garage-unix-socket/script/simulate_ring.py

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#!/usr/bin/env python3
import hashlib
import bisect
import xxhash
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import numpy as np
REPLICATION_FACTOR = 3
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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()
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def walk_ring_from_pos(tokens, dcs, start):
ret = []
ret_dcs = set()
delta = 0
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while len(ret) < REPLICATION_FACTOR:
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
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"""
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())):
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print("-", node, ": ", ntok)
"""
def count_partitions_per_node(ring_node_list):
tokens_of_node = {}
for nodelist in ring_node_list:
for 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("#partitions per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print("-", node, ": ", ntok)
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def method1(nodes):
tokens = []
dcs = set()
for (node_id, dc, n_tokens) in nodes:
dcs |= set([dc])
for i in range(n_tokens):
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token = hash_str(f"{node_id} {i}")
tokens.append((token, dc, node_id))
tokens.sort(key=lambda tok: tok[0])
space_of_node = {}
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def walk_ring(v):
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i = bisect.bisect_left([tok for tok, _, _ in tokens], hash_str(v))
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return walk_ring_from_pos(tokens, dcs, i)
ring_node_list = [walk_ring_from_pos(tokens, dcs, i) for i in range(len(tokens))]
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return walk_ring, ring_node_list
def method2(nodes):
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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):
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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]
dcs = list(set(node_dc for _, node_dc, _ in nodes))
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def walk_ring(v):
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# 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)
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return walk_ring_from_pos(partition_nodes, dcs, i)
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ring_node_list = [walk_ring_from_pos(partition_nodes, dcs, i) for i in range(len(partition_nodes))]
return walk_ring, ring_node_list
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def method3(nodes):
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partition_bits = 10
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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
dcs = list(set(node_dc for _, node_dc, _ in nodes))
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def walk_ring(v):
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vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
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return walk_ring_from_pos(partitions, dcs, i)
ring_node_list = [walk_ring_from_pos(partitions, dcs, i) for i in range(len(partitions))]
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return walk_ring, ring_node_list
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def method4(nodes):
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partition_bits = 10
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
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for ri in range(REPLICATION_FACTOR):
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
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def walk_ring(v):
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
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assert len(set([node_dc for node_dc, _ in partitions[i]])) == min(REPLICATION_FACTOR, len(dcs))
return [node_id for _, node_id in partitions[i]]
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ring_node_list = [[node_id for _, node_id in p] for p in partitions]
return walk_ring, ring_node_list
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def evaluate_method(method, nodes):
walk_ring, ring_node_list = method(nodes)
print("Ring length:", len(ring_node_list))
count_partitions_per_node(ring_node_list)
print("Number of data items per node (100000 simulation):")
node_data_counts = {}
for i in range(100000):
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inodes = walk_ring(f"{i}")
for n in inodes:
if n not in node_data_counts:
node_data_counts[n] = 0
node_data_counts[n] += 1
for n, v in sorted(list(node_data_counts.items())):
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print("-", n, ": ", v)
dclist_per_ntok = {}
for node_id, _, ntok in nodes:
if ntok not in dclist_per_ntok:
dclist_per_ntok[ntok] = []
dclist_per_ntok[ntok].append(node_data_counts[node_id])
list_normalized = []
for ntok, dclist in dclist_per_ntok.items():
avg = sum(dclist)/len(dclist)
for v in dclist:
list_normalized.append(v / avg)
print("variance wrt. same-ntok mean:", "%.2f%%"%(np.var(list_normalized)*100))
num_changes_sum = [0, 0, 0, 0]
for n in nodes:
nodes2 = [nn for nn in nodes if nn != n]
_, ring_node_list_2 = method(nodes2)
if len(ring_node_list_2) != len(ring_node_list):
continue
num_changes = [0, 0, 0, 0]
for (ns1, ns2) in zip(ring_node_list, ring_node_list_2):
changes = sum(1 for x in ns1 if x not in ns2)
num_changes[changes] += 1
for i, v in enumerate(num_changes):
num_changes_sum[i] += v / len(ring_node_list)
print("removing", n[1], n[0], ":", " ".join(["%.2f%%"%(x*100/len(ring_node_list)) for x in num_changes]))
print("1-node removal: partitions moved on 0/1/2/3 nodes: ", " ".join(["%.2f%%"%(x*100/len(nodes)) for x in num_changes_sum]))
if __name__ == "__main__":
print("------")
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print("method 1 (standard ring)")
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nodes = [('digitale', 'atuin', 64),
('drosera', 'atuin', 64),
('datura', 'atuin', 64),
('io', 'jupiter', 128)]
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nodes2 = [('digitale', 'atuin', 64),
('drosera', 'atuin', 64),
('datura', 'atuin', 64),
('io', 'jupiter', 128),
('isou', 'jupiter', 64),
('mini', 'grog', 32),
('mixi', 'grog', 32),
('moxi', 'grog', 32),
('modi', 'grog', 32),
('geant', 'grisou', 128),
('gipsie', 'grisou', 128),
]
evaluate_method(method1, nodes2)
print("------")
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print("method 2 (custom ring)")
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nodes = [('digitale', 'atuin', 1),
('drosera', 'atuin', 1),
('datura', 'atuin', 1),
('io', 'jupiter', 2)]
nodes2 = [('digitale', 'atuin', 2),
('drosera', 'atuin', 2),
('datura', 'atuin', 2),
('io', 'jupiter', 4),
('isou', 'jupiter', 2),
('mini', 'grog', 1),
('mixi', 'grog', 1),
('moxi', 'grog', 1),
('modi', 'grog', 1),
('geant', 'grisou', 4),
('gipsie', 'grisou', 4),
]
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evaluate_method(method2, nodes2)
print("------")
print("method 3 (maglev)")
evaluate_method(method3, nodes2)
print("------")
print("method 4 (maglev, multi-dc twist)")
evaluate_method(method4, nodes2)