def test_get_expired():
d = LocalStorage()
d.store(DHTID.generate("key"), b"val", get_dht_time() + 0.1)
time.sleep(0.5)
assert d.get(
DHTID.generate("key")) == (None, None), "Expired value must be deleted"
print("Test get expired passed")
def test_maxsize_cache():
d = LocalStorage(maxsize=1)
d.store(DHTID.generate("key1"), b"val1", get_dht_time() + 1)
d.store(DHTID.generate("key2"), b"val2", get_dht_time() + 200)
assert d.get(DHTID.generate(
"key2"))[0] == b"val2", "Value with bigger exp. time must be kept"
assert d.get(DHTID.generate(
"key1"))[0] is None, "Value with less exp time, must be deleted"
def test_change_expiration_time():
d = LocalStorage()
d.store(DHTID.generate("key"), b"val1", get_dht_time() + 1)
assert d.get(DHTID.generate("key"))[0] == b"val1", "Wrong value"
d.store(DHTID.generate("key"), b"val2", get_dht_time() + 200)
time.sleep(1)
assert d.get(DHTID.generate(
"key"))[0] == b"val2", "Value must be changed, but still kept in table"
print("Test change expiration time passed")
async def simple_traverse_dht(query_id: DHTID, initial_nodes: Collection[DHTID], beam_size: int,
get_neighbors: Callable[[DHTID], Awaitable[Tuple[Collection[DHTID], bool]]],
visited_nodes: Collection[DHTID] = ()) -> Tuple[List[DHTID], Set[DHTID]]:
"""
Traverse the DHT graph using get_neighbors function, find :beam_size: nearest nodes according to DHTID.xor_distance.
:note: This is a simplified (but working) algorithm provided for documentation purposes. Actual DHTNode uses
`traverse_dht` - a generalization of this this algorithm that allows multiple queries and concurrent workers.
:param query_id: search query, find k_nearest neighbors of this DHTID
:param initial_nodes: nodes used to pre-populate beam search heap, e.g. [my_own_DHTID, ...maybe_some_peers]
:param beam_size: beam search will not give up until it exhausts this many nearest nodes (to query_id) from the heap
Recommended value: A beam size of k_nearest * (2-5) will yield near-perfect results.
:param get_neighbors: A function that returns neighbors of a given node and controls beam search stopping criteria.
async def get_neighbors(node: DHTID) -> neighbors_of_that_node: List[DHTID], should_continue: bool
If should_continue is False, beam search will halt and return k_nearest of whatever it found by then.
:param visited_nodes: beam search will neither call get_neighbors on these nodes, nor return them as nearest
:returns: a list of k nearest nodes (nearest to farthest), and a set of all visited nodes (including visited_nodes)
"""
visited_nodes = set(visited_nodes) # note: copy visited_nodes because we will add more nodes to this collection.
initial_nodes = [node_id for node_id in initial_nodes if node_id not in visited_nodes]
if not initial_nodes:
return [], visited_nodes
unvisited_nodes = [(distance, uid) for uid, distance in zip(initial_nodes, query_id.xor_distance(initial_nodes))]
heapq.heapify(unvisited_nodes) # nearest-first heap of candidates, unlimited size
nearest_nodes = [(-distance, node_id) for distance, node_id in heapq.nsmallest(beam_size, unvisited_nodes)]
heapq.heapify(nearest_nodes) # farthest-first heap of size beam_size, used for early-stopping and to select results
while len(nearest_nodes) > beam_size:
heapq.heappop(nearest_nodes)
visited_nodes |= set(initial_nodes)
upper_bound = -nearest_nodes[0][0] # distance to farthest element that is still in beam
was_interrupted = False # will set to True if host triggered beam search to stop via get_neighbors
while (not was_interrupted) and len(unvisited_nodes) != 0 and unvisited_nodes[0][0] <= upper_bound:
_, node_id = heapq.heappop(unvisited_nodes) # note: this --^ is the smallest element in heap (see heapq)
neighbors, was_interrupted = await get_neighbors(node_id)
neighbors = [node_id for node_id in neighbors if node_id not in visited_nodes]
visited_nodes.update(neighbors)
for neighbor_id, distance in zip(neighbors, query_id.xor_distance(neighbors)):
if distance <= upper_bound or len(nearest_nodes) < beam_size:
heapq.heappush(unvisited_nodes, (distance, neighbor_id))
heapq_add_or_replace = heapq.heappush if len(nearest_nodes) < beam_size else heapq.heappushpop
heapq_add_or_replace(nearest_nodes, (-distance, neighbor_id))
upper_bound = -nearest_nodes[0][0] # distance to beam_size-th nearest element found so far
return [node_id for _, node_id in heapq.nlargest(beam_size, nearest_nodes)], visited_nodes
def test_routing_table_search():
for table_size, lower_active, upper_active in [(10, 10, 10),
(10_000, 800, 1100)]:
node_id = DHTID.generate()
routing_table = RoutingTable(node_id, bucket_size=20, depth_modulo=5)
num_added = 0
total_nodes = 0
for phony_neighbor_port in random.sample(range(1_000_000), table_size):
routing_table.add_or_update_node(
DHTID.generate(), f'{LOCALHOST}:{phony_neighbor_port}')
new_total = sum(
len(bucket.nodes_to_endpoint)
for bucket in routing_table.buckets)
num_added += new_total > total_nodes
total_nodes = new_total
def test_empty_table():
""" Test RPC methods with empty routing table """
peer_port, peer_id, peer_started = find_open_port(), DHTID.generate(
), mp.Event()
peer_proc = mp.Process(target=run_protocol_listener,
args=(peer_port, peer_id, peer_started),
daemon=True)
peer_proc.start(), peer_started.wait()
test_success = mp.Event()
def _tester():
