chgeuer

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Dispatcher;
using System.Web.Http.SelfHost;

namespace SelfHost
{

chgeuer

Backend Architectures

Twitter

ror, scala, jetty, erlang, thrift, mongrel, comet server, my-sql, memchached, varnish, kestrel(mq), starling, gizzard, cassandra, hadoop, vertica, munin, nagios, awstats

• Scaling Twitter: Making Twitter 10000 Percent Faster
• Scaling Twitter
• Blaine Cook on Scaling Twitter - YouTube

chgeuer

#!/usr/bin/python

'''
Python implementation of passcode hashing algorithm used on the Samsung Galaxy S4 GT-I9505 4.2.2
Correct PIN for hash and salt below is 1234.

Get 40-character hash value in ascii hex format from file /data/system/password.key on the phone

Get salt in signed numeric format by doing sqlite3 query SELECT value FROM locksettings WHERE name = 'lockscreen.password_salt' on /data/system/locksettings.db

chgeuer

Elixir Native UI - Boyd Multerer https://www.youtube.com/watch?v=77FW-jrCyCs

• Only dependencies are Elixir, Erlang, and glut to access OpenGL.
• No UI threads! Individual processes can be used to track mouse
• Slides track mouse as long as button is down https://youtu.be/77FW-jrCyCs?t=37m35s
• Sliders can be rotated https://youtu.be/77FW-jrCyCs?t=40m4s
• 500 lines animating still a few ms to render https://youtu.be/77FW-jrCyCs?t=43m34s

Thinking In Ecto - Darin Wilson https://www.youtube.com/watch?v=YQxopjai0CU

1. Repository pattern https://youtu.be/YQxopjai0CU?t=2m12s
2. Explicitness https://youtu.be/YQxopjai0CU?t=5m29s

chgeuer

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

chgeuer

import argparse
import sys 
import grp
import pwd
import subprocess
import os
import json

class PreRegistration:

chgeuer

ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

Convert WAV to MP3, mix down to mono (use 1 audio channel), set bit rate to 64 kbps and sample rate to 22050 Hz:

chgeuer

running:

bash create-vod-hls.sh beach.mkv

will produce:

    beach/
      |- playlist.m3u8
 |- 360p.m3u8