cgthayer

==========================================          ==========================================
             TMUX COMMAND                                        WINDOW (TAB)
==========================================          ==========================================

List    tmux ls                                     List         ^b w
New          -s <session>                           Create       ^b c
Attach       att -t <session>                       Rename       ^b , <name>
Rename       rename-session -t <old> <new>          Last         ^b l               (lower-L)
Kill         kill-session -t <session>              Close        ^b &

cgthayer

import copy

Infinity = 1e6

class GraphU:
    """Undirected graph, with edge cost and nodes have string names.
    Okay to use int or float cost, but must be positive.
    Assumes only one edge between any node n1 and n2.
    """
    def __init__(self, edges=()):

cgthayer

Basics

Images are read-only templates, but you can diff and push them to save many versions. Containers are instances of images, that are also directories and usually a single running process.

Images can be layered, you start from a base and make changes. Containers are versioned so that you can make changes and save the filesystem state as a new Image.

cgthayer

#!/usr/bin/env python                                                                                                                                                                                                                                                                                             
import hashlib
import sys

bsz = 8192
for f in sys.argv[1:]:
  sha1sum = hashlib.sha1()
  with open(f, 'rb') as source:
    while True:
      block = source.read(bsz)

cgthayer

>>> from django.db import transaction
>>> transaction.set_autocommit(autocommit=False)
>>> o = Organization_v2.objects.get(name='pdemo')
>>> del_info = o.delete()
>>> del_info
(1404, {'data.Property': 408, [..more stuff..], 'data.Organization_v2': 1})
>>> Property.objects.filter(scope__organization_id=o).count()
0
>>> transaction.rollback()
>>> o = Organization_v2.objects.get(name='pdemo')

cgthayer

Django DRF Cheat Sheet

Django Rest Framework

Overview:

    http request --> url_route --> view --> serializer --> data-dict response

cgthayer

s = """Gur Mra bs Clguba, ol Gvz Crgref

Ornhgvshy vf orggre guna htyl.
Rkcyvpvg vf orggre guna vzcyvpvg.
Fvzcyr vf orggre guna pbzcyrk.
Pbzcyrk vf orggre guna pbzcyvpngrq.
Syng vf orggre guna arfgrq.
Fcnefr vf orggre guna qrafr.
Ernqnovyvgl pbhagf.
Fcrpvny pnfrf nera'g fcrpvny rabhtu gb oernx gur ehyrf.

cgthayer

$ pip install django
$ django-admin startproject myproj
$ cd myproj
$ django-admin startapp myapp
$ export DJANGO_SETTINGS_MODULE=myproj.settings
$ django-admin runserver
Performing system checks…
System check identified no issues (0 silenced).
February 11, 2020–05:12:45
Django version 1.11.9, using settings 'myproj.settings'

cgthayer

$ python manage.py migrate
Operations to perform:
 Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
 Applying contenttypes.0001_initial… OK
 Applying auth.0001_initial… OK
 Applying admin.0001_initial… OK
 Applying admin.0002_logentry_remove_auto_add… OK
 Applying contenttypes.0002_remove_content_type_name… OK
 Applying auth.0002_alter_permission_name_max_length… OK

cgthayer

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD