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GIT Notes

Shortcuts

Nearly every page on GitHub has a keyboard shortcut to perform actions faster. https://help.github.com/articles/using-keyboard-shortcuts/

Squash branch changes

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Software Engineering Tools

• Efficient data transfer through zero copy

What is?

• IO bound work

Command Line Tools

Querying RESTful APIs

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Python Greenlets

Tutorial: http://mauveweb.co.uk/posts/2014/07/gevent-asynchronous-io-made-easy.html

Exception example: RuntimeError('application not registered on db instance and no application bound to current context',)

The app context is not transfered between threads / greenlets. Please see:

• Stackoverflow
• Doc: flask.copy_current_request_context

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Schedule

Day 1: Unix 101

• Homebrew, Coreutils
• Tools: ssh, nc, awk, grep, vim, cut, sort, tmux, less, tail, cut, ssh, htop, psql
• Dotfiles: Configs: ~/.bashrc, ~/.pgpass, ~/.s3cfg, ~/.psqlrc, ~/ssh/config
• What is
  • source /data/virtualenv/default/bin/activate
  • ssh deploy@::1
• SSH tunnels
• Reverse tunnel

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Blogs

• highscalability.com
• softwareengineeringdaily.com
• news.ycombinator.com
• martinfowler.com
• jacquesmattheij.com
• kitchensoap.com
• scotch.io
• techspot.zzzeek.org

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Unit test ideas

Deterministic VS Stocastic

Unit tests should always be deterministic / reproducable. It is hard to debug when tests might fail randomly.

• Assign a seed to the RNG

Avoid conditional-statements

Unit tests should always follow the same execution path, and hit all asserts regardless of the global or local state. This ensures consistent behaviour and that there is no assumptions on whether conditional control flows have been accurately written.

Create fixtures from database not datasets

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Java

• Polymorphism
  • the ability of a variable, function, or object to take multiple forms
  • to define one interface with multiple implementations
  • compile-time: - using the same method name, but different signature
  • run-time: - using a reference type to control which method is called
• @Override Annodation
  • Runtime polymorphism
• Java determins which version super/sub class method to execute based on reference type of call

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Python Socket Timeout

The Problem

It is well known that the standard python socket library has no default timeout (returns None).

[ec2-user@worker-node ~]$ python
>>> import socket
>>> socket.getdefaulttimeout()

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AWSTemplateFormatVersion: 2010-09-09
Resources:
  VPC:
    Type: 'AWS::EC2::VPC'
    Properties:
      CidrBlock: 10.0.0.0/16
  InternetGateway:
    Type: 'AWS::EC2::InternetGateway'
  GatewayToInternet:
    Type: 'AWS::EC2::VPCGatewayAttachment'

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AWS MySQL Debugging

This tutorial provides a means to enable slow query logs on MySQL.

Setting Up Parameters

Enable these on AWS RDS Parameter Groups.

slow_query_log: 1
long_query_time: 10