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

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

janl

Chemex Quick Guide

Not this is rocket sience :)

Water

Fill the water heater with a finger more than 1 liter of water. Set it on its power-base, hit the button that’s all the way out on the handle. This starts the heating process. Now hit the “minus” (“-”) button so you see a red light on the 90° marker. Let it heat up. In the meantime:

Beans

jedy

// https://blogs.oracle.com/janp/entry/how_the_scp_protocol_works
package main

import (
	"fmt"

	"golang.org/x/crypto/ssh"
)

const privateKey = `content of id_rsa`

mike-zhang

// Implementation of a UDP proxy

package main

import (
	"flag"
	"fmt"
	"log"
	"net"
	"os"

mislav

Jim Weirich:

This is how I explain it… Ruby has Procs and Lambdas. Procs are created with Proc.new { }, lambdas are created with lambda {} and ->() {}.

In Ruby 1.8, proc {} creates lambda, and Ruby 1.9 it creates procs (don't ask).

Lambdas use method semantics when handling parameters, procs use assignment semantics when handling parameters.

This means lambdas, like methods, will raise an ArgumentError when called with fewer arguments than they were defined with. Procs will simply assign nil to variables for arguments that were not passed in.

mislav

find ~ -name '*.log' -print0 | xargs -0 -L1 stat -f'%z %N' | sort -rn | tee fat-logfiles.txt | head

awk '{ total += $1 } END { printf "total: %5.2f MiB\n", total/1024/1024 }' < fat-logfiles.txt

mislav

The reason why you might get certificate errors in Ruby 2.0 when talking HTTPS is because there isn't a default certificate bundle that OpenSSL (which was used when building Ruby) trusts.

Update: this problem is solved in edge versions of rbenv and RVM.

$ ruby -rnet/https -e "Net::HTTP.get URI('https://github.com')"
net/http.rb:917:in `connect': SSL_connect returned=1 errno=0 state=SSLv3
  read server certificate B: certificate verify failed (OpenSSL::SSL::SSLError)

You can work around the issue by installing a certificate bundle that you trust. I trust Mozilla and curl.

mislav

I use tmux splits (panes). Inside one of these panes there's a Vim process, and it has its own splits (windows).

In Vim I have key bindings C-h/j/k/l set to switch windows in the given direction. (Vim default mappings for windows switching are the same, but prefixed with C-W.) I'd like to use the same keystrokes for switching tmux panes.

An extra goal that I've solved with a dirty hack is to toggle between last active panes with C-\.

Here's how it should work:

pmarreck

#!/usr/bin/env ruby

# Teststack: A way to preload your Rails app stack for your iterative test running
# Based on ideas from Jesse Storimer here:
# http://www.jstorimer.com/blogs/workingwithcode/8136295-screencast-faster-rails-test-runs-with-unix
# https://gist.github.com/jstorimer/5862436
# Usage: Run this file without args to run the server; run it with test file args to connect to the server and run tests

require 'socket'