hellerbarde

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

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

troyfontaine

Resize root partition (or how to remove the default /home partition) on CentOS 7 online

This process requires that you are able to ssh OR log in locally using the root user account and that no services be running as users out of /home on the target machine.

The examples are from a default installation with no customization-you NEED to know what you're working with for volumes/partitions to not horribly break things.

By default, CentOS 7 uses XFS for the file system and Logical Volume Manager (LVM), creating 3 partitions: /,/home and swap.

NOTE: If you want to be sure that nothing is writing to /home you can either modify the host to boot into single-user mode OR try to use the systemctl isolate runlevel1.target command to switch (not tested! should work).

davoclavo

emacs --daemon to run in the background. emacsclient.emacs24 <filename/dirname> to open in terminal

NOTE: "M-m and SPC can be used interchangeably".

• Undo - C-/
• Redo - C-?
• Change case: 1. Camel Case : M-c 2. Upper Case : M-u

3. Lower Case : M-l

bastman

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

ryanmaclean

# Run using "sudo accept_xcode_license.sh"
#
# Solving the OSX Yosemite Xcode Command Line Tools Licensing problem
# for multiple updates in order to script post-install tasks. 
# Typical error reads after running "xcode-select --install" when setting up 
# Homebrew is: "Agreeing to the Xcode/iOS license requires admin priviledges, 
# please re-run as root via sudo"
#
# CREDIT:
# Based on a tip found at http://krypted.com/mac-os-x/licensing-the-xcode-command-line-tools/

natecook1000

// NSCalendar+Swift.swift
// A set of Swift-idiomatic methods for NSCalendar
//
// (c) 2015 Nate Cook, licensed under the MIT license

extension NSCalendar {
    /// Returns the hour, minute, second, and nanoseconds of a given date.
    func getTimeFromDate(date: NSDate) -> (hour: Int, minute: Int, second: Int, nanosecond: Int) {
        var (hour, minute, second, nanosecond) = (0, 0, 0, 0)
        getHour(&hour, minute: &minute, second: &second, nanosecond: &nanosecond, fromDate: date)

veritas1

FactoryGirl.define do
  factory :slideshow_image, class: "Image" do
    association :imageable, :factory => :slideshow
    # other attributes for slideshow model
  end
  
  factory :article_image, class: "Image" do
    association :imageable, :factory => :article
    # other attributes for article model
  end