javouhey

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

• They are the people who get things done. Effective Engineers produce results.

Adopt the Right Mindsets

javouhey

#!/boot/bzImage

# Linux kernel initialization code, translated to bash
# (Minus floppy disk handling, because seriously, it's 2017.)
# Not 100% accurate, but gives you a good idea of how kernel init works
# GPLv2, Copyright 2017 Hector Martin <marcan@marcan.st>
# Based on Linux 4.10-rc2.

# Note: pretend chroot is a builtin and affects the current process
# Note: kernel actually uses major/minor device numbers instead of device name

javouhey

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

javouhey

#!/usr/bin/env python

import sys, os, time, atexit
from signal import SIGTERM

class Daemon:
    """
    A generic daemon class.

    Usage: subclass the Daemon class and override the run() method

javouhey

function goinit {
	export GOROOT=/usr/local/Cellar/go/1.2.1/libexec
	if [ $# -lt 1 ]
	then
		echo "No directories were created."
		export GOPATH=$(pwd -P)
		export PATH=$PATH:$GOPATH:$GOPATH/bin
	else
		echo "$1 being created"
		mkdir $1

javouhey

module CallPrice
    function callprice(S0, K, r, T, sigma, paths)
        Csum = 0.0
        for j = 1:paths	
            Zs = randn()
            Zj = T*(r-sigma.^2/2) + Zs*T.^0.5*sigma
            STj = exp(Zj)*S0
            Csum += exp(-r*T)*max(STj - K,0.0)
        end
        return Csum/paths

javouhey

This is the list of exit codes for wget:

0       No problems occurred
1       Generic error code
2       Parse error — for instance, when parsing command-line options, the .wgetrc or .netrc…
3       File I/O error
4       Network failure
5       SSL verification failure
6       Username/password authentication failure
7       Protocol errors

javouhey

#!/bin/bash
# bash generate random alphanumeric string
#

# bash generate random 32 character alphanumeric string (upper and lowercase) and 
NEW_UUID=$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1)

# bash generate random 32 character alphanumeric string (lowercase only)
cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1

javouhey

These are snippets of py.test in action, used in a talk given at 
PyCon AU 2012 in Hobart, Tasmania. They are all relevant for 
py.test 2.2 except where specified. Where taken from open source 
projects I have listed a URL, some examples are from the py.test 
documentation, some are from my workplace.

Apart from things called test_*, these functions should probably
be in your conftest.py, although they can generally start life in
your test files.

javouhey

// A sprintf-like function using d3.js
// https://gist.github.com/2045912

function d3_sprintf(strings, formatters) {
  return formatters.reduce(function (strings, formatter, i) {
    strings[i] = formatter(strings[i]);
    return strings
  }, strings).join("");
};