ragingwind

Backend Architectures

Twitter

ror, scala, jetty, erlang, thrift, mongrel, comet server, my-sql, memchached, varnish, kestrel(mq), starling, gizzard, cassandra, hadoop, vertica, munin, nagios, awstats

• Introduce Gizzard of Twitter - 트위터의 새로운 분산 관리 라이브러리 Gizzard를 소개합니다.
• The Architecture Twitter Uses to Deal with 150M Active Users, 300K QPS, a 22 MB/S Firehose, and Send Tweets in Under 5 Seconds
• Scaling Twitter: Making Twitter 10000 Percent Faster

cgrand

(ns net.cgrand.decay
  "Exponentially decaying lists. See http://awelonblue.wordpress.com/2013/01/24/exponential-decay-of-history-improved/
  for background and http://clj-me.cgrand.net/2013/02/12/decaying-lists-log-scale-for-lists/ for documentation")

;; PRNG, formulas straight from java.util.Random javadoc
(defn- seed ^long [^long n]
  (bit-and (unchecked-multiply n 0x5DEECE66D)
    (unchecked-dec (bit-shift-left 1 48))))

(defn- next-seed ^long [^long seed]

elimisteve

// Steve Phillips / elimisteve
// 2013.01.03

// Programming Challenge: Launch 4 threads, goroutines, coroutines, or whatever your language uses for concurrency,
// in addition to the main thread. In the first 3, add numbers together (see sample code below) and pass the results
// to the 4th thread. That 4th thread should receive the 3 results, add the numbers together, format the results as
// a string (see sample code), and pass the result back to `main` to be printed.
//
// Do this as succinctly and readably as possible. _Go!_ #golang #programming #concurrency #challenge
package main

jmgimeno

(defn bfc
  [program]
  (let [allowed #{\+ \- \< \> \[ \] \.}
        src (->> program (filter allowed)
                 (interpose \space) (apply str))
        fns (zipmap '(- + < > . ?) (repeatedly gensym))]
    (letfn [(bfc* [s]
              (if (vector? s)
                `(while (not (~(fns '?))) ~@(map bfc* s))
                `(~(fns s))))]

stuarthalloway

;; Datomic example code
(use '[datomic.api :only (db q) :as d])

;; ?answer binds a scalar
(q '[:find ?answer :in ?answer]
   42)

;; of course you can bind more than one of anything
(q '[:find ?last ?first :in ?last ?first]
   "Doe" "John")

cs224

;;; implementation in clojure of the levenshtein allison algorithm as defined here:
;;; http://www.csse.monash.edu.au/~lloyd/tildeFP/Haskell/1998/Edit01/

(defn min3 [w nw n]
  (if (< w nw) w (min nw n)))

(defn generate-diagonale [a b nw fn-diag-above fn-diag-below start]
  (if start
    (lazy-cat (list nw) (generate-diagonale a b nw fn-diag-above fn-diag-below false))
    (if (or (empty? a) (empty? b)) '()

edoloughlin

(ns my.util.sql
  (:use clojure.contrib.condition)
  (:require
    [clojure.contrib.sql :as sql]
    [clj-record.core     :as rec]
    [my.util.error       :as err]))

(def *transaction-error* nil) ; While a transaction-wrapper is running, bound to the last error message set by rollback-with-raise

(defn rollback-with-raise