# note: we run everything in a separate process to re-initialize all global states from scratch
# this helps us avoid undesirable side-effects when running multiple tests in sequence
loop = asyncio.get_event_loop()
protocol = loop.run_until_complete(
DHTProtocol.create(DHTID.generate(),
bucket_size=20,
depth_modulo=5,
wait_timeout=5,
num_replicas=3,
listen=False))
key, value, expiration = DHTID.generate(), [
random.random(), {
'ololo': 'pyshpysh'
}
], get_dht_time() + 1e3
recv_value_bytes, recv_expiration, nodes_found = loop.run_until_complete(
protocol.call_find(f'{LOCALHOST}:{peer_port}', [key]))[key]
assert recv_value_bytes is None and recv_expiration is None and len(
nodes_found) == 0
assert all(
loop.run_until_complete(
protocol.call_store(f'{LOCALHOST}:{peer_port}', [key],
[MSGPackSerializer.dumps(value)],
expiration))), "peer rejected store"
recv_value_bytes, recv_expiration, nodes_found = loop.run_until_complete(
protocol.call_find(f'{LOCALHOST}:{peer_port}', [key]))[key]
recv_value = MSGPackSerializer.loads(recv_value_bytes)
assert len(nodes_found) == 0
assert recv_value == value and recv_expiration == expiration, "call_find_value expected " \
f"{value} (expires by {expiration}) but got {recv_value} (expires by {recv_expiration})"
assert loop.run_until_complete(
protocol.call_ping(f'{LOCALHOST}:{peer_port}')) == peer_id
assert loop.run_until_complete(
protocol.call_ping(f'{LOCALHOST}:{find_open_port()}')) is None
test_success.set()
tester = mp.Process(target=_tester, daemon=True)
tester.start()
tester.join()
assert test_success.is_set()
peer_proc.terminate()
async def call_store(
self,
peer: Endpoint,
keys: Sequence[DHTID],
values: Sequence[BinaryDHTValue],
expiration_time: Union[DHTExpiration, Sequence[DHTExpiration]],
in_cache: Optional[Union[bool,
Sequence[bool]]] = None) -> Sequence[bool]:
"""
Ask a recipient to store several (key, value : expiration_time) items or update their older value
:param peer: request this peer to store the data
:param keys: a list of N keys digested by DHTID.generate(source=some_dict_key)
:param values: a list of N serialized values (bytes) for each respective key
:param expiration_time: a list of N expiration timestamps for each respective key-value pair (see get_dht_time())
:param in_cache: a list of booleans, True = store i-th key in cache, value = store i-th key locally
:note: the difference between storing normally and in cache is that normal storage is guaranteed to be stored
until expiration time (best-effort), whereas cached storage can be evicted early due to limited cache size
:return: list of [True / False] True = stored, False = failed (found newer value or no response)
if peer did not respond (e.g. due to timeout or congestion), returns None
"""
if isinstance(expiration_time, DHTExpiration):
expiration_time = [expiration_time] * len(keys)
in_cache = in_cache if in_cache is not None else [False] * len(
keys) # default value (None)
in_cache = [in_cache] * len(keys) if isinstance(
in_cache, bool) else in_cache # single bool
keys, values, expiration_time, in_cache = map(
list, [keys, values, expiration_time, in_cache])
assert len(keys) == len(values) == len(expiration_time) == len(
in_cache), "Data is not aligned"
store_request = dht_pb2.StoreRequest(keys=list(
map(DHTID.to_bytes, keys)),
values=values,
expiration_time=expiration_time,
in_cache=in_cache,
peer=self.node_info)
try:
async with self.rpc_semaphore:
response = await self._get(peer).rpc_store(
store_request, timeout=self.wait_timeout)
if response.peer and response.peer.node_id:
peer_id = DHTID.from_bytes(response.peer.node_id)
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=True))
return response.store_ok
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to store at {peer}: {error.code()}")
asyncio.create_task(
self.update_routing_table(
self.routing_table.get(endpoint=peer),
peer,
responded=False))
return [False] * len(keys)
async def rpc_ping(self, peer_info: dht_pb2.NodeInfo,
context: grpc.ServicerContext):
""" Some node wants us to add it to our routing table. """
if peer_info.node_id and peer_info.rpc_port:
sender_id = DHTID.from_bytes(peer_info.node_id)
rpc_endpoint = replace_port(context.peer(),
new_port=peer_info.rpc_port)
asyncio.create_task(
self.update_routing_table(sender_id, rpc_endpoint))
return self.node_info
def test_routing_table_parameters():
for (bucket_size, modulo, min_nbuckets, max_nbuckets) in [
(20, 5, 45, 65),
(50, 5, 35, 45),
(20, 10, 650, 800),
(20, 1, 7, 15),
]:
node_id = DHTID.generate()
routing_table = RoutingTable(node_id,
bucket_size=bucket_size,
depth_modulo=modulo)
for phony_neighbor_port in random.sample(range(1_000_000), 10_000):
routing_table.add_or_update_node(
DHTID.generate(), f'{LOCALHOST}:{phony_neighbor_port}')
for bucket in routing_table.buckets:
assert len(bucket.replacement_nodes) == 0 or len(
bucket.nodes_to_endpoint) <= bucket.size
assert min_nbuckets <= len(routing_table.buckets) <= max_nbuckets, (
f"Unexpected number of buckets: {min_nbuckets} <= {len(routing_table.buckets)} <= {max_nbuckets}"
)
async def create(cls,
node_id: DHTID,
bucket_size: int,
depth_modulo: int,
num_replicas: int,
wait_timeout: float,
parallel_rpc: Optional[int] = None,
cache_size: Optional[int] = None,
listen=True,
listen_on='0.0.0.0:*',
channel_options: Optional[Sequence[Tuple[str,
Any]]] = None,
**kwargs) -> DHTProtocol:
"""
A protocol that allows DHT nodes to request keys/neighbors from other DHT nodes.
