Fixup _sort_server_list to be slightly more efficient

Also document that we are using the algorithm described in RFC2782 and
ensure we handle zero weight correctly.
This commit is contained in:
Erik Johnston 2019-08-20 11:49:44 +01:00
parent 7777d353bf
commit 1f9df1cc7b
1 changed files with 11 additions and 2 deletions

View File

@ -94,10 +94,18 @@ def _sort_server_list(server_list):
results = []
for priority in sorted(priority_map):
servers = priority_map.pop(priority)
servers = priority_map[priority]
# This algorithms follows the algorithm described in RFC2782.
#
# N.B. Weights can be zero, which means that you should pick that server
# last *or* that its the only server in this priority.
# We sort to ensure zero weighted items are first.
servers.sort(key=lambda s: s.weight)
total_weight = sum(s.weight for s in servers)
while servers:
total_weight = sum(s.weight for s in servers)
target_weight = random.randint(0, total_weight)
for s in servers:
@ -108,6 +116,7 @@ def _sort_server_list(server_list):
results.append(s)
servers.remove(s)
total_weight -= s.weight
return results