From 77e55361958a56dab1305f93a7cfde4e7adc6705 Mon Sep 17 00:00:00 2001
From: Ryan Boren <ryan@git.wordpress.org>
Date: Mon, 11 Feb 2013 18:08:14 +0000
Subject: [PATCH] Use microtime() instead of incrementors for last_changed to
 to avoid race conditions with cache evictions.

Props westi
fixes #23448


git-svn-id: https://develop.svn.wordpress.org/trunk@23401 602fd350-edb4-49c9-b593-d223f7449a82
---
 wp-includes/comment.php          | 16 +++-------------
 wp-includes/general-template.php |  2 +-
 wp-includes/post.php             |  9 ++-------
 wp-includes/taxonomy.php         |  9 ++-------
 4 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index d6ecda976c..65e18a7e4a 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -251,7 +251,7 @@ class WP_Comment_Query {
 		$key = md5( serialize( compact(array_keys($defaults)) )  );
 		$last_changed = wp_cache_get( 'last_changed', 'comment' );
 		if ( ! $last_changed ) {
-			$last_changed = 1;
+			$last_changed = microtime();
 			wp_cache_set( 'last_changed', $last_changed, 'comment' );
 		}
 		$cache_key = "get_comments:$key:$last_changed";
@@ -1292,12 +1292,7 @@ function wp_insert_comment($commentdata) {
 	$comment = get_comment($id);
 	do_action('wp_insert_comment', $id, $comment);
 
-	if ( function_exists( 'wp_cache_incr' ) ) {
-		wp_cache_incr( 'last_changed', 1, 'comment' );
-	} else {
-		$last_changed = wp_cache_get( 'last_changed', 'comment' );
-		wp_cache_set( 'last_changed', $last_changed + 1, 'comment' );
-	}
+	wp_cache_set( 'last_changed', microtime(), 'comment' );
 
 	return $id;
 }
@@ -2050,12 +2045,7 @@ function clean_comment_cache($ids) {
 	foreach ( (array) $ids as $id )
 		wp_cache_delete($id, 'comment');
 
-	if ( function_exists( 'wp_cache_incr' ) ) {
-		wp_cache_incr( 'last_changed', 1, 'comment' );
-	} else {
-		$last_changed = wp_cache_get( 'last_changed', 'comment' );
-		wp_cache_set( 'last_changed', $last_changed + 1, 'comment' );
-	}
+	wp_cache_set( 'last_changed', microtime(), 'comment' );
 }
 
 /**
diff --git a/wp-includes/general-template.php b/wp-includes/general-template.php
index 85f3bf71f5..4385e4b2e3 100644
--- a/wp-includes/general-template.php
+++ b/wp-includes/general-template.php
@@ -919,7 +919,7 @@ function wp_get_archives($args = '') {
 
 	$last_changed = wp_cache_get( 'last_changed', 'posts' );
 	if ( ! $last_changed ) {
-		$last_changed = 1;
+		$last_changed = microtime();
 		wp_cache_set( 'last_changed', $last_changed, 'posts' );
 	}
 
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 716447f2ae..bab809896e 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -3653,7 +3653,7 @@ function get_pages($args = '') {
 	$key = md5( serialize( compact(array_keys($defaults)) ) );
 	$last_changed = wp_cache_get( 'last_changed', 'posts' );
 	if ( ! $last_changed ) {
-		$last_changed = 1;
+		$last_changed = microtime();
 		wp_cache_set( 'last_changed', $last_changed, 'posts' );
 	}
 
@@ -4672,12 +4672,7 @@ function clean_post_cache( $post ) {
 		do_action( 'clean_page_cache', $post->ID );
 	}
 
-	if ( function_exists( 'wp_cache_incr' ) ) {
-		wp_cache_incr( 'last_changed', 1, 'posts' );
-	} else {
-		$last_changed = wp_cache_get( 'last_changed', 'posts' );
-		wp_cache_set( 'last_changed', $last_changed + 1, 'posts' );
-	}
+	wp_cache_set( 'last_changed', microtime(), 'posts' );
 }
 
 /**
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index cd579d0f8d..cbaecdfa13 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -1242,7 +1242,7 @@ function get_terms($taxonomies, $args = '') {
 	$key = md5( serialize( compact(array_keys($defaults)) ) . serialize( $taxonomies ) . $filter_key );
 	$last_changed = wp_cache_get( 'last_changed', 'terms' );
 	if ( ! $last_changed ) {
-		$last_changed = 1;
+		$last_changed = microtime();
 		wp_cache_set( 'last_changed', $last_changed, 'terms' );
 	}
 	$cache_key = "get_terms:$key:$last_changed";
@@ -2711,12 +2711,7 @@ function clean_term_cache($ids, $taxonomy = '', $clean_taxonomy = true) {
 		do_action('clean_term_cache', $ids, $taxonomy);
 	}
 
-	if ( function_exists( 'wp_cache_incr' ) ) {
-		wp_cache_incr( 'last_changed', 1, 'terms' );
-	} else {
-		$last_changed = wp_cache_get( 'last_changed', 'terms' );
-		wp_cache_set( 'last_changed', $last_changed + 1, 'terms' );
-	}
+	wp_cache_set( 'last_changed', microtime(), 'terms' );
 }
 
 /**