async def test_skeleton_syncer(request, event_loop, chaindb_fresh,
chaindb_1000):
client_peer, server_peer = await get_directly_linked_peers(
request,
event_loop,
alice_headerdb=FakeAsyncHeaderDB(chaindb_fresh.db),
bob_headerdb=FakeAsyncHeaderDB(chaindb_1000.db))
client_peer_pool = MockPeerPoolWithConnectedPeers([client_peer])
client = FastChainSyncer(ByzantiumTestChain(chaindb_fresh.db),
chaindb_fresh, client_peer_pool)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer])
server_request_handler = ETHRequestServer(
FakeAsyncChainDB(chaindb_1000.db), server_peer_pool)
asyncio.ensure_future(server_request_handler.run())
client_peer.logger.info("%s is serving 1000 blocks", client_peer)
server_peer.logger.info("%s is syncing up 1000 blocks", server_peer)
await asyncio.wait_for(client.run(), timeout=20)
head = chaindb_fresh.get_canonical_head()
assert head == chaindb_1000.get_canonical_head()
# Now download the state for the chain's head.
state_downloader = StateDownloader(chaindb_fresh, chaindb_fresh.db,
head.state_root, client_peer_pool)
await asyncio.wait_for(state_downloader.run(), timeout=20)
assert head.state_root in chaindb_fresh.db
async def test_regular_syncer_fallback(request, event_loop, chaindb_fresh,
chaindb_20):
"""
Test the scenario where a header comes in that's not in memory (but is in the DB)
"""
client_peer, server_peer = await get_directly_linked_peers(
request,
event_loop,
alice_headerdb=FakeAsyncHeaderDB(chaindb_fresh.db),
bob_headerdb=FakeAsyncHeaderDB(chaindb_20.db))
client = FallbackTesting_RegularChainSyncer(
ByzantiumTestChain(chaindb_fresh.db), chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_peer]))
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer])
server_request_handler = ETHRequestServer(FakeAsyncChainDB(chaindb_20.db),
server_peer_pool)
asyncio.ensure_future(server_request_handler.run())
server_peer.logger.info("%s is serving 20 blocks", server_peer)
client_peer.logger.info("%s is syncing up 20", client_peer)
def finalizer():
event_loop.run_until_complete(client.cancel())
# Yield control so that client/server.run() returns, otherwise asyncio will complain.
event_loop.run_until_complete(asyncio.sleep(0.1))
request.addfinalizer(finalizer)
asyncio.ensure_future(client.run())
await wait_for_head(chaindb_fresh, chaindb_20.get_canonical_head())
head = chaindb_fresh.get_canonical_head()
assert head.state_root in chaindb_fresh.db
async def test_header_gapfill_syncer(request,
event_loop,
event_bus,
chaindb_with_gaps,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_with_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client = HeaderChainGapSyncer(
LatestTestChain(chaindb_with_gaps.db),
chaindb_with_gaps,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus)
)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer], event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(ETHRequestServer(
event_bus, TO_NETWORKING_BROADCAST_CONFIG, AsyncChainDB(chaindb_1000.db),
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
async with background_asyncio_service(client):
await wait_for_head(
# We check for 249 because 250 exists from the very beginning (the checkpoint)
chaindb_with_gaps, chaindb_1000.get_canonical_block_header_by_number(249))
async def test_fast_syncer(request, event_loop, event_bus, chaindb_fresh,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client_peer_pool = MockPeerPoolWithConnectedPeers([client_peer],
event_bus=event_bus)
client = FastChainSyncer(LatestTestChain(chaindb_fresh.db),
chaindb_fresh, client_peer_pool)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(event_bus, TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_1000.db))):
client_peer.logger.info("%s is serving 1000 blocks", client_peer)
server_peer.logger.info("%s is syncing up 1000 blocks",
server_peer)
async with background_asyncio_service(client) as manager:
await asyncio.wait_for(manager.wait_finished(), timeout=20)
head = chaindb_fresh.get_canonical_head()
assert head == chaindb_1000.get_canonical_head()
def make_eth1_request_server(cls,
app_config: Eth1AppConfig,
base_db: BaseAtomicDB,
event_bus: EndpointAPI) -> Service:
server: Service
if app_config.database_mode is Eth1DbMode.LIGHT:
header_db = AsyncHeaderDB(base_db)
server = LightRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
header_db
)
elif app_config.database_mode is Eth1DbMode.FULL:
chain_db = AsyncChainDB(base_db)
server = ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
chain_db
)
else:
raise Exception(f"Unsupported Database Mode: {app_config.database_mode}")
return server
async def test_regular_syncer(request, event_loop, event_bus, chaindb_fresh,
chaindb_20):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_20.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client = RegularChainSyncer(
ByzantiumTestChain(chaindb_fresh.db), chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus))
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(event_bus, TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_20.db))):
