Merge pull request #19793 from wss-ycabrera/PBI_900245_task_worker_fix

Fix bug 19792:  Backstage does not immediately apply new schedules for scheduled items

.changeset/dry-yaks-type.md

@@ -0,0 +1,8 @@
+---
+'@backstage/backend-tasks': patch
+---
+
+When starting a task that existed before, with a faster schedule than it
+previously had, the task will now correctly obey the faster schedule
+immediately. Before this fix, the new schedule was only obeyed after the next
+pending (according to the old schedule) run had completed.

packages/backend-tasks/src/tasks/TaskWorker.test.ts

@@ -330,6 +330,48 @@ describe('TaskWorker', () => {
       const before = fn1.mock.calls.length;
       await promise2;
       expect(fn1.mock.calls.length).toBeGreaterThan(before);
+
+      await knex.destroy();
+    },
+  );
+
+  it.each(databases.eachSupportedId())(
+    'next_run_start_at is always the min between schedule changes, %p',
+    async databaseId => {
+      const knex = await databases.init(databaseId);
+      await migrateBackendTasks(knex);
+
+      const fn = jest.fn(
+        async () => new Promise<void>(resolve => setTimeout(resolve, 50)),
+      );
+      const settings: TaskSettingsV2 = {
+        version: 2,
+        cadence: '*/15 * * * *',
+        initialDelayDuration: 'PT2M',
+        timeoutAfterDuration: 'PT1M',
+      };
+
+      const worker = new TaskWorker('task99', fn, knex, logger);
+      await worker.persistTask(settings);
+      const row1 = (await knex<DbTasksRow>(DB_TASKS_TABLE))[0];
+
+      const settings2 = {
+        ...settings,
+        cadence: '*/2 * * * *',
+        initialDelayDuration: 'PT1M',
+      };
+      await worker.persistTask(settings2);
+      const row2 = (await knex<DbTasksRow>(DB_TASKS_TABLE))[0];
+
+      expect(row2.next_run_start_at).not.toStrictEqual(row1.next_run_start_at);
+
+      const settings3 = { ...settings };
+      await worker.persistTask(settings3);
+      const row3 = (await knex<DbTasksRow>(DB_TASKS_TABLE))[0];
+
+      expect(row3.next_run_start_at).toStrictEqual(row2.next_run_start_at);
+
+      await knex.destroy();
     },
   );
 });

packages/backend-tasks/src/tasks/TaskWorker.ts

@@ -192,14 +192,36 @@ export class TaskWorker {
 
     // It's OK if the task already exists; if it does, just replace its
     // settings with the new value and start the loop as usual.
+    const settingsJson = JSON.stringify(settings);
     await this.knex<DbTasksRow>(DB_TASKS_TABLE)
       .insert({
         id: this.taskId,
-        settings_json: JSON.stringify(settings),
+        settings_json: settingsJson,
         next_run_start_at: startAt,
       })
       .onConflict('id')
-      .merge(['settings_json']);
+      .merge(
+        this.knex.client.config.client.includes('mysql')
+          ? {
+              settings_json: settingsJson,
+              next_run_start_at: this.knex.raw(
+                `CASE WHEN ?? < ?? THEN ?? ELSE ?? END`,
+                [startAt, 'next_run_start_at', startAt, 'next_run_start_at'],
+              ),
+            }
+          : {
+              settings_json: this.knex.ref('excluded.settings_json'),
+              next_run_start_at: this.knex.raw(
+                `CASE WHEN ?? < ?? THEN ?? ELSE ?? END`,
+                [
+                  'excluded.next_run_start_at',
+                  `${DB_TASKS_TABLE}.next_run_start_at`,
+                  'excluded.next_run_start_at',
+                  `${DB_TASKS_TABLE}.next_run_start_at`,
+                ],
+              ),
+            },
+      );
   }
 
   /**