def test_prune_dag_should_remove_nodes_preceding_given_node(self):
dag = DAG()
dag.add_edges(sources=['b', 'c'], target='a')
dag.add_edges(sources=['a'], target='d')
dag.add_edges(sources=['d'], target='e')
self.assertCountEqual(['c', 'b', 'a', 'd', 'e'], dag.to_string())
dag.prune_upto('d')
self.assertCountEqual(['d', 'e'], dag.to_string())
def test_add_edge(self):
dag = DAG()
dag.add_edges(sources=['b', 'c'], target='a')
self.assertCountEqual(dag.heads(), ['a'])
self.assertTrue(dag.has('a'))
self.assertTrue(dag.has('b'))
self.assertTrue(dag.has('c'))
self.assertFalse(dag.has('d'))
self.assertTrue(dag.has_path('b', 'a'))
self.assertFalse(dag.has_path('a', 'b'))
def test_find_not_reachable_with_some_reachable_reversed_order(self):
dag = DAG()
dag.add_edges(sources=['b', 'c'], target='a')
dag.add_edges(sources=['d'], target='e')
# The first argument is the shares sent by a node. They are send in the
# order d, e, b, c. We assume that if there is a path from c to a,
# then there is a path as d -> e -> b -> c, and therefore return empty
# list
self.assertCountEqual(
dag.find_not_reachable(['d', 'e', 'b', 'c'], 'a'), [])
def test_prune_should_remove_nodes_preceding_given_hash(self):
dag = DAG()
dag.add_edges(sources=['b', 'c'], target='a')
dag.add_edges(sources=['a'], target='d')
dag.add_edges(sources=['d'], target='e')
env = simpy.Environment()
node = Node(env=env, name='node 1')
node.dag = dag
node.blocks_received = ['c', 'b', 'a', 'd', 'e']
self.assertCountEqual(['c', 'b', 'a', 'd', 'e'], dag.to_string())
node._prune()
self.assertCountEqual(['d', 'e'], node.dag.to_string())
def test_find_not_reachable_with_some_reachable(self):
dag = DAG()
dag.add_edges(sources=['b', 'c'], target='a')
dag.add_edges(sources=['d'], target='e')
self.assertCountEqual(
dag.find_not_reachable(['b', 'c', 'd', 'e'], 'a'), ['d', 'e'])
class Node:
prune_depth = 2
# Set configs as otherwise configparses takes too long to 'get' them again
message_processing_time = int(config["simulation"]["message_processing_time"])
share_period = int(config["shares"]["period"])
randomise_share_period = config.getboolean("shares", "randomise")
block_probability = float(config["shares"]["block_probability"])
shares_limit = int(config["shares"]["limit"])
run_time = int(config["simulation"]["run_time"])
def __init__(self, *, env, name):
self.seq_no = 0
self.env = env
self.name = name
self.out_pipe = BroadcastPipe(env=env, sender=self.name)
self.in_pipe = simpy.Store(self.env)
self.neighbours = set()
self.dag = DAG()
# required to help prune dag for large simulations
self.blocks_received = []
self.shares_sent = []
# Track num_shares_sent separately as shares_sent is pruned when block is received
self.num_shares_sent = 0
self.shares_not_rewarded = {}
self.num_blocks = 0
def heads(self):
return self.dag.heads()
def add_neighbour(self, neighbour, reversed=True):
self.neighbours.add(neighbour)
self.out_pipe.add_receiver(neighbour.in_pipe)
if reversed and self not in neighbour.neighbours:
neighbour.add_neighbour(self)
def add_neighbours(self, neighbours: list, reversed=True):
for neighbour in neighbours:
self.add_neighbour(neighbour, reversed)
def get_next_share_time(self):
period = self.share_period
if self.randomise_share_period:
return get_random(period=period)
else:
return period
def generate_shares(self):
"""Process to generate shares at random intervals."""
block_probability = self.block_probability
while True:
# wait for next share
limit = self.shares_limit
if limit != -1 and self.seq_no >= limit:
yield self.env.timeout(self.run_time)
else:
yield self.env.timeout(self.get_next_share_time())
share = Share(
source=self.name,
heads=self.heads(),
env=self.env,
seq_no=self.seq_no,
is_block=get_random(period=1) < block_probability,
)
self.seq_no += 1
if share.is_block:
self.num_blocks += 1
msg = ShareMessage(share=share)
self.add_to_dag(msg.share.hash, msg.share.heads)
self.send(msg)
self.shares_sent.append(msg.share.hash)
self.num_shares_sent += 1
self.handle_block_found(msg)
def _log_send(self, msg, forward):
_type = "s" if not forward else "f"
if _type == "s":
logging.info(f"{int(self.env.now)} {_type} n: {self.name} {msg}")
else:
logging.debug(f"{int(self.env.now)} {_type} n: {self.name} {msg}")
def send(self, msg, forward=False):
self._log_send(msg, forward)
self.out_pipe.put(msg)
def receive(self):
"""A process which consumes messages."""
while True:
msg = yield self.in_pipe.get()
logging.info(f"{int(self.env.now)} r n: {self.name} {msg}")
self.env.process(self.handle_receive(msg.copy()))
def forward(self, msg):
msg.decrement_count()
self.send(msg, forward=True)
def add_to_dag(self, hash, heads):
self.dag.add_edges(sources=heads, target=hash)
def handle_receive(self, msg):
yield self.env.timeout(self.message_processing_time)
msg_in_dag = self.dag.has(msg.share.hash)
if not msg_in_dag:
if msg.should_forward():
self.forward(msg)
self.add_to_dag(msg.share.hash, msg.share.heads)
self.handle_received_block_found(msg)
def handle_received_block_found(self, msg):
if not msg.share.is_block:
return
if msg.share.source == self.name:
return
self.handle_block_found(msg)
def handle_block_found(self, msg):
# find delta between latest share this node already sent and
# the last one referenced in the receieved share.
not_rewarded = self.dag.find_not_reachable(self.shares_sent, msg.share.hash)
if not_rewarded:
self.shares_not_rewarded[msg.share.hash] = not_rewarded
self.blocks_received.append(msg.share.hash)
self._prune()
def _prune(self):
"""Prune dag, blocks_received and shares_sent up to last two blocks received"""
if len(self.blocks_received) <= self.prune_depth:
return
prune_upto = self.blocks_received[-self.prune_depth :][0]
pruned_hashes = self.dag.prune_upto(prune_upto)
del self.blocks_received[: -self.prune_depth]
self._prune_shares_sent(pruned_hashes)
def _prune_shares_sent(self, pruned_hashes):
# Possible improvement - the implementation here goes over shares_sent twice.
for hash in pruned_hashes:
if hash in self.shares_sent:
self.shares_sent.remove(hash)
def start(self):
logging.info(f"{self.name} starting...")
self.env.process(self.receive())
self.env.process(self.generate_shares())