As a side-effect, DHTProtocol also maintains a routing table as described in
https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf
See DHTNode (node.py) for a more detailed description.
:note: the rpc_* methods defined in this class will be automatically exposed to other DHT nodes,
for instance, def rpc_ping can be called as protocol.call_ping(endpoint, dht_id) from a remote machine
Only the call_* methods are meant to be called publicly, e.g. from DHTNode
Read more: https://github.com/bmuller/rpcudp/tree/master/rpcudp
"""
self = cls(_initialized_with_create=True)
self.node_id, self.bucket_size, self.num_replicas = node_id, bucket_size, num_replicas
self.wait_timeout, self.channel_options = wait_timeout, channel_options
self.storage, self.cache = LocalStorage(), LocalStorage(
maxsize=cache_size)
self.routing_table = RoutingTable(node_id, bucket_size, depth_modulo)
self.rpc_semaphore = asyncio.Semaphore(
parallel_rpc if parallel_rpc is not None else float('inf'))
if listen: # set up server to process incoming rpc requests
grpc.experimental.aio.init_grpc_aio()
self.server = grpc.experimental.aio.server(**kwargs)
dht_grpc.add_DHTServicer_to_server(self, self.server)
found_port = self.server.add_insecure_port(listen_on)
assert found_port != 0, f"Failed to listen to {listen_on}"
self.node_info = dht_pb2.NodeInfo(node_id=node_id.to_bytes(),
rpc_port=found_port)
self.port = found_port
await self.server.start()
else: # not listening to incoming requests, client-only mode
# note: use empty node_info so peers wont add you to their routing tables
self.node_info, self.server, self.port = dht_pb2.NodeInfo(
), None, None
if listen_on != '0.0.0.0:*' or len(kwargs) != 0:
warn(
f"DHTProtocol has no server (due to listen=False), listen_on"
f"and kwargs have no effect (unused kwargs: {kwargs})")
return self
def test_ids_depth():
for i in range(100):
ids = [random.randint(0, 4096) for i in range(random.randint(1, 256))]
ours = DHTID.longest_common_prefix_length(*map(DHTID, ids))
ids_bitstr = [
"".join(
bin(bite)[2:].rjust(8, '0')
for bite in uid.to_bytes(20, 'big')) for uid in ids
]
reference = len(shared_prefix(*ids_bitstr))
assert reference == ours, f"ours {ours} != reference {reference}, ids: {ids}"
def test_routing_table_basic():
node_id = DHTID.generate()
routing_table = RoutingTable(node_id, bucket_size=20, depth_modulo=5)
added_nodes = []
for phony_neighbor_port in random.sample(range(10000), 100):
phony_id = DHTID.generate()
routing_table.add_or_update_node(phony_id,
f'{LOCALHOST}:{phony_neighbor_port}')
assert phony_id in routing_table
assert f'{LOCALHOST}:{phony_neighbor_port}' in routing_table
assert routing_table[phony_id] == f'{LOCALHOST}:{phony_neighbor_port}'
assert routing_table[f'{LOCALHOST}:{phony_neighbor_port}'] == phony_id
added_nodes.append(phony_id)
assert routing_table.buckets[
0].lower == DHTID.MIN and routing_table.buckets[-1].upper == DHTID.MAX
for bucket in routing_table.buckets:
assert len(
bucket.replacement_nodes
) == 0, "There should be no replacement nodes in a table with 100 entries"
assert 3 <= len(routing_table.buckets) <= 10, len(routing_table.buckets)
random_node = random.choice(added_nodes)
assert routing_table.get(node_id=random_node) == routing_table[random_node]
dummy_node = DHTID.generate()
assert (dummy_node
not in routing_table) == (routing_table.get(node_id=dummy_node) is
None)
for node in added_nodes:
found_bucket_index = routing_table.get_bucket_index(node)
for bucket_index, bucket in enumerate(routing_table.buckets):
if bucket.lower <= node < bucket.upper:
break
else:
raise ValueError(
"Naive search could not find bucket. Universe has gone crazy.")
