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generators.py
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generators.py
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import asyncio
import time
import python_utils
from python_utils import types
async def abatcher(
generator: types.AsyncIterator,
batch_size: types.Optional[int] = None,
interval: types.Optional[types.delta_type] = None,
):
'''
Asyncio generator wrapper that returns items with a given batch size or
interval (whichever is reached first).
'''
batch: list = []
assert batch_size or interval, 'Must specify either batch_size or interval'
# If interval is specified, use it to determine when to yield the batch
# Alternatively set a really long timeout to keep the code simpler
if interval:
interval_s = python_utils.delta_to_seconds(interval)
else:
# Set the timeout to 10 years
interval_s = 60 * 60 * 24 * 365 * 10.0
next_yield = time.perf_counter() + interval_s
pending: types.Set = set()
while True:
try:
done, pending = await asyncio.wait(
pending
or [
asyncio.create_task(generator.__anext__()), # type: ignore
],
timeout=interval_s,
return_when=asyncio.FIRST_COMPLETED,
)
if done:
for result in done:
batch.append(result.result())
except StopAsyncIteration:
if batch:
yield batch
break
if batch_size is not None and len(batch) == batch_size:
yield batch
batch = []
if interval and batch and time.perf_counter() > next_yield:
yield batch
batch = []
# Always set the next yield time to the current time. If the
# loop is running slow due to blocking functions we do not
# want to burst too much
next_yield = time.perf_counter() + interval_s
def batcher(iterable, batch_size):
'''
Generator wrapper that returns items with a given batch size
'''
batch = []
for item in iterable:
batch.append(item)
if len(batch) == batch_size:
yield batch
batch = []
if batch:
yield batch