From cda68f14f973a8003116e2810f607b9de2e0474e Mon Sep 17 00:00:00 2001
From: duck_ <duck_@1a063a9b-81f0-0310-95a4-ce76da25c4cd>
Date: Thu, 15 Sep 2011 20:23:00 +0000
Subject: [PATCH] Introduce wp_suspend_cache_addition() to allow reduced memory
 usage when cache additions aren't useful. Fixes #5389.

git-svn-id: http://svn.automattic.com/wordpress/trunk@18681 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/cache.php     |  3 +++
 wp-includes/functions.php | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/wp-includes/cache.php b/wp-includes/cache.php
index 70753aa2d..02b28f70c 100644
--- a/wp-includes/cache.php
+++ b/wp-includes/cache.php
@@ -294,6 +294,9 @@ class WP_Object_Cache {
 	 * @return bool False if cache key and group already exist, true on success
 	 */
 	function add( $key, $data, $group = 'default', $expire = '' ) {
+		if ( wp_suspend_cache_addition() )
+			return false;
+
 		if ( empty ($group) )
 			$group = 'default';
 
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index e453c3943..ab208f9a9 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -3709,6 +3709,30 @@ function wp_guess_url() {
 	return rtrim($url, '/');
 }
 
+/**
+ * Temporarily suspend cache additions.
+ *
+ * Stops more data being added to the cache, but still allows cache retrieval.
+ * This is useful for actions, such as imports, when a lot of data would otherwise
+ * be almost uselessly added to the cache.
+ *
+ * Suspension lasts for a single page load at most. Remember to call this
+ * function again if you wish to re-enable cache adds earlier.
+ *
+ * @since 3.3.0
+ *
+ * @param bool $suspend Optional. Suspends additions if true, re-enables them if false.
+ * @return bool The current suspend setting
+ */
+function wp_suspend_cache_addition( $suspend = null ) {
+	static $_suspend = false;
+
+	if ( is_bool( $suspend ) )
+		$_suspend = $suspend;
+
+	return $_suspend;
+}
+
 /**
  * Suspend cache invalidation.
  *