andrey pechorin pechorin

Введение

Начать стоит отсюда. Не пугайтесь то, что это книга по незнакомой OS, эти термины практически везде одинаковые и здесь они изложены в понятной для начинающих форме.

http://www.qnx.com/developers/docs/6.4.1/neutrino/getting_started/s1_procs.html

Прочесть нужно треть главы до подраздела "Starting a process", если С не пугает, читайте полностью. После прочтения вы будете понимать, что такое process, thread, mutex, priorites, semaphores, scheduler, contex-switch, kernel states.

Ruby

My issues with Modules

In researching topics for RailsCasts I often read code in Rails and other gems. This is a great exercise to do. Not only will you pick up some coding tips, but it can help you better understand what makes code readable.

A common practice to organize code in gems is to divide it into modules. When this is done extensively I find it becomes very difficult to read. Before I explain further, a quick detour on instance_eval.

You can find instance_eval used in many DSLs: from routes to state machines. Here's an example from Thinking Sphinx.

class Article &lt; ActiveRecord::Base

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

tmux cheatsheet

As configured in my dotfiles.

start new:

tmux

start new with session name:

YARD CHEATSHEET http://yardoc.org

May 2020 - updated fork: https://gist.github.com/phansch/db18a595d2f5f1ef16646af72fe1fb0e

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

	-- http://stackoverflow.com/questions/1124603/grouped-limit-in-postgresql-show-the-first-n-rows-for-each-group
	-- http://www.postgresql.jp/document/9.2/html/tutorial-window.html

	CREATE TABLE empsalary (
	depname varchar(10) not null
	, empno integer not null
	, salary integer not null
	);

	INSERT INTO empsalary (depname, empno, salary) VALUES ('develop', 11, 5200);

	-- show running queries (pre 9.2)
	SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
	FROM pg_stat_activity
	WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
	ORDER BY query_start desc;

	-- show running queries (9.2)
	SELECT pid, age(clock_timestamp(), query_start), usename, query
	FROM pg_stat_activity
	WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'

	# example
	# date = Date.today
	# ExchangeWithFallback.new(
	# SynchronizedRates.new(
	# DoubleConvertThrough.new('RUB',
	# InverseRatesFor.new( {from: 'RUB'},
	# RatesUpdatedWithFallback.new(
	# ActiveRecordRates.new(CurrencyRate.where(date: date, bank: 'cbr')),
	# LazyRates.new { CentralBankOfRussia.new.update_rates(date) } )))))

	brew update
	brew versions FORMULA
	cd `brew --prefix`
	git checkout HASH Library/Formula/FORMULA.rb # use output of "brew versions"
	brew install FORMULA
	brew switch FORMULA VERSION
	git checkout -- Library/Formula/FORMULA.rb # reset formula

	## Example: Using Subversion 1.6.17
	#

	# ...

	gem 'carrierwave'
	gem 'fog', '~> 1.0.0' # Need to specify version, as carrierwave references older (0.9.0) which doesn't allow configuration of Rackspace UK Auth URL