[Task Manager] Tests for the ability to run tasks of varying durations in parallel (#51572)

This PR adds a test that ensures Task Manager is capable of picking up new tasks in parallel to a long running tasks that might otherwise hold up task execution.

This doesn't add functionality - just a missing test case.

x-pack/test/plugin_api_integration/plugins/task_manager/index.js

@@ -4,9 +4,20 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
+const { EventEmitter } = require('events');
+
 import { initRoutes } from './init_routes';
 
+
+const once = function (emitter, event) {
+  return new Promise(resolve => {
+    emitter.once(event, resolve);
+  });
+};
+
 export default function TaskTestingAPI(kibana) {
+  const taskTestingEvents = new EventEmitter();
+
   return new kibana.Plugin({
     name: 'sampleTask',
     require: ['elasticsearch', 'task_manager'],
@@ -52,6 +63,10 @@ export default function TaskTestingAPI(kibana) {
                 refresh: true,
               });
 
+              if (params.waitForEvent) {
+                await once(taskTestingEvents, params.waitForEvent);
+              }
+
               return {
                 state: { count: (prevState.count || 0) + 1 },
                 runAt: millisecondsFromNow(params.nextRunMilliseconds),
@@ -88,7 +103,7 @@ export default function TaskTestingAPI(kibana) {
         },
       });
 
-      initRoutes(server);
+      initRoutes(server, taskTestingEvents);
     },
   });
 }

x-pack/test/plugin_api_integration/plugins/task_manager/init_routes.js

@@ -23,11 +23,11 @@ const taskManagerQuery = {
   }
 };
 
-export function initRoutes(server) {
+export function initRoutes(server, taskTestingEvents) {
   const taskManager = server.plugins.task_manager;
 
   server.route({
-    path: '/api/sample_tasks',
+    path: '/api/sample_tasks/schedule',
     method: 'POST',
     config: {
       validate: {
@@ -38,26 +38,19 @@ export function initRoutes(server) {
             params: Joi.object().required(),
             state: Joi.object().optional(),
             id: Joi.string().optional()
-          }),
-          ensureScheduled: Joi.boolean()
-            .default(false)
-            .optional(),
+          })
         }),
       },
     },
     async handler(request) {
       try {
-        const { ensureScheduled = false, task: taskFields } = request.payload;
+        const { task: taskFields } = request.payload;
         const task = {
           ...taskFields,
           scope: [scope],
         };
 
-        const taskResult = await (
-          ensureScheduled
-            ? taskManager.ensureScheduled(task, { request })
-            : taskManager.schedule(task, { request })
-        );
+        const taskResult = await (taskManager.schedule(task, { request }));
 
         return taskResult;
       } catch (err) {
@@ -66,6 +59,60 @@ export function initRoutes(server) {
     },
   });
 
+  server.route({
+    path: '/api/sample_tasks/ensure_scheduled',
+    method: 'POST',
+    config: {
+      validate: {
+        payload: Joi.object({
+          task: Joi.object({
+            taskType: Joi.string().required(),
+            interval: Joi.string().optional(),
+            params: Joi.object().required(),
+            state: Joi.object().optional(),
+            id: Joi.string().optional()
+          })
+        }),
+      },
+    },
+    async handler(request) {
+      try {
+        const { task: taskFields } = request.payload;
+        const task = {
+          ...taskFields,
+          scope: [scope],
+        };
+
+        const taskResult = await (taskManager.ensureScheduled(task, { request }));
+
+        return taskResult;
+      } catch (err) {
+        return err;
+      }
+    },
+  });
+
+  server.route({
+    path: '/api/sample_tasks/event',
+    method: 'POST',
+    config: {
+      validate: {
+        payload: Joi.object({
+          event: Joi.string().required()
+        }),
+      },
+    },
+    async handler(request) {
+      try {
+        const { event } = request.payload;
+        taskTestingEvents.emit(event);
+        return { event };
+      } catch (err) {
+        return err;
+      }
+    },
+  });
+
   server.route({
     path: '/api/sample_tasks',
     method: 'GET',

x-pack/test/plugin_api_integration/test_suites/task_manager/task_manager_integration.js

@@ -58,7 +58,7 @@ export default function ({ getService }) {
     }
 
     function scheduleTask(task) {
-      return supertest.post('/api/sample_tasks')
+      return supertest.post('/api/sample_tasks/schedule')
         .set('kbn-xsrf', 'xxx')
         .send({ task })
         .expect(200)
@@ -66,13 +66,20 @@ export default function ({ getService }) {
     }
 
     function scheduleTaskIfNotExists(task) {
-      return supertest.post('/api/sample_tasks')
+      return supertest.post('/api/sample_tasks/ensure_scheduled')
         .set('kbn-xsrf', 'xxx')
-        .send({ task, ensureScheduled: true })
+        .send({ task })
         .expect(200)
         .then((response) => response.body);
     }
 
+    function releaseTasksWaitingForEventToComplete(event) {
+      return supertest.post('/api/sample_tasks/event')
+        .set('kbn-xsrf', 'xxx')
+        .send({ event })
+        .expect(200);
+    }
+
     it('should support middleware', async () => {
       const historyItem = _.random(1, 100);
 
@@ -204,5 +211,45 @@ export default function ({ getService }) {
       expect(Date.parse(currentTask.runAt) - originalRunAt).to.be.greaterThan(expectedDiff - buffer);
       expect(Date.parse(currentTask.runAt) - originalRunAt).to.be.lessThan(expectedDiff + buffer);
     }
+
+    it('should run tasks in parallel, allowing for long running tasks along side faster tasks', async () => {
+      /**
+       * It's worth noting this test relies on the /event endpoint that forces Task Manager to hold off
+       * on completing a task until a call is made by the test suite.
+       * If we begin testing with multiple Kibana instacnes in Parallel this will likely become flaky.
+       * If you end up here because the test is flaky, this might be why.
+       */
+      const fastTask = await scheduleTask({
+        taskType: 'sampleTask',
+        interval: `1s`,
+        params: { },
+      });
+
+      const longRunningTask = await scheduleTask({
+        taskType: 'sampleTask',
+        interval: `1s`,
+        params: {
+          waitForEvent: 'rescheduleHasHappened'
+        },
+      });
+
+      function getTaskById(tasks, id) {
+        return tasks.filter(task => task.id === id)[0];
+      }
+
+      await retry.try(async () => {
+        const tasks = (await currentTasks()).docs;
+        expect(getTaskById(tasks, fastTask.id).state.count).to.eql(2);
+      });
+
+      await releaseTasksWaitingForEventToComplete('rescheduleHasHappened');
+
+      await retry.try(async () => {
+        const tasks = (await currentTasks()).docs;
+
+        expect(getTaskById(tasks, fastTask.id).state.count).to.greaterThan(2);
+        expect(getTaskById(tasks, longRunningTask.id).state.count).to.eql(1);
+      });
+    });
   });
 }