import hashlib
import bisect
import xxhash
def hash_str(s):
xxh = xxhash.xxh64()
xxh.update(s.encode('ascii'))
return xxh.hexdigest()
def sha256_str(s):
return hashlib.sha256(s.encode('ascii')).hexdigest()
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 = hash_str(f"{node_id} {i}")
tokens.append((token, dc, node_id))
tokens.sort(key=lambda tok: tok[0])
#print(tokens)
count_tokens_per_node(tokens)
space_of_node = {}
def walk_ring(v, rep):
i = bisect.bisect_left([tok for tok, _, _ in tokens], hash_str(v))
return walk_ring_from_pos(tokens, dcs, i, rep)
return walk_ring
def method2(nodes):
partition_bits = 8
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 = hash_str(f"partition {i} node {node_id} token {tok}")
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):
# xxh = xxhash.xxh32()
# xxh.update(v.encode('ascii'))
# vh = xxh.intdigest()
# i = vh % (2**partition_bits)
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
return walk_ring_from_pos(partition_nodes, dcs, i, rep)
return walk_ring
def method3(nodes):
partition_bits = 8
queues = []
for (node_id, node_dc, n_tokens) in nodes:
que = [(i, hash_str(f"{node_id} {i}")) for i in range(2**partition_bits)]
que.sort(key=lambda x: x[1])
que = [x[0] for x in que]
queues.append((node_id, node_dc, n_tokens, que))
partitions = [None for _ in range(2**partition_bits)]
queues.sort(key=lambda x: hash_str(x[0]))
# Maglev
remaining = 2**partition_bits
while remaining > 0:
for toktok in range(100):
for iq in range(len(queues)):
node_id, node_dc, n_tokens, node_queue = queues[iq]
if toktok >= n_tokens:
continue
for qi, qv in enumerate(node_queue):
if partitions[qv] == None:
partitions[qv] = (qv, node_dc, node_id)
remaining -= 1
queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
break
count_tokens_per_node(partitions)
dcs = list(set(node_dc for _, node_dc, _ in nodes))
def walk_ring(v, rep):
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
return walk_ring_from_pos(partitions, dcs, i, rep)
return walk_ring
def method4(nodes):
partition_bits = 8
max_replicas = 3
partitions = [[] for _ in range(2**partition_bits)]
dcs = list(set(node_dc for _, node_dc, _ in nodes))
# Maglev, improved for several replicas on several DCs
for ri in range(max_replicas):
queues = []
for (node_id, node_dc, n_tokens) in nodes:
que = [(i, hash_str(f"{node_id} {i}")) for i in range(2**partition_bits)]
que.sort(key=lambda x: x[1])
que = [x[0] for x in que]
queues.append((node_id, node_dc, n_tokens, que))
queues.sort(key=lambda x: hash_str("{} {}".format(ri, x[0])))
remaining = 2**partition_bits
while remaining > 0:
for toktok in range(100):
for iq in range(len(queues)):
node_id, node_dc, n_tokens, node_queue = queues[iq]
if toktok >= n_tokens:
continue
for qi, qv in enumerate(node_queue):
if len(partitions[qv]) != ri:
continue
p_dcs = set([x[0] for x in partitions[qv]])
p_nodes = [x[1] for x in partitions[qv]]
if node_dc not in p_dcs or (len(p_dcs) == len(dcs) and node_id not in p_nodes):
partitions[qv].append((node_dc, node_id))
remaining -= 1
queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
break
# count
tokens_of_node = {}
for nodelist in partitions:
for node_dc, node_id in nodelist:
if node_id not in tokens_of_node:
tokens_of_node[node_id] = 0
tokens_of_node[node_id] += 1
print("#tokens per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print(node, ": ", ntok)
def walk_ring(v, rep):
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
assert len(set([node_dc for node_dc, _ in partitions[i]])) == min(max_replicas, len(dcs))
return [node_id for _, node_id in partitions[i]]
return walk_ring
def evaluate_method(walk_ring):
node_data_counts = {}
for i in range(100000):
nodes = walk_ring(f"{i}", 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__":
print("------")
print("method 1 (standard ring)")
nodes = [('digitale', 'atuin', 64),
('drosera', 'atuin', 64),
('datura', 'atuin', 64),
('io', 'jupiter', 128)]
method1_walk_ring = method1(nodes)
evaluate_method(method1_walk_ring)
print("------")
print("method 2 (custom ring)")
nodes = [('digitale', 'atuin', 10),
('drosera', 'atuin', 10),
('datura', 'atuin', 10),
('io', 'jupiter', 20)]
method2_walk_ring = method2(nodes)
evaluate_method(method2_walk_ring)
print("------")
print("method 3 (maglev)")
nodes = [('digitale', 'atuin', 4),
('drosera', 'atuin', 4),
('datura', 'atuin', 4),
('io', 'jupiter', 8),
#('mini', 'grog', 2),
#('mixi', 'grog', 2),
#('moxi', 'grog', 2),
#('modi', 'grog', 2),
]
method3_walk_ring = method3(nodes)
evaluate_method(method3_walk_ring)
print("------")
print("method 4 (maglev, multi-dc twist)")
nodes = [('digitale', 'atuin', 8),
('drosera', 'atuin', 8),
('datura', 'atuin', 8),
('io', 'jupiter', 16),
('mini', 'grog', 4),
('mixi', 'grog', 4),
('moxi', 'grog', 4),
('modi', 'grog', 4),
('geant', 'grisou', 16),
('gipsie', 'grisou', 16),
#('isou', 'jupiter', 8),
]
method4_walk_ring = method4(nodes)
evaluate_method(method4_walk_ring)