assert bucket_index == found_bucket_index
def test_ids_basic():
# basic functionality tests
for i in range(100):
id1, id2 = DHTID.generate(), DHTID.generate()
assert DHTID.MIN <= id1 < DHTID.MAX and DHTID.MIN <= id2 <= DHTID.MAX
assert DHTID.xor_distance(id1, id1) == DHTID.xor_distance(id2,
id2) == 0
assert DHTID.xor_distance(id1, id2) > 0 or (id1 == id2)
assert len(PickleSerializer.dumps(id1)) - len(
PickleSerializer.dumps(int(id1))) < 40
assert DHTID.from_bytes(bytes(id1)) == id1 and DHTID.from_bytes(
id2.to_bytes()) == id2
async def _refresh_routing_table(self, *, period: Optional[float]) -> None:
""" Tries to find new nodes for buckets that were unused for more than self.staleness_timeout """
while period is not None: # if None run once, otherwise run forever
refresh_time = get_dht_time()
staleness_threshold = refresh_time - period
stale_buckets = [
bucket for bucket in self.protocol.routing_table.buckets
if bucket.last_updated < staleness_threshold
]
for bucket in stale_buckets:
refresh_id = DHTID(
random.randint(bucket.lower, bucket.upper - 1))
await self.find_nearest_nodes(refresh_id)
await asyncio.sleep(
max(0.0, period - (get_dht_time() - refresh_time)))
async def rpc_store(
self, request: dht_pb2.StoreRequest,
context: grpc.ServicerContext) -> dht_pb2.StoreResponse:
""" Some node wants us to store this (key, value) pair """
if request.peer: # if requested, add peer to the routing table
asyncio.create_task(self.rpc_ping(request.peer, context))
assert len(request.keys) == len(request.values) == len(
request.expiration_time) == len(request.in_cache)
response = dht_pb2.StoreResponse(store_ok=[], peer=self.node_info)
for key_bytes, value_bytes, expiration_time, in_cache in zip(
request.keys, request.values, request.expiration_time,
request.in_cache):
local_memory = self.cache if in_cache else self.storage
response.store_ok.append(
local_memory.store(DHTID.from_bytes(key_bytes), value_bytes,
expiration_time))
return response
async def call_find(self, peer: Endpoint, keys: Collection[DHTID]) -> \
Optional[Dict[DHTID, Tuple[Optional[BinaryDHTValue], Optional[DHTExpiration], Dict[DHTID, Endpoint]]]]:
"""
Request keys from a peer. For each key, look for its (value, expiration time) locally and
k additional peers that are most likely to have this key (ranked by XOR distance)
:returns: A dict key => Tuple[optional value, optional expiration time, nearest neighbors]
value: value stored by the recipient with that key, or None if peer doesn't have this value
expiration time: expiration time of the returned value, None if no value was found
neighbors: a dictionary[node_id : endpoint] containing nearest neighbors from peer's routing table
If peer didn't respond, returns None
"""
keys = list(keys)
find_request = dht_pb2.FindRequest(keys=list(map(DHTID.to_bytes,
keys)),
peer=self.node_info)
try:
async with self.rpc_semaphore:
response = await self._get(peer).rpc_find(
find_request, timeout=self.wait_timeout)
if response.peer and response.peer.node_id:
peer_id = DHTID.from_bytes(response.peer.node_id)
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=True))
assert len(response.values) == len(response.expiration_time) == len(response.nearest) == len(keys), \
"DHTProtocol: response is not aligned with keys and/or expiration times"
output = {} # unpack data without special NOT_FOUND_* values
for key, value, expiration_time, nearest in zip(
keys, response.values, response.expiration_time,
response.nearest):
value = value if value != _NOT_FOUND_VALUE else None
expiration_time = expiration_time if expiration_time != _NOT_FOUND_EXPIRATION else None
nearest = dict(
zip(map(DHTID.from_bytes, nearest.node_ids),
nearest.endpoints))
output[key] = (value, expiration_time, nearest)
return output
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to find at {peer}: {error.code()}")
asyncio.create_task(
self.update_routing_table(
self.routing_table.get(endpoint=peer),
peer,
responded=False))
async def call_ping(self, peer: Endpoint) -> Optional[DHTID]:
"""
Get peer's node id and add him to the routing table. If peer doesn't respond, return None
:param peer: string network address, e.g. 123.123.123.123:1337 or [2a21:6с8:b192:2105]:8888
:note: if DHTProtocol was created with listen=True, also request peer to add you to his routing table
:return: node's DHTID, if peer responded and decided to send his node_id
