nelsnelson’s gists

nelsnelson / seccomp-example.sh

Created February 13, 2014 21:39

lxc 1.0.0.beta1 seccomp example

	$ cat seccomp-example.sh
	#! /usr/bin/env bash

	cat << EOF > /tmp/config
	lxc.seccomp = /tmp/whitelist
	EOF
	cat << EOF > /tmp/whitelist
	1
	whitelist
	0

nelsnelson / InterruptDemo.java

Last active December 14, 2015 12:39

Test demo to show how future.cancel(true); does not seem to be working. test/InterruptDemo.java

	package test;

	import java.lang.InterruptedException;
	import java.lang.Runnable;
	import java.util.Calendar;
	import java.util.concurrent.Callable;
	import java.util.concurrent.Executor;
	import java.util.concurrent.ExecutorService;
	import java.util.concurrent.Executors;
	import java.util.concurrent.Future;

nelsnelson / future_cancellation_test.rb

Last active December 14, 2015 12:39

This is a test of the future.cancel(true) method.

	#! /usr/bin/env jruby

	=begin
	$ ./interrupt.rb
	Current time: Monday March 4 03/04/2013 21:40:06.304
	Scheduled event for 10 seconds from now
	f1: Current time: Monday March 4 03/04/2013 21:40:06.341
	Cancelling f1
	f2: Current time: Monday March 4 03/04/2013 21:40:11.357
	Got f1: Current time: Monday March 4 03/04/2013 21:40:11.361

nelsnelson / latency.markdown

Created October 25, 2012 22:07 — forked from hellerbarde/latency.markdown

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             
Syscall on Intel 5150 ...................... 105 ns
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Context switch on Intel 5150 ............. 4,300 ns  =   4 µs

Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs

nelsnelson / non_persistent_test.rb

Created March 2, 2012 03:55 — forked from jeremyevans/non_persistent_test.rb

Testing non-persistent fields on persisted identity-mapped entity instances in JRuby and Sequel through jdbc-postgres

	#! /usr/bin/env jruby

	require 'rubygems'
	require 'sequel'

	gem 'jdbc-postgres'

	DB = Sequel.connect('jdbc:postgresql://localhost:5432/test?user=test&password=test')

	DB.create_table? :test do

nelsnelson / non_persistent_test.rb

Created March 1, 2012 03:46

Testing non-persistent fields on persisted identity-mapped entity instances in JRuby and Sequel through jdbc-postgres

	#! /usr/bin/env jruby

	require 'rubygems'
	require 'sequel'

	gem 'jdbc-postgres'

	@connection = Sequel.connect('jdbc:postgresql://localhost:5432/test?user=test&password=test')
	Sequel::Model.db = @connection
	Sequel::Model.plugin :identity_map

nelsnelson / method_test.rb

Created August 23, 2011 23:43

I don't get it. Can anybody explain to me what is happening here?

	#! /usr/bin/env ruby

	module Helper
	def help1
	@help1 \|\|= [ :success1 ]
	end
	def help1=(a)
	@help1 = a
	end
	def help2

nelsnelson / wrapper_test.rb

Created August 22, 2011 03:29

This is a demo of an error I am seeing when attempting to access self inside the initialize method of a class

	#! /usr/bin/env jruby

	require 'java'

	java_import java.util.Date

	class Klass
	def initialize
	puts "Hi. I'd like to see what I look like during initialization. :)"
	puts "self # => #{self} (#{self.class})"

nelsnelson / pip_fail.txt

Created June 30, 2011 16:09

An example of pip for python failing to install readline

	nels.nelson@peregrine:~$ sudo pip install readlline
	Downloading/unpacking readlline
	Could not find any downloads that satisfy the requirement readlline
	No distributions at all found for readlline
	Storing complete log in /Users/nels.nelson/.pip/pip.log
	nels.nelson@peregrine:~$ sudo easy_install readline
	Searching for readline
	Reading http://pypi.python.org/simple/readline/
	Reading http://www.python.org/
	Reading http://github.com/ludwigschwardt/python-readline

nelsnelson / gist:946971

Created April 28, 2011 18:35

To store a 1:1 (one pixel = 1/72 inch) image of the entire surface of the Earth

	Assuming image resolution:
	72ppi = 5184 pixels per square inch

	Surface area of the Earth:
	510,072,000 km2 = (7.90613181 × 10 to the 17th) square inches

	Assuming (for a lossless PNG) an average storage size of:
	~7.76 bits per pixel

	7.90613181 × 10 to the 17th square inches

Nels Nelson nelsnelson

Latency numbers every programmer should know