futured 0.3

Functional interface for concurrent futures, including asynchronous I/O.

Futured provides a simple consistent interface for concurrent functional programming in Python. It can wrap any callable to return concurrent.futures.Future objects, and it can wrap any async coroutine to return asyncio.Future objects.

Usage

threaded, processed

Transform any callable into one which runs in a thread or process pool, and returns a future.

from futured import threaded, processed
import requests

fetch = threaded(requests.Session().get)
fetch(url)  # returns Future

fs = (fetch(url + path) for path in paths)
fetch.results(fs)  # generates results in order
fetch.results(fs, timeout=...)  # generates results as completed

fetch.map(urls)  # generates results in order
fetch.map(urls, timeout=...)  # generates results as completed
fetch.mapzip(urls)  # generates (url, result) pairs as completed

Naturally futured wrappers can be used as decorators, but arguments can also be partially bound.

@threaded
def slow():
   ...

fetch = threaded(requests.Session().get, url)
fetch(params=...)

Methods are supported, as well as a decorated utility for automatically subclassing.

from futured import decorated

FutureSession = decorated(requests.Session, request=threaded)

 # equivalent to
class FutureSession(requests.Session):
    request = threaded(requests.Session.request)

Thread and process pool executors may be customized and reused.

threaded(max_workers=...)(func, ...)
processed(max_workers=...)(func, ...)

futured classes have a waiting context manager which collects results from tasks. Futures can be registered at creation, or appended to the list of tasks.

with threaded.waiting(future,... ) as tasks:
    tasks.append(future)
tasks  # results in order

asynced

The same interface works for aynscio. For convenience, there's also a synchronous run method.

from futured import asynced
import aiohttp

fetch = asynced(aiohttp.ClientSession().get)
fetch(url)  # returns coroutine
fetch.run(url)  # single synchronous call

 # generate results as described above
fetch.results(fs)
fetch.map(urls)
fetch.mapzip(urls)

command

command wraps subprocess.Popen to provide a Future compatible interface.

from futured import futured, command

command('ls').result()  # returns stdout or raises stderr
command('ls').pipe('wc')  # pipes into next command, or | ('wc',... )
for line in command('ls'):  # iterable lines
command.coroutine('ls')  # returns coroutine

futured(command, 'ls')  # supports `map` interface
asynced(command.coroutine, 'ls')  # supports `map` interface with timeout

forked

forked allows iteration in separate child processes.

from futured import forked

for value in forked(values, max_workers=...):
    # in a child process
 # in parent after children have exited

Installation

$ pip install futured

Tests

100% branch coverage.

$ pytest [--cov]

Changes

0.3

• forked has optional maximum number of workers
• waiting context manager
• command pipes (|)
• distributed.Client support

0.2

• command.coroutine creates asyncio subprocesses
• futured.mapzip generates results zipped with arguments
• asynced.run supports asynchronous iterators