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ExecutionContext for Long Running Tasks

Rule #1 of Akka: don’t block inside actors. If you do have blocking / high latency calls, wrap them in a future and toss them into a different execution context specifically meant for high latency tasks.

import java.util.concurrent.Executors
    
class ClassyActor extends Actor {
  val numThreads = 10
  val pool = Executors.newFixedThreadPool(numThreads)
  val ctx = ExecutionContext.fromExecutorService(pool)
  
  def receive: Actor.Receive = {
    // An message that needs some high latency work done
    case m: Message =>
      val future = Future {
        // do something with m: Message
      } (ctx)

      future.onComplete({
        case Success(s) =>
          // do something when the task successfully completed
        case Failure(f) =>
          // do something when the task failed
      }) (ctx)
  }
}
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Bro, do you even #chromecast?

Bro, do you even #chromecast?

Tags: chromecast
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Getting the Titan-0.3.2 Java Driver to work in Scala

Attempting to use the Java driver for Titan-0.3.2 (the current stable Titan release) with Cassandra v1.2.6 in a Scala project throws the following Astyanax error:

java.lang.NoSuchMethodError: org.apache.cassandra.thrift.TBinaryProtocol: method (Lorg/apache/thrift/transport/TTransport;)V not found

This can be traced back to a bug in Astyanax v1.56.37 which was fixed in v1.56.43.

This can be fixed by ensuring that this dependency is listed above the Titan driver in your pom.xml or sbt.build.

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Setup Ruby (2.x) on Rails (4.x) in 10 lines or less

As a first time user of Ruby and Rails, I was able to setup a sane environment on Ubuntu Server 12.04 (x64) in less than 10 commands:

cd $HOME
curl -L https://get.rvm.io | bash
source $HOME/.rvm/scripts/rvm
rvm requirements
rvm install ruby
rvm use ruby --default
rvm rubygems current
gem install rails

And, if you already have a rails app to run, continue along with:

cd myapp
bundle install
rails server

This will get you up and running with a dev server.

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Prevent Facebook from tracking you on the Web

A simple search for “facebook like button tracking you” turns up a bunch of articles and blog posts about how Facebook is creeping on you wherever you go; even if you’re not signed in or actively clicking their ubiquitous like button. For example: http://bit.ly/1fwCi5i

I’ve come up with a simple solution to the problem.

Caveat: This will prevent you from being able to use Facebook.

Step 1: Add the following entries to your hosts file

127.0.0.1 facebook.com
127.0.0.1 www.facebook.com
127.0.0.1 connect.facebook.net

If you’re not familiar with editing your hosts file, here’s a tutorial.

Step 2: Reboot

And done!

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Joda Time with Scala

When trying to use Joda-Time in a Scala project, I encountered a rather cryptic error:

scala: error while loading Instant, class file '/Users/asdf/.m2/repository/joda-time/joda-time/2.3/joda-time-2.3.jar(org/joda/time/Instant.class)' is broken
(class java.lang.RuntimeException/bad constant pool tag 9 at byte 48)

This can be solved by adding the joda-convert dependency into Maven/SBT.

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tommyrefenes:

When I started Super Meat Boy, I knew that proper controls would be the make or break for the game. I’m very picky about controls in games, to the point if the game doesn’t control well, I don’t care who makes it or what it is, I will stop playing it. I often get asked which formulas I used for…

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pip install scipy on Ubuntu

On Ubuntu 12.04 Server, a pip install scipy barfs with

library dfftpack has Fortran sources but no Fortran compiler found

because it wants you to

sudo apt-get install libamd2.2.0 libblas3gf libc6 libgcc1 libgfortran3 liblapack3gf libumfpack5.4.0 libstdc++6 build-essential gfortran python-all-dev libatlas-base-dev

pip install numpy

before you try to pip install scipy

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Going up.

Going up.

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Glass half full

Glass half full