huydx huydx

I've had many people ask me questions about OpenTracing, often in relation to OpenZipkin. I've seen assertions about how it is vendor neutral and is the lock-in cure. This post is not a sanctioned, polished or otherwise muted view, rather what I personally think about what it is and is not, and what it helps and does not help with. Scroll to the very end if this is too long. Feel free to add a comment if I made any factual mistakes or you just want to add a comment.

So, what is OpenTracing?

OpenTracing is documentation and library interfaces for distributed tracing instrumentation. To be "OpenTracing" requires bundling its interfaces in your work, so that others can use it to time distributed operations with the same library.

So, who is it for?

OpenTracing interfaces are targeted to authors of instrumentation libraries, and those who want to collaborate with traces created by them. Ex something started a trace somewhere and I add a notable event to that trace. Structure logging was recently added to O

I've had many people ask me questions about OpenTracing, often in relation to OpenZipkin. I've seen assertions about how it is vendor neutral and is the lock-in cure. This post is not a sanctioned, polished or otherwise muted view, rather what I personally think about what it is and is not, and what it helps and does not help with. Scroll to the very end if this is too long. Feel free to add a comment if I made any factual mistakes or you just want to add a comment.

So, what is OpenTracing?

OpenTracing is documentation and library interfaces for distributed tracing instrumentation. To be "OpenTracing" requires bundling its interfaces in your work, so that others can use it to time distributed operations with the same library.

So, who is it for?

OpenTracing interfaces are targeted to authors of instrumentation libraries, and those who want to collaborate with traces created by them. Ex something started a trace somewhere and I add a notable event to that trace. Structure logging was recently added to O

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

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

JEP-123 で利用時に指定する方法が提案されてJava8で使えるようになったらしい。Linuxだと標準で /dev/random を使うからエントロピーが全部消費されてる状態だとブロックされてた。

Link

ActionFunction の紹介

この記事は Play framework Advent Calendar 2014 の7日目です。

昨日は @dorako321 さんの Play framework Advent Calendar 2014 6日目位置情報を使ってみようでした。

明日は @nazoking さんの play2.3 の sbt-web を使わず node で代替システムを作るための資料です。

さて、そんなこんなで~~公式ドキュメントではまだ語られていない~~ ActionFunction とそのサブトレイトについて紹介したいと思います。 (公式ドキュメントにも記載ありました https://www.playframework.com/documentation/2.3.x/ScalaActionsComposition#Different-request-types )

	/**
	* In a static language like scala, how could we repeatedly flatten a datastructure without reflection?
	* This is an interesting example of using implicit parameters to do the work for you.
	*/
	object DeepFlatten {

	// what should this really be called? ;)
	trait Flattenable[F[_]] {
	def flatten[A](f: F[F[A]]): F[A]
	}

	object jto {

	type _1 = Succ[_0]
	type _2 = Succ[_1]
	type _3 = Succ[_2]
	type _4 = Succ[_3]
	type _5 = Succ[_4]

	// Natural numbers (extracted from shapeless)

	case class Hoge(x: Int) {
	lazy val i = x + 1
	lazy val foo = (1 to 10).par.map(_*i)
	}

	Hoge(1).foo

	package main

	//
	// Starting point is from http://gcmurphy.wordpress.com/2012/11/30/using-epoll-in-go/
	//

	import (
	"fmt"
	"os"
	"syscall"