tractor/tests/test_streaming.py

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"""
Streaming via async gen api
"""
import time
import trio
import tractor
import pytest
async def stream_seq(sequence):
for i in sequence:
yield i
await trio.sleep(0.1)
# block indefinitely waiting to be cancelled by ``aclose()`` call
with trio.open_cancel_scope() as cs:
await trio.sleep(float('inf'))
assert 0
assert cs.cancelled_caught
async def stream_from_single_subactor():
"""Verify we can spawn a daemon actor and retrieve streamed data.
"""
async with tractor.find_actor('brokerd') as portals:
if not portals:
# only one per host address, spawns an actor if None
async with tractor.open_nursery() as nursery:
# no brokerd actor found
portal = await nursery.start_actor(
'streamerd',
rpc_module_paths=[__name__],
statespace={'global_dict': {}},
)
seq = range(10)
agen = await portal.run(
__name__,
'stream_seq', # the func above
sequence=list(seq), # has to be msgpack serializable
)
# it'd sure be nice to have an asyncitertools here...
iseq = iter(seq)
ival = next(iseq)
async for val in agen:
assert val == ival
try:
ival = next(iseq)
except StopIteration:
# should cancel far end task which will be
# caught and no error is raised
await agen.aclose()
await trio.sleep(0.3)
try:
await agen.__anext__()
except StopAsyncIteration:
# stop all spawned subactors
await portal.cancel_actor()
# await nursery.cancel()
def test_stream_from_single_subactor(arb_addr):
"""Verify streaming from a spawned async generator.
"""
tractor.run(stream_from_single_subactor, arbiter_addr=arb_addr)
# this is the first 2 actors, streamer_1 and streamer_2
async def stream_data(seed):
for i in range(seed):
yield i
await trio.sleep(0) # trigger scheduler
# this is the third actor; the aggregator
async def aggregate(seed):
"""Ensure that the two streams we receive match but only stream
a single set of values to the parent.
"""
async with tractor.open_nursery() as nursery:
portals = []
for i in range(1, 3):
# fork point
portal = await nursery.start_actor(
name=f'streamer_{i}',
rpc_module_paths=[__name__],
)
portals.append(portal)
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send_chan, recv_chan = trio.open_memory_channel(500)
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async def push_to_chan(portal):
async for value in await portal.run(
__name__, 'stream_data', seed=seed
):
# leverage trio's built-in backpressure
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await send_chan.send(value)
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await send_chan.send(None)
print(f"FINISHED ITERATING {portal.channel.uid}")
# spawn 2 trio tasks to collect streams and push to a local queue
async with trio.open_nursery() as n:
for portal in portals:
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n.start_soon(push_to_chan, portal)
unique_vals = set()
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async for value in recv_chan:
if value not in unique_vals:
unique_vals.add(value)
# yield upwards to the spawning parent actor
yield value
if value is None:
break
assert value in unique_vals
print("FINISHED ITERATING in aggregator")
await nursery.cancel()
print("WAITING on `ActorNursery` to finish")
print("AGGREGATOR COMPLETE!")
# this is the main actor and *arbiter*
async def a_quadruple_example():
# a nursery which spawns "actors"
async with tractor.open_nursery() as nursery:
seed = int(1e3)
pre_start = time.time()
portal = await nursery.run_in_actor(
'aggregator',
aggregate,
seed=seed,
)
start = time.time()
# the portal call returns exactly what you'd expect
# as if the remote "aggregate" function was called locally
result_stream = []
async for value in await portal.result():
result_stream.append(value)
print(f"STREAM TIME = {time.time() - start}")
print(f"STREAM + SPAWN TIME = {time.time() - pre_start}")
assert result_stream == list(range(seed)) + [None]
return result_stream
async def cancel_after(wait):
with trio.move_on_after(wait):
return await a_quadruple_example()
@pytest.fixture(scope='module')
def time_quad_ex(arb_addr):
start = time.time()
results = tractor.run(cancel_after, 3, arbiter_addr=arb_addr)
diff = time.time() - start
assert results
return results, diff
def test_a_quadruple_example(time_quad_ex):
"""This also serves as a kind of "we'd like to be this fast test"."""
results, diff = time_quad_ex
assert results
assert diff < 2.5
@pytest.mark.parametrize(
'cancel_delay',
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list(map(lambda i: i/10, range(3, 9)))
)
def test_not_fast_enough_quad(arb_addr, time_quad_ex, cancel_delay):
"""Verify we can cancel midway through the quad example and all actors
cancel gracefully.
"""
results, diff = time_quad_ex
delay = max(diff - cancel_delay, 0)
results = tractor.run(cancel_after, delay, arbiter_addr=arb_addr)
assert results is None