jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

hdiedrich

# You will need to make this file executable (chmod u+x) and run it with sudo
apt-get update
apt-get --fix-missing -y install build-essential m4 libncurses5-dev libssh-dev unixodbc-dev libgmp3-dev libwxgtk2.8-dev libglu1-mesa-dev fop xsltproc default-jdk
mkdir -p /src/erlang
cd /src/erlang
wget http://www.erlang.org/download/otp_src_R15B01.tar.gz
tar -xvzf otp_src_R15B01.tar.gz
chmod -R 777 otp_src_R15B01
cd otp_src_R15B01
./configure

andelf

#!/usr/bin/env escript
% -*- mode: erlang -*-

main([BeamFile]) ->
    {ok,{_,[{abstract_code,{_,AC}}]}} = beam_lib:chunks(BeamFile,[abstract_code]),
    io:fwrite("~s~n", [erl_prettypr:format(erl_syntax:form_list(AC))]).

krestenkrab

EStone test completed
**** CPU speed UNKNOWN MHz ****
**** Total time 1.740884613333333 seconds ****
**** ESTONES = 260159.54 ****

{'ESTONES',2.601595e+05}
    Title                            Millis        Estone       %    Loops      

list manipulation                    52.07      29171.60    7          6400
small messages                      391.62       7915.86   10          1515

bryanhunter

#!/bin/bash
# Pull this file down, make it executable and run it with sudo
# wget https://gist.githubusercontent.com/bryanhunter/10380945/raw/build-erlang-17.0.sh
# chmod u+x build-erlang-17.0.sh
# sudo ./build-erlang-17.0.sh

if [ $(id -u) != "0" ]; then
echo "You must be the superuser to run this script" >&2
exit 1
fi

doitian

Tips about implementing parse_transform

• First write code to generate in a file, and compile it using erlc -S to check what the compiled forms look like
• Use [https://github.com/esl/parse_trans]

Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

joseluisq

Add Git Branch Name to Terminal Prompt (Linux/Mac)

Open ~/.bash_profile in your favorite editor and add the following content to the bottom.

# Git branch in prompt.

parse_git_branch() {

maksadbek

package main

import "fmt"

type Node struct {
	prev *Node
	next *Node
	key  interface{}
}

filipevarjao

class List extends Object {
    List() { super(); }
    List append(List l) {
      return this; // dummy
    }
}

class Nil extends List {
    Nil() { super (); }