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## Project description

# Scurl

[![Build Status](https://travis-ci.org/scrapy/scurl.svg?branch=master)](https://travis-ci.org/scrapy/scurl)

Scurl is a library that is meant to replace some functions in urllib, such as urlparse,
urlsplit and urljoin. It is built using the Chromium url parse source, which is called GURL.

In addition, this library is built to support the Scrapy project (hence the name Scurl).
Therefore, an additional function is built, which is canonicalize_url, the bottleneck
function in Scrapy spiders. It uses the canonicalize function from GURL to canonicalize
the path, fragment and query of the urls.

Since the library is built based on Chromium source, the performance is greatly
increased. The performance of urlparse, urlsplit and urljoin is 2-3 times faster than
the urllib.

At the moment, we run the tests from urllib and w3lib. Nearly all the tests
from urllib have passed (we are still working on passing all the tests :) ).

## Credits

We want to give special thanks to [urlparse4](https://github.com/commonsearch/urlparse4)
since this project is built based on it.

## Supported functions

Since scurl meant to replace those functions in urllib, these are supported by Scurl:
urlparse, urljoin, urlsplit and canonicalize_url.

## Installation

Scurl has not been deployed to pypi yet. Currently the only way to install Scurl is
cloning this repository


git clone https://github.com/scrapy/scurl
cd scurl
pip install -r requirements.txt
make clean
make build_ext
make install


## Available Make commands

Make commands create a shorter way to type commands while developing :)

make clean

This will clean the build dir and the files that are generated when running build_ext command

make test

This will run all the tests found in the /tests folder

make build_ext

This will run the command python setup.py build_ext --inplace, which builds Cython code
for this project.

make sdist

This will run python setup.py sdist command on this project.

make install

This will run python setup.py install command on this project.

make develop

This will run python setup.py develop command on this project.

make perf

Run the performance tests on urlparse, urlsplit and urljoin.

make cano:

Run the performance tests on canonicalize_url.

## Profiling

Scurl repository has the built-in profiling tool, which you can turn on by adding this
lines to the top of the *.pyx files in scurl/scurl:


# cython: profile=True


Then you can run python benchmarks/cython_profile.py --func [function-name] to get the
cprofiling result. Currently, Scurl supports profiling urlparse, urlsplit and canonicalize.

This is not the most convenient way to profile Scurl with cprofiler, but we will come
up with a way of improving this soon!

## Benchmarking result report

### urlparse, urlsplit and urljoin
This shows the performance difference between urlparse, urlsplit and urljoin from
urllib.parse and those of Scurl (this is measured by running these functions with the
urls from the file chromiumUrls.txt, which can also be found in this project):

The chromiumUrls.txt file contains ~83k urls. This measure the time it takes to run the
performance_test.py test.

| | urlparse | urlsplit | urljoin |
| ------------- |:-------------:|:-----------:|:--------:|
| urllib.parse | 0.52 sec | 0.39 sec | 1.33 sec |
| Scurl | 0.19 sec | 0.10 sec | 0.17 sec |

### Canonicalize urls
The speed of canonicalize_url from [scrapy/w3lib](https://github.com/scrapy/w3lib)
compared to the speed of canonicalize_url from Scurl (this is measured by running
canonicalize_url with the urls from the file chromiumUrls.txt, which can also be
found in this project):

This measures the speed of both functions. The test can be found in canonicalize_test.py
file.

| |canonicalize_url |
| ------------- |:---------------:|
| scrapy/w3lib | 22,757 items/sec|
| Scurl | 46,199 items/sec|

## Feedback

Any feedback is highly appreciated :) Please feel free to submit any
error/feedback in the repository issue tab!

## Project details

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