, wp_cache_get( $key, 'group-test2' ), 'test_wp_cache_flush_groups: group-test2 should contain my-val' );
+
+		$results = wp_cache_flush_group( array( 'group-test', 'group-test2' ) );
+
+		if ( wp_using_ext_object_cache() ) {
+			$this->assertWPError( $results );
+		    $this->assertSame( 'unsupported', $results->get_error_code() );
+		} else {
+			$this->assertIsArray( $results );
+			$this->assertCount( 2, $results );
+			$this->assertFalse( wp_cache_get( $key, 'group-test' ), 'test_wp_cache_flush_groups: group-test should return false' );
+			$this->assertFalse( wp_cache_get( $key, 'group-test2' ), 'test_wp_cache_flush_groups: group-test2 should return false' );
+			$this->assertSame( $val, wp_cache_get( $key, 'group-kept' ), 'test_wp_cache_flush_groups: group-kept should still contain my-val' );
+		}
+	}
 }

tests/phpunit/tests/pluggable.php

@@ -332,6 +332,7 @@ public function get_pluggable_function_signatures() {
 					'wp_cache_add_non_persistent_groups' => array( 'groups' ),
 					'wp_cache_switch_to_blog'            => array( 'blog_id' ),
 					'wp_cache_reset'                     => array(),
+					'wp_cache_flush_group'               => array( 'group' ),
 				)
 			);
 		}