"""
try:
async with self.rpc_semaphore:
peer_info = await self._get(peer).rpc_ping(
self.node_info, timeout=self.wait_timeout)
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to ping {peer}: {error.code()}")
peer_info = None
responded = bool(peer_info and peer_info.node_id)
peer_id = DHTID.from_bytes(peer_info.node_id) if responded else None
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=responded))
return peer_id
async def rpc_find(self, request: dht_pb2.FindRequest,
context: grpc.ServicerContext) -> dht_pb2.FindResponse:
"""
Someone wants to find keys in the DHT. For all keys that we have locally, return value and expiration
Also return :bucket_size: nearest neighbors from our routing table for each key (whether or not we found value)
"""
if request.peer: # if requested, add peer to the routing table
asyncio.create_task(self.rpc_ping(request.peer, context))
response = dht_pb2.FindResponse(values=[],
expiration_time=[],
nearest=[],
peer=self.node_info)
for key_id in map(DHTID.from_bytes, request.keys):
maybe_value, maybe_expiration_time = self.storage.get(key_id)
cached_value, cached_expiration_time = self.cache.get(key_id)
if (cached_expiration_time or
-float('inf')) > (maybe_expiration_time or -float('inf')):
maybe_value, maybe_expiration_time = cached_value, cached_expiration_time
nearest_neighbors = self.routing_table.get_nearest_neighbors(
key_id,
k=self.bucket_size,
exclude=DHTID.from_bytes(request.peer.node_id))
if nearest_neighbors:
peer_ids, endpoints = zip(*nearest_neighbors)
else:
peer_ids, endpoints = [], []
response.values.append(
maybe_value if maybe_value is not None else _NOT_FOUND_VALUE)
response.expiration_time.append(
maybe_expiration_time
if maybe_expiration_time else _NOT_FOUND_EXPIRATION)
response.nearest.append(
dht_pb2.Peers(node_ids=list(map(DHTID.to_bytes, peer_ids)),
endpoints=endpoints))
return response
def _tester():
# note: we run everything in a separate process to re-initialize all global states from scratch
# this helps us avoid undesirable side-effects when running multiple tests in sequence
loop = asyncio.get_event_loop()
for listen in [
False, True
]: # note: order matters, this test assumes that first run uses listen=False
protocol = loop.run_until_complete(
DHTProtocol.create(DHTID.generate(),
bucket_size=20,
depth_modulo=5,
wait_timeout=5,
num_replicas=3,
listen=listen))
print(f"Self id={protocol.node_id}", flush=True)
assert loop.run_until_complete(
protocol.call_ping(f'{LOCALHOST}:{peer1_port}')) == peer1_id
key, value, expiration = DHTID.generate(), [
random.random(), {
'ololo': 'pyshpysh'
}
], get_dht_time() + 1e3
store_ok = loop.run_until_complete(
protocol.call_store(f'{LOCALHOST}:{peer1_port}', [key],
[MSGPackSerializer.dumps(value)],
expiration))
assert all(store_ok), "DHT rejected a trivial store"
# peer 1 must know about peer 2
recv_value_bytes, recv_expiration, nodes_found = loop.run_until_complete(
protocol.call_find(f'{LOCALHOST}:{peer1_port}', [key]))[key]
recv_value = MSGPackSerializer.loads(recv_value_bytes)
(recv_id, recv_endpoint) = next(iter(nodes_found.items()))
assert recv_id == peer2_id and ':'.join(recv_endpoint.split(':')[-2:]) == f"{LOCALHOST}:{peer2_port}", \
f"expected id={peer2_id}, peer={LOCALHOST}:{peer2_port} but got {recv_id}, {recv_endpoint}"
assert recv_value == value and recv_expiration == expiration, \
f"call_find_value expected {value} (expires by {expiration}) " \
f"but got {recv_value} (expires by {recv_expiration})"
# peer 2 must know about peer 1, but not have a *random* nonexistent value
dummy_key = DHTID.generate()
recv_dummy_value, recv_dummy_expiration, nodes_found_2 = loop.run_until_complete(
protocol.call_find(f'{LOCALHOST}:{peer2_port}',
[dummy_key]))[dummy_key]
assert recv_dummy_value is None and recv_dummy_expiration is None, "Non-existent keys shouldn't have values"
(recv_id, recv_endpoint) = next(iter(nodes_found_2.items()))
assert recv_id == peer1_id and recv_endpoint == f"{LOCALHOST}:{peer1_port}", \
f"expected id={peer1_id}, peer={LOCALHOST}:{peer1_port} but got {recv_id}, {recv_endpoint}"
# cause a non-response by querying a nonexistent peer
dummy_port = find_open_port()
assert loop.run_until_complete(
protocol.call_find(f"{LOCALHOST}:{dummy_port}", [key])) is None
if listen:
loop.run_until_complete(protocol.shutdown())
print("DHTProtocol test finished successfully!")
