Changeset 34310

Timestamp:

09/18/2015 07:27:39 PM (9 years ago)

Author:

boonebgorges

Message:

Split the comment query.

WP_Comment_Query now fetches comments in two stages: (1) a query to get the
IDs of comments matching the query vars, and (2) a query to populate the
objects corresponding to the matched IDs. The two queries are cached
separately, so that sites with persistent object caches will continue to have
complete cache coverage for normal comment queries.

Splitting the query allows our cache strategy to be more modest and precise, as
full comment data is only stored once per comment. It also makes it possible
to introduce logic for paginated threading, which is necessary to address
certain performance problems.

See #8071.
data is only stored once per comment, instead of along with

Location:

trunk

Files:

• src/wp-includes/class-wp-comment-query.php (modified) (7 diffs)
• src/wp-includes/comment-functions.php (modified) (1 diff)
• tests/phpunit/tests/comment/metaCache.php (modified) (2 diffs)
• tests/phpunit/tests/comment/query.php (modified) (2 diffs)

trunk/src/wp-includes/class-wp-comment-query.php

@@ -34 +34 @@
      */
     public $meta_query = false;
+
+    /**
+     * Metadata query clauses.
+     *
+     * @since 4.4.0
+     * @access protected
+     * @var array
+     */
+    protected $meta_query_clauses;
 
     /**
@@ -262 +271 @@
         global $wpdb;
 
-        $groupby = '';
-
         $this->parse_query();
 
@@ -282 +289 @@
         $this->meta_query->parse_query_vars( $this->query_vars );
         if ( ! empty( $this->meta_query->queries ) ) {
-            $meta_query_clauses = $this->meta_query->get_sql( 'comment', $wpdb->comments, 'comment_ID', $this );
+            $this->meta_query_clauses = $this->meta_query->get_sql( 'comment', $wpdb->comments, 'comment_ID', $this );
         }
 
@@ -292 +299 @@
             wp_cache_set( 'last_changed', $last_changed, 'comment' );
         }
-        $cache_key = "get_comments:$key:$last_changed";
-
-        if ( $cache = wp_cache_get( $cache_key, 'comment' ) ) {
-            $this->comments = $cache;
+        $cache_key = "get_comment_ids:$key:$last_changed";
+
+        $comment_ids = wp_cache_get( $cache_key, 'comment' );
+        if ( false === $comment_ids ) {
+            $comment_ids = $this->get_comment_ids();
+            wp_cache_add( $cache_key, $comment_ids, 'comment' );
+        }
+
+        // If querying for a count only, there's nothing more to do.
+        if ( $this->query_vars['count'] ) {
+            // $comment_ids is actually a count in this case.
+            return intval( $comment_ids );
+        }
+
+        $comment_ids = array_map( 'intval', $comment_ids );
+
+        if ( 'ids' == $this->query_vars['fields'] ) {
+            $this->comments = $comment_ids;
             return $this->comments;
         }
 
+        _prime_comment_caches( $comment_ids, $this->query_vars['update_comment_meta_cache'] );
+
+        // Fetch full comment objects from the primed cache.
+        $_comments = array();
+        foreach ( $comment_ids as $comment_id ) {
+            if ( $_comment = wp_cache_get( $comment_id, 'comment' ) ) {
+                $_comments[] = $_comment;
+            }
+        }
+
+        /**
+         * Filter the comment query results.
+         *
+         * @since 3.1.0
+         *
+         * @param array            $results  An array of comments.
+         * @param WP_Comment_Query &$this    Current instance of WP_Comment_Query, passed by reference.
+         */
+        $_comments = apply_filters_ref_array( 'the_comments', array( $_comments, &$this ) );
+
+        // Convert to WP_Comment instances
+        $comments = array_map( 'get_comment', $_comments );
+
+        $this->comments = $comments;
+        return $this->comments;
+    }
+
+    /**
+     * Used internally to get a list of comment IDs matching the query vars.
+     *
+     * @since 4.4.0
+     * @access protected
+     *
+     * @global wpdb $wpdb
+     */
+    protected function get_comment_ids() {
+        global $wpdb;
+
+        $groupby = '';
         $where = array();
 
