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https://github.com/dchevell/flask-executor
Adds concurrent.futures support to Flask
https://github.com/dchevell/flask-executor
Last synced: 6 days ago
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Adds concurrent.futures support to Flask
- Host: GitHub
- URL: https://github.com/dchevell/flask-executor
- Owner: dchevell
- License: mit
- Created: 2018-08-19T05:48:29.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2023-01-14T22:01:18.000Z (almost 2 years ago)
- Last Synced: 2024-07-15T11:15:42.423Z (4 months ago)
- Language: Python
- Homepage:
- Size: 151 KB
- Stars: 173
- Watchers: 7
- Forks: 26
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
Flask-Executor
==============
[](https://github.com/dchevell/flask-executor/actions/workflows/tests.yml)
[](https://codecov.io/gh/dchevell/flask-executor)
[](https://pypi.python.org/pypi/Flask-Executor)
[](https://github.com/dchevell/flask-executor/blob/master/LICENSE)
Sometimes you need a simple task queue without the overhead of separate worker processes or powerful-but-complex libraries beyond your requirements. Flask-Executor is an easy to use wrapper for the `concurrent.futures` module that lets you initialise and configure executors via common Flask application patterns. It's a great way to get up and running fast with a lightweight in-process task queue.
Installation
------------
Flask-Executor is available on PyPI and can be installed with:
pip install flask-executor
Quick start
-----------
Here's a quick example of using Flask-Executor inside your Flask application:
```python
from flask import Flask
from flask_executor import Executor
app = Flask(__name__)
executor = Executor(app)
def send_email(recipient, subject, body):
# Magic to send an email
return True
@app.route('/signup')
def signup():
# Do signup form
executor.submit(send_email, recipient, subject, body)
```
Contexts
--------
When calling `submit()` or `map()` Flask-Executor will wrap `ThreadPoolExecutor` callables with a
copy of both the current application context and current request context. Code that must be run in
these contexts or that depends on information or configuration stored in `flask.current_app`,
`flask.request` or `flask.g` can be submitted to the executor without modification.
Note: due to limitations in Python's default object serialisation and a lack of shared memory space between subprocesses, contexts cannot be pushed to `ProcessPoolExecutor()` workers.
Futures
-------
You may want to preserve access to Futures returned from the executor, so that you can retrieve the
results in a different part of your application. Flask-Executor allows Futures to be stored within
the executor itself and provides methods for querying and returning them in different parts of your
app::
```python
@app.route('/start-task')
def start_task():
executor.submit_stored('calc_power', pow, 323, 1235)
return jsonify({'result':'success'})
@app.route('/get-result')
def get_result():
if not executor.futures.done('calc_power'):
return jsonify({'status': executor.futures._state('calc_power')})
future = executor.futures.pop('calc_power')
return jsonify({'status': done, 'result': future.result()})
```
Decoration
----------
Flask-Executor lets you decorate methods in the same style as distributed task queues like
Celery:
```python
@executor.job
def fib(n):
if n <= 2:
return 1
else:
return fib(n-1) + fib(n-2)
@app.route('/decorate_fib')
def decorate_fib():
fib.submit(5)
fib.submit_stored('fibonacci', 5)
fib.map(range(1, 6))
return 'OK'
```
Default Callbacks
-----------------
Future objects can have callbacks attached by using `Future.add_done_callback`. Flask-Executor
lets you specify default callbacks that will be applied to all new futures created by the executor:
```python
def some_callback(future):
# do something with future
executor.add_default_done_callback(some_callback)
# Callback will be added to the below task automatically
executor.submit(pow, 323, 1235)
```
Propagate Exceptions
--------------------
Normally any exceptions thrown by background threads or processes will be swallowed unless explicitly
checked for. To instead surface all exceptions thrown by background tasks, Flask-Executor can add
a special default callback that raises any exceptions thrown by tasks submitted to the executor::
```python
app.config['EXECUTOR_PROPAGATE_EXCEPTIONS'] = True
```
Documentation
-------------
Check out the full documentation at [flask-executor.readthedocs.io](https://flask-executor.readthedocs.io)!