test_success.set()
def _tester():
# note: we run everything in a separate process to re-initialize all global states from scratch
# this helps us avoid undesirable side-effects when running multiple tests in sequence
loop = asyncio.get_event_loop()
me = loop.run_until_complete(
DHTNode.create(initial_peers=random.sample(dht.keys(), 5),
parallel_rpc=10))
# test 1: find self
nearest = loop.run_until_complete(
me.find_nearest_nodes([me.node_id], k_nearest=1))[me.node_id]
assert len(nearest) == 1 and ':'.join(
nearest[me.node_id].split(':')[-2:]) == f"{LOCALHOST}:{me.port}"
# test 2: find others
for i in range(10):
ref_endpoint, query_id = random.choice(list(dht.items()))
nearest = loop.run_until_complete(
me.find_nearest_nodes([query_id], k_nearest=1))[query_id]
assert len(nearest) == 1
found_node_id, found_endpoint = next(iter(nearest.items()))
assert found_node_id == query_id and ':'.join(
found_endpoint.split(':')[-2:]) == ref_endpoint
# test 3: find neighbors to random nodes
accuracy_numerator = accuracy_denominator = 0 # top-1 nearest neighbor accuracy
jaccard_numerator = jaccard_denominator = 0 # jaccard similarity aka intersection over union
all_node_ids = list(dht.values())
for i in range(100):
query_id = DHTID.generate()
k_nearest = random.randint(1, 20)
exclude_self = random.random() > 0.5
nearest = loop.run_until_complete(
me.find_nearest_nodes([query_id],
k_nearest=k_nearest,
exclude_self=exclude_self))[query_id]
nearest_nodes = list(nearest) # keys from ordered dict
assert len(
nearest_nodes
) == k_nearest, "beam search must return exactly k_nearest results"
assert me.node_id not in nearest_nodes or not exclude_self, "if exclude, results shouldn't contain self"
assert np.all(np.diff(query_id.xor_distance(nearest_nodes)) >= 0
), "results must be sorted by distance"
ref_nearest = heapq.nsmallest(k_nearest + 1,
all_node_ids,
key=query_id.xor_distance)
if exclude_self and me.node_id in ref_nearest:
ref_nearest.remove(me.node_id)
if len(ref_nearest) > k_nearest:
ref_nearest.pop()
accuracy_numerator += nearest_nodes[0] == ref_nearest[0]
accuracy_denominator += 1
jaccard_numerator += len(
set.intersection(set(nearest_nodes), set(ref_nearest)))
jaccard_denominator += k_nearest
accuracy = accuracy_numerator / accuracy_denominator
print("Top-1 accuracy:", accuracy) # should be 98-100%
jaccard_index = jaccard_numerator / jaccard_denominator
print("Jaccard index (intersection over union):",
jaccard_index) # should be 95-100%
assert accuracy >= 0.9, f"Top-1 accuracy only {accuracy} ({accuracy_numerator} / {accuracy_denominator})"
assert jaccard_index >= 0.9, f"Jaccard index only {accuracy} ({accuracy_numerator} / {accuracy_denominator})"
# test 4: find all nodes
dummy = DHTID.generate()
nearest = loop.run_until_complete(
me.find_nearest_nodes([dummy], k_nearest=len(dht) + 100))[dummy]
assert len(nearest) == len(dht) + 1
assert len(
set.difference(set(nearest.keys()),
set(all_node_ids) | {me.node_id})) == 0
# test 5: node without peers
other_node = loop.run_until_complete(DHTNode.create())
nearest = loop.run_until_complete(
other_node.find_nearest_nodes([dummy]))[dummy]
assert len(nearest) == 1 and nearest[
other_node.node_id] == f"{LOCALHOST}:{other_node.port}"
nearest = loop.run_until_complete(
other_node.find_nearest_nodes([dummy], exclude_self=True))[dummy]
assert len(nearest) == 0
# test 6 store and get value
true_time = get_dht_time() + 1200
assert loop.run_until_complete(
me.store("mykey", ["Value", 10], true_time))
for node in [me, other_node]:
val, expiration_time = loop.run_until_complete(me.get("mykey"))
assert expiration_time == true_time, "Wrong time"
assert val == ["Value", 10], "Wrong value"
# test 7: bulk store and bulk get
keys = 'foo', 'bar', 'baz', 'zzz'
values = 3, 2, 'batman', [1, 2, 3]
store_ok = loop.run_until_complete(
me.store_many(keys, values, expiration_time=get_dht_time() + 999))
assert all(store_ok.values()), "failed to store one or more keys"
response = loop.run_until_complete(me.get_many(keys[::-1]))
for key, value in zip(keys, values):
assert key in response and response[key][0] == value
test_success.set()
def test_get_empty():
d = LocalStorage()
assert d.get(DHTID.generate(
source="key")) == (None,
None), "LocalStorage returned non-existent value"
print("Test get expired passed")
def test_store():
d = LocalStorage()
d.store(DHTID.generate("key"), b"val", get_dht_time() + 0.5)
assert d.get(DHTID.generate("key"))[0] == b"val", "Wrong value"
print("Test store passed")
async def create(cls,
node_id: Optional[DHTID] = None,
initial_peers: List[Endpoint] = (),
bucket_size: int = 20,
num_replicas: int = 5,
depth_modulo: int = 5,
parallel_rpc: int = None,
wait_timeout: float = 5,
refresh_timeout: Optional[float] = None,
bootstrap_timeout: Optional[float] = None,
num_workers: int = 1,
cache_locally: bool = True,
cache_nearest: int = 1,
cache_size=None,
listen: bool = True,
listen_on: Endpoint = "0.0.0.0:*",
**kwargs) -> DHTNode:
"""
:param node_id: current node's identifier, determines which keys it will store locally, defaults to random id
:param initial_peers: connects to these peers to populate routing table, defaults to no peers
:param bucket_size: max number of nodes in one k-bucket (k). Trying to add {k+1}st node will cause a bucket to
either split in two buckets along the midpoint or reject the new node (but still save it as a replacement)
Recommended value: k is chosen s.t. any given k nodes are very unlikely to all fail after staleness_timeout
:param num_replicas: number of nearest nodes that will be asked to store a given key, default = bucket_size (≈k)
:param depth_modulo: split full k-bucket if it contains root OR up to the nearest multiple of this value (≈b)
:param parallel_rpc: maximum number of concurrent outgoing RPC requests emitted by DHTProtocol
Reduce this value if your RPC requests register no response despite the peer sending the response.
