From 6b848ead036b439f443e629c60aec181120deb83 Mon Sep 17 00:00:00 2001
From: Gidi Meir Morris <github@gidi.io>
Date: Wed, 22 Jul 2020 10:45:22 +0100
Subject: [PATCH 1/2] removed next tick scheduling as we dont use it and its
 test was too flaky

---
 .../server/lib/bulk_operation_buffer.test.ts  | 42 -------------------
 .../server/lib/bulk_operation_buffer.ts       | 11 +----
 2 files changed, 2 insertions(+), 51 deletions(-)

diff --git a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
index 9293656233026..2c6d2b64f5d44 100644
--- a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
+++ b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
@@ -54,48 +54,6 @@ describe('Bulk Operation Buffer', () => {
       expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
     });
 
-    test('batch updates are executed at most by the next Event Loop tick by default', async () => {
-      const bulkUpdate: jest.Mocked<BulkOperation<TaskInstance, Error>> = jest.fn((tasks) => {
-        return Promise.resolve(tasks.map(incrementAttempts));
-      });
-
-      const bufferedUpdate = createBuffer(bulkUpdate);
-
-      const task1 = createTask();
-      const task2 = createTask();
-      const task3 = createTask();
-      const task4 = createTask();
-      const task5 = createTask();
-      const task6 = createTask();
-
-      return new Promise((resolve) => {
-        Promise.all([bufferedUpdate(task1), bufferedUpdate(task2)]).then((_) => {
-          expect(bulkUpdate).toHaveBeenCalledTimes(1);
-          expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
-          expect(bulkUpdate).not.toHaveBeenCalledWith([task3, task4]);
-        });
-
-        setTimeout(() => {
-          // on next tick
-          setTimeout(() => {
-            // on next tick
-            expect(bulkUpdate).toHaveBeenCalledTimes(2);
-            Promise.all([bufferedUpdate(task5), bufferedUpdate(task6)]).then((_) => {
-              expect(bulkUpdate).toHaveBeenCalledTimes(3);
-              expect(bulkUpdate).toHaveBeenCalledWith([task5, task6]);
-              resolve();
-            });
-          }, 0);
-
-          expect(bulkUpdate).toHaveBeenCalledTimes(1);
-          Promise.all([bufferedUpdate(task3), bufferedUpdate(task4)]).then((_) => {
-            expect(bulkUpdate).toHaveBeenCalledTimes(2);
-            expect(bulkUpdate).toHaveBeenCalledWith([task3, task4]);
-          });
-        }, 0);
-      });
-    });
-
     test('batch updates can be customised to execute after a certain period', async () => {
       const bulkUpdate: jest.Mocked<BulkOperation<TaskInstance, Error>> = jest.fn((tasks) => {
         return Promise.resolve(tasks.map(incrementAttempts));
diff --git a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.ts b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.ts
index fca7ce02e0cd7..c8e5b837fa36c 100644
--- a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.ts
+++ b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.ts
@@ -93,11 +93,8 @@ export function createBuffer<Input extends Entity, ErrorOutput, Output extends E
               // the race is started in response to the first operation into the buffer
               // so we flush once the remaining operations come in (which is `bufferMaxOperations - 1`)
               storeUpdateBuffer.pipe(bufferCount(bufferMaxOperations - 1)),
-              bufferMaxDuration
-                ? // if theres a max duration, flush buffer based on that
-                  from(resolveIn(bufferMaxDuration))
-                : // ensure we flush by the end of the "current" event loop tick
-                  from(resolveImmediate()),
+              // flush buffer once max duration has passed
+              from(resolveIn(bufferMaxDuration)),
             ]).pipe(first(), mapTo(FLUSH))
           : from([DONT_FLUSH]);
       }),
@@ -118,10 +115,6 @@ export function createBuffer<Input extends Entity, ErrorOutput, Output extends E
   };
 }
 
-function resolveImmediate() {
-  return new Promise(setImmediate);
-}
-
 function resolveIn(ms: number) {
   return new Promise((resolve) => {
     setTimeout(resolve, ms);

From fcc46227b2e0437c51322f6a462e8eade3e4325f Mon Sep 17 00:00:00 2001
From: Gidi Meir Morris <github@gidi.io>
Date: Wed, 22 Jul 2020 11:15:39 +0100
Subject: [PATCH 2/2] reenable test

---
 .../task_manager/server/lib/bulk_operation_buffer.test.ts       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
index 76f4d1beac3cd..2c6d2b64f5d44 100644
--- a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
+++ b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
@@ -33,7 +33,7 @@ function errorAttempts(task: TaskInstance): Err<OperationError<TaskInstance, Err
   });
 }
 
-describe.skip('Bulk Operation Buffer', () => {
+describe('Bulk Operation Buffer', () => {
   describe('createBuffer()', () => {
     test('batches up multiple Operation calls', async () => {
       const bulkUpdate: jest.Mocked<BulkOperation<TaskInstance, Error>> = jest.fn(