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riak_ring_gossiper.erl
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riak_ring_gossiper.erl
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%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%% http://www.apache.org/licenses/LICENSE-2.0
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
-module(riak_ring_gossiper).
-export([start_link/0, init/0]).
-export([gossip_to/1, get_ring_from/1, remove_from_cluster/1]).
start_link() -> {ok, spawn_link(node(), ?MODULE, init, [])}.
%% @private
init() ->
register(riak_ring_gossiper, self()),
loop(write).
loop(Write) ->
MaxInterval = case Write of
write -> 600;
no_write -> riak:get_app_env(gossip_interval)
end,
Interval = random:uniform(MaxInterval),
receive
{gossip_ring, ExternRing} ->
{ok, MyRing} = riak_ring_manager:get_my_ring(),
case riak_ring:reconcile(ExternRing, MyRing) of
{no_change, _} ->
loop(Write);
{new_ring, NewRing} ->
riak_ring_manager:set_my_ring(NewRing),
{ok, MyNewRing} = maybe_claim(),
riak_ring_manager:set_my_ring(MyNewRing),
Changed = riak_ring:diff_nodes(MyNewRing, NewRing),
[gossip_to(X) ||
X <- [riak_ring:random_node(MyNewRing)|Changed],
X =/= node()],
riak_eventer:notify(riak_ring_gossiper, changed_ring,
{gossip_changed, length(Changed)}),
loop(write)
end;
{set_ring, ExternRing} ->
riak_eventer:notify(riak_ring_gossiper,
fresh_ring, fresh_ring),
riak_ring_manager:set_my_ring(
riak_ring:fresh_from_extern(ExternRing, node())),
{ok, MyNewRing} = maybe_claim(),
riak_ring_manager:set_my_ring(MyNewRing),
Changed = riak_ring:diff_nodes(MyNewRing, ExternRing),
[gossip_to(X) ||
X <- [riak_ring:random_node(MyNewRing)|Changed],
X =/= node()],
riak_eventer:notify(riak_ring_gossiper, changed_ring,
{set_changed, length(Changed)}),
loop(write);
{get_ring, RemoteNode} ->
set_remote_ring(RemoteNode),
loop(Write)
after Interval ->
riak_eventer:notify(riak_ring_gossiper, interval, interval),
{ok, MyRing} = riak_ring_manager:get_my_ring(),
VNodes2Start = case length(riak_ring:all_members(MyRing)) of
1 -> riak_ring:my_indices(MyRing);
_ -> [riak_ring:random_other_index(MyRing)|
riak_ring:my_indices(MyRing)]
end,
[gen_server:cast({riak_vnode_master, node()},
{start_vnode, I}) || I <- VNodes2Start],
case Write of
no_write -> nop;
write -> riak_ring_manager:write_ringfile()
end,
Me = node(),
case riak_ring:random_node(MyRing) of
Me -> nop;
RandNode -> gossip_to(RandNode)
end,
loop(no_write)
end.
gossip_to(RemoteNode) ->
riak_eventer:notify(riak_ring_gossiper, send, RemoteNode),
{ok, MyRing} = riak_ring_manager:get_my_ring(),
riak_connect:cast(RemoteNode, {gossip_ring, MyRing}).
set_remote_ring(RemoteNode) ->
riak_eventer:notify(riak_ring_gossiper, set_remote_ring, RemoteNode),
{ok, MyRing} = riak_ring_manager:get_my_ring(),
riak_connect:cast(RemoteNode, {set_ring, MyRing}).
get_ring_from(RemoteNode) ->
riak_eventer:notify(riak_ring_gossiper, get_remote_ring, RemoteNode),
riak_connect:cast(RemoteNode, {get_ring, node()}).
maybe_claim() ->
{ok, Ring} = riak_ring_manager:get_my_ring(),
{WMod, WFun} = riak:get_app_env(wants_claim_fun),
case apply(WMod, WFun, [Ring]) of
no -> {ok, Ring};
{yes, Wanted} ->
riak_eventer:notify(riak_ring_gossiper, want_claim, Wanted),
do_claim(Ring, Wanted)
end.
do_claim(Ring,Wanted) ->
case Wanted of
0 -> {ok, Ring};
_ ->
{CMod, CFun} = riak:get_app_env(choose_claim_fun),
do_claim(apply(CMod, CFun, [Ring]), Wanted-1)
end.
remove_from_cluster(ExitingNode) ->
rpc:call(ExitingNode, application, set_env, [riak, wants_claim_fun,
{riak_claim, never_wants_claim}]),
% ignore return of rpc as this should succeed even if node is offline
{ok, Ring} = riak_ring_manager:get_my_ring(),
AllOwners = riak_ring:all_owners(Ring),
AllIndices = [I || {I,_Owner} <- AllOwners],
Indices = [I || {I,Owner} <- AllOwners,
Owner =:= ExitingNode],
riak_eventer:notify(riak_ring_gossiper, remove_from_cluster,
{ExitingNode, length(Indices)}),
Others = lists:delete(ExitingNode, riak_ring:all_members(Ring)),
ExitRing = lists:foldl(
fun(I,R) ->
riak_ring:transfer_node(I,
lists:nth(crypto:rand_uniform(1,length(Others)+1),Others),R) end,
Ring, Indices),
riak_ring_manager:set_my_ring(ExitRing),
[gossip_to(X) || X <- Others],
[gen_server:cast({riak_vnode_master, ExitingNode}, {start_vnode, P}) ||
P <- AllIndices].