:param wait_timeout: a kademlia rpc request is deemed lost if we did not recieve a reply in this many seconds
:param refresh_timeout: refresh buckets if no node from that bucket was updated in this many seconds
if staleness_timeout is None, DHTNode will not refresh stale buckets (which is usually okay)
:param bootstrap_timeout: after one of peers responds, await other peers for at most this many seconds
:param num_workers: concurrent workers in traverse_dht (see traverse_dht num_workers param)
:param cache_locally: if True, caches all values (stored or found) in a node-local cache
:param cache_nearest: whenever DHTNode finds a value, it will also store (cache) this value on this many
nodes nearest nodes visited by search algorithm. Prefers nodes that are nearest to :key: but have no value yet
:param cache_size: if specified, local cache will store up to this many records (as in LRU cache)
:param listen: if True (default), this node will accept incoming request and otherwise be a DHT "citzen"
if False, this node will refuse any incoming request, effectively being only a "client"
:param listen_on: network interface, e.g. "0.0.0.0:1337" or "localhost:*" (* means pick any port) or "[::]:7654"
:param channel_options: options for grpc.aio.insecure_channel, e.g. [('grpc.enable_retries', 0)]
see https://grpc.github.io/grpc/core/group__grpc__arg__keys.html for a list of all options
:param kwargs: extra parameters used in grpc.aio.server
"""
self = cls(_initialized_with_create=True)
self.node_id = node_id = node_id if node_id is not None else DHTID.generate(
)
self.num_replicas, self.num_workers = num_replicas, num_workers
self.cache_locally, self.cache_nearest = cache_locally, cache_nearest
self.refresh_timeout = refresh_timeout
self.protocol = await DHTProtocol.create(self.node_id, bucket_size,
depth_modulo, num_replicas,
wait_timeout, parallel_rpc,
cache_size, listen, listen_on,
**kwargs)
self.port = self.protocol.port
if initial_peers:
# stage 1: ping initial_peers, add each other to the routing table
bootstrap_timeout = bootstrap_timeout if bootstrap_timeout is not None else wait_timeout
start_time = get_dht_time()
ping_tasks = map(self.protocol.call_ping, initial_peers)
finished_pings, unfinished_pings = await asyncio.wait(
ping_tasks, return_when=asyncio.FIRST_COMPLETED)
# stage 2: gather remaining peers (those who respond within bootstrap_timeout)
if unfinished_pings:
finished_in_time, stragglers = await asyncio.wait(
unfinished_pings,
timeout=bootstrap_timeout - get_dht_time() + start_time)
for straggler in stragglers:
straggler.cancel()
finished_pings |= finished_in_time
if not finished_pings:
warn(
"DHTNode bootstrap failed: none of the initial_peers responded to a ping."
)
# stage 3: traverse dht to find my own nearest neighbors and populate the routing table
# ... maybe receive some values that we are meant to store (see protocol.update_routing_table)
# note: using asyncio.wait instead of wait_for because wait_for cancels task on timeout
await asyncio.wait([
asyncio.create_task(self.find_nearest_nodes([self.node_id])),
asyncio.sleep(bootstrap_timeout - get_dht_time() + start_time)
],
return_when=asyncio.FIRST_COMPLETED)
if self.refresh_timeout is not None:
asyncio.create_task(
self._refresh_routing_table(period=self.refresh_timeout))
return self
num_added += new_total > total_nodes
total_nodes = new_total
num_replacements = sum(
len(bucket.replacement_nodes) for bucket in routing_table.buckets)
all_active_neighbors = list(
chain(*(bucket.nodes_to_endpoint.keys()
for bucket in routing_table.buckets)))
assert lower_active <= len(all_active_neighbors) <= upper_active
assert len(all_active_neighbors) == num_added
assert num_added + num_replacements == table_size
# random queries
for i in range(1000):
k = random.randint(1, 100)
query_id = DHTID.generate()
exclude = query_id if random.random() < 0.5 else None
our_knn, our_endpoints = zip(*routing_table.get_nearest_neighbors(
query_id, k=k, exclude=exclude))
reference_knn = heapq.nsmallest(k,
all_active_neighbors,
key=query_id.xor_distance)
assert all(our == ref
for our, ref in zip_longest(our_knn, reference_knn))
assert all(
our_endpoint == routing_table[our_node]
for our_node, our_endpoint in zip(our_knn, our_endpoints))
# queries from table
for i in range(1000):
k = random.randint(1, 100)
async def get_many(
self,
keys: Collection[DHTKey],
sufficient_expiration_time: Optional[DHTExpiration] = None,
num_workers: Optional[int] = None,
beam_size: Optional[int] = None
) -> Dict[DHTKey, Tuple[Optional[DHTValue], Optional[DHTExpiration]]]:
"""
