re-implement mergeVNodeHook to prevent memory leak (fix #4990)

src/core/vdom/helpers/merge-hook.js

@@ -1,18 +1,34 @@
 /* @flow */
 
-export function mergeVNodeHook (def: Object, hookKey: string, hook: Function, key: string) {
-  key = key + hookKey
-  const injectedHash: Object = def.__injected || (def.__injected = {})
-  if (!injectedHash[key]) {
-    injectedHash[key] = true
-    const oldHook: ?Function = def[hookKey]
-    if (oldHook) {
-      def[hookKey] = function () {
-        oldHook.apply(this, arguments)
-        hook.apply(this, arguments)
-      }
+import { remove } from 'shared/util'
+import { createFnInvoker } from './update-listeners'
+
+export function mergeVNodeHook (def: Object, hookKey: string, hook: Function) {
+  let invoker
+  const oldHook = def[hookKey]
+
+  function wrappedHook () {
+    hook.apply(this, arguments)
+    // important: remove merged hook to ensure it's called only once
+    // and prevent memory leak
+    remove(invoker.fns, wrappedHook)
+  }
+
+  if (!oldHook) {
+    // no existing hook
+    invoker = createFnInvoker([wrappedHook])
+  } else {
+    /* istanbul ignore if */
+    if (oldHook.fns && oldHook.merged) {
+      // already a merged invoker
+      invoker = oldHook
+      invoker.fns.push(wrappedHook)
     } else {
-      def[hookKey] = hook
+      // existing plain hook
+      invoker = createFnInvoker([oldHook, wrappedHook])
     }
   }
+
+  invoker.merged = true
+  def[hookKey] = invoker
 }

src/core/vdom/helpers/update-listeners.js

@@ -19,25 +19,20 @@ const normalizeEvent = cached((name: string): {
   }
 })
 
-function createEventHandle (fn: Function | Array<Function>): {
-  fn: Function | Array<Function>;
-  invoker: Function;
-} {
-  const handle = {
-    fn,
-    invoker: function () {
-      const fn = handle.fn
-      if (Array.isArray(fn)) {
-        for (let i = 0; i < fn.length; i++) {
-          fn[i].apply(null, arguments)
-        }
-      } else {
-        // return handler return value for single handlers
-        return fn.apply(null, arguments)
+export function createFnInvoker (fns: Function | Array<Function>): Function {
+  function invoker () {
+    const fns = invoker.fns
+    if (Array.isArray(fns)) {
+      for (let i = 0; i < fns.length; i++) {
+        fns[i].apply(null, arguments)
       }
+    } else {
+      // return handler return value for single handlers
+      return fns.apply(null, arguments)
     }
   }
-  return handle
+  invoker.fns = fns
+  return invoker
 }
 
 export function updateListeners (
@@ -58,19 +53,19 @@ export function updateListeners (
         vm
       )
     } else if (!old) {
-      if (!cur.invoker) {
-        cur = on[name] = createEventHandle(cur)
+      if (!cur.fns) {
+        cur = on[name] = createFnInvoker(cur)
       }
-      add(event.name, cur.invoker, event.once, event.capture)
+      add(event.name, cur, event.once, event.capture)
     } else if (cur !== old) {
-      old.fn = cur
+      old.fns = cur
       on[name] = old
     }
   }
   for (name in oldOn) {
     if (!on[name]) {
       event = normalizeEvent(name)
-      remove(event.name, oldOn[name].invoker, event.capture)
+      remove(event.name, oldOn[name], event.capture)
     }
   }
 }

src/core/vdom/modules/directives.js

@@ -1,8 +1,8 @@
 /* @flow */
 
+import { emptyNode } from 'core/vdom/patch'
 import { resolveAsset } from 'core/util/options'
 import { mergeVNodeHook } from 'core/vdom/helpers/index'
-import { emptyNode } from 'core/vdom/patch'
 
 export default {
   create: updateDirectives,
@@ -54,7 +54,7 @@ function _update (oldVnode, vnode) {
       }
     }
     if (isCreate) {
-      mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', callInsert, 'dir-insert')
+      mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', callInsert)
     } else {
       callInsert()
     }
@@ -65,7 +65,7 @@ function _update (oldVnode, vnode) {
       for (let i = 0; i < dirsWithPostpatch.length; i++) {
         callHook(dirsWithPostpatch[i], 'componentUpdated', vnode, oldVnode)
       }
-    }, 'dir-postpatch')
+    })
   }
 