server_peer.logger.info("%s is serving 20 blocks", server_peer)
client_peer.logger.info("%s is syncing up 20", client_peer)
async with background_asyncio_service(client):
await wait_for_head(chaindb_fresh,
chaindb_20.get_canonical_head())
head = chaindb_fresh.get_canonical_head()
assert head.state_root in chaindb_fresh.db
async def test_proxy_peer_requests(request, event_bus, other_event_bus,
event_loop, chaindb_20, client_and_server):
server_event_bus = event_bus
client_event_bus = other_event_bus
client_peer, server_peer = client_and_server
client_peer_pool = MockPeerPoolWithConnectedPeers(
[client_peer], event_bus=client_event_bus)
server_peer_pool = MockPeerPoolWithConnectedPeers(
[server_peer], event_bus=server_event_bus)
async with AsyncExitStack() as stack:
await stack.enter_async_context(
run_peer_pool_event_server(client_event_bus,
client_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
run_peer_pool_event_server(server_event_bus,
server_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
background_asyncio_service(
ETHRequestServer(server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_20.db))))
client_proxy_peer_pool = ETHProxyPeerPool(
client_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(client_proxy_peer_pool))
proxy_peer_pool = ETHProxyPeerPool(server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(proxy_peer_pool))
proxy_peer = await client_proxy_peer_pool.ensure_proxy_peer(
client_peer.session)
headers = await proxy_peer.eth_api.get_block_headers(0, 1, 0, False)
assert len(headers) == 1
block_header = headers[0]
assert block_header.block_number == 0
receipts = await proxy_peer.eth_api.get_receipts(headers)
assert len(receipts) == 1
receipt = receipts[0]
assert receipt[1][0] == block_header.receipt_root
block_bundles = await proxy_peer.eth_api.get_block_bodies(headers)
assert len(block_bundles) == 1
first_bundle = block_bundles[0]
assert first_bundle[1][0] == block_header.transaction_root
node_data = await proxy_peer.eth_api.get_node_data(
(block_header.state_root, ))
assert node_data[0][0] == block_header.state_root
async def test_proxy_peer_requests_with_timeouts(request, event_bus,
other_event_bus, event_loop,
client_and_server):
server_event_bus = event_bus
client_event_bus = other_event_bus
client_peer, server_peer = client_and_server
client_peer_pool = MockPeerPoolWithConnectedPeers(
[client_peer], event_bus=client_event_bus)
server_peer_pool = MockPeerPoolWithConnectedPeers(
[server_peer], event_bus=server_event_bus)
async with contextlib.AsyncExitStack() as stack:
await stack.enter_async_context(
run_peer_pool_event_server(client_event_bus,
client_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
run_peer_pool_event_server(server_event_bus,
server_peer_pool,
handler_type=ETHPeerPoolEventServer))
# We just want an ETHRequestServer that doesn't answer us but we still have to run
# *something* to at least subscribe to the events. Otherwise Lahja's safety check will yell
# at us for sending requests into the void.
for event_type in ETHRequestServer(None, None,
None)._subscribed_events:
server_event_bus.subscribe(event_type, lambda _: None)
client_proxy_peer_pool = ETHProxyPeerPool(
client_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(client_proxy_peer_pool))
server_proxy_peer_pool = ETHProxyPeerPool(
server_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(server_proxy_peer_pool))
proxy_peer = await client_proxy_peer_pool.ensure_proxy_peer(
client_peer.session)
with pytest.raises(asyncio.TimeoutError):
await proxy_peer.eth_api.get_block_headers(0,
1,
0,
False,
timeout=0.01)
with pytest.raises(asyncio.TimeoutError):
await proxy_peer.eth_api.get_receipts((), timeout=0.01)
with pytest.raises(asyncio.TimeoutError):
await proxy_peer.eth_api.get_block_bodies((), timeout=0.01)
with pytest.raises(asyncio.TimeoutError):
await proxy_peer.eth_api.get_node_data((), timeout=0.01)
async def test_requests_when_peer_in_client_vanishs(request, event_bus,
other_event_bus,
event_loop, chaindb_20,
client_and_server):
server_event_bus = event_bus
client_event_bus = other_event_bus
client_peer, server_peer = client_and_server
client_peer_pool = MockPeerPoolWithConnectedPeers(
[client_peer], event_bus=client_event_bus)
server_peer_pool = MockPeerPoolWithConnectedPeers(
[server_peer], event_bus=server_event_bus)
async with contextlib.AsyncExitStack() as stack:
await stack.enter_async_context(
run_peer_pool_event_server(client_event_bus,
client_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
run_peer_pool_event_server(server_event_bus,
server_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
background_asyncio_service(
ETHRequestServer(server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
MainnetChain.vm_configuration,
AsyncChainDB(chaindb_20.db))))
client_proxy_peer_pool = ETHProxyPeerPool(
client_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(client_proxy_peer_pool))
server_proxy_peer_pool = ETHProxyPeerPool(
server_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(server_proxy_peer_pool))
