aiothrottles 0.0.1a1

Throttles for Python coroutines.

aiothrottles

aiothrottles synchronization primitives are designed to be extension (along the time) to asyncio synchronization primitives.

aiothrottles has the following basic synchronization primitives:

• Throttle

Getting started

aiothrottles requires python 3.5+. Install package using pip

pip install aiothrottles

Throttle

Implements a rate limiting for asyncio task. A throttle can be used to guarantee exclusive access to a shared resources and locks access for a given time after releasing.

The preferred way to use a Throttle is an async with statement:

throttle = Throttle('1/s')

# ... later
async with throttle:
    # access shared state

which is equivalent to:

throttle  = Throttle('1/s')

# ... later
await throttle.acquire()
try:
    # access shared state
finally:
    throttle.release()

rates

The allowed call rate is determined by the rate argument. Pass the rate in the format {integer limit}/{unit time} or {limit's numerator}/{limit's denominator}{unit time}. For, example:

• rates with integer limits
  • 4/s, 5/m, 6/h, 7/d
  • 1/second, 2/minute, 3/hour, 4/day
• rates with rational limits
  • 1/3s, 12/37m, 1/5h, 8/3d

Examples

decorator

Use of Throttle as decorator for coroutines:

import time
from aiothrottles import throttle  # Throttle alias

@throttle(rate='1/s')
async def foo(n):
    print(n, time.time())

for i in range(5):
    await foo(i)

# 0 1563272100.4413373
# 1 1563272101.4427333
# 2 1563272102.4441307
# 3 1563272103.445542
# 4 1563272104.4468124

awaitable

Use of aiothrottles.Throttle as awaitable object:

import time
from aiothrottles import Throttle

throttle = Throttle(rate='1/s')

async def foo(n):
    print(n, time.time())

for i in range(5):
    await throttle
    await foo(i)

# 0 1563275828.253736
# 1 1563275829.2547996
# 2 1563275830.2562528
# 3 1563275831.257302
# 4 1563275832.2587304

context manager

Use of aiothrottles.Throttle as context:

import time
from aiothrottles import Throttle

throttle = Throttle(rate='1/s')

async def foo(n):
    print(n, time.time())

for i in range(5):
    async with throttle:
        await foo(i)

# 0 1563275898.6722345
# 1 1563275899.673589
# 2 1563275900.6750457
# 3 1563275901.6763387
# 4 1563275902.6777005

License

aiothrottles is released under the BSD 3-Clause License.