# -*- coding: utf-8 -*-
import asyncio
from .decorator import overload
from .concurrent import ConcurrentExecutor, safe_run
from .assertions import assert_corofunction, assert_iter
[docs]@overload
@asyncio.coroutine
def each(coro, iterable, limit=0, loop=None,
collect=False, timeout=None, return_exceptions=False, *args, **kw):
"""
Concurrently iterates values yielded from an iterable, passing them to
an asynchronous coroutine.
You can optionally collect yielded values passing collect=True param,
which would be equivalent to `paco.map()``.
Mapped values will be returned as an ordered list.
Items order is preserved based on origin iterable order.
Concurrency level can be configurable via `limit` param.
All coroutines will be executed in the same loop.
This function is a coroutine.
This function can be composed in a pipeline chain with ``|`` operator.
Arguments:
coro (coroutinefunction): coroutine iterator function that accepts
iterable values.
iterable (iterable|asynchronousiterable): an iterable collection
yielding coroutines functions.
limit (int): max iteration concurrency limit. Use ``0`` for no limit.
collect (bool): return yielded values from coroutines. Default False.
loop (asyncio.BaseEventLoop): optional event loop to use.
return_exceptions (bool): enable/disable returning exceptions in case
of error. `collect` param must be True.
timeout (int|float): timeout can be used to control the maximum number
of seconds to wait before returning. timeout can be an int or
float. If timeout is not specified or None, there is no limit to
the wait time.
*args (mixed): optional variadic arguments to pass to the
coroutine iterable function.
Returns:
results (list): ordered list of values yielded by coroutines
Raises:
TypeError: in case of invalid input arguments.
Usage::
async def mul_2(num):
return num * 2
await paco.each(mul_2, [1, 2, 3, 4, 5])
# => None
await paco.each(mul_2, [1, 2, 3, 4, 5], collect=True)
# => [2, 4, 6, 8, 10]
"""
assert_corofunction(coro=coro)
assert_iter(iterable=iterable)
# By default do not collect yielded values from coroutines
results = None
if collect:
# Store ordered results
results = [None] * len(iterable)
# Create concurrent executor
pool = ConcurrentExecutor(limit=limit, loop=loop)
@asyncio.coroutine
def collector(index, item):
result = yield from safe_run(coro(item, *args, **kw),
return_exceptions=return_exceptions)
if collect:
results[index] = result
return result
# Iterate and pass elements to coroutine
for index, value in enumerate(iterable):
pool.add(collector(index, value))
# Wait until all the coroutines finishes
yield from pool.run(return_exceptions=return_exceptions,
ignore_empty=True,
timeout=timeout)
# Returns list of mapped results in order
return results