From ddc823a3e9039e6f8f2278cd5a34d9af125bf3df Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Thu, 22 Jun 2017 03:18:18 +0000
Subject: [PATCH] Cache results in `get_objects_in_term()`.

This helps to reduce database queries when generating nav menus.

Props spacedmonkey.
Fixes #37094.

git-svn-id: https://develop.svn.wordpress.org/trunk@40921 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/taxonomy.php     | 12 +++++-
 tests/phpunit/tests/taxonomy.php | 69 ++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index f703b5a56b..1a0d170848 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -650,7 +650,17 @@ function get_objects_in_term( $term_ids, $taxonomies, $args = array() ) {
 	$taxonomies = "'" . implode( "', '", array_map( 'esc_sql', $taxonomies ) ) . "'";
 	$term_ids = "'" . implode( "', '", $term_ids ) . "'";
 
-	$object_ids = $wpdb->get_col("SELECT tr.object_id FROM $wpdb->term_relationships AS tr INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ($taxonomies) AND tt.term_id IN ($term_ids) ORDER BY tr.object_id $order");
+	$sql = "SELECT tr.object_id FROM $wpdb->term_relationships AS tr INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ($taxonomies) AND tt.term_id IN ($term_ids) ORDER BY tr.object_id $order";
+
+	$last_changed = wp_cache_get_last_changed( 'terms' );
+	$cache_key = 'get_objects_in_term:' . md5( $sql ) . ":$last_changed";
+	$cache = wp_cache_get( $cache_key, 'terms' );
+	if ( false === $cache ) {
+		$object_ids = $wpdb->get_col( $sql );
+		wp_cache_set( $cache_key, $object_ids, 'terms' );
+	} else {
+		$object_ids = (array) $cache;
+	}
 
 	if ( ! $object_ids ){
 		return array();
diff --git a/tests/phpunit/tests/taxonomy.php b/tests/phpunit/tests/taxonomy.php
index 9a4e8b2a0f..252280eef4 100644
--- a/tests/phpunit/tests/taxonomy.php
+++ b/tests/phpunit/tests/taxonomy.php
@@ -291,6 +291,75 @@ class Tests_Taxonomy extends WP_UnitTestCase {
 		$this->assertEquals( array_reverse( $posts_with_tag ), get_objects_in_term( $tag_id, 'post_tag', array( 'order' => 'desc' ) ) );
 	}
 
+	/**
+	 * @ticket 37094
+	 */
+	public function test_term_assignment_should_invalidate_get_objects_in_term_cache() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$posts = self::factory()->post->create_many( 2 );
+		$term_id = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		wp_set_object_terms( $posts[1], $term_id, 'wptests_tax' );
+
+		// Prime cache.
+		$before = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertEqualSets( array( $posts[1] ), $before );
+
+		wp_set_object_terms( $posts[1], array(), 'wptests_tax' );
+
+		$after = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertSame( array(), $after );
+	}
+
+	/**
+	 * @ticket 37094
+	 */
+	public function test_term_deletion_should_invalidate_get_objects_in_term_cache() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$posts = self::factory()->post->create_many( 2 );
+		$term_id = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		wp_set_object_terms( $posts[1], $term_id, 'wptests_tax' );
+
+		// Prime cache.
+		$before = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertEqualSets( array( $posts[1] ), $before );
+
+		wp_delete_term( $term_id, 'wptests_tax' );
+
+		$after = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertSame( array(), $after );
+	}
+
+	/**
+	 * @ticket 37094
+	 */
+	public function test_post_deletion_should_invalidate_get_objects_in_term_cache() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$posts = self::factory()->post->create_many( 2 );
+		$term_id = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		wp_set_object_terms( $posts[1], $term_id, 'wptests_tax' );
+
+		// Prime cache.
+		$before = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertEqualSets( array( $posts[1] ), $before );
+
+		wp_delete_post( $posts[1], true );
+
+		$after = get_objects_in_term( $term_id, 'wptests_tax' );
+		$this->assertSame( array(), $after );
+	}
+
 	/**
 	 * @ticket 25706
 	 */