proxy_peer = await client_proxy_peer_pool.ensure_proxy_peer(
client_peer.session)
# We remove the peer from the client and assume to see PeerConnectionLost exceptions raised
client_peer_pool.connected_nodes.pop(client_peer.session)
with pytest.raises(PeerConnectionLost):
await proxy_peer.eth_api.get_block_headers(0, 1, 0, False)
with pytest.raises(PeerConnectionLost):
await proxy_peer.eth_api.get_receipts(())
with pytest.raises(PeerConnectionLost):
await proxy_peer.eth_api.get_block_bodies(())
with pytest.raises(PeerConnectionLost):
await proxy_peer.eth_api.get_node_data(())
async def test_queening_queue_recovers_from_penalty_with_one_peer(
event_bus, chaindb_fresh, chaindb_20, has_parallel_peasant_call):
local_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
remote_context = ChainContextFactory(headerdb__db=chaindb_20.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=local_context,
bob_peer_context=remote_context,
event_bus=event_bus,
)
async with peer_pair as (connection_to_local, connection_to_remote):
local_peer_pool = MockPeerPoolWithConnectedPeers(
[connection_to_remote],
event_bus=event_bus,
)
async with run_peer_pool_event_server(
event_bus, local_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_20.db),
)):
queue = QueeningQueue(local_peer_pool)
async with background_asyncio_service(queue):
queen = await asyncio.wait_for(queue.get_queen_peer(),
timeout=0.01)
assert queen == connection_to_remote
queue.penalize_queen(connection_to_remote, delay=0.1)
assert queue.queen is None
with pytest.raises(asyncio.TimeoutError):
# The queen should be penalized for this entire period, and
# there are no alternative peers, so this call should hang:
await asyncio.wait_for(queue.get_queen_peer(),
timeout=0.05)
if has_parallel_peasant_call:
waiting_on_peasant = asyncio.ensure_future(
queue.pop_fastest_peasant())
# But after waiting long enough, even with just one peer, the blocking
# call should return. Whether or not there is also a waiting call looking for
# a peasant.
final_queen = await asyncio.wait_for(queue.get_queen_peer(),
timeout=0.075)
assert final_queen == connection_to_remote
if has_parallel_peasant_call:
waiting_on_peasant.cancel()
with pytest.raises(asyncio.CancelledError):
await waiting_on_peasant
async def test_skeleton_syncer(request, event_loop, chaindb_fresh,
chaindb_1000):
client_peer, server_peer = await get_directly_linked_peers(
request,
event_loop,
alice_headerdb=FakeAsyncHeaderDB(chaindb_fresh.db),
bob_headerdb=FakeAsyncHeaderDB(chaindb_1000.db))
client_peer_pool = MockPeerPoolWithConnectedPeers([client_peer])
client = FastChainSyncer(ByzantiumTestChain(chaindb_fresh.db),
chaindb_fresh, client_peer_pool)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer])
server = RegularChainSyncer(
ByzantiumTestChain(chaindb_1000.db),
chaindb_1000,
server_peer_pool,
)
asyncio.ensure_future(server.run())
server_request_handler = ETHRequestServer(
FakeAsyncChainDB(chaindb_1000.db), server_peer_pool)
asyncio.ensure_future(server_request_handler.run())
client_peer.logger.info("%s is serving 1000 blocks", client_peer)
server_peer.logger.info("%s is syncing up 1000 blocks", server_peer)
def finalizer():
event_loop.run_until_complete(server.cancel())
# Yield control so that server.run() returns, otherwise asyncio will complain.
event_loop.run_until_complete(asyncio.sleep(0.1))
request.addfinalizer(finalizer)
# FastChainSyncer.run() will return as soon as it's caught up with the peer.
await asyncio.wait_for(client.run(), timeout=20)
head = chaindb_fresh.get_canonical_head()
assert head == chaindb_1000.get_canonical_head()
# Now download the state for the chain's head.
state_downloader = StateDownloader(chaindb_fresh, chaindb_fresh.db,
head.state_root, client_peer_pool)
await asyncio.wait_for(state_downloader.run(), timeout=20)
assert head.state_root in chaindb_fresh.db
async def test_header_gap_fill_detects_invalid_attempt(caplog,
event_loop,
event_bus,
chaindb_with_gaps,
chaindb_1000,
chaindb_uncle):
client_context = ChainContextFactory(headerdb__db=chaindb_with_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_uncle.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client = SequentialHeaderChainGapSyncer(
LatestTestChain(chaindb_with_gaps.db),
chaindb_with_gaps,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus)
)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer], event_bus=event_bus)
uncle_chaindb = AsyncChainDB(chaindb_uncle.db)
async with run_peer_pool_event_server(
event_bus, server_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(ETHRequestServer(
event_bus, TO_NETWORKING_BROADCAST_CONFIG, uncle_chaindb,
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
# We check for 499 because 500 exists from the very beginning (the checkpoint)
expected_block_number = 499
async with background_asyncio_service(client):
try:
await wait_for_head(
chaindb_with_gaps,
chaindb_1000.get_canonical_block_header_by_number(expected_block_number),
sync_timeout=5,
)
except asyncio.TimeoutError:
