gerritjvv

(require '[clojure.core.async :refer [go-loop chan <! close!]])
(require '[fun-utils.core :refer [go-seq]])

;When writing go blocks there is a repeating pattern to avoid 100% cpu spin when the channel is closed.

;e.g.
;if we run the below code, the loop will spin without pause.


;;running this code will cause nil to be printed without pause

gerritjvv

(def msgs [ {"a" {:stat1 1 :stat2 10} "b" {:stat1 1}} {"a" {:stat1 1}}])

(def merged (apply merge-with (partial merge-with +) msgs))
;; {"a" {:stat1 2, :stat2 10}, "b" {:stat1 1}}
(prn merged)
;; {"a" {:stat1 2, :stat2 10}, "b" {:stat1 1}}

(= (-> merged first second :stat1) 2)
;; true

gerritjvv

# -*- mode: ruby -*-
# vi: set ft=ruby :

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|


  config.vm.provider "virtualbox" do |v|
     v.customize ["modifyvm", :id, "--memory", "2048"]

gerritjvv

!/usr/bin/env bash

NODE="$1"

echo "Bootstrapping node $1"

function install_setup(){
  yum update
  yum -y install wget vim snappy-devel snappy lzo lzop elinks glibc.i686
}

gerritjvv

(defn safe-inc [l ^long x]
  (if l
    (+ ^long l x)
    x))

// Compiled from form-init2140241509718408406.clj (version 1.5 : 49.0, super bit)
public final class no.disassemble$eval1752$safe_inc__1753 extends clojure.lang.AFunction implements clojure.lang.IFn$OLO {

  // Field descriptor #9 Lclojure/lang/Var;
  public static final clojure.lang.Var const__0;

gerritjvv

(require '[fun-utils.agent :as fagent] :reload)

(def agnt (fagent/agent {} :mailbox-len 10))

;send to the agent
(fagent/send agnt assoc-in [:a :b] 2)

;deref
 @agnt
 ;;{:a {:b 2}}

gerritjvv

(import '(java.io InputStreamReader FileInputStream BufferedReader))
(import '(java.util.zip GZIPInputStream))

(defn gz-line-counter [^String file-name]
  (let [^BufferedReader reader (BufferedReader. (InputStreamReader. (GZIPInputStream. (FileInputStream. file-name))))]
    (try
      (loop [i 0]
        (if (.readLine reader)
          (recur (inc i))
          i))

gerritjvv

package lazyseq;

import org.junit.Test;

import clojure.lang.AFn;
import clojure.lang.ASeq;
import clojure.lang.ArraySeq;
import clojure.lang.Cons;
import clojure.lang.IPersistentMap;
import clojure.lang.ISeq;

gerritjvv

int ret = new ProcessBuilder("gzip", "-t", "t.txt.gz").inheritIO().start().waitFor()

gerritjvv

Caution: Partitioning lazy sequence code freeze

(def l [1 2 3 4 5])
;create a simple lazy sequence function testing only
;(rdr l) returns a lazy sequence from l
(def rdr (fn reader[x] (cons (first x) (lazy-seq (reader  (rest x))))))

;the line below will freeze
(doall (partition-all 2 (rdr l)) )