:param keys: traverse the DHT and find the value for each of these keys (or (None, None) if not key found)
:param sufficient_expiration_time: if the search finds a value that expires after this time,
default = time of call, find any value that did not expire by the time of call
If min_expiration_time=float('inf'), this method will find a value with _latest_ expiration
:param beam_size: maintains up to this many nearest nodes when crawling dht, default beam_size = bucket_size
:param num_workers: override for default num_workers, see traverse_dht num_workers param
:returns: for each key: value and its expiration time. If nothing is found , returns (None, None) for that key
:note: in order to check if get returned a value, please check (expiration_time is None)
"""
key_ids = [DHTID.generate(key) for key in keys]
id_to_original_key = dict(zip(key_ids, keys))
sufficient_expiration_time = sufficient_expiration_time or get_dht_time(
)
beam_size = beam_size if beam_size is not None else self.protocol.bucket_size
num_workers = num_workers if num_workers is not None else self.num_workers
# search metadata
unfinished_key_ids = set(
key_ids) # track key ids for which the search is not terminated
node_to_endpoint: Dict[
DHTID, Endpoint] = dict() # global routing table for all queries
SearchResult = namedtuple(
"SearchResult",
["binary_value", "expiration_time", "source_node_id"])
latest_results = {
key_id: SearchResult(b'', -float('inf'), None)
for key_id in key_ids
}
# stage 1: value can be stored in our local cache
for key_id in key_ids:
maybe_value, maybe_expiration_time = self.protocol.storage.get(
key_id)
if maybe_expiration_time is None:
maybe_value, maybe_expiration_time = self.protocol.cache.get(
key_id)
if maybe_expiration_time is not None and maybe_expiration_time > latest_results[
key_id].expiration_time:
latest_results[key_id] = SearchResult(maybe_value,
maybe_expiration_time,
self.node_id)
if maybe_expiration_time >= sufficient_expiration_time:
unfinished_key_ids.remove(key_id)
# stage 2: traverse the DHT for any unfinished keys
for key_id in unfinished_key_ids:
node_to_endpoint.update(
self.protocol.routing_table.get_nearest_neighbors(
key_id, self.protocol.bucket_size, exclude=self.node_id))
async def get_neighbors(
peer: DHTID, queries: Collection[DHTID]
) -> Dict[DHTID, Tuple[List[DHTID], bool]]:
queries = list(queries)
response = await self.protocol.call_find(node_to_endpoint[peer],
queries)
if not response:
return {query: ([], False) for query in queries}
output: Dict[DHTID, Tuple[List[DHTID], bool]] = {}
for key_id, (maybe_value, maybe_expiration_time,
peers) in response.items():
node_to_endpoint.update(peers)
if maybe_expiration_time is not None and maybe_expiration_time > latest_results[
key_id].expiration_time:
latest_results[key_id] = SearchResult(
maybe_value, maybe_expiration_time, peer)
should_interrupt = (latest_results[key_id].expiration_time >=
sufficient_expiration_time)
output[key_id] = list(peers.keys()), should_interrupt
return output
nearest_nodes_per_query, visited_nodes = await traverse_dht(
queries=list(unfinished_key_ids),
initial_nodes=list(node_to_endpoint),
beam_size=beam_size,
num_workers=num_workers,
queries_per_call=int(len(unfinished_key_ids)**0.5),
get_neighbors=get_neighbors,
visited_nodes={
key_id: {self.node_id}
for key_id in unfinished_key_ids
})
# stage 3: cache any new results depending on caching parameters
for key_id, nearest_nodes in nearest_nodes_per_query.items():
latest_value_bytes, latest_expiration_time, latest_node_id = latest_results[
key_id]
should_cache = latest_expiration_time >= sufficient_expiration_time # if we found a newer value, cache it
if should_cache and self.cache_locally:
self.protocol.cache.store(key_id, latest_value_bytes,
latest_expiration_time)
if should_cache and self.cache_nearest:
num_cached_nodes = 0
for node_id in nearest_nodes:
if node_id == latest_node_id:
continue
asyncio.create_task(
self.protocol.call_store(node_to_endpoint[node_id],
[key_id],
[latest_value_bytes],
[latest_expiration_time],
in_cache=True))
num_cached_nodes += 1
if num_cached_nodes >= self.cache_nearest:
break
# stage 4: deserialize data and assemble function output
find_result: Dict[DHTKey, Tuple[Optional[DHTValue],
Optional[DHTExpiration]]] = {}
for key_id, (latest_value_bytes, latest_expiration_time,
_) in latest_results.items():
if latest_expiration_time != -float('inf'):
latest_value = self.serializer.loads(latest_value_bytes)
find_result[id_to_original_key[key_id]] = (
latest_value, latest_expiration_time)
else:
find_result[id_to_original_key[key_id]] = None, None
return find_result
