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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/37625">37625</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/37625","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>boonebgorges</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2016-06-02 18:27:43 +0000 (Thu, 02 Jun 2016)</dd>
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<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Comments: Improve caching for hierarchical queries.
Hierarchical comment queries work by first fetching the IDs of top-level
comments, and then filling the descendant tree one level at a time based on the
top-level results. When top-level comment IDs are found in the cache,
`WP_Comment_Query` does not generate the SQL used to fetch these comments. In
this case, the `fill_descendants()` query does not have enough information
to fill children. As a result, descendant comments were failing to be filled
in cases where the top-level comments were found in the cache.
This was a minor bug previously, because comment caches were not maintained
between pageloads. Since comment caches are now persistent <a href="https://core.trac.wordpress.org/changeset/37613">[37613]</a>, the problem
becomes evident anywhere that a persistent object cache is in use.
The solution is to cache parent-child relationships, so that when top-level
comments are found in the cache, descendant comments should be found there as
well.
Fixes <a href="https://core.trac.wordpress.org/ticket/36487">#36487</a>.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpincludesclasswpcommentqueryphp">trunk/src/wp-includes/class-wp-comment-query.php</a></li>
<li><a href="#trunktestsphpunittestscommentqueryphp">trunk/tests/phpunit/tests/comment/query.php</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunksrcwpincludesclasswpcommentqueryphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-includes/class-wp-comment-query.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-includes/class-wp-comment-query.php 2016-06-02 15:06:29 UTC (rev 37624)
+++ trunk/src/wp-includes/class-wp-comment-query.php 2016-06-02 18:27:43 UTC (rev 37625)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -742,12 +742,13 @@
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( $this->query_vars['hierarchical'] && ! $this->query_vars['parent'] ) {
- $this->query_vars['parent'] = 0;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $parent = $this->query_vars['parent'];
+ if ( $this->query_vars['hierarchical'] && ! $parent ) {
+ $parent = 0;
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( '' !== $this->query_vars['parent'] ) {
- $this->sql_clauses['where']['parent'] = $wpdb->prepare( 'comment_parent = %d', $this->query_vars['parent'] );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( '' !== $parent ) {
+ $this->sql_clauses['where']['parent'] = $wpdb->prepare( 'comment_parent = %d', $parent );
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> if ( is_array( $this->query_vars['user_id'] ) ) {
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -941,20 +942,49 @@
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $key = md5( serialize( wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) ) ) );
+ $last_changed = wp_cache_get( 'last_changed', 'comment' );
+ if ( ! $last_changed ) {
+ $last_changed = microtime();
+ wp_cache_set( 'last_changed', $last_changed, 'comment' );
+ }
+
</ins><span class="cx" style="display: block; padding: 0 10px"> // Fetch an entire level of the descendant tree at a time.
</span><span class="cx" style="display: block; padding: 0 10px"> $level = 0;
</span><span class="cx" style="display: block; padding: 0 10px"> do {
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $parent_ids = $levels[ $level ];
- if ( ! $parent_ids ) {
- break;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // Parent-child relationships may be cached. Only query for those that are not.
+ $child_ids = $uncached_parent_ids = array();
+ $_parent_ids = $levels[ $level ];
+ foreach ( $_parent_ids as $parent_id ) {
+ $cache_key = "get_comment_child_ids:$parent_id:$key:$last_changed";
+ $parent_child_ids = wp_cache_get( $cache_key, 'comment' );
+ if ( false !== $parent_child_ids ) {
+ $child_ids = array_merge( $child_ids, $parent_child_ids );
+ } else {
+ $uncached_parent_ids[] = $parent_id;
+ }
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $where = 'WHERE ' . $_where . ' AND comment_parent IN (' . implode( ',', array_map( 'intval', $parent_ids ) ) . ')';
- $comment_ids = $wpdb->get_col( "{$this->sql_clauses['select']} {$this->sql_clauses['from']} {$where} {$this->sql_clauses['groupby']} ORDER BY comment_date_gmt ASC, comment_ID ASC" );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( $uncached_parent_ids ) {
+ $where = 'WHERE ' . $_where . ' AND comment_parent IN (' . implode( ',', array_map( 'intval', $uncached_parent_ids ) ) . ')';
+ $level_comments = $wpdb->get_results( "SELECT $wpdb->comments.comment_ID, $wpdb->comments.comment_parent {$this->sql_clauses['from']} {$where} {$this->sql_clauses['groupby']} ORDER BY comment_date_gmt ASC, comment_ID ASC" );
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // Cache parent-child relationships.
