291 lines
9.7 KiB
Python
Executable File
291 lines
9.7 KiB
Python
Executable File
#!/usr/bin/env python3
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import hashlib
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import bisect
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import xxhash
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import numpy as np
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REPLICATION_FACTOR = 3
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def hash_str(s):
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xxh = xxhash.xxh64()
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xxh.update(s.encode('ascii'))
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return xxh.hexdigest()
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def sha256_str(s):
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return hashlib.sha256(s.encode('ascii')).hexdigest()
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def walk_ring_from_pos(tokens, dcs, start):
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ret = []
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ret_dcs = set()
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delta = 0
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while len(ret) < REPLICATION_FACTOR:
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i = (start + delta) % len(tokens)
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delta = delta + 1
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(token_k, token_dc, token_node) = tokens[i]
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if token_dc not in ret_dcs:
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ret_dcs |= set([token_dc])
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ret.append(token_node)
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elif len(ret_dcs) == len(dcs) and token_node not in ret:
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ret.append(token_node)
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return ret
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"""
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def count_tokens_per_node(tokens):
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tokens_of_node = {}
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for _, _, token_node in tokens:
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if token_node not in tokens_of_node:
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tokens_of_node[token_node] = 0
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tokens_of_node[token_node] += 1
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print("#tokens per node:")
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for node, ntok in sorted(list(tokens_of_node.items())):
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print("-", node, ": ", ntok)
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"""
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def count_partitions_per_node(ring_node_list):
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tokens_of_node = {}
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for nodelist in ring_node_list:
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for node_id in nodelist:
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if node_id not in tokens_of_node:
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tokens_of_node[node_id] = 0
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tokens_of_node[node_id] += 1
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print("#partitions per node:")
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for node, ntok in sorted(list(tokens_of_node.items())):
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print("-", node, ": ", ntok)
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def method1(nodes):
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tokens = []
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dcs = set()
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for (node_id, dc, n_tokens) in nodes:
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dcs |= set([dc])
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for i in range(n_tokens):
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token = hash_str(f"{node_id} {i}")
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tokens.append((token, dc, node_id))
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tokens.sort(key=lambda tok: tok[0])
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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)
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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
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def method2(nodes):
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partition_bits = 10
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partitions = list(range(2**partition_bits))
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def partition_node(i):
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h, hn, hndc = None, None, None
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for (node_id, node_dc, n_tokens) in nodes:
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for tok in range(n_tokens):
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hnode = hash_str(f"partition {i} node {node_id} token {tok}")
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if h is None or hnode < h:
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h = hnode
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hn = node_id
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hndc = node_dc
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return (i, hndc, hn)
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partition_nodes = [partition_node(i) for i in partitions]
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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()
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# xxh.update(v.encode('ascii'))
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# vh = xxh.intdigest()
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# i = vh % (2**partition_bits)
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vh = hashlib.sha256(v.encode('ascii')).digest()
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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))]
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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 = []
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for (node_id, node_dc, n_tokens) in nodes:
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que = [(i, hash_str(f"{node_id} {i}")) for i in range(2**partition_bits)]
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que.sort(key=lambda x: x[1])
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que = [x[0] for x in que]
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queues.append((node_id, node_dc, n_tokens, que))
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partitions = [None for _ in range(2**partition_bits)]
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queues.sort(key=lambda x: hash_str(x[0]))
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# Maglev
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remaining = 2**partition_bits
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while remaining > 0:
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for toktok in range(100):
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for iq in range(len(queues)):
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node_id, node_dc, n_tokens, node_queue = queues[iq]
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if toktok >= n_tokens:
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continue
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for qi, qv in enumerate(node_queue):
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if partitions[qv] == None:
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partitions[qv] = (qv, node_dc, node_id)
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remaining -= 1
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queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
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break
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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()
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i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
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return walk_ring_from_pos(partitions, dcs, i)
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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
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partitions = [[] for _ in range(2**partition_bits)]
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dcs = list(set(node_dc for _, node_dc, _ in nodes))
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# Maglev, improved for several replicas on several DCs
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for ri in range(REPLICATION_FACTOR):
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queues = []
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for (node_id, node_dc, n_tokens) in nodes:
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que = [(i, hash_str(f"{node_id} {i}")) for i in range(2**partition_bits)]
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que.sort(key=lambda x: x[1])
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que = [x[0] for x in que]
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queues.append((node_id, node_dc, n_tokens, que))
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queues.sort(key=lambda x: hash_str("{} {}".format(ri, x[0])))
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remaining = 2**partition_bits
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while remaining > 0:
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for toktok in range(100):
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for iq in range(len(queues)):
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node_id, node_dc, n_tokens, node_queue = queues[iq]
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if toktok >= n_tokens:
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continue
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for qi, qv in enumerate(node_queue):
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if len(partitions[qv]) != ri:
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continue
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p_dcs = set([x[0] for x in partitions[qv]])
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p_nodes = [x[1] for x in partitions[qv]]
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if node_dc not in p_dcs or (len(p_dcs) == len(dcs) and node_id not in p_nodes):
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partitions[qv].append((node_dc, node_id))
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remaining -= 1
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queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
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break
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def walk_ring(v):
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vh = hashlib.sha256(v.encode('ascii')).digest()
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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))
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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]
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return walk_ring, ring_node_list
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def evaluate_method(method, nodes):
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walk_ring, ring_node_list = method(nodes)
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print("Ring length:", len(ring_node_list))
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count_partitions_per_node(ring_node_list)
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print("Number of data items per node (100000 simulation):")
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node_data_counts = {}
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for i in range(100000):
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inodes = walk_ring(f"{i}")
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for n in inodes:
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if n not in node_data_counts:
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node_data_counts[n] = 0
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node_data_counts[n] += 1
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for n, v in sorted(list(node_data_counts.items())):
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print("-", n, ": ", v)
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dclist_per_ntok = {}
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for node_id, _, ntok in nodes:
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if ntok not in dclist_per_ntok:
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dclist_per_ntok[ntok] = []
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dclist_per_ntok[ntok].append(node_data_counts[node_id])
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list_normalized = []
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for ntok, dclist in dclist_per_ntok.items():
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avg = sum(dclist)/len(dclist)
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for v in dclist:
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list_normalized.append(v / avg)
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print("variance wrt. same-ntok mean:", "%.2f%%"%(np.var(list_normalized)*100))
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num_changes_sum = [0, 0, 0, 0]
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for n in nodes:
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nodes2 = [nn for nn in nodes if nn != n]
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_, ring_node_list_2 = method(nodes2)
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if len(ring_node_list_2) != len(ring_node_list):
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continue
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num_changes = [0, 0, 0, 0]
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for (ns1, ns2) in zip(ring_node_list, ring_node_list_2):
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changes = sum(1 for x in ns1 if x not in ns2)
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num_changes[changes] += 1
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for i, v in enumerate(num_changes):
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num_changes_sum[i] += v / len(ring_node_list)
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print("removing", n[1], n[0], ":", " ".join(["%.2f%%"%(x*100/len(ring_node_list)) for x in num_changes]))
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print("1-node removal: partitions moved on 0/1/2/3 nodes: ", " ".join(["%.2f%%"%(x*100/len(nodes)) for x in num_changes_sum]))
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if __name__ == "__main__":
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print("------")
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print("method 1 (standard ring)")
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nodes = [('digitale', 'atuin', 64),
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('drosera', 'atuin', 64),
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('datura', 'atuin', 64),
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('io', 'jupiter', 128)]
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nodes2 = [('digitale', 'atuin', 64),
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('drosera', 'atuin', 64),
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('datura', 'atuin', 64),
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('io', 'jupiter', 128),
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('isou', 'jupiter', 64),
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('mini', 'grog', 32),
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('mixi', 'grog', 32),
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('moxi', 'grog', 32),
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('modi', 'grog', 32),
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('geant', 'grisou', 128),
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('gipsie', 'grisou', 128),
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]
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evaluate_method(method1, nodes2)
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print("------")
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print("method 2 (custom ring)")
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nodes = [('digitale', 'atuin', 4),
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('drosera', 'atuin', 4),
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('datura', 'atuin', 4),
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('io', 'jupiter', 8)]
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nodes2 = [('digitale', 'atuin', 8),
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('drosera', 'atuin', 8),
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('datura', 'atuin', 8),
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('io', 'jupiter', 16),
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('isou', 'jupiter', 8),
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('mini', 'grog', 4),
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('mixi', 'grog', 4),
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('moxi', 'grog', 4),
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('modi', 'grog', 4),
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('geant', 'grisou', 16),
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('gipsie', 'grisou', 16),
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]
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evaluate_method(method2, nodes2)
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print("------")
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print("method 3 (maglev)")
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evaluate_method(method3, nodes2)
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print("------")
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print("method 4 (maglev, multi-dc twist)")
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evaluate_method(method4, nodes2)
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