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fix: always use microtasks for nextTick (#8450)

fix #7109, #7546, #7707, #7834, #8109
reopen #6566
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sodatea authored and yyx990803 committed Dec 19, 2018
1 parent ced774b commit 850555d1faa9be7d8306adffd95c7dee5e58717f
@@ -1,9 +1,9 @@
/* @flow */
/* globals MessageChannel */
/* globals MutationObserver */

import { noop } from 'shared/util'
import { handleError } from './error'
import { isIOS, isNative } from './env'
import { isIE, isIOS, isNative } from './env'

const callbacks = []
let pending = false
@@ -17,76 +17,67 @@ function flushCallbacks () {
}
}

// Here we have async deferring wrappers using both microtasks and (macro) tasks.
// In < 2.4 we used microtasks everywhere, but there are some scenarios where
// microtasks have too high a priority and fire in between supposedly
// sequential events (e.g. #4521, #6690) or even between bubbling of the same
// event (#6566). However, using (macro) tasks everywhere also has subtle problems
// when state is changed right before repaint (e.g. #6813, out-in transitions).
// Here we use microtask by default, but expose a way to force (macro) task when
// needed (e.g. in event handlers attached by v-on).
let microTimerFunc
let macroTimerFunc
let useMacroTask = false
// Here we have async deferring wrappers using microtasks.
// In 2.5 we used (macro) tasks (in combination with microtasks).
// However, it has subtle problems when state is changed right before repaint
// (e.g. #6813, out-in transitions).
// Also, using (macro) tasks in event handler would cause some weird behaviors
// that cannot be circumvented (e.g. #7109, #7153, #7546, #7834, #8109).
// So we now use microtasks everywhere, again.
// A major drawback of this tradeoff is that there are some scenarios
// where microtasks have too high a priority and fire in between supposedly
// sequential events (e.g. #4521, #6690, which have workarounds)
// or even between bubbling of the same event (#6566).
let timerFunc

// Determine (macro) task defer implementation.
// Technically setImmediate should be the ideal choice, but it's only available
// in IE. The only polyfill that consistently queues the callback after all DOM
// events triggered in the same loop is by using MessageChannel.
/* istanbul ignore if */
if (typeof setImmediate !== 'undefined' && isNative(setImmediate)) {
macroTimerFunc = () => {
setImmediate(flushCallbacks)
}
} else if (typeof MessageChannel !== 'undefined' && (
isNative(MessageChannel) ||
// PhantomJS
MessageChannel.toString() === '[object MessageChannelConstructor]'
)) {
const channel = new MessageChannel()
const port = channel.port2
channel.port1.onmessage = flushCallbacks
macroTimerFunc = () => {
port.postMessage(1)
}
} else {
/* istanbul ignore next */
macroTimerFunc = () => {
setTimeout(flushCallbacks, 0)
}
}

// Determine microtask defer implementation.
// The nextTick behavior leverages the microtask queue, which can be accessed
// via either native Promise.then or MutationObserver.
// MutationObserver has wider support, however it is seriously bugged in
// UIWebView in iOS >= 9.3.3 when triggered in touch event handlers. It
// completely stops working after triggering a few times... so, if native
// Promise is available, we will use it:
/* istanbul ignore next, $flow-disable-line */
if (typeof Promise !== 'undefined' && isNative(Promise)) {
const p = Promise.resolve()
microTimerFunc = () => {
timerFunc = () => {
p.then(flushCallbacks)
// in problematic UIWebViews, Promise.then doesn't completely break, but
// In problematic UIWebViews, Promise.then doesn't completely break, but
// it can get stuck in a weird state where callbacks are pushed into the
// microtask queue but the queue isn't being flushed, until the browser
// needs to do some other work, e.g. handle a timer. Therefore we can
// "force" the microtask queue to be flushed by adding an empty timer.
if (isIOS) setTimeout(noop)
}
} else {
// fallback to macro
microTimerFunc = macroTimerFunc
}