assert "Attempted to fill gap with invalid header" in caplog.text
# Monkey patch the uncle chaindb to effectively make the attacker peer
# switch to the correct chain.
uncle_chaindb.db = chaindb_1000.db
await wait_for_head(
chaindb_with_gaps,
chaindb_1000.get_canonical_block_header_by_number(expected_block_number)
)
else:
raise AssertionError("Succeeded when it was expected to fail")
async def test_regular_syncer(request, event_loop, chaindb_fresh, chaindb_20):
client_peer, server_peer = await get_directly_linked_peers(
request,
event_loop,
alice_headerdb=FakeAsyncHeaderDB(chaindb_fresh.db),
bob_headerdb=FakeAsyncHeaderDB(chaindb_20.db))
client = RegularChainSyncer(FrontierTestChain(chaindb_fresh.db),
chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_peer]))
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer])
server = RegularChainSyncer(
FrontierTestChain(chaindb_20.db),
chaindb_20,
server_peer_pool,
)
asyncio.ensure_future(server.run())
server_request_handler = ETHRequestServer(FakeAsyncChainDB(chaindb_20.db),
server_peer_pool)
asyncio.ensure_future(server_request_handler.run())
server_peer.logger.info("%s is serving 20 blocks", server_peer)
client_peer.logger.info("%s is syncing up 20", client_peer)
def finalizer():
event_loop.run_until_complete(
asyncio.gather(
client.cancel(),
server.cancel(),
loop=event_loop,
))
# Yield control so that client/server.run() returns, otherwise asyncio will complain.
event_loop.run_until_complete(asyncio.sleep(0.1))
request.addfinalizer(finalizer)
asyncio.ensure_future(client.run())
await wait_for_head(client.db, server.db.get_canonical_head())
head = client.db.get_canonical_head()
assert head.state_root in client.db.db
def make_eth1_request_server(self, app_config: Eth1AppConfig,
db_manager: BaseManager) -> BaseService:
if app_config.database_mode is Eth1DbMode.LIGHT:
header_db = db_manager.get_headerdb() # type: ignore
server: BaseService = LightRequestServer(
self.event_bus, TO_NETWORKING_BROADCAST_CONFIG, header_db)
elif app_config.database_mode is Eth1DbMode.FULL:
chain_db = db_manager.get_chaindb() # type: ignore
server = ETHRequestServer(self.event_bus,
TO_NETWORKING_BROADCAST_CONFIG, chain_db)
else:
raise Exception(
f"Unsupported Database Mode: {app_config.database_mode}")
return server
async def test_regular_syncer_fallback(request, event_loop, event_bus,
chaindb_fresh, chaindb_20):
"""
Test the scenario where a header comes in that's not in memory (but is in the DB)
"""
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_20.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client = FallbackTesting_RegularChainSyncer(
ByzantiumTestChain(chaindb_fresh.db), chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus))
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(event_bus, TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_20.db))):
server_peer.logger.info("%s is serving 20 blocks", server_peer)
client_peer.logger.info("%s is syncing up 20", client_peer)
def finalizer():
event_loop.run_until_complete(client.cancel())
# Yield control so that client/server.run() returns, otherwise
# asyncio will complain.
event_loop.run_until_complete(asyncio.sleep(0.1))
request.addfinalizer(finalizer)
asyncio.ensure_future(client.run())
await wait_for_head(chaindb_fresh, chaindb_20.get_canonical_head())
head = chaindb_fresh.get_canonical_head()
assert head.state_root in chaindb_fresh.db
async def test_sequential_header_gapfill_syncer(request,
event_loop,
event_bus,
chaindb_with_gaps,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_with_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
chain_with_gaps = LatestTestChain(chaindb_with_gaps.db)
client = SequentialHeaderChainGapSyncer(
chain_with_gaps,
chaindb_with_gaps,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus)
)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer], event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(ETHRequestServer(
event_bus, TO_NETWORKING_BROADCAST_CONFIG, AsyncChainDB(chaindb_1000.db),
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
async with background_asyncio_service(client):
await wait_for_head(
# We check for 499 because 500 is there from the very beginning (the checkpoint)
chaindb_with_gaps, chaindb_1000.get_canonical_block_header_by_number(499)
)
# This test is supposed to only fill in headers, so the following should fail.
# If this ever succeeds it probably means the fixture was re-created with trivial
# blocks and the test will fail and remind us what kind of fixture we want here.
with pytest.raises(BlockNotFound):
chain_with_gaps.get_canonical_block_by_number(499)
async def test_no_duplicate_node_data(request, event_loop, event_bus,
chaindb_fresh, chaindb_20):
"""
Test that when a peer calls GetNodeData to ETHRequestServer, with duplicate node hashes,
that ETHRequestServer only responds with unique nodes.
