Metadata-Version: 2.1
Name: dike
Version: 0.3.1
Summary: Python asyncio tools for web service resilience.
Home-page: https://github.com/chr1st1ank/dike
License: Apache-2.0
Author: Christian Krudewig
Author-email: chr1st1ank@krudewig-online.de
Requires-Python: >=3.7.1,<4.0
Classifier: Development Status :: 5 - Production/Stable
Classifier: Framework :: AsyncIO
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Natural Language :: English
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Provides-Extra: dev
Provides-Extra: doc
Provides-Extra: test
Requires-Dist: pymdown-extensions[docs] (>=8.2,<9.0)
Description-Content-Type: text/markdown

# dike

**Python asyncio tools for web service resilience**

* Documentation: <https://chr1st1ank.github.io/dike/>
* License: Apache-2.0

[<img src="https://img.shields.io/pypi/v/dike.svg" alt="Release Status">](https://pypi.python.org/pypi/dike)
[<img src="https://github.com/chr1st1ank/dike/actions/workflows/test.yml/badge.svg?branch=main" alt="CI Status">](https://github.com/chr1st1ank/dike/actions)
[![codecov](https://codecov.io/gh/chr1st1ank/dike/branch/main/graph/badge.svg?token=4oBkRHXbfa)](https://codecov.io/gh/chr1st1ank/dike)


## Features

### Concurrency limiting for asynchronous functions
The `@limit_jobs` decorator allows to limit the number of concurrent excecutions of a coroutine 
function. This can be useful for limiting queueing times or for limiting the load put
onto backend services.

Example with an external web request using the [httpx](https://github.com/encode/httpx) library:

```python
import asyncio
import dike
import httpx


@dike.limit_jobs(limit=2)
async def web_request():
    """Sends a slow web request"""
    async with httpx.AsyncClient() as client:
        response = await client.get("https://httpstat.us/200?sleep=100")
    return response


async def main():
    # Send three requests at the same time
    call1 = web_request()
    call2 = web_request()
    call3 = web_request()
    responses = await asyncio.gather(call1, call2, call3, return_exceptions=True)
    # Print the responses
    for r in responses:
        if isinstance(r, dike.TooManyCalls):
            print("too many calls")
        else:
            print(r)


asyncio.run(main())
```

The output shows that the first two requests succeed. The third one hits the concurrency limit and a TooManyCalls exception is returned:
```
<Response [200 OK]>
<Response [200 OK]>
too many calls
```

### Mini-batching for asynchronous function calls
The `@batch` decorator groups function calls into batches and only calls the wrapped function 
with the aggregated input.

This is useful if the function scales well with the size of the input arguments but you're
getting the input data in smaller bits, e.g. as individual HTTP requests.

The arguments can be batched together as a Python list or optionally also as numpy array.

Example:

```python
import asyncio
import dike


@dike.batch(target_batch_size=3, max_waiting_time=10)
async def add_args(arg1, arg2):
    """Elementwise sum of the values in arg1 and arg2"""
    print(f"arg1: {arg1}")
    print(f"arg2: {arg2}")
    return [a1 + a2 for a1, a2 in zip(arg1, arg2)]


async def main():
    result = await asyncio.gather(
        add_args([0], [1]),
        add_args([1], [1]),
        add_args([2, 3], [1, 1]),
    )

    print(f"Result: {result}")


asyncio.run(main())
```

Output:
```
arg1: [0, 1, 2, 3]
arg2: [1, 1, 1, 1]
Result: [[1], [2], [3, 4]]
```

## Installation
Simply install from pypi. The library is pure Python without any dependencies other than the
standard library.
```
pip install dike
```

