This is a pre-production deployment of Warehouse. Changes made here affect the production instance of PyPI (pypi.python.org).
Help us improve Python packaging - Donate today!

Powerful polling utility with many configurable options

Project Description
[![Build Status](https://travis-ci.org/justiniso/polling.svg?branch=master)](https://travis-ci.org/justiniso/polling)

polling
=============

Polling is a powerful python utility used to wait for a function to return a certain expected condition.
Some possible uses cases include:

- Wait for API response to return with code 200
- Wait for a file to exist (or not exist)
- Wait for a thread lock on a resource to expire

# Installation

pip install polling

# Examples

### Example: Poll every minute until a url returns 200 status code

```python
import requests
polling.poll(
lambda: requests.get('http://google.com').status_code == 200,
step=60,
poll_forever=True)
```

If you are creating a new cloud provider instance (e.g. waiting for an EC2 instance to come online), you can continue to poll despite getting ConnectionErrors:

```python
import requests
polling.poll(
lambda: requests.get('your.instance.ip').status_code == 200,
step=60,
ignore_exceptions=(requests.exceptions.ConnectionError,),
poll_forever=True)
```

### Example: Poll for a file to exist

```python
# This call will wait until the file exists, checking every 0.1 seconds and stopping after 3 seconds have elapsed
file_handle = polling.poll(
lambda: open('/tmp/myfile.txt'),
ignore_exceptions=(IOError,),
timeout=3,
step=0.1)

# Polling will return the value of your polling function, so you can now interact with it
file_handle.close()
```

### Example: Polling for Selenium WebDriver elements

```python
from selenium import webdriver
driver = webdriver.Firefox()

driver.get('http://google.com')
search_box = polling.poll(
lambda: driver.find_element_by_id('search'),
step=0.5,
timeout=7)

search_box.send_keys('python polling')
```

### Example: Using the polling timeout exception

```python
# An exception will be raised by the polling function on timeout (or the maximum number of calls is exceeded).
# This exception will have a 'values' attribute. This is a queue with all values that did not meet the condition.
# You can access them in the except block.

import random
try:
polling.poll(lambda: random.choice([0, (), False]), step=0.5, timeout=1)
except polling.TimeoutException, te:
while not te.values.empty():
# Print all of the values that did not meet the exception
print te.values.get()
```


### Example: Using a custom condition callback function

```python
import requests

def is_correct_response(response):
"""Check that the response returned 'success'"""
return response == 'success'

polling.poll(
lambda: requests.put('http://mysite.com/api/user', data={'username': 'Jill'},
check_success=is_correct_response,
step=1,
timeout=10)
```

# Release notes

## 0.2.0

- Allow users to access a "last" attribute on the exceptions. This should hold the last evaluated value, which is the more common use case than getting the first value.
- Fix a bug that actually ran 1 more time than value specified by max_tries

## 0.1.0

- First version

Release History

Release History

This version
History Node

0.3.0

History Node

0.2.0

History Node

0.1.0

Download Files

Download Files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
polling-0.3.0.tar.gz (5.0 kB) Copy SHA256 Checksum SHA256 Source Mar 8, 2016

Supported By

WebFaction WebFaction Technical Writing Elastic Elastic Search Pingdom Pingdom Monitoring Dyn Dyn DNS Sentry Sentry Error Logging CloudAMQP CloudAMQP RabbitMQ Heroku Heroku PaaS Kabu Creative Kabu Creative UX & Design Fastly Fastly CDN DigiCert DigiCert EV Certificate Rackspace Rackspace Cloud Servers DreamHost DreamHost Log Hosting