Embeds: Improve consistency of update and refresh logic for oEmbed caching between `oembed_cache` and post meta.

* Allow updating oEmbed cache during `parse-embed` requests for non-post editors (such as widgets).
* Update any existing `oembed_cache` post when `usecache` and TTL has passed.
* Do not overwrite a previously valid cache with `{{unknown}}`.

Props dlh.
See #34115.
Fixes #42310.

Built from https://develop.svn.wordpress.org/trunk@42009


git-svn-id: http://core.svn.wordpress.org/trunk@41843 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/ajax-actions.php

@@ -3027,6 +3027,15 @@ function wp_ajax_parse_embed() {
 	$parsed = false;
 	$wp_embed->return_false_on_fail = true;
 
+	if ( 0 === $post_id ) {
+		/*
+		 * Refresh oEmbeds cached outside of posts that are past their TTL.
+		 * Posts are excluded because they have separate logic for refreshing
+		 * their post meta caches. See WP_Embed::cache_oembed().
+		 */
+		$wp_embed->usecache = false;
+	}
+
 	if ( is_ssl() && 0 === strpos( $url, 'http://' ) ) {
 		// Admin is ssl and the user pasted non-ssl URL.
 		// Check if the provider supports ssl embeds and use that for the preview.

wp-includes/class-wp-embed.php

@@ -284,12 +284,34 @@ class WP_Embed {
 				kses_remove_filters();
 			}
 
-			wp_insert_post( wp_slash( array(
+			$insert_post_args = array(
 				'post_name' => $key_suffix,
-				'post_content' => $html ? $html : '{{unknown}}',
 				'post_status' => 'publish',
 				'post_type' => 'oembed_cache',
+			);
+
+			if ( $html ) {
+				if ( $cached_post_id ) {
+					wp_update_post( wp_slash( array(
+						'ID' => $cached_post_id,
+						'post_content' => $html,
 					) ) );
+				} else {
+					wp_insert_post( wp_slash( array_merge(
+						$insert_post_args,
+						array(
+							'post_content' => $html,
+						)
+					) ) );
+				}
+			} elseif ( ! $cache ) {
+				wp_insert_post( wp_slash( array_merge(
+					$insert_post_args,
+					array(
+						'post_content' => '{{unknown}}',
+					)
+				) ) );
+			}
 
 			if ( $has_kses ) {
 				kses_init_filters();

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-beta3-42008';
+$wp_version = '4.9-beta3-42009';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.