From 6aaf8efefffdb0d4b93f178b2bb36cd3c6bc31b8 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Thu, 8 Sep 2022 09:59:51 +0800
Subject: [PATCH] fix(runtime-core): avoid double firing when mounting inside a
 watcher callback

fix #6614
---
 packages/runtime-core/__tests__/scheduler.spec.ts | 12 ++++++++++++
 packages/runtime-core/src/scheduler.ts            |  6 +++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/packages/runtime-core/__tests__/scheduler.spec.ts b/packages/runtime-core/__tests__/scheduler.spec.ts
index 1f7199f6edf..dc9bace9c9c 100644
--- a/packages/runtime-core/__tests__/scheduler.spec.ts
+++ b/packages/runtime-core/__tests__/scheduler.spec.ts
@@ -534,4 +534,16 @@ describe('scheduler', () => {
     // should not be called
     expect(spy).toHaveBeenCalledTimes(0)
   })
+
+  it('flushPreFlushCbs inside a pre job', async () => {
+    const spy = jest.fn()
+    const job = () => {
+      spy()
+      flushPreFlushCbs()
+    }
+    job.pre = true
+    queueJob(job)
+    await nextTick()
+    expect(spy).toHaveBeenCalledTimes(1)
+  })
 })
diff --git a/packages/runtime-core/src/scheduler.ts b/packages/runtime-core/src/scheduler.ts
index 109541d280b..923f3ec8251 100644
--- a/packages/runtime-core/src/scheduler.ts
+++ b/packages/runtime-core/src/scheduler.ts
@@ -133,7 +133,11 @@ export function queuePostFlushCb(cb: SchedulerJobs) {
   queueFlush()
 }
 
-export function flushPreFlushCbs(seen?: CountMap, i = flushIndex) {
+export function flushPreFlushCbs(
+  seen?: CountMap,
+  // if currently flushing, skip the current job itself
+  i = isFlushing ? flushIndex + 1 : 0
+) {
   if (__DEV__) {
     seen = seen || new Map()
   }