pasync 0.3.1

An event loop for python async

pasync - A simple event loop for async python

This minimal package is mainly used to explore implementing an async runtime in Python.

Usage

Runner

The main construct that you'll often work with is Runner.

A runner is actually a wrapper around an event loop.

It comes with two flavors: non-blocking runner and blocking runner.

• A blocking runner will run all the tasks till end, blocking the main thread. When given a set of tasks, it will refuse to accept any task in the meaning time.
• A non-blocking runner will run all the tasks in another thread. Unlike a blocking runenr, it can accepts additional tasks in the meaning time.

By default, a runner is blocking.

• Blocking runner

  async def gen_num(n):
    return n
  
  with Runner() as runner:
    assert runner.run(gen_num(1)) == 1
    assert runner.gather(gen_num(1), gen_num(2)) == [1, 2]
  

• Non-blocking runner

  async def gen_num(n):
    return n
  
  with Runner(non_blocking = True) as runner:
    assert runner.run(gen_num(1)) == None                  # Not support returning results yet
    assert runner.gather(gen_num(1), gen_num(2)) == None   # Not support returning results yet
  

Pitfalls

1. Currently, non-blocking runner cannot return results of tasks yet. This can be worked around by making the top-level task return None, while all the subtasks's results are consumed inside the top-level task