Yongjian yongjianwang

Collections Redesign Proposal

I'm going to start off by motivating what I'm doing here. And I want to be clear that I'm not "dissing" the existing collections implementation or anything as unproductively negative as that. It was a really good experiment, it was a huge step forward given what we knew back in 2.8, but now it's time to learn from that experiment and do better. This proposal uses what I believe are the lessons we can learn about what worked, what didn't work, and what is and isn't important about collections in Scala.

This is going to start out sounding really negative and pervasively dismissive, but bear with me! There's a point to all my ranting. I want to be really clear about my motivations for the proposal being the way that it is.

Problems

Generic Interfaces

As compiled by Kevin Wright a.k.a @thecoda

(executive producer of the movie, and I didn't even know it... clever huh?)

please, please, please - If you know of any slides/code/whatever not on here, then ping me on twitter or comment this Gist!

This gist will be updated as and when I find new information. So it's probably best not to fork it, or you'll miss the updates!

Monday June 16th

Akka Cluster Implementation Notes

Slightly disorganized but reasonably complete notes on the algorithms, strategies and optimizations of the Akka Cluster implementation. Could use a lot more links and context etc., but was just written for my own understanding. Might be expanded later.

Links to papers and talks that have inspired the implementation can be found on the 10 last pages of this presentation.

Akka Gossip

Gossip state

This is the Gossip state representation:

	package wrappers

	import play.api._
	import play.api.mvc._
	import scala.concurrent._
	import scala.concurrent.Future
	import play.mvc.Http.Status
	import ExecutionContext.Implicits.global
	import play.libs.Akka
	import akka.actor.{Actor, Props}

	object TopicAssistant {
	case class Subscribe(topic: String)
	case object SubscribeAck
	}

	// Start this actor with name "topicAssistant" on each node in the cluster
	class TopicAssistant extends Actor {
	import TopicAssistant._

	ClusterReceptionistExtension(context.system).registerService(self)

	/**
	* Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
	*/
	package akka.contrib.mailbox

	import scala.concurrent.duration._
	import java.util.concurrent.atomic.AtomicInteger
	import java.util.concurrent.atomic.AtomicLong
	import com.typesafe.config.Config
	import akka.actor.{ ActorContext, ActorRef, ActorSystem, ExtendedActorSystem }

	// scala 2.7 simple type constraint. This can only constrain a type parameter of this function.
	// Below, in ListW.sumint28, we can't use this approach because we want to constrain T,
	// a type param of the enclosing trait.
	def sumint27A[T <: Int](l: List[T]) : Int = l.reduceLeft((a: Int, b: Int) => a + b)

	trait IntLike[X] extends (X => Int)
	object IntLike {
	implicit val intIntLike: IntLike[Int] = new IntLike[Int] { def apply(x: Int) = identity(x) }
	}