/**
* Wrap a function so that if any code inside triggers state change,
* the changes are queued using a (macro) task instead of a microtask.
*/
export function withMacroTask (fn: Function): Function {
return fn._withTask || (fn._withTask = function () {
useMacroTask = true
try {
return fn.apply(null, arguments)
} finally {
useMacroTask = false
}
} else if (!isIE && typeof MutationObserver !== 'undefined' && (
isNative(MutationObserver) ||
// PhantomJS and iOS 7.x
MutationObserver.toString() === '[object MutationObserverConstructor]'
)) {
// Use MutationObserver where native Promise is not available,
// e.g. PhantomJS, iOS7, Android 4.4
// (#6466 MutationObserver is unreliable in IE11)
let counter = 1
const observer = new MutationObserver(flushCallbacks)
const textNode = document.createTextNode(String(counter))
observer.observe(textNode, {
characterData: true
})
timerFunc = () => {
counter = (counter + 1) % 2
textNode.data = String(counter)
}
} else if (typeof setImmediate !== 'undefined' && isNative(setImmediate)) {
// Fallback to setImmediate.
// Techinically it leverages the (macro) task queue,
// but it is still a better choice than setTimeout.
timerFunc = () => {
setImmediate(flushCallbacks)
}
} else {
// Fallback to setTimeout.
timerFunc = () => {
setTimeout(flushCallbacks, 0)
}
}

export function nextTick (cb?: Function, ctx?: Object) {
@@ -104,11 +95,7 @@ export function nextTick (cb?: Function, ctx?: Object) {
})
if (!pending) {
pending = true
if (useMacroTask) {
macroTimerFunc()
} else {
microTimerFunc()
}
timerFunc()
}
// $flow-disable-line
if (!cb && typeof Promise !== 'undefined') {
@@ -35,6 +35,17 @@ function updateDOMProps (oldVnode: VNodeWithData, vnode: VNodeWithData) {
}
}

// #4521: if a click event triggers update before the change event is
// dispatched on a checkbox/radio input, the input's checked state will
// be reset and fail to trigger another update.
// The root cause here is that browsers may fire microtasks in between click/change.
// In Chrome / Firefox, click event fires before change, thus having this problem.
// In Safari / Edge, the order is opposite.
// Note: in Edge, if you click too fast, only the click event would fire twice.
if (key === 'checked' && !isNotInFocusAndDirty(elm, cur)) {
continue
}

if (key === 'value') {
// store value as _value as well since
// non-string values will be stringified
@@ -2,7 +2,7 @@

import { isDef, isUndef } from 'shared/util'
import { updateListeners } from 'core/vdom/helpers/index'
import { withMacroTask, isIE, supportsPassive } from 'core/util/index'
import { isIE, supportsPassive } from 'core/util/index'
import { RANGE_TOKEN, CHECKBOX_RADIO_TOKEN } from 'web/compiler/directives/model'

// normalize v-model event tokens that can only be determined at runtime.
@@ -44,7 +44,6 @@ function add (
capture: boolean,
passive: boolean
) {
handler = withMacroTask(handler)
target.addEventListener(
event,
handler,
@@ -14,20 +14,20 @@ module.exports = {
.assert.containsText('#case-1', '3')
.assert.checked('#case-1 input', false)

// #6566
.assert.containsText('#case-2 button', 'Expand is True')
.assert.containsText('.count-a', 'countA: 0')
.assert.containsText('.count-b', 'countB: 0')
// // #6566
// .assert.containsText('#case-2 button', 'Expand is True')
// .assert.containsText('.count-a', 'countA: 0')
// .assert.containsText('.count-b', 'countB: 0')

.click('#case-2 button')
.assert.containsText('#case-2 button', 'Expand is False')
.assert.containsText('.count-a', 'countA: 1')
.assert.containsText('.count-b', 'countB: 0')
// .click('#case-2 button')
// .assert.containsText('#case-2 button', 'Expand is False')
// .assert.containsText('.count-a', 'countA: 1')
// .assert.containsText('.count-b', 'countB: 0')

.click('#case-2 button')
.assert.containsText('#case-2 button', 'Expand is True')
.assert.containsText('.count-a', 'countA: 1')
.assert.containsText('.count-b', 'countB: 1')
// .click('#case-2 button')
// .assert.containsText('#case-2 button', 'Expand is True')
// .assert.containsText('.count-a', 'countA: 1')
// .assert.containsText('.count-b', 'countB: 1')

.end()
}

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