@@ -472 +532 @@
             $fields = 'COUNT(*)';
         } else {
-            switch ( strtolower( $this->query_vars['fields'] ) ) {
-                case 'ids':
-                    $fields = "$wpdb->comments.comment_ID";
-                    break;
-                default:
-                    $fields = "*";
-                    break;
-            }
+            $fields = "$wpdb->comments.comment_ID";
         }
 
@@ -626 +679 @@
         }
 
-        if ( ! empty( $meta_query_clauses ) ) {
-            $join .= $meta_query_clauses['join'];
+        if ( ! empty( $this->meta_query_clauses ) ) {
+            $join .= $this->meta_query_clauses['join'];
 
             // Strip leading 'AND'.
-            $where[] = preg_replace( '/^\s*AND\s*/', '', $meta_query_clauses['where'] );
+            $where[] = preg_replace( '/^\s*AND\s*/', '', $this->meta_query_clauses['where'] );
 
             if ( ! $this->query_vars['count'] ) {
@@ -678 +731 @@
 
         if ( $this->query_vars['count'] ) {
-            return $wpdb->get_var( $this->request );
-        }
-
-        if ( 'ids' == $this->query_vars['fields'] ) {
-            $this->comments = $wpdb->get_col( $this->request );
-            return array_map( 'intval', $this->comments );
-        }
-
-        $results = $wpdb->get_results( $this->request );
-        /**
-         * Filter the comment query results.
-         *
-         * @since 3.1.0
-         *
-         * @param array            $results  An array of comments.
-         * @param WP_Comment_Query &$this    Current instance of WP_Comment_Query, passed by reference.
-         */
-        $_comments = apply_filters_ref_array( 'the_comments', array( $results, &$this ) );
-
-        // Convert to WP_Comment instances
-        $comments = array_map( 'get_comment', $_comments );
-
-        wp_cache_add( $cache_key, $comments, 'comment' );
-        if ( '*' === $fields ) {
-            update_comment_cache( $comments, $this->query_vars['update_comment_meta_cache'] );
-        }
-
-        $this->comments = $comments;
-        return $this->comments;
+            return intval( $wpdb->get_var( $this->request ) );
+        } else {
+            $comment_ids = $wpdb->get_col( $this->request );
+            return array_map( 'intval', $comment_ids );
+        }
     }
 

trunk/src/wp-includes/comment-functions.php

@@ -2378 +2378 @@
 
 /**
+ * Adds any comments from the given IDs to the cache that do not already exist in cache.
+ *
+ * @since 4.4.0
+ * @access private
+ *
+ * @see update_comment_cache()
+ *
+ * @global wpdb $wpdb
+ *
+ * @param array $comment_ids       Array of comment IDs.
+ * @param bool  $update_meta_cache Optional. Whether to update the meta cache. Default true.
+ */
+function _prime_comment_caches( $comment_ids, $update_meta_cache = true ) {
+    global $wpdb;
+
+    $non_cached_ids = _get_non_cached_ids( $comment_ids, 'comment' );
+    if ( !empty( $non_cached_ids ) ) {
+        $fresh_comments = $wpdb->get_results( sprintf( "SELECT $wpdb->comments.* FROM $wpdb->comments WHERE comment_ID IN (%s)", join( ",", array_map( 'intval', $non_cached_ids ) ) ) );
+
+        update_comment_cache( $fresh_comments, $update_meta_cache );
+    }
+}
+
+/**
  * Lazy load comment meta when inside of a `WP_Query` loop.
  *

trunk/tests/phpunit/tests/comment/metaCache.php

@@ -17 +17 @@
             update_comment_meta( $cid, 'foo', 'bar' );
         }
+
+        // Clear comment cache, just in case.
+        clean_comment_cache( $comment_ids );
 
         $q = new WP_Comment_Query( array(
@@ -42 +45 @@
             update_comment_meta( $cid, 'foo', 'bar' );
         }
+
+        // Clear comment cache, just in case.
+        clean_comment_cache( $comment_ids );
 
         $q = new WP_Comment_Query( array(

trunk/tests/phpunit/tests/comment/query.php

@@ -1668 +1668 @@
         $q1->query( array(
             'post_id' => $p,
+            'fields' => 'ids',
         ) );
 
@@ -1675 +1676 @@
         $q2->query( array(
             'post_id' => $p,
+            'fields' => 'ids',
             'foo' => 'bar',
         ) );