async def wait_for_announcement(self) -> Tuple[LESPeer, les.HeadInfo]:
"""Wait for a new announcement from any of our connected peers.
Returns a tuple containing the LESPeer on which the announcement was received and the
announcement info.
Raises StopRequested when LightChain.stop() has been called.
"""
should_stop = False
async def wait_for_stop_event():
nonlocal should_stop
await self._should_stop.wait()
should_stop = True
# Wait for either a new announcement or the _should_stop event.
done, pending = await asyncio.wait(
[self._announcement_queue.get(),
wait_for_stop_event()],
return_when=asyncio.FIRST_COMPLETED)
# The asyncio.wait() call above may return both tasks as done, but never both as pending,
# although to be future-proof (in case more than 2 tasks are passed in to wait()), we
# iterate over all pending tasks and cancel all of them.
for task in pending:
task.cancel()
if should_stop:
raise StopRequested()
return done.pop().result()
async def wait_for_announcement(self) -> Tuple[LESPeer, les.HeadInfo]:
"""Wait for a new announcement from any of our connected peers.
Returns a tuple containing the LESPeer on which the announcement was received and the
announcement info.
Raises StopRequested when LightChain.stop() has been called.
"""
should_stop = False
async def wait_for_stop_event():
nonlocal should_stop
await self._should_stop.wait()
should_stop = True
# Wait for either a new announcement or the _should_stop event.
done, pending = await asyncio.wait(
[self._announcement_queue.get(), wait_for_stop_event()],
return_when=asyncio.FIRST_COMPLETED)
# The async call above returns as soon as one of our 2 coroutines complete, so we know
# for sure we'll have one task in the <done> and one task in the <pending> set.
pending.pop().cancel()
if should_stop:
raise StopRequested()
return done.pop().result()
async def fetch_headers(self, start_block: int, peer: LESPeer) -> List[BlockHeader]:
for i in range(self.max_consecutive_timeouts):
if self._should_stop.is_set():
raise StopRequested()
try:
return await peer.fetch_headers_starting_at(start_block)
except asyncio.TimeoutError:
self.logger.info(
"Timeout when fetching headers from %s (attempt %d of %d)",
peer, i + 1, self.max_consecutive_timeouts)
# TODO: Figure out what's a good value to use here.
await asyncio.sleep(0.5)
raise TooManyTimeouts()