async def fetch_headers_starting_at(
self, start_block: int, cancel_token: CancelToken) -> List[BlockHeader]:
"""Fetches up to self.max_headers_fetch starting at start_block.
Returns a list containing those headers in ascending order of block number.
"""
request_id = gen_request_id()
self.sub_proto.send_get_block_headers(
start_block, self.max_headers_fetch, request_id, reverse=False)
reply = await self._wait_for_reply(request_id, cancel_token)
if not reply['headers']:
raise EmptyGetBlockHeadersReply(
"No headers in reply. start_block=={}".format(start_block))
self.logger.info(
"fetched headers from %s to %s", reply['headers'][0].block_number,
reply['headers'][-1].block_number)
return reply['headers']
async def _fetch_headers_starting_at(
self, peer: LESPeer, start_block: int) -> List[BlockHeader]:
"""Fetches up to self.max_headers_fetch starting at start_block.
:return: a list containing those headers in ascending order of block number.
:raise EmptyGetBlockHeadersReply: if no headers are returned
"""
request_id = gen_request_id()
peer.sub_proto.send_get_block_headers(
start_block, peer.max_headers_fetch, request_id, reverse=False)
reply = await self._wait_for_reply(request_id)
if not reply['headers']:
raise EmptyGetBlockHeadersReply(
"No headers in reply. start_block=={}".format(start_block))
self.logger.debug(
"fetched headers from %s to %s", reply['headers'][0].block_number,
reply['headers'][-1].block_number)
return reply['headers']