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[Fiber] PureComponent #8118

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Merged
merged 1 commit into from
Oct 27, 2016
Merged

[Fiber] PureComponent #8118

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47 changes: 35 additions & 12 deletions src/renderers/shared/fiber/ReactFiberClassComponent.js
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ var {
} = require('ReactFiberUpdateQueue');
var { isMounted } = require('ReactFiberTreeReflection');
var ReactInstanceMap = require('ReactInstanceMap');
var shallowEqual = require('shallowEqual');

module.exports = function(scheduleUpdate : (fiber: Fiber, priorityLevel : PriorityLevel) => void) {

Expand Down Expand Up @@ -73,6 +74,28 @@ module.exports = function(scheduleUpdate : (fiber: Fiber, priorityLevel : Priori
},
};

function checkShouldComponentUpdate(workInProgress, oldProps, newProps, newState) {
const updateQueue = workInProgress.updateQueue;
if (oldProps === null || (updateQueue && updateQueue.isForced)) {
return true;
}

const instance = workInProgress.stateNode;
if (typeof instance.shouldComponentUpdate === 'function') {
return instance.shouldComponentUpdate(newProps, newState);
}

const type = workInProgress.type;
if (type.prototype && type.prototype.isPureReactComponent) {
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Sorta unfortunate if we need to check this every time. @sebmarkbage is there a place we could store this flag on the fiber?

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We could add a new TypeOfWork https://github.com/facebook/react/blob/master/src/renderers/shared/fiber/ReactTypeOfWork.js

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I figured we start off with all of these being detected on demand and then we can create optimized paths for common patterns. E.g. for things that have shouldComponentUpdate, and things that are pure components and things that have no update life-cycles etc. by storing that in the tag like @acdlite said.

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Ideally the element itself could already have this information in its tag so that we don't even have to detect this during mount.

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@sebmarkbage sebmarkbage Oct 27, 2016 •
edited
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However, this can explode number of code paths so I figured we might want to optimize for collections of common patterns. For example: isPureComponent + no life-cycles. isPureComponent + only componentDidUpdate/componentWillUnmount but no other life-cycles. That way we can branch early and not do any of the checks. Never schedule update effects etc. EDIT: Although I guess it could also be a bitmask that allows this check to be optimized regardless of other early branches.

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@acdlite acdlite Oct 27, 2016 •
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I like the bitmask idea

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Maybe let's wait on the bitmap thing for now until we know the layout we want for it.

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Oh yeah I didn't mean I would add it now :D

return (
!shallowEqual(oldProps, newProps) ||
!shallowEqual(instance.state, newState)
);
}

return true;
}

function adoptClassInstance(workInProgress : Fiber, instance : any) : void {
instance.updater = updater;
workInProgress.stateNode = instance;
Expand Down Expand Up @@ -116,7 +139,6 @@ module.exports = function(scheduleUpdate : (fiber: Fiber, priorityLevel : Priori
// Called on a preexisting class instance. Returns false if a resumed render
// could be reused.
function resumeMountClassInstance(workInProgress : Fiber) : boolean {
const instance = workInProgress.stateNode;
let newState = workInProgress.memoizedState;
let newProps = workInProgress.pendingProps;
if (!newProps) {
Expand All @@ -132,13 +154,12 @@ module.exports = function(scheduleUpdate : (fiber: Fiber, priorityLevel : Priori
// componentWillMount and before this componentWillMount? Probably
// unsupported anyway.

const updateQueue = workInProgress.updateQueue;

// If this completed, we might be able to just reuse this instance.
if (typeof instance.shouldComponentUpdate === 'function' &&
!(updateQueue && updateQueue.isForced) &&
workInProgress.memoizedProps !== null &&
!instance.shouldComponentUpdate(newProps, newState)) {
if (!checkShouldComponentUpdate(
workInProgress,
workInProgress.memoizedProps,
newProps,
newState
)) {
return false;
}

Expand Down Expand Up @@ -196,10 +217,12 @@ module.exports = function(scheduleUpdate : (fiber: Fiber, priorityLevel : Priori
newState = previousState;
}

if (typeof instance.shouldComponentUpdate === 'function' &&
!(updateQueue && updateQueue.isForced) &&
oldProps !== null &&
!instance.shouldComponentUpdate(newProps, newState)) {
if (!checkShouldComponentUpdate(
workInProgress,
oldProps,
newProps,
newState
)) {
// TODO: Should this get the new props/state updated regardless?
return false;
}
Expand Down