import hashlib
import bisect
import xxhash
def walk_ring_from_pos(tokens, dcs, start, rep):
ret = []
ret_dcs = set()
delta = 0
while len(ret) < rep:
i = (start + delta) % len(tokens)
delta = delta + 1
(token_k, token_dc, token_node) = tokens[i]
if token_dc not in ret_dcs:
ret_dcs |= set([token_dc])
ret.append(token_node)
elif len(ret_dcs) == len(dcs) and token_node not in ret:
ret.append(token_node)
return ret
def count_tokens_per_node(tokens):
tokens_of_node = {}
for _, _, token_node in tokens:
if token_node not in tokens_of_node:
tokens_of_node[token_node] = 0
tokens_of_node[token_node] += 1
print("#tokens per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print(node, ": ", ntok)
def method1(nodes):
tokens = []
dcs = set()
for (node_id, dc, n_tokens) in nodes:
dcs |= set([dc])
for i in range(n_tokens):
token = hashlib.sha256(f"{node_id} {i}".encode('ascii')).hexdigest()
tokens.append((token, dc, node_id))
tokens.sort(key=lambda tok: tok[0])
count_tokens_per_node(tokens)
space_of_node = {}
def walk_ring(v, rep):
i = bisect.bisect_left([tok for tok, _, _ in tokens], hashlib.sha256(v).hexdigest())
return walk_ring_from_pos(tokens, dcs, i, rep)
return walk_ring
def method2(nodes):
partition_bits = 10
partitions = list(range(2**partition_bits))
def partition_node(i):
h, hn, hndc = None, None, None
for (node_id, node_dc, n_tokens) in nodes:
for tok in range(n_tokens):
#hnode = hashlib.sha256(f"{i} {node_id} {tok}".encode('ascii')).hexdigest()
xxh = xxhash.xxh64()
xxh.update(f"partition {i} node {node_id} token {tok}".encode('ascii'))
hnode = xxh.digest()
if h is None or hnode < h:
h = hnode
hn = node_id
hndc = node_dc
return (i, hndc, hn)
partition_nodes = [partition_node(i) for i in partitions]
count_tokens_per_node(partition_nodes)
dcs = list(set(node_dc for _, node_dc, _ in nodes))
def walk_ring(v, rep):
vh = hashlib.sha256(v).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
return walk_ring_from_pos(partition_nodes, dcs, i, rep)
return walk_ring
def evaluate_method(walk_ring):
node_data_counts = {}
for i in range(100000):
nodes = walk_ring(f"{i}".encode('ascii'), 3)
for n in nodes:
if n not in node_data_counts:
node_data_counts[n] = 0
node_data_counts[n] += 1
print("Number of data items per node:")
for n, v in sorted(list(node_data_counts.items())):
print(n, ": ", v)
if __name__ == "__main__":
nodes = [('digitale', 'atuin', 10),
('drosera', 'atuin', 10),
('datura', 'atuin', 10),
('io', 'jupiter', 20),
('meta', 'pipo', 10),
('mega', 'pipo', 10),
('mina', 'pipo', 10),
#('moni', 'pipo', 10),
#('mimi', 'pipo', 10),
#('mesi', 'pipo', 10),
]
print("------")
print("method 1")
method1_walk_ring = method1(nodes)
evaluate_method(method1_walk_ring)
print("------")
print("method 2")
method2_walk_ring = method2(nodes)
evaluate_method(method2_walk_ring)
