openstack/deb-python-cassandra-driver
Code Issues Proposed changes

avoid quadratic token processing for RF > nodes

Browse Source 
PYTHON-379
This commit is contained in:
Adam Holmberg
2016-08-08 14:14:49 -05:00
parent d244ece986
commit f29150482a
1 changed files with 7 additions and 3 deletions
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10
cassandra/metadata.py
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@@ -469,8 +469,6 @@ class NetworkTopologyStrategy(ReplicationStrategy):
(str(k), int(v)) for k, v in dc_replication_factors.items())
def make_token_replica_map(self, token_to_host_owner, ring):
# note: this does not account for hosts having different racks
replica_map = defaultdict(list)
dc_rf_map = dict((dc, int(rf))
for dc, rf in self.dc_replication_factors.items() if rf > 0)
@@ -478,16 +476,19 @@ class NetworkTopologyStrategy(ReplicationStrategy):
# belong to that DC
dc_to_token_offset = defaultdict(list)
dc_racks = defaultdict(set)
hosts_per_dc = defaultdict(set)
for i, token in enumerate(ring):
host = token_to_host_owner[token]
dc_to_token_offset[host.datacenter].append(i)
if host.datacenter and host.rack:
dc_racks[host.datacenter].add(host.rack)
hosts_per_dc[host.datacenter].add(host)
# A map of DCs to an index into the dc_to_token_offset value for that dc.
# This is how we keep track of advancing around the ring for each DC.
dc_to_current_index = defaultdict(int)
replica_map = defaultdict(list)
for i in range(len(ring)):
replicas = replica_map[ring[i]]
@@ -506,12 +507,14 @@ class NetworkTopologyStrategy(ReplicationStrategy):
dc_to_current_index[dc] = index
replicas_remaining = dc_rf_map[dc]
replicas_this_dc = 0
skipped_hosts = []
racks_placed = set()
racks_this_dc = dc_racks[dc]
hosts_this_dc = len(hosts_per_dc[dc])
for token_offset in islice(cycle(token_offsets), index, index + num_tokens):
host = token_to_host_owner[ring[token_offset]]
if replicas_remaining == 0:
if replicas_remaining == 0 or replicas_this_dc == hosts_this_dc:
break
if host in replicas:
@@ -522,6 +525,7 @@ class NetworkTopologyStrategy(ReplicationStrategy):
continue
replicas.append(host)
replicas_this_dc += 1
replicas_remaining -= 1
racks_placed.add(host.rack)