| Author |
Message |
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| mlogan at futuresource.co |
 Posted: Thu Sep 02, 2004 7:04 pm |
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Guest
|
Is it possible to have multiple nodes on a single machine listening for
the same multicast packets at the same time? How can this be
accomplished within erts?
Cheers,
Martin
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| kramer at acm.org |
| Posted: Thu Sep 02, 2004 7:39 pm |
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Guest
|
The following works on the OSX and Linux for me. I had trouble opening
the multicast socket on WinXP, but no patience to figure out the cause.
cheers,
- Reto
Open a multicast port with:
Res = gen_udp:open(get_port(), [binary,
{reuseaddr,true},
{ip,get_addr()},
{multicast_loop,true},
{add_membership,{get_addr(),
{0,0,0,0}}}]),
where
get_addr() ->
{ok, App} = application:get_application(),
case application:get_env(App, addr) of
{ok, Val} ->
Val;
undefined ->
?ADDR
end.
get_port() -> ...
and the env key of the .app file is
{env, [{addr, {239,0,0,1}}, % the multicast ip addr
{port, 10042}, % the port we multicast at
{period, 1000}]}, % heartbeat interval in ms
Send packets with
Packet = {node_name, node()},
ok = gen_udp:send(State#state.socket,
get_addr(),
get_port(),
term_to_binary(Packet)),
and receive packets like this:
receive
{udp, Socket, IP, InPortNo, Packet} ->
{node_name, Node} = binary_to_term(Packet),
#
On Sep 2, 2004, at 12:03 PM, Martin J. Logan wrote:
> Is it possible to have multiple nodes on a single machine listening for
> the same multicast packets at the same time? How can this be
> accomplished within erts?
>
> Cheers,
> Martin
>
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| kramer at acm.org |
| Posted: Fri Sep 03, 2004 1:59 am |
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Guest
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[ups, sent this from wrong account initially]
Martin,
Here's a complete testcase that you can run locally. It's a dumbed down
version of a larget app.
Compile this file and then run it in two terminals with:
erl -sname foo -s discover_server run
erl -sname bar -s discover_server run
Each node (foo and bar) will send numbered heartbeats to the multicast
address and each one will pick up it's own packets as well as packets
send by the other node.
(foo_at_yoghurt)1> Running for 5 minutes.
received packet 1 from node foo_at_yoghurt
received packet 2 from node foo_at_yoghurt
received packet 1 from node bar_at_yoghurt
received packet 3 from node foo_at_yoghurt
received packet 2 from node bar_at_yoghurt
received packet 4 from node foo_at_yoghurt
received packet 3 from node bar_at_yoghurt
received packet 5 from node foo_at_yoghurt
(bar_at_yoghurt)1> Running for 5 minutes.
received packet 2 from node foo_at_yoghurt
received packet 1 from node bar_at_yoghurt
received packet 3 from node foo_at_yoghurt
received packet 2 from node bar_at_yoghurt
received packet 4 from node foo_at_yoghurt
received packet 3 from node bar_at_yoghurt
This is running on one OSX box. E.g. foo picks up it's own heartbeat
2, and bar picks up that same packet (foo's heartbeat 2) as well. So
here they are not eating each others packets, but each process sees the
same packets.
Run it to see what you'll get on your setup.
cheers,
- Reto
%%%-------------------------------------------------------------------
%%% File : discover_server.erl
%%% Author : reto <kramer_at_acm.org>
%%% Description : Basic multicast based heart-beating
%%%-------------------------------------------------------------------
-module(discover_server).
-behaviour(gen_server).
%%--------------------------------------------------------------------
%% Include files
%%--------------------------------------------------------------------
%%--------------------------------------------------------------------
%% External exports
-export([start_link/0]).
-export([run/0]).
-export([trigger_heartbeat/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-record(state, {socket, % multicast udp socket
nodes, % set of nodes (atoms)
send_timer, % timer used to send heartbeats
counter
}).
-define(HB_PERIOD_MS, 1000). % (if not in .app) default hb interval
-define(ADDR, {239,0,42,1}). % (if not in .app) default addr
-define(PORT, 10042). % (if not in .app) default port
-define(SERVER, ?MODULE).
