riak / src / riak_vnode_sidekick.erl

justin 1c37b76 










































Andy Gross 8d96d21 
justin 1c37b76 

Andy Gross 8d96d21 
justin 1c37b76 

















Andy Gross 8d96d21 
justin 1c37b76 

Andy Gross 8d96d21 
justin 1c37b76 

Andy Gross 8d96d21 
justin 1c37b76 










Andy Gross 8d96d21 
justin 1c37b76 


















%% 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_vnode_sidekick).
-behaviour(gen_fsm).

-export([start/2]).
-export([init/1, handle_event/3, handle_sync_event/4,
         handle_info/3, terminate/3, code_change/4]).
-export([home/2,not_home/2]).

-define(TIMEOUT, 60000).     % poll time for normal operation
-define(LONGTIMEOUT, 120000). % if a vnode-merkle exchange in progress

-record(state, {vnode,idx,counter}).

% The vnode sidekick notices when a vnode is not "home"
% (when it is serving as an imperfect recipient of puts)
% and if it is not home and the home node is reachable,
% the sidekick initiates handoff.

start(VNode,Idx) ->
    gen_fsm:start(?MODULE, [VNode,Idx], []).
init([VNode,Idx]) ->
    StateData = #state{vnode=VNode,idx=Idx,counter=0},
    {ok,home,StateData,?TIMEOUT}.

home(timeout, StateData=#state{vnode=VNode,idx=Idx,counter=Count}) ->
    {ok, MyRing} = riak_ring_manager:get_my_ring(),
    Me = node(),
    case riak_ring:index_owner(MyRing, Idx) of
        Me ->
            gen_server2:cast(VNode, activate),
            case Count > 9 of
                true ->
                    gen_server2:cast(VNode, cache_purge),
                    {next_state,home,StateData#state{counter=0},?TIMEOUT};
                false ->
                    {next_state,home,StateData#state{counter=Count+1},?TIMEOUT}
            end;
        _ ->
            {next_state,not_home,StateData,1}
    end.

not_home(timeout, StateData=#state{vnode=VNode,idx=Idx}) ->
    {ok, MyRing} = riak_ring_manager:get_my_ring(),
    TargetNode = riak_ring:index_owner(MyRing, Idx),
    Me = node(),
    case TargetNode of % just in case we took ownership
        Me -> {next_state,home,StateData,?TIMEOUT}; 
        _ -> 
            case net_adm:ping(TargetNode) of
                pang -> {next_state,not_home,StateData,?TIMEOUT};
                pong ->
                    ObjList = gen_server2:call(VNode, list, 60000),
                    case ObjList of
                        [] ->
                            gen_server2:cast(VNode, {rexit, "sidekick"}),
                            {next_state,not_home,StateData,?LONGTIMEOUT};
                        _ -> 
                            gen_server2:cast(VNode, deactivate),
                            Merk = make_merk(VNode, Idx, ObjList),
                            gen_server:cast({riak_vnode_master, TargetNode},
                                            {vnode_merkle, {VNode,Idx,Merk}}),
                            {next_state,not_home,StateData,?LONGTIMEOUT}
                    end
            end
    end.

make_merk(VNode, Idx, ObjList) ->
    riak_eventer:notify(riak_vnode_sidekick, merkle_prep, Idx),
    merkerl:build_tree([{K,crypto:sha(V)} || {K,{ok,V}} <- 
                        [{K,gen_server2:call(VNode, {get_binary, K})} ||
                           K <- ObjList]]).

%% @private
code_change(_OldVsn, StateName, State, _Extra) -> {ok, StateName, State}.

%% @private
handle_event(_Event, _StateName, StateData) ->
    {stop,badmsg,StateData}.

%% @private
handle_sync_event(_Event, _From, _StateName, StateData) ->
    {stop,badmsg,StateData}.

%% @private
handle_info(vnode_shutdown, _StateName, StateData) ->
    {stop,normal,StateData}.

%% @private
terminate(_Reason, _StateName, _State) -> ok.
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