   if (!isCreate) {

src/platforms/web/runtime/components/transition.js

@@ -47,7 +47,7 @@ export function extractTransitionData (comp: Component): Object {
   // extract listeners and pass them directly to the transition methods
   const listeners: ?Object = options._parentListeners
   for (const key in listeners) {
-    data[camelize(key)] = listeners[key].fn
+    data[camelize(key)] = listeners[key]
   }
   return data
 }
@@ -132,11 +132,12 @@ export default {
     // component instance. This key will be used to remove pending leaving nodes
     // during entering.
     const id: string = `__transition-${this._uid}-`
-    const key: string = child.key = child.key == null
+    child.key = child.key == null
       ? id + child.tag
       : isPrimitive(child.key)
         ? (String(child.key).indexOf(id) === 0 ? child.key : id + child.key)
         : child.key
+
     const data: Object = (child.data || (child.data = {})).transition = extractTransitionData(this)
     const oldRawChild: VNode = this._vnode
     const oldChild: VNode = getRealChild(oldRawChild)
@@ -158,16 +159,14 @@ export default {
         mergeVNodeHook(oldData, 'afterLeave', () => {
           this._leaving = false
           this.$forceUpdate()
-        }, key)
+        })
         return placeholder(h, rawChild)
       } else if (mode === 'in-out') {
         let delayedLeave
         const performLeave = () => { delayedLeave() }
-        mergeVNodeHook(data, 'afterEnter', performLeave, key)
-        mergeVNodeHook(data, 'enterCancelled', performLeave, key)
-        mergeVNodeHook(oldData, 'delayLeave', leave => {
-          delayedLeave = leave
-        }, key)
+        mergeVNodeHook(data, 'afterEnter', performLeave)
+        mergeVNodeHook(data, 'enterCancelled', performLeave)
+        mergeVNodeHook(oldData, 'delayLeave', leave => { delayedLeave = leave })
       }
     }
 

src/platforms/web/runtime/modules/events.js

@@ -10,6 +10,7 @@ import { RANGE_TOKEN, CHECKBOX_RADIO_TOKEN } from 'web/compiler/directives/model
 // user-attached handlers.
 function normalizeEvents (on) {
   let event
+  /* istanbul ignore if */
   if (on[RANGE_TOKEN]) {
     // IE input[type=range] only supports `change` event
     event = isIE ? 'change' : 'input'

src/platforms/web/runtime/modules/transition.js

@@ -83,11 +83,7 @@ export function enter (vnode: VNodeWithData, toggleDisplay: ?() => void) {
   }
 
   const expectsCSS = css !== false && !isIE9
-  const userWantsControl =
-    enterHook &&
-    // enterHook may be a bound method which exposes
-    // the length of original fn as _length
-    (enterHook._length || enterHook.length) > 1
+  const userWantsControl = getHookAgumentsLength(enterHook)
 
   const cb = el._enterCb = once(() => {
     if (expectsCSS) {
@@ -116,7 +112,7 @@ export function enter (vnode: VNodeWithData, toggleDisplay: ?() => void) {
         pendingNode.elm._leaveCb()
       }
       enterHook && enterHook(el, cb)
-    }, 'transition-insert')
+    })
   }
 
   // start enter transition
@@ -181,11 +177,7 @@ export function leave (vnode: VNodeWithData, rm: Function) {
   } = data
 
   const expectsCSS = css !== false && !isIE9
-  const userWantsControl =
-    leave &&
-    // leave hook may be a bound method which exposes
-    // the length of original fn as _length
-    (leave._length || leave.length) > 1
+  const userWantsControl = getHookAgumentsLength(leave)
 
   const explicitLeaveDuration = isObject(duration) ? duration.leave : duration
   if (process.env.NODE_ENV !== 'production' && explicitLeaveDuration != null) {
@@ -271,6 +263,27 @@ function isValidDuration (val) {
   return typeof val === 'number' && !isNaN(val)
 }
 
+/**
+ * Normalize a transition hook's argument length. The hook may be:
+ * - a merged hook (invoker) with the original in .fns
+ * - a wrapped component method (check ._length)
+ * - a plain function (.length)
+ */
+function getHookAgumentsLength (fn: Function): boolean {
+  if (!fn) return false
+  const invokerFns = fn.fns
+  if (invokerFns) {
+    // invoker
+    return getHookAgumentsLength(
+      Array.isArray(invokerFns)
+        ? invokerFns[0]
+        : invokerFns
+    )
+  } else {
+    return (fn._length || fn.length) > 1
+  }
+}
+
 function _enter (_: any, vnode: VNodeWithData) {
   if (!vnode.data.show) {
     enter(vnode)