Notes from the 'Performance Talk' session

Speaker

Kristofor Selden

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setProperties

run loop

• Does not matter if multiple componets respond to an event and change stuff
• Waterfall: sync, actions, render, afterRender, destroy, timers

What are Bindings in Ember?

• Ember.Binding
• fooBinding
• Ember.computed

View Bindings

Observes changes, schedules work later on the run loop

observer = function(){
  Ember.run.scheduleOnce(
    'render', bindView, 'rerenderIfNeeded'
  );
};

Bindings vs Computed Properties

Having watched people devlop o nEmber for the last year, one thing...

Two-way vs one-way bindings

• Installs two observers vs one on create
• Two way sync invloves suspending the other direction's observer

2-way vs 1-way computer properties

• none

Computed proeprties vs bindings

• CP can be setup on the prototype
• Bindings can't be setup until create
• Bindings have ordering issues
• Conputed proeprties are lazy
• Unfotunately CP notify changes synchronously (for now)

Computed properties are Lazy

Observing Property Paths Affect CP Laziness

• CP will fire a change when they are invalidated regarless if they will compute to a different value
• Property paths will fire a change if their parent node change sregardless if they resolve to the same value

Array Observers are Synchronous

ArrayProxy eagerly consumes 'content'

App.PricesController = Em.ArrayController.extend({ // ... content : function(){ return this.get('fruitsController.@each.price'); }.property('fruitsController.@each.price'); });

Dangers of Binding through viewName

Views are like the rendering trees behind things. It's unstable to be adding bindings between siblings. Be wary of using the viewName to bind.

autorun

If you do something that needs to defer and you haven't started dqing it we'll set it to flush and give it a timeout.

On the willChange a view will tear something down.

Try not to have these in your normal flow.

Observer memory leaks

• Only case you need to teardown an observer added in init on willDestroy: addObserver(otherObj, 'prop', this, 'something')
• Use willClearRender to teardown stuff installed on render
• Use willDestroyElement to teardown stuff isntalled on didInsertElement

Future Concerns

• Garbage during rendering

Published

Tags

• emberjs 18
• embercamp 10