Created
July 8, 2010 17:52
-
-
Save seanlynch/468357 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
%% @author Northscale <info@northscale.com> | |
%% @copyright 2009 NorthScale, Inc. | |
%% | |
%% Licensed 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(ns_pubsub). | |
-behaviour(gen_event). | |
-record(state, {func, func_state}). | |
-record(subscribe_all_state, {noderefs, name, func, func_state}). | |
-export([code_change/3, init/1, handle_call/2, handle_event/2, handle_info/2, | |
terminate/2]). | |
-export([subscribe/2, subscribe/3, | |
subscribe_all/2, subscribe_all/3, | |
unsubscribe/2, unsubscribe_all/1]). | |
%% | |
%% API | |
%% | |
subscribe(Name, Pid) when is_pid(Pid) -> | |
subscribe(Name, msg_fun(Pid), ignored). | |
subscribe(Name, Fun, State) -> | |
Ref = make_ref(), | |
ok = gen_event:add_sup_handler(Name, {?MODULE, Ref}, | |
#state{func=Fun, func_state=State}), | |
Ref. | |
%% Subscribe to the same event on all nodes | |
subscribe_all(Name, Pid) when is_pid(Pid) -> | |
subscribe_all(Name, msg_fun(Pid), ignored). | |
subscribe_all(Name, Fun, State) -> | |
Ref = make_ref(), | |
ok = gen_event:add_sup_handler(ns_node_disco_events, {?MODULE, Ref}, | |
#subscribe_all_state{noderefs=[], name=Name, | |
func=Fun, | |
func_state=State}), | |
ok = gen_event:call(ns_node_disco_events, {?MODULE, Ref}, | |
{init_nodes, ns_node_disco:nodes_actual_proper()}), | |
Ref. | |
unsubscribe(Name, Ref) -> | |
gen_event:delete_handler(Name, {?MODULE, Ref}, unsubscribed). | |
%% We don't need the name for this because it's in the state of the | |
%% handler installed on ns_node_disco_events | |
unsubscribe_all(Ref) -> | |
gen_event:delete_handler(ns_node_disco_events, {?MODULE, Ref}, | |
unsubscribed). | |
%% | |
%% gen_event callbacks | |
%% | |
code_change(_OldVsn, State, _Extra) -> | |
{ok, State}. | |
init(State) -> | |
{ok, State}. | |
%% Only set initial nodes if we haven't yet received an event | |
handle_call({init_nodes, Nodes}, State = #subscribe_all_state{noderefs=[]}) -> | |
NodeRefs = [{Node, subscribe_node(Node, State)} || Node <- Nodes], | |
{ok, ok, State#subscribe_all_state{noderefs=NodeRefs}}; | |
handle_call({init_nodes, _}, State = #subscribe_all_state{noderefs=[_|_]}) -> | |
{ok, ok, State}. | |
handle_event(Event, State = #state{func=Fun, func_state=FS}) -> | |
NewState = Fun(Event, FS), | |
{ok, State#state{func_state=NewState}}; | |
handle_event({ns_node_disco_events, _OldNodes, Nodes}, | |
State = #subscribe_all_state{noderefs=NodeRefs}) -> | |
NewNodeRefs = [{N, subscribe_node(N, State)} || | |
N <- Nodes, not lists:keymember(N, 1, NodeRefs)], | |
KeepNodeRefs = [NR || NR = {N, _} <- NodeRefs, not lists:member(N, Nodes)], | |
{ok, State#subscribe_all_state{noderefs=NewNodeRefs ++ KeepNodeRefs}}. | |
handle_info(_Msg, State) -> | |
{ok, State}. | |
terminate(Reason, #subscribe_all_state{noderefs=NodeRefs, name=Name}) -> | |
error_logger:info_msg("~p removing subscribe_all handler ~p: ~p~n", | |
[?MODULE, Name, Reason]), | |
lists:foreach(fun ({Node, Ref}) -> | |
unsubscribe({Name, Node}, Ref) | |
end, NodeRefs); | |
terminate(Reason, State) -> | |
error_logger:info_msg("~p unsubscribed ~p: ~p~n", [?MODULE, State, Reason]). | |
%% | |
%% Internal functions | |
%% | |
%% Function sending a message to a pid | |
msg_fun(Pid) -> | |
fun (Event, State) -> | |
Pid ! Event, | |
State | |
end. | |
subscribe_node(Node, #subscribe_all_state{name=Name, func=Fun, | |
func_state=FState}) -> | |
subscribe({Name, Node}, Fun, FState). |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
%% @author Northscale <info@northscale.com> | |
%% @copyright 2009 NorthScale, Inc. | |
%% | |
%% Licensed 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. | |
%% | |
%% Centralized time service | |
-module(ns_tick). | |
-behaviour(gen_server). | |
-define(EVENT_MANAGER, ns_tick_event). | |
-define(INTERVAL, 1000). | |
-define(SERVER, ?MODULE). | |
-export([start_link/0]). | |
-export([code_change/3, handle_call/3, handle_cast/2, handle_info/2, init/1, | |
terminate/2]). | |
-export([tick/1]). % used internally via rpc | |
-record(state, {time}). | |
%% | |
%% API | |
%% | |
start_link() -> | |
misc:start_singleton_gen_server(?MODULE, [], []). | |
%% | |
%% gen_server callbacks | |
%% | |
code_change(_OldVsn, State, _Extra) -> | |
{ok, State}. | |
init([]) -> | |
timer:send_interval(?INTERVAL, tick), | |
{ok, #state{}}. | |
handle_call(unhandled, unhandled, unhandled) -> | |
unhandled. | |
handle_cast(unhandled, unhandled) -> | |
unhandled. | |
%% Called once per second on the node where the gen_server runs | |
handle_info(tick, State) -> | |
Now = erlang:now(), | |
rpc:eval_everywere(?MODULE, tick, [Now]), | |
{noreply, State#state{time=Now}}. | |
terminate(_Reason, _State) -> | |
ok. | |
%% | |
%% Internal functions | |
%% | |
%% Called on all nodes via RPC to send an event to the local event manager | |
tick(Now) -> | |
gen_event:notify(?EVENT_MANAGER, {tick, Now}). |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment