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Scaling your API with rate limiters

The following are examples of the four types rate limiters discussed in the accompanying blog post. In the examples below I've used pseudocode-like Ruby, so if you're unfamiliar with Ruby you should be able to easily translate this approach to other languages. Complete examples in Ruby are also provided later in this gist.

In most cases you'll want all these examples to be classes, but I've used simple functions here to keep the code samples brief.

Request rate limiter

This uses a basic token bucket algorithm and relies on the fact that Redis scripts execute atomically. No other operations can run between fetching the count and writing the new count.

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(cliped from http://stackoverflow.com/a/21786764/117292)

The least obstrusive way is to use a CurrentUserMiddleware to store the current user in a thread local object:

current_user.py

from threading import local

_user = local()

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def batch_queryset(queryset, batchsize=2000):
    queryset = queryset.order_by("pk")
    total = queryset.count()
    with transaction.atomic():
        for start in range(0, total, batchsize):
            end = min(start + batchsize, total)
            yield queryset[start: end]

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import line_profiler
profile = line_profiler.LineProfiler()


@profile
def my_function_in_django_code():
    ....

 with open('output.txt', 'w') as stream:

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Semantic Commit Messages

See how a minor change to your commit message style can make you a better programmer.

Format: <type>(<scope>): <subject>

<scope> is optional

Example

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#!/usr/bin/env python3

# Copyright 2014 Brett Slatkin, Pearson Education Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#

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document.body.contentEditable=true;

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1. undo the commits from the local repository (it means you haven't git push them)

1.1 If you only want to add more changes to the previous commit, or change the commit message

git reset --soft HEAD~

1.2 If you also want to un-add the files which you added using git add command

git reset HEAD~

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from keras import backend as K


def focal_loss(gamma=2):
    def loss(y_true, y_pred):
        epsilon = K.epsilon()
        y_pred = K.clip(y_pred, epsilon, 1 - epsilon)
        pt = K.max(y_true * y_pred, axis=-1)
        batch_loss = -K.pow((1 - pt), gamma) * K.log(pt)
        return K.mean(batch_loss)

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conda create -n NAME_OF_YOUR_ENV python=3.6

it will create a virtual env with python 3.6

conda env remove -n NAME_OF_YOUR_ENV

it will remove your virtual env