+ $parent_map = array_fill_keys( $uncached_parent_ids, array() );
+ foreach ( $level_comments as $level_comment ) {
+ $parent_map[ $level_comment->comment_parent ][] = $level_comment->comment_ID;
+ $child_ids[] = $level_comment->comment_ID;
+ }
+
+ foreach ( $parent_map as $parent_id => $children ) {
+ $cache_key = "get_comment_child_ids:$parent_id:$key:$last_changed";
+ wp_cache_set( $cache_key, $children, 'comment' );
+ }
+ }
+
</ins><span class="cx" style="display: block; padding: 0 10px"> $level++;
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $levels[ $level ] = $comment_ids;
- } while ( $comment_ids );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $levels[ $level ] = $child_ids;
+ } while ( $child_ids );
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> // Prime comment caches for non-top-level comments.
</span><span class="cx" style="display: block; padding: 0 10px"> $descendant_ids = array();
</span></span></pre></div>
<a id="trunktestsphpunittestscommentqueryphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/comment/query.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/comment/query.php 2016-06-02 15:06:29 UTC (rev 37624)
+++ trunk/tests/phpunit/tests/comment/query.php 2016-06-02 18:27:43 UTC (rev 37625)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -2430,7 +2430,52 @@
</span><span class="cx" style="display: block; padding: 0 10px"> $clauses['where'] .= $wpdb->prepare( ' AND comment_ID != %d AND comment_ID != %d', $this->to_exclude[0], $this->to_exclude[1] );
</span><span class="cx" style="display: block; padding: 0 10px"> return $clauses;
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+
</ins><span class="cx" style="display: block; padding: 0 10px"> /**
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * @ticket 36487
+ */
+ public function test_cache_should_be_hit_when_querying_descendants() {
+ global $wpdb;
+
+ $p = self::factory()->post->create();
+ $comment_1 = self::factory()->comment->create( array(
+ 'comment_post_ID' => $p,
+ 'comment_approved' => '1',
+ ) );
+ $comment_2 = self::factory()->comment->create( array(
+ 'comment_post_ID' => $p,
+ 'comment_approved' => '1',
+ 'comment_parent' => $comment_1,
+ ) );
+ $comment_3 = self::factory()->comment->create( array(
+ 'comment_post_ID' => $p,
+ 'comment_approved' => '1',
+ 'comment_parent' => $comment_1,
+ ) );
+ $comment_4 = self::factory()->comment->create( array(
+ 'comment_post_ID' => $p,
+ 'comment_approved' => '1',
+ 'comment_parent' => $comment_2,
+ ) );
+
+ $q1 = new WP_Comment_Query( array(
+ 'post_id' => $p,
+ 'hierarchical' => true,
+ ) );
+ $q1_ids = wp_list_pluck( $q1->comments, 'comment_ID' );
+
+ $num_queries = $wpdb->num_queries;
+ $q2 = new WP_Comment_Query( array(
+ 'post_id' => $p,
+ 'hierarchical' => true,
+ ) );
+ $q2_ids = wp_list_pluck( $q2->comments, 'comment_ID' );
+
+ $this->assertEqualSets( $q1_ids, $q2_ids );
+ $this->assertSame( $num_queries, $wpdb->num_queries );
+ }
+
+ /**
</ins><span class="cx" style="display: block; padding: 0 10px"> * @ticket 27571
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> public function test_update_comment_post_cache_should_be_disabled_by_default() {
</span></span></pre>
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