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# Copyright 2021-2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
import asyncio
import logging
import traceback
import collections
import sys
from typing import Awaitable, Set, TypeVar
from functools import wraps
from pyee import EventEmitter
from .colors import color
# -----------------------------------------------------------------------------
# Logging
# -----------------------------------------------------------------------------
logger = logging.getLogger(__name__)
# -----------------------------------------------------------------------------
def setup_event_forwarding(emitter, forwarder, event_name):
def emit(*args, **kwargs):
forwarder.emit(event_name, *args, **kwargs)
emitter.on(event_name, emit)
# -----------------------------------------------------------------------------
def composite_listener(cls):
"""
Decorator that adds a `register` and `deregister` method to a class, which
registers/deregisters all methods named `on_<event_name>` as a listener for
the <event_name> event with an emitter.
"""
# pylint: disable=protected-access
def register(self, emitter):
for method_name in dir(cls):
if method_name.startswith('on_'):
emitter.on(method_name[3:], getattr(self, method_name))
def deregister(self, emitter):
for method_name in dir(cls):
if method_name.startswith('on_'):
emitter.remove_listener(method_name[3:], getattr(self, method_name))
cls._bumble_register_composite = register
cls._bumble_deregister_composite = deregister
return cls
# -----------------------------------------------------------------------------
_T = TypeVar('_T')
class AbortableEventEmitter(EventEmitter):
def abort_on(self, event: str, awaitable: Awaitable[_T]) -> Awaitable[_T]:
"""
Set a coroutine or future to abort when an event occur.
"""
future = asyncio.ensure_future(awaitable)
if future.done():
return future
def on_event(*_):
if future.done():
return
msg = f'abort: {event} event occurred.'
if isinstance(future, asyncio.Task):
# python < 3.9 does not support passing a message on `Task.cancel`
if sys.version_info < (3, 9, 0):
future.cancel()
else:
future.cancel(msg)
else:
future.set_exception(asyncio.CancelledError(msg))
def on_done(_):
self.remove_listener(event, on_event)
self.on(event, on_event)
future.add_done_callback(on_done)
return future
# -----------------------------------------------------------------------------
class CompositeEventEmitter(AbortableEventEmitter):
def __init__(self):
super().__init__()
self._listener = None
@property
def listener(self):
return self._listener
@listener.setter
def listener(self, listener):
# pylint: disable=protected-access
if self._listener:
# Call the deregistration methods for each base class that has them
for cls in self._listener.__class__.mro():
if hasattr(cls, '_bumble_register_composite'):
cls._bumble_deregister_composite(listener, self)
self._listener = listener
if listener:
# Call the registration methods for each base class that has them
for cls in listener.__class__.mro():
if hasattr(cls, '_bumble_deregister_composite'):
cls._bumble_register_composite(listener, self)
# -----------------------------------------------------------------------------
class AsyncRunner:
class WorkQueue:
def __init__(self, create_task=True):
self.queue = None
self.task = None
self.create_task = create_task
def enqueue(self, coroutine):
# Create a task now if we need to and haven't done so already
if self.create_task and self.task is None:
self.task = asyncio.create_task(self.run())
# Lazy-create the coroutine queue
if self.queue is None:
self.queue = asyncio.Queue()
# Enqueue the work
self.queue.put_nowait(coroutine)
async def run(self):
while True:
item = await self.queue.get()
try:
await item
except Exception as error:
logger.warning(
f'{color("!!! Exception in work queue:", "red")} {error}'
)
# Shared default queue
default_queue = WorkQueue()
# Shared set of running tasks
running_tasks: Set[Awaitable] = set()
@staticmethod
def run_in_task(queue=None):
"""
Function decorator used to adapt an async function into a sync function
"""
def decorator(func):
@wraps(func)
def wrapper(*args, **kwargs):
coroutine = func(*args, **kwargs)
if queue is None:
# Create a task to run the coroutine
async def run():
try:
await coroutine
except Exception:
logger.warning(
f'{color("!!! Exception in wrapper:", "red")} '
f'{traceback.format_exc()}'
)
asyncio.create_task(run())
else:
# Queue the coroutine to be awaited by the work queue
queue.enqueue(coroutine)
return wrapper
return decorator
@staticmethod
def spawn(coroutine):
"""
Spawn a task to run a coroutine in a "fire and forget" mode.
Using this method instead of just calling `asyncio.create_task(coroutine)`
is necessary when you don't keep a reference to the task, because `asyncio`
only keeps weak references to alive tasks.
"""
task = asyncio.create_task(coroutine)
AsyncRunner.running_tasks.add(task)
task.add_done_callback(AsyncRunner.running_tasks.remove)
# -----------------------------------------------------------------------------
class FlowControlAsyncPipe:
"""
Asyncio pipe with flow control. When writing to the pipe, the source is
paused (by calling a function passed in when the pipe is created) if the
amount of queued data exceeds a specified threshold.
"""
def __init__(
self,
pause_source,
resume_source,
write_to_sink=None,
drain_sink=None,
threshold=0,
):
self.pause_source = pause_source
self.resume_source = resume_source
self.write_to_sink = write_to_sink
self.drain_sink = drain_sink
self.threshold = threshold
self.queue = collections.deque() # Queue of packets
self.queued_bytes = 0 # Number of bytes in the queue
self.ready_to_pump = asyncio.Event()
self.paused = False
self.source_paused = False
self.pump_task = None
def start(self):
if self.pump_task is None:
self.pump_task = asyncio.create_task(self.pump())
self.check_pump()
def stop(self):
if self.pump_task is not None:
self.pump_task.cancel()
self.pump_task = None
def write(self, packet):
self.queued_bytes += len(packet)
self.queue.append(packet)
# Pause the source if we're over the threshold
if self.queued_bytes > self.threshold and not self.source_paused:
logger.debug(f'pausing source (queued={self.queued_bytes})')
self.pause_source()
self.source_paused = True
self.check_pump()
def pause(self):
if not self.paused:
self.paused = True
if not self.source_paused:
self.pause_source()
self.source_paused = True
self.check_pump()
def resume(self):
if self.paused:
self.paused = False
if self.source_paused:
self.resume_source()
self.source_paused = False
self.check_pump()
def can_pump(self):
return self.queue and not self.paused and self.write_to_sink is not None
def check_pump(self):
if self.can_pump():
self.ready_to_pump.set()
else:
self.ready_to_pump.clear()
async def pump(self):
while True:
# Wait until we can try to pump packets
await self.ready_to_pump.wait()
# Try to pump a packet
if self.can_pump():
packet = self.queue.pop()
self.write_to_sink(packet)
self.queued_bytes -= len(packet)
# Drain the sink if we can
if self.drain_sink:
await self.drain_sink()
# Check if we can accept more
if self.queued_bytes <= self.threshold and self.source_paused:
logger.debug(f'resuming source (queued={self.queued_bytes})')
self.source_paused = False
self.resume_source()
self.check_pump()
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