From fff2440ba5b05e3846a76ea5dc3a1dc552670f9b Mon Sep 17 00:00:00 2001
From: Peter Wilson <wilson@peterwilson.cc>
Date: Sat, 16 Mar 2019 06:42:50 +0000
Subject: [PATCH] Cron: Ensure identical single events aren't scheduled less
 than 10min apart.

Improves the logic in `wp_schedule_single_event()` to ensure an identical event is not scheduled within ten minutes.

This moves the logic for checking for identical events to be self contained rather than relying on `wp_next_scheduled()` as this fails to account for events with a past timestamp when wp-cron fails to trigger or for multiple identical events being scheduled already.

Props bodohugobarwich.
Fixes #44818.


Built from https://develop.svn.wordpress.org/trunk@44917


git-svn-id: http://core.svn.wordpress.org/trunk@44748 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/cron.php    | 49 ++++++++++++++++++++++++++++++++++++-----
 wp-includes/version.php |  2 +-
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/wp-includes/cron.php b/wp-includes/cron.php
index dd348784b9..bd6138256c 100644
--- a/wp-includes/cron.php
+++ b/wp-includes/cron.php
@@ -79,9 +79,49 @@ function wp_schedule_single_event( $timestamp, $hook, $args = array() ) {
 		return $pre;
 	}
 
-	// Don't schedule a duplicate if there's already an identical event due within 10 minutes of it
-	$next = wp_next_scheduled( $hook, $args );
-	if ( $next && abs( $next - $timestamp ) <= 10 * MINUTE_IN_SECONDS ) {
+	/*
+	 * Check for a duplicated event.
+	 *
+	 * Don't schedule an event if there's already an identical event
+	 * within 10 minutes.
+	 *
+	 * When scheduling events within ten minutes of the current time,
+	 * all past identical events are considered duplicates.
+	 *
+	 * When scheduling an event with a past timestamp (ie, before the
+	 * current time) all events scheduled within the next ten minutes
+	 * are considered duplicates.
+	 */
+	$crons     = (array) _get_cron_array();
+	$key       = md5( serialize( $event->args ) );
+	$duplicate = false;
+
+	if ( $event->timestamp < time() + 10 * MINUTE_IN_SECONDS ) {
+		$min_timestamp = 0;
+	} else {
+		$min_timestamp = $event->timestamp - 10 * MINUTE_IN_SECONDS;
+	}
+
+	if ( $event->timestamp < time() ) {
+		$max_timestamp = time() + 10 * MINUTE_IN_SECONDS;
+	} else {
+		$max_timestamp = $event->timestamp + 10 * MINUTE_IN_SECONDS;
+	}
+
+	foreach ( $crons as $event_timestamp => $cron ) {
+		if ( $event_timestamp < $min_timestamp ) {
+			continue;
+		}
+		if ( $event_timestamp > $max_timestamp ) {
+			break;
+		}
+		if ( isset( $cron[ $event->hook ][ $key ] ) ) {
+			$duplicate = true;
+			break;
+		}
+	}
+
+	if ( $duplicate ) {
 		return false;
 	}
 
@@ -107,9 +147,6 @@ function wp_schedule_single_event( $timestamp, $hook, $args = array() ) {
 		return false;
 	}
 
-	$key = md5( serialize( $event->args ) );
-
-	$crons = _get_cron_array();
 	$crons[ $event->timestamp ][ $event->hook ][ $key ] = array(
 		'schedule' => $event->schedule,
 		'args'     => $event->args,
diff --git a/wp-includes/version.php b/wp-includes/version.php
index f9811736a7..f8bc63a916 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.2-alpha-44916';
+$wp_version = '5.2-alpha-44917';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.