Note: A nice extension to the test would be to check that a warning is
raised about sending the duplicate hashes in the first place.
"""
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_20.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_to_server, server_to_client):
server_peer_pool = MockPeerPoolWithConnectedPeers([server_to_client],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
MainnetChain.vm_configuration,
AsyncChainDB(chaindb_20.db),
)):
root_hash = chaindb_20.get_canonical_head().state_root
state_root = chaindb_20.db[root_hash]
returned_nodes = await client_to_server.eth_api.get_node_data(
(root_hash, root_hash))
assert returned_nodes == (
# Server must not send back duplicates, just the single root node
(root_hash, state_root), )
def _make_request_server(self) -> ETHRequestServer:
return ETHRequestServer(
self.chaindb,
self.peer_pool,
token=self.cancel_token,
)
async def test_proxy_peer_requests(request, event_bus, other_event_bus,
event_loop, chaindb_20, client_and_server):
server_event_bus = event_bus
client_event_bus = other_event_bus
client_peer, server_peer = client_and_server
client_peer_pool = MockPeerPoolWithConnectedPeers(
[client_peer], event_bus=client_event_bus)
server_peer_pool = MockPeerPoolWithConnectedPeers(
[server_peer], event_bus=server_event_bus)
async with contextlib.AsyncExitStack() as stack:
await stack.enter_async_context(
run_peer_pool_event_server(client_event_bus,
client_peer_pool,
handler_type=ETHPeerPoolEventServer))
await stack.enter_async_context(
run_peer_pool_event_server(server_event_bus,
server_peer_pool,
handler_type=ETHPeerPoolEventServer))
base_db = chaindb_20.db
await stack.enter_async_context(
background_asyncio_service(
ETHRequestServer(
server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(base_db),
)))
await stack.enter_async_context(
background_asyncio_service(
WitRequestServer(
server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
base_db,
)))
client_proxy_peer_pool = ETHProxyPeerPool(
client_event_bus, TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(client_proxy_peer_pool))
proxy_peer_pool = ETHProxyPeerPool(server_event_bus,
TO_NETWORKING_BROADCAST_CONFIG)
await stack.enter_async_context(
background_asyncio_service(proxy_peer_pool))
proxy_peer = await client_proxy_peer_pool.ensure_proxy_peer(
client_peer.session)
headers = await proxy_peer.eth_api.get_block_headers(0, 1, 0, False)
assert len(headers) == 1
block_header = headers[0]
assert block_header.block_number == 0
receipts = await proxy_peer.eth_api.get_receipts(headers)
assert len(receipts) == 1
receipt = receipts[0]
assert receipt[1][0] == block_header.receipt_root
block_bundles = await proxy_peer.eth_api.get_block_bodies(headers)
assert len(block_bundles) == 1
first_bundle = block_bundles[0]
assert first_bundle[1][0] == block_header.transaction_root
node_data = await proxy_peer.eth_api.get_node_data(
(block_header.state_root, ))
assert node_data[0][0] == block_header.state_root
block_hash = block_header.hash
node_hashes = tuple(Hash32Factory.create_batch(5))
# Populate the server's witness DB so that it can reply to our request.
wit_db = AsyncWitnessDB(base_db)
wit_db.persist_witness_hashes(block_hash, node_hashes)
response = await proxy_peer.wit_api.get_block_witness_hashes(block_hash
)
assert set(response) == set(node_hashes)
async def test_beam_syncer(
request,
event_loop,
event_bus,
chaindb_fresh,
chaindb_churner,
beam_to_block,
checkpoint=None):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_churner.db)
peer_pair = ETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
# Need a name that will be unique per xdist-process, otherwise
# lahja IPC endpoints in each process will clobber each other
unique_process_name = uuid.uuid4()
# manually add endpoint for beam vm to make requests
pausing_config = ConnectionConfig.from_name(f"PausingEndpoint-{unique_process_name}")
# manually add endpoint for trie data gatherer to serve requests
gatherer_config = ConnectionConfig.from_name(f"GathererEndpoint-{unique_process_name}")
client_peer_pool = MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer], event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(ETHRequestServer(
event_bus, TO_NETWORKING_BROADCAST_CONFIG, AsyncChainDB(chaindb_churner.db)
)), AsyncioEndpoint.serve(
pausing_config
) as pausing_endpoint, AsyncioEndpoint.serve(gatherer_config) as gatherer_endpoint:
client_chain = make_pausing_beam_chain(
((0, PetersburgVM), ),
chain_id=999,
db=chaindb_fresh.db,
event_bus=pausing_endpoint,
loop=event_loop,
)
client = BeamSyncer(
client_chain,
chaindb_fresh.db,
AsyncChainDB(chaindb_fresh.db),
client_peer_pool,
gatherer_endpoint,
force_beam_block_number=beam_to_block,
checkpoint=checkpoint,
)
client_peer.logger.info("%s is serving churner blocks", client_peer)
server_peer.logger.info("%s is syncing up churner blocks", server_peer)
import_server = BlockImportServer(
pausing_endpoint,
client_chain,
token=client.cancel_token,
)
asyncio.ensure_future(import_server.run())
await pausing_endpoint.connect_to_endpoints(gatherer_config)
asyncio.ensure_future(client.run())
# We can sync at least 10 blocks in 1s at current speeds, (or reach the current one)
# Trying to keep the tests short-ish. A fuller test could always set the target header
# to the chaindb_churner canonical head, and increase the timeout significantly
target_block_number = min(beam_to_block + 10, 129)
target_head = chaindb_churner.get_canonical_block_header_by_number(target_block_number)
await wait_for_head(chaindb_fresh, target_head, sync_timeout=10)
assert target_head.state_root in chaindb_fresh.db
# first stop the import server, so it doesn't hang waiting for state data
await import_server.cancel()
await client.cancel()
async def test_header_syncer(request,
event_loop,
event_bus,
chaindb_fresh,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client = HeaderChainSyncer(
LatestTestChain(chaindb_fresh.db),
chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus)
)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer], event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool, handler_type=ETHPeerPoolEventServer
), background_asyncio_service(ETHRequestServer(
event_bus, TO_NETWORKING_BROADCAST_CONFIG, AsyncChainDB(chaindb_1000.db),
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
# Artificially split header sync into two parts, to verify that
# cycling to the next sync works properly. Split by erasing the canonical
# lookups in a middle chunk. We have to erase a range of them because of
# how the skeleton syncer asks for every ~192 headers. The skeleton request
# would skip right over a single missing header.
erase_block_numbers = range(500, 700)
erased_canonicals = []
for blocknum in erase_block_numbers:
dbkey = SchemaV1.make_block_number_to_hash_lookup_key(blocknum)
canonical_hash = chaindb_1000.db[dbkey]
erased_canonicals.append((dbkey, canonical_hash))
del chaindb_1000.db[dbkey]
async with background_asyncio_service(client):
target_head = chaindb_1000.get_canonical_block_header_by_number(
erase_block_numbers[0] - 1
)
await wait_for_head(chaindb_fresh, target_head)
# gut check that we didn't skip past the erased range of blocks
head = chaindb_fresh.get_canonical_head()
assert head.block_number < erase_block_numbers[0]
# TODO validate that the skeleton syncer has cycled??
# Replace the missing headers so that syncing can resume
for dbkey, canonical_hash in erased_canonicals:
chaindb_1000.db[dbkey] = canonical_hash
# Do we have to do anything here to have the server notify the client
# that it's capable of serving more headers now? ... Apparently not.
await wait_for_head(chaindb_fresh, chaindb_1000.get_canonical_head())
async def test_header_gap_fill_detects_invalid_attempt(caplog, event_loop,
event_bus,
chaindb_with_gaps,
chaindb_1000,
chaindb_uncle):
client_context = ChainContextFactory(headerdb__db=chaindb_with_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_uncle.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
client_peer_pool = MockPeerPoolWithConnectedPeers([client_peer],
event_bus=event_bus)
client = SequentialHeaderChainGapSyncer(
LatestTestChain(chaindb_with_gaps.db), chaindb_with_gaps,
client_peer_pool)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
uncle_chaindb = AsyncChainDB(chaindb_uncle.db)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
uncle_chaindb,
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
# We check for 499 because 500 exists from the very beginning (the checkpoint)
expected_block_number = 499
final_header = chaindb_1000.get_canonical_block_header_by_number(
expected_block_number)
async with background_asyncio_service(client):
try:
await wait_for_head(
chaindb_with_gaps,
final_header,
sync_timeout=5,
)
except asyncio.TimeoutError:
assert "Attempted to fill gap with invalid header" in caplog.text
# Monkey patch the uncle chaindb to effectively make the attacker peer
# switch to the correct chain.
uncle_chaindb.db = chaindb_1000.db
# The hack goes on: Now that our attacker peer turned friendly we may be stuck
# waiting for a new skeleton peer forever. This isn't a real life scenario
# because: a.) an attacker probably won't turn friendly and b.) new blocks and
# peers will constantly yield new skeleton peers.
# This ugly hack will tick the chain tip monitor as we simulate a joining peer.
for subscriber in client_peer_pool._subscribers:
subscriber.register_peer(client_peer)
await wait_for_head(
chaindb_with_gaps,
final_header,
sync_timeout=20,
)
else:
raise AssertionError(
"Succeeded when it was expected to fail")
async def test_sequential_header_gapfill_syncer(request, event_loop, event_bus,
chaindb_with_gaps,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_with_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
chain_with_gaps = LatestTestChain(chaindb_with_gaps.db)
client = SequentialHeaderChainGapSyncer(
chain_with_gaps, chaindb_with_gaps,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus))
# Ensure we use small chunks to be able to test pause/resume properly
client._max_backfill_header_at_once = 100
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_1000.db),
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
async with background_asyncio_service(client):
# We intentionally only sync up to a block *below* the first gap to have a more
# difficult scenario for pause/resume. We want to make sure we not only can pause
# at the times where we synced up to an actual gap. Instead we want to be sure
# we can pause after we synced up to the `_max_backfill_header_at_once` limit which
# may be shorter than the actual gap in the chain.
await wait_for_head(
chaindb_with_gaps,
chaindb_1000.get_canonical_block_header_by_number(100))
# Pause the syncer for a moment and check if it continued syncing (it should not!)
client.pause()
# Verify that we stopped the chain fast enough, before the gap was fully filled
# This is a potential source of test flakiness
with pytest.raises(HeaderNotFound):
chaindb_with_gaps.get_canonical_block_header_by_number(249)
await asyncio.sleep(1)
# Make sure that the gap filling doesn't complete for a while. We could
# theoretically get false positives if it's not paused but very slow to fill headers
with pytest.raises(HeaderNotFound):
chaindb_with_gaps.get_canonical_block_header_by_number(249)
# Now resume syncing
client.resume()
await wait_for_head(
# We check for 499 because 500 is there from the very beginning (the checkpoint)
chaindb_with_gaps,
chaindb_1000.get_canonical_block_header_by_number(499))
# This test is supposed to only fill in headers, so the following should fail.
# If this ever succeeds it probably means the fixture was re-created with trivial
# blocks and the test will fail and remind us what kind of fixture we want here.
with pytest.raises(BlockNotFound):
chain_with_gaps.get_canonical_block_by_number(499)
async def test_block_gapfill_syncer(request, event_loop, event_bus,
chaindb_with_block_gaps, chaindb_1000):
client_context = ChainContextFactory(
headerdb__db=chaindb_with_block_gaps.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer, server_peer):
syncer = BodyChainGapSyncer(
LatestTestChain(chaindb_with_block_gaps.db),
chaindb_with_block_gaps,
MockPeerPoolWithConnectedPeers([client_peer], event_bus=event_bus),
)
# In production, this would be the block time but we want our test to pause/resume swiftly
syncer._idle_time = 0.01
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_1000.db),
)):
server_peer.logger.info("%s is serving 1000 blocks", server_peer)
client_peer.logger.info("%s is syncing up 1000", client_peer)
async with background_asyncio_service(syncer):
chain_with_gaps = LatestTestChain(chaindb_with_block_gaps.db)
fat_chain = LatestTestChain(chaindb_1000.db)
# Ensure we can pause/resume immediately and not just after syncing has started
syncer.pause()
syncer.resume()
# Sync the first 100 blocks, then check that pausing/resume works
await wait_for_block(
chain_with_gaps,
fat_chain.get_canonical_block_by_number(100))
# Pause the syncer and take note how far we have synced at this point
syncer.pause()
# We need to give async code a moment to settle before we save the progress to
# ensure it has stabilized before we save it.
await asyncio.sleep(0.25)
paused_chain_gaps = chain_with_gaps.chaindb.get_chain_gaps()
# Consider it victory if after 0.5s no new blocks were written to the database
await asyncio.sleep(0.5)
assert paused_chain_gaps == chain_with_gaps.chaindb.get_chain_gaps(
)
# Resume syncing
syncer.resume()
await wait_for_block(
chain_with_gaps,
fat_chain.get_canonical_block_by_number(1000),
sync_timeout=20)
for block_num in range(1, 1001):
assert chain_with_gaps.get_canonical_block_by_number(
block_num) == fat_chain.get_canonical_block_by_number(
block_num)
# We need to give the async calls a moment to settle before we can read the updated
# chain gaps.
await asyncio.sleep(0.25)
assert chain_with_gaps.chaindb.get_chain_gaps() == ((), 1001)
async def test_header_syncer(request, event_loop, event_bus, chaindb_fresh,
chaindb_1000):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_1000.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_to_server, server_to_client):
client = HeaderChainSyncer(
LatestTestChain(chaindb_fresh.db), chaindb_fresh,
MockPeerPoolWithConnectedPeers([client_to_server],
event_bus=event_bus))
server_peer_pool = MockPeerPoolWithConnectedPeers([server_to_client],
event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(
event_bus,
TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_1000.db),
)):
server_to_client.logger.info("%s is serving 1000 blocks",
server_to_client)
client_to_server.logger.info("%s is syncing up 1000",
client_to_server)
# Artificially split header sync into two parts, to verify that
# cycling to the next sync works properly. Split by erasing the canonical
# lookups in a middle chunk. We have to erase a range of them because of
# how the skeleton syncer asks for every ~192 headers. The skeleton request
# would skip right over a single missing header.
erase_block_numbers = range(500, 700)
erased_canonicals = []
for blocknum in erase_block_numbers:
dbkey = SchemaV1.make_block_number_to_hash_lookup_key(blocknum)
canonical_hash = chaindb_1000.db[dbkey]
erased_canonicals.append((dbkey, canonical_hash))
del chaindb_1000.db[dbkey]
async with background_asyncio_service(client):
target_head = chaindb_1000.get_canonical_block_header_by_number(
erase_block_numbers[0] - 1)
await wait_for_head(chaindb_fresh, target_head)
# gut check that we didn't skip past the erased range of blocks
head = chaindb_fresh.get_canonical_head()
assert head.block_number < erase_block_numbers[0]
# TODO validate that the skeleton syncer has cycled??
# Replace the missing headers so that syncing can resume
for dbkey, canonical_hash in erased_canonicals:
chaindb_1000.db[dbkey] = canonical_hash
complete_chain_tip = chaindb_1000.get_canonical_head()
# Not entirely certain that sending new block hashes is necessary, but...
# it shouldn't hurt anything. Trying to fix this flaky test:
# https://app.circleci.com/pipelines/github/ethereum/trinity/6855/workflows/131f9b03-8c99-4419-8e88-d2ef216e3dbb/jobs/259263/steps # noqa: E501
server_to_client.eth_api.send_new_block_hashes(
NewBlockHash(complete_chain_tip.hash,
complete_chain_tip.block_number), )
await wait_for_head(chaindb_fresh, complete_chain_tip)
async def _beam_syncing(
request,
event_loop,
event_bus,
chaindb_fresh,
chaindb_churner,
beam_to_block,
checkpoint=None,
VM_at_0=PetersburgVM,
enable_state_backfill=False,
):
client_context = ChainContextFactory(headerdb__db=chaindb_fresh.db)
server_context = ChainContextFactory(headerdb__db=chaindb_churner.db)
peer_pair = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
backfiller = LatestETHPeerPairFactory(
alice_peer_context=client_context,
bob_peer_context=server_context,
event_bus=event_bus,
)
async with peer_pair as (client_peer,
server_peer), backfiller as (client2_peer,
backfill_peer):
# Need a name that will be unique per xdist-process, otherwise
# lahja IPC endpoints in each process will clobber each other
unique_process_name = uuid.uuid4()
# manually add endpoint for beam vm to make requests
pausing_config = ConnectionConfig.from_name(
f"PausingEndpoint-{unique_process_name}")
# manually add endpoint for trie data gatherer to serve requests
gatherer_config = ConnectionConfig.from_name(
f"GathererEndpoint-{unique_process_name}")
client_peer_pool = MockPeerPoolWithConnectedPeers(
[client_peer, backfill_peer],
event_bus=event_bus,
)
server_peer_pool = MockPeerPoolWithConnectedPeers([server_peer],
event_bus=event_bus)
backfill_peer_pool = MockPeerPoolWithConnectedPeers(
[client2_peer], event_bus=event_bus)
async with run_peer_pool_event_server(
event_bus, server_peer_pool,
handler_type=ETHPeerPoolEventServer
), run_peer_pool_event_server(
event_bus, backfill_peer_pool,
handler_type=ETHPeerPoolEventServer
), background_asyncio_service(
ETHRequestServer(event_bus, TO_NETWORKING_BROADCAST_CONFIG,
AsyncChainDB(chaindb_churner.db))
), AsyncioEndpoint.serve(
pausing_config) as pausing_endpoint, AsyncioEndpoint.serve(
gatherer_config) as gatherer_endpoint:
client_chain = make_pausing_beam_chain(
((0, VM_at_0), ),
chain_id=999,
consensus_context_class=ConsensusContext,
db=chaindb_fresh.db,
event_bus=pausing_endpoint,
metrics_registry=NoopMetricsRegistry(),
loop=event_loop,
)
client = BeamSyncer(
client_chain,
chaindb_fresh.db,
AsyncChainDB(chaindb_fresh.db),
client_peer_pool,
gatherer_endpoint,
NoopMetricsRegistry(),
force_beam_block_number=beam_to_block,
checkpoint=checkpoint,
enable_state_backfill=enable_state_backfill,
enable_backfill=False,
)
client_peer.logger.info("%s is serving churner blocks",
client_peer)
backfill_peer.logger.info("%s is serving backfill state",
backfill_peer)
server_peer.logger.info("%s is syncing up churner blocks",
server_peer)
import_server = BlockImportServer(
pausing_endpoint,
client_chain,
)
async with background_asyncio_service(import_server):
await pausing_endpoint.connect_to_endpoints(gatherer_config)
async with background_asyncio_service(client):
yield client