%%====================================================================
%% External functions
%%====================================================================
%%--------------------------------------------------------------------
%% Function: start_link/0
%% Description: Starts the server
%%--------------------------------------------------------------------
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%%====================================================================
%% Server functions
%%====================================================================
%%--------------------------------------------------------------------
%% Function: init/1
%% Description: Initiates the server
%% Returns: {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%%--------------------------------------------------------------------
init([]) ->
process_flag(trap_exit, true),
{ok, Socket} = gen_udp:open(get_port(), [binary,
{reuseaddr,true},
{ip,get_addr()},
{multicast_loop,true},
{add_membership,{get_addr(),
{0,0,0,0}}}]),
% net_kernel:monitor_nodes(true),
{ok, TRef} = timer:apply_interval(get_period(),
?MODULE, trigger_heartbeat, []),
{ok, #state{socket=Socket,
nodes=sets:new(),
send_timer=TRef,
counter=1}}.
%%--------------------------------------------------------------------
%% Function: handle_call/3
%% Description: Handling call messages
%% Returns: {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} | (terminate/2 is called)
%% {stop, Reason, State} (terminate/2 is called)
%%--------------------------------------------------------------------
handle_call(Request, From, State) ->
Reply = ok,
{reply, Reply, State}.
%%--------------------------------------------------------------------
%% Function: handle_cast/2
%% Description: Handling cast messages
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%--------------------------------------------------------------------
handle_cast({send_heartbeat}, State) ->
send_heartbeat(State),
NewState = State#state{counter = State#state.counter + 1},
{noreply, NewState};
handle_cast(Msg, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: handle_info/2
%% Description: Handling all non call/cast messages
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%--------------------------------------------------------------------
handle_info({udp, Socket, IP, InPortNo, Packet}, State) ->
{node_name, Node,
counter, Counter} = binary_to_term(Packet),
io:format("received packet ~p from node ~p~n",[Counter, Node]),
{noreply, State};
handle_info(Info, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: terminate/2
%% Description: Shutdown the server
%% Returns: any (ignored by gen_server)
%%--------------------------------------------------------------------
terminate(Reason, State) ->
ok.
%%--------------------------------------------------------------------
%% Func: code_change/3
%% Purpose: Convert process state when code is changed
%% Returns: {ok, NewState}
%%--------------------------------------------------------------------
code_change(OldVsn, State, Extra) ->
{ok, State}.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
trigger_heartbeat() ->
gen_server:cast(?SERVER, {send_heartbeat}).
send_heartbeat(State) ->
Packet = {node_name, node(),
counter, State#state.counter},
ok = gen_udp:send(State#state.socket,
get_addr(),
get_port(),
term_to_binary(Packet)).
get_addr() ->
case application:get_application() of
undefined ->
?ADDR;
{ok, App} ->
case application:get_env(App, addr) of
undefined ->
?ADDR;
{ok, Val} ->
Val
end
end.
get_port() ->
case application:get_application() of
undefined ->
?PORT;
{ok, App} ->
case application:get_env(App, port) of
undefined ->
?PORT;
{ok, Val} ->
Val
end
end.
get_period() ->
case application:get_application() of
undefined ->
?HB_PERIOD_MS;
{ok, App} ->
case application:get_env(App, period) of
undefined ->
?HB_PERIOD_MS;
{ok, Val} ->
Val
end
end.
%%--------------------------------------------------------------------
%%% debug functions
%%--------------------------------------------------------------------
run() ->
{ok, Pid} = ?MODULE:start_link(),
io:format("Running for 5 minutes.~n",[]),
timer:sleep(5*60*1000),
io:format("done.~n",[]).
#
On Sep 2, 2004, at 12:39 PM, Reto Kramer wrote:
> The following works on the OSX and Linux for me. I had trouble
> opening the multicast socket on WinXP, but no patience to figure out
> the cause.
>
> cheers,
> - Reto
>
> Open a multicast port with:
> Res = gen_udp:open(get_port(), [binary,
> {reuseaddr,true},
> {ip,get_addr()},
> {multicast_loop,true},
> {add_membership,{get_addr(),
> {0,0,0,0}}}]),
>
> where
> get_addr() ->
> {ok, App} = application:get_application(),
> case application:get_env(App, addr) of
> {ok, Val} ->
> Val;
> undefined ->
> ?ADDR
> end.
> get_port() -> ...
>
> and the env key of the .app file is
> {env, [{addr, {239,0,0,1}}, % the multicast ip addr
> {port, 10042}, % the port we multicast at
> {period, 1000}]}, % heartbeat interval in ms
>
> Send packets with
> Packet = {node_name, node()},
> ok = gen_udp:send(State#state.socket,
> get_addr(),
> get_port(),
> term_to_binary(Packet)),
>
> and receive packets like this:
> receive
> {udp, Socket, IP, InPortNo, Packet} ->
> {node_name, Node} = binary_to_term(Packet),
>
> #
>
> On Sep 2, 2004, at 12:03 PM, Martin J. Logan wrote:
>
>> Is