From 6b2e15f6c516acfa0d0e50c2c07c6f40519c6feb Mon Sep 17 00:00:00 2001
From: Mikhail Golenkov <mikhailgolenkov@catalyst-au.net>
Date: Thu, 2 Jan 2020 17:34:19 +1100
Subject: [PATCH] MDL-67485 task: Release the task runner lock before throwing
 exception.

---
 lib/classes/task/manager.php |  2 ++
 lib/cronlib.php              | 34 +++++++++++++++++++++++-----------
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/lib/classes/task/manager.php b/lib/classes/task/manager.php
index 091974bfb07..016ac4c69c5 100644
--- a/lib/classes/task/manager.php
+++ b/lib/classes/task/manager.php
@@ -553,6 +553,7 @@ class manager {
      *
      * @param int $timestart
      * @return \core\task\adhoc_task or null if not found
+     * @throws \moodle_exception
      */
     public static function get_next_adhoc_task($timestart) {
         global $DB;
@@ -609,6 +610,7 @@ class manager {
      *
      * @param int $timestart - The start of the cron process - do not repeat any tasks that have been run more recently than this.
      * @return \core\task\scheduled_task or null
+     * @throws \moodle_exception
      */
     public static function get_next_scheduled_task($timestart) {
         global $DB;
diff --git a/lib/cronlib.php b/lib/cronlib.php
index db0193fe857..2ccbb3d5d9f 100644
--- a/lib/cronlib.php
+++ b/lib/cronlib.php
@@ -87,6 +87,7 @@ function cron_run() {
  * Execute all queued scheduled tasks, applying necessary concurrency limits and time limits.
  *
  * @param   int     $timenow The time this process started.
+ * @throws \moodle_exception
  */
 function cron_run_scheduled_tasks(int $timenow) {
     // Allow a restriction on the number of scheduled task runners at once.
@@ -109,19 +110,21 @@ function cron_run_scheduled_tasks(int $timenow) {
     $starttime = time();
 
     // Run all scheduled tasks.
-    while (!\core\task\manager::static_caches_cleared_since($timenow) &&
-            $task = \core\task\manager::get_next_scheduled_task($timenow)) {
-        cron_run_inner_scheduled_task($task);
-        unset($task);
+    try {
+        while (!\core\task\manager::static_caches_cleared_since($timenow) &&
+                $task = \core\task\manager::get_next_scheduled_task($timenow)) {
+            cron_run_inner_scheduled_task($task);
+            unset($task);
 
-        if ((time() - $starttime) > $maxruntime) {
-            mtrace("Stopping processing of scheduled tasks as time limit has been reached.");
-            break;
+            if ((time() - $starttime) > $maxruntime) {
+                mtrace("Stopping processing of scheduled tasks as time limit has been reached.");
+                break;
+            }
         }
+    } finally {
+        // Release the scheduled task runner lock.
+        $scheduledlock->release();
     }
-
-    // Release the scheduled task runner lock.
-    $scheduledlock->release();
 }
 
 /**
@@ -130,6 +133,7 @@ function cron_run_scheduled_tasks(int $timenow) {
  * @param   int     $timenow The time this process started.
  * @param   int     $keepalive Keep this function alive for N seconds and poll for new adhoc tasks.
  * @param   bool    $checklimits Should we check limits?
+ * @throws \moodle_exception
  */
 function cron_run_adhoc_tasks(int $timenow, $keepalive = 0, $checklimits = true) {
     // Allow a restriction on the number of adhoc task runners at once.
@@ -168,7 +172,15 @@ function cron_run_adhoc_tasks(int $timenow, $keepalive = 0, $checklimits = true)
             break;
         }
 
-        $task = \core\task\manager::get_next_adhoc_task(time());
+        try {
+            $task = \core\task\manager::get_next_adhoc_task(time());
+        } catch (Exception $e) {
+            if ($adhoclock) {
+                // Release the adhoc task runner lock.
+                $adhoclock->release();
+            }
+            throw $e;
+        }
 
         if ($task) {
             if ($waiting) {