Remove scheduled jobs that do not match their cron expression

When you change a cron expression in the config, you do not
want jobs that were scheduled ahead to be executed on the old
config cron expression.

The cleanup makes the config change take immediate effect.

Author: Anton Evers

app/code/Magento/Cron/Observer/ProcessCronQueueObserver.php

@@ -109,12 +109,17 @@ class ProcessCronQueueObserver implements ObserverInterface
     /**
      * @var \Psr\Log\LoggerInterface
      */
-    private $logger;
+    protected $logger;
 
     /**
      * @var \Magento\Framework\App\State
      */
-    private $state;
+    protected $state;
+
+    /**
+     * @var array
+     */
+    protected $invalid = [];
 
     /**
      * @param \Magento\Framework\ObjectManagerInterface $objectManager
@@ -180,15 +185,17 @@ public function execute(\Magento\Framework\Event\Observer $observer)
             $this->generate($groupId);
             if ($this->request->getParam('group') !== null
                 && $this->request->getParam('group') !== '\'' . ($groupId) . '\''
-                && $this->request->getParam('group') !== $groupId) {
+                && $this->request->getParam('group') !== $groupId
+            ) {
                 continue;
             }
             if (($this->request->getParam(self::STANDALONE_PROCESS_STARTED) !== '1') && (
                     $this->scopeConfig->getValue(
                         'system/cron/' . $groupId . '/use_separate_process',
                         \Magento\Store\Model\ScopeInterface::SCOPE_STORE
                     ) == 1
-                )) {
+                )
+            ) {
                 $this->shell->execute(
                     $phpPath . ' %s cron:run --group=' . $groupId . ' --' . Cli::INPUT_KEY_BOOTSTRAP . '='
                     . self::STANDALONE_PROCESS_STARTED . '=1',
@@ -336,7 +343,9 @@ public function generate($groupId)
          * generate global crontab jobs
          */
         $jobs = $this->config->getJobs();
+        $this->invalid = [];
         $this->generateJobs($jobs[$groupId], $exists, $groupId);
+        $this->cleanupScheduleMismatches();
 
         /**
          * save time schedules generation was ran with no expiration
@@ -469,13 +478,20 @@ public function saveSchedule($jobCode, $cronExpression, $timeInterval, $exists)
         $currentTime = $this->timezone->scopeTimeStamp();
         $timeAhead = $currentTime + $timeInterval;
         for ($time = $currentTime; $time < $timeAhead; $time += self::SECONDS_IN_MINUTE) {
-            $timestamp = strftime('%Y-%m-%d %H:%M:00', $time);
-            if (!empty($exists[$jobCode . '/' . $timestamp])) {
-                // already scheduled
+            $scheduledAt = strftime('%Y-%m-%d %H:%M:00', $time);
+            $alreadyScheduled = !empty($exists[$jobCode . '/' . $scheduledAt]);
+            $schedule = $this->generateSchedule($jobCode, $cronExpression, $time);
+            $valid = $schedule->trySchedule();
+            if (!$valid) {
+                if ($alreadyScheduled) {
+                    if (!isset($this->invalid[$jobCode])) {
+                        $this->invalid[$jobCode] = [];
+                    }
+                    $this->invalid[$jobCode][] = $scheduledAt;
+                }
                 continue;
             }
-            $schedule = $this->generateSchedule($jobCode, $cronExpression, $time);
-            if ($schedule->trySchedule()) {
+            if (!$alreadyScheduled) {
                 // time matches cron expression
                 $schedule->save();
             }
@@ -516,6 +532,9 @@ public function getScheduleTimeInterval($groupId)
     }
 
     /**
+     * Clean up scheduled jobs that are disabled in the configuration
+     * This can happen when you turn off a cron job in the config and flush the cache
+     *
      * @param $groupId
      */
     public function cleanupDisabledJobs($groupId)
@@ -551,4 +570,24 @@ public function getCronExpression($jobConfig)
         }
         return $cronExpression;
     }
+
+    /**
+     * Clean up scheduled jobs that do not match their cron expression anymore
+     * This can happen when you change the cron expression and flush the cache
+     *
+     * @return $this
+     */
+    public function cleanupScheduleMismatches()
+    {
+        foreach ($this->invalid as $jobCode => $scheduledAtList) {
+            /** @var \Magento\Cron\Model\ResourceModel\Schedule $scheduleResource */
+            $scheduleResource = $this->scheduleFactory->create()->getResource();
+            $scheduleResource->getConnection()->delete($scheduleResource->getMainTable(), [
+                'status=?' => Schedule::STATUS_PENDING,
+                'job_code=?' => $jobCode,
+                'scheduled_at in (?)' => $scheduledAtList,
+            ]);
+        }
+        return $this;
+    }
 }