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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (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.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
%% License for the specific language governing rights and limitations
%% under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developers of the Original Code are LShift Ltd,
%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
%% Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created by LShift Ltd are Copyright (C) 2007-2010 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2010 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(delegate).
-define(DELEGATE_PROCESS_COUNT_MULTIPLIER, 2).
-behaviour(gen_server2).
-export([start_link/1, invoke_async/2, invoke/2,
server/1, process_count/0]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-spec(start_link/1 :: (non_neg_integer()) -> {'ok', pid()}).
-spec(invoke_async/2 :: (pid() | [pid()], fun((pid()) -> any())) -> 'ok').
-spec(invoke/2 :: (pid() | [pid()], fun((pid()) -> A)) -> A).
-spec(server/1 :: (node() | non_neg_integer()) -> atom()).
-spec(process_count/0 :: () -> non_neg_integer()).
-endif.
%%----------------------------------------------------------------------------
start_link(Hash) ->
gen_server2:start_link({local, server(Hash)},
?MODULE, [], []).
invoke(Pid, FPid) when is_pid(Pid) ->
[{Status, Res, _}] = invoke_per_node([{node(Pid), [Pid]}], FPid),
{Status, Res};
invoke(Pids, FPid) when is_list(Pids) ->
invoke_per_node(split_delegate_per_node(Pids), FPid).
invoke_async(Pid, FPid) when is_pid(Pid) ->
invoke_async_per_node([{node(Pid), [Pid]}], FPid),
ok;
invoke_async(Pids, FPid) when is_list(Pids) ->
invoke_async_per_node(split_delegate_per_node(Pids), FPid),
ok.
%%----------------------------------------------------------------------------
internal_call(Node, Thunk) when is_atom(Node) ->
gen_server2:call({server(Node), Node}, {thunk, Thunk}, infinity).
internal_cast(Node, Thunk) when is_atom(Node) ->
gen_server2:cast({server(Node), Node}, {thunk, Thunk}).
split_delegate_per_node(Pids) ->
orddict:to_list(
lists:foldl(
fun (Pid, D) ->
orddict:update(node(Pid),
fun (Pids1) -> [Pid | Pids1] end,
[Pid], D)
end,
orddict:new(), Pids)).
invoke_per_node([{Node, Pids}], FPid) when Node == node() ->
local_delegate(Pids, FPid);
invoke_per_node(NodePids, FPid) ->
lists:append(delegate_per_node(NodePids, FPid, fun internal_call/2)).
invoke_async_per_node([{Node, Pids}], FPid) when Node == node() ->
local_delegate(Pids, FPid);
invoke_async_per_node(NodePids, FPid) ->
delegate_per_node(NodePids, FPid, fun internal_cast/2),
ok.
local_delegate(Pids, FPid) ->
[safe_invoke(FPid, Pid) || Pid <- Pids].
delegate_per_node(NodePids, FPid, DelegateFun) ->
Self = self(),
[spawn(fun() ->
Self ! {result, DelegateFun(Node,
fun() -> local_delegate(Pids, FPid) end)}
end) || {Node, Pids} <- NodePids],
gather_results([], length(NodePids)).
gather_results(ResultsAcc, 0) ->
ResultsAcc;
gather_results(ResultsAcc, ToGo) ->
receive {result, Result} ->
gather_results([Result | ResultsAcc], ToGo - 1)
end.
server(Node) when is_atom(Node) ->
case get({delegate_server_name, Node}) of
undefined ->
case rpc:call(Node, delegate, process_count, []) of
{badrpc, _} ->
delegate_process_1; % Have to return something, if we're
% just casting then we don't want to
% blow up
Count ->
Name = server(erlang:phash2(self(), Count)),
put({delegate_server_name, Node}, Name),
Name
end;
Name -> Name
end;
server(Hash) ->
list_to_atom("delegate_process_" ++ integer_to_list(Hash)).
safe_invoke(FPid, Pid) ->
% We need the catch here for the local case. In the remote case there will
% already have been a catch in handle_ca{ll,st} below, but that's OK, catch
% is idempotent.
case catch FPid(Pid) of
{'EXIT', Reason} ->
{error, {'EXIT', Reason}, Pid};
Result ->
{ok, Result, Pid}
end.
process_count() ->
?DELEGATE_PROCESS_COUNT_MULTIPLIER * erlang:system_info(schedulers).
%%--------------------------------------------------------------------
init([]) ->
{ok, no_state}.
handle_call({thunk, Thunk}, _From, State) ->
{reply, catch Thunk(), State}.
handle_cast({thunk, Thunk}, State) ->
catch Thunk(),
{noreply, State}.
handle_info(_Info, State) ->
{noreply, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%--------------------------------------------------------------------
|
