SerhiiKozachenko

;; This stuff is pretty useful in many contexts.

 ...
 (:import (com.google.common.cache CacheBuilder CacheLoader))
 ...
  
  

quantataraxia.core> (with (-> (CacheBuilder/newBuilder)
                              (.weakKeys)

SerhiiKozachenko

(let [f (future
          (try
            (Thread/sleep 10000)
            (catch Throwable e
              (println e)
              (println "isInterrupted:" (.isInterrupted (Thread/currentThread)))
              (println "isAlive:" (.isAlive (Thread/currentThread)))
              (println "interrupted:" (Thread/interrupted)))))]
  (Thread/sleep 500)
  (future-cancel f)

SerhiiKozachenko

;; I keep forgetting how to do this stuff for some reason, so here goes:

(let [c (async/chan 1 (map #(* % 2)))]
  (async/go
    (loop []
      (when-let [e (async/<! c)]
        (println "async/go, e:" e)
        (recur))))
  (async/>!! c 1)
  (async/>!! c 2))

SerhiiKozachenko

;; www.Quanto.ga
;;
;; cp/upmap is from https://github.com/TheClimateCorporation/claypoole


quantataraxia.core> (do
                      (println "MAP:")
                      (println (time (doall (map (fn [x] (Thread/sleep x) x)
                                                  (range 500 50 -9)))))
                      (println "PMAP:")

SerhiiKozachenko

;; Performance of with-local-vars vs. atom vs. volatile vs. unsynchronized-mutable field.


(definterface IOObject
  (setVal [new-val])
  (getVal [])
  (oswap [f])
  (oswap [f x])
  (oswap [f x y])
  (oswap [f x y z]))

SerhiiKozachenko

PostgreSQL is Enough

• Simplify: move code into database functions
• Just Use Postgres for Everything
• PostgreSQL is the worlds’ best database
• Postgres is eating the database world
• Hacker News discussion

Background and Cron Jobs

SerhiiKozachenko

echo 'export PATH=$HOME/local/bin:$PATH' >> ~/.bashrc
. ~/.bashrc
mkdir ~/local
mkdir ~/node-latest-install
cd ~/node-latest-install
curl http://nodejs.org/dist/node-latest.tar.gz | tar xz --strip-components=1
./configure --prefix=~/local
make install # ok, fine, this step probably takes more than 30 seconds...
curl https://www.npmjs.org/install.sh | sh

SerhiiKozachenko

How to install MongoDB 2.0 on Mac OS X (>= Leopard)

Procedure

The whole install procedure is like the following.
You would have to do 7 steps.

1. Download the latest tar file, and expand it.
2. Move it to /usr/local/, and make a symbolic link to the folder.
3. Add path to MongoDB binaries.
4. Make an user that "mongod" runs on, and group that owns the user.

SerhiiKozachenko

Requires:

• Homebrew (http://mxcl.github.io/homebrew/)

• Ruby

Verify Homebrew is not sick:

brew doctor

SerhiiKozachenko

// suggested shell cmd line to run this:
//
//   mongo --shell example2.js
// 
// Note: the { out : … } parameter is for mongodb 1.8+

db.things.insert( { _id : 1, tags : ['dog', 'cat'] } );
db.things.insert( { _id : 2, tags : ['cat'] } );
db.things.insert( { _id : 3, tags : ['mouse', 'cat', 'dog'] } );
db.things.insert( { _id : 4, tags : []  } );