[cron] Improved the scheduling of the install sync cron job.

Author: fajardoleo

includes/class-freemius.php

@@ -5451,7 +5451,7 @@ function _plugin_code_type_changed() {
 
             if ( $this->is_registered() ) {
                 // Schedule code type changes event.
-                $this->schedule_install_sync();
+                $this->maybe_schedule_install_sync_cron();
             }
 
             /**
@@ -6514,6 +6514,33 @@ private function maybe_schedule_sync_cron() {
             $this->schedule_sync_cron();
         }
 
+        /**
+         * Instead of running blocking install sync event, execute non blocking scheduled cron job.
+         *
+         * @param int $except_blog_id Since 2.0.0 when running in a multisite network environment, the cron execution is consolidated. This param allows excluding specified blog ID from being the cron job executor.
+         *
+         * @author Leo Fajardo (@leorw)
+         * @since  2.9.1
+         */
+        private function maybe_schedule_install_sync_cron( $except_blog_id = 0 ) {
+            if ( ! $this->is_user_in_admin() ) {
+                return;
+            }
+
+            if ( $this->is_clone() ) {
+                return;
+            }
+
+            if (
+                // The event has been properly scheduled, so no need to reschedule it.
+                is_numeric( $this->next_install_sync() )
+            ) {
+                return;
+            }
+
+            $this->schedule_cron( 'install_sync', 'install_sync', 'single', WP_FS__SCRIPT_START_TIME, false, $except_blog_id );
+        }
+
         /**
          * @author Vova Feldman (@svovaf)
          * @since  1.1.7.3
@@ -6611,22 +6638,6 @@ private function get_install_sync_cron_blog_id() {
             return $this->get_cron_blog_id( 'install_sync' );
         }
 
-        /**
-         * Instead of running blocking install sync event, execute non blocking scheduled wp-cron.
-         *
-         * @author Vova Feldman (@svovaf)
-         * @since  1.1.7.3
-         *
-         * @param int $except_blog_id Since 2.0.0 when running in a multisite network environment, the cron execution is consolidated. This param allows excluding excluded specified blog ID from being the cron executor.
-         */
-        private function schedule_install_sync( $except_blog_id = 0 ) {
-            if ( $this->is_clone() ) {
-                return;
-            }
-
-            $this->schedule_cron( 'install_sync', 'install_sync', 'single', WP_FS__SCRIPT_START_TIME, false, $except_blog_id );
-        }
-
         /**
          * Unix timestamp for previous install sync cron execution or false if never executed.
          *
@@ -7432,7 +7443,7 @@ function _activate_plugin_event_hook() {
 
                 // Schedule re-activation event and sync.
 //				$this->sync_install( array(), true );
-                $this->schedule_install_sync();
+                $this->maybe_schedule_install_sync_cron();
 
                 // If activating the premium module version, add an admin notice to congratulate for an upgrade completion.
                 if ( $is_premium_version_activation ) {
@@ -8623,7 +8634,7 @@ private function update_plugin_version_event() {
                 return;
             }
 
-            $this->schedule_install_sync();
+            $this->maybe_schedule_install_sync_cron();
 //			$this->sync_install( array(), true );
         }
 
@@ -15981,7 +15992,7 @@ private function update_multisite_data_after_site_deactivation( $context_blog_id
             if ( $this->is_install_sync_scheduled() &&
                  $context_blog_id == $this->get_install_sync_cron_blog_id()
             ) {
-                $this->schedule_install_sync( $context_blog_id );
+                $this->maybe_schedule_install_sync_cron( $context_blog_id );
             }
         }