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Posted to commits@couchdb.apache.org by rn...@apache.org on 2014/08/01 11:11:23 UTC
[37/48] mem3 commit: updated refs/heads/windsor-merge to ff02b9a
Stop donating once the target level is achieved
Also switched to a record accumulator for clarity.
BugzID: 24466
Project: http://git-wip-us.apache.org/repos/asf/couchdb-mem3/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb-mem3/commit/5ec7d044
Tree: http://git-wip-us.apache.org/repos/asf/couchdb-mem3/tree/5ec7d044
Diff: http://git-wip-us.apache.org/repos/asf/couchdb-mem3/diff/5ec7d044
Branch: refs/heads/windsor-merge
Commit: 5ec7d0440ea9b4c63e7b35e365380109a108b0c8
Parents: 51838ca
Author: Adam Kocoloski <ad...@cloudant.com>
Authored: Wed Oct 30 11:53:22 2013 -0400
Committer: Robert Newson <rn...@apache.org>
Committed: Wed Jul 23 18:46:27 2014 +0100
----------------------------------------------------------------------
src/mem3_rebalance.erl | 48 +++++++++++++++++++++++++++++++++------------
1 file changed, 36 insertions(+), 12 deletions(-)
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http://git-wip-us.apache.org/repos/asf/couchdb-mem3/blob/5ec7d044/src/mem3_rebalance.erl
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diff --git a/src/mem3_rebalance.erl b/src/mem3_rebalance.erl
index af050f6..234cad2 100644
--- a/src/mem3_rebalance.erl
+++ b/src/mem3_rebalance.erl
@@ -35,6 +35,14 @@
-include("mem3.hrl").
+-record (gacc, {
+ node,
+ targets,
+ moves,
+ limit,
+ target_level
+}).
+
%% @equiv expand(1000)
-spec expand() -> [{atom(), #shard{}, node()}].
expand() ->
@@ -137,11 +145,15 @@ global_expand(TargetNodes0, LocalOps, Limit) ->
Acc;
({Node0, Count}, Acc) ->
Node = list_to_existing_atom(binary_to_list(Node0)),
- % Compute the max number of shards to donate.
- DC0 = erlang:min(Count - TargetLevel, Limit - length(Acc)),
- InternalAcc0 = {Node, TargetNodes0, Acc, DC0},
+ InternalAcc0 = #gacc{
+ node = Node,
+ targets = TargetNodes0,
+ moves = Acc,
+ limit = erlang:min(Count - TargetLevel, Limit - length(Acc)),
+ target_level = TargetLevel
+ },
try mem3_shards:fold(fun donate_fold/2, InternalAcc0) of
- {_, _, Moves, _} ->
+ #gacc{moves = Moves} ->
Moves
catch
{complete, Moves} ->
@@ -150,9 +162,15 @@ global_expand(TargetNodes0, LocalOps, Limit) ->
end,
lists:foldl(FoldFun, LocalOps, CountByNode).
-donate_fold(_Shard, {_, _, Moves, 0}) ->
+donate_fold(_Shard, #gacc{limit = 0, moves = Moves}) ->
throw({complete, Moves});
-donate_fold(#shard{node = Node} = Shard, {Node, Nodes, Moves, DC}) ->
+donate_fold(#shard{node = Node} = Shard, #gacc{node = Node} = Acc0) ->
+ #gacc{
+ targets = Nodes,
+ moves = Moves,
+ limit = DC,
+ target_level = TargetLevel
+ } = Acc0,
Zone = mem3:node_info(Node, <<"zone">>),
Shards = apply_shard_moves(mem3:shards(Shard#shard.dbname), Moves),
InZone = filter_map_by_zone(shards_by_node(Shards, Nodes), Zone),
@@ -162,21 +180,27 @@ donate_fold(#shard{node = Node} = Shard, {Node, Nodes, Moves, DC}) ->
end, SortedByCount),
case {lists:member(Shard, Shards), Candidates} of
{false, _} ->
- {Node, Nodes, Moves, DC};
+ Acc0;
{true, []} ->
- {Node, Nodes, Moves, DC};
+ Acc0;
{true, [{Node, _} | _]} ->
- {Node, Nodes, Moves, DC};
+ Acc0;
{true, [{Target, _} | _]} ->
% Execute the move only if the target has fewer shards for this DB
% than the source. Otherwise we'd generate a local imbalance.
SourceCount = get_shard_count(Node, SortedByCount),
TargetCount = get_shard_count(Target, SortedByCount),
- if TargetCount < SourceCount ->
+ % Execute the move only if the target needs shards.
+ NodeKey = couch_util:to_binary(Target),
+ Total = couch_util:get_value(NodeKey, shard_count_by_node(Moves)),
+ if (TargetCount < SourceCount), (Total < TargetLevel) ->
print({move, Shard, Target}),
- {Node, Nodes, [{move, Shard, Target} | Moves], DC - 1};
+ Acc0#gacc{
+ moves = [{move, Shard, Target} | Moves],
+ limit = DC - 1
+ };
true ->
- {Node, Nodes, Moves, DC}
+ Acc0
end
end;
donate_fold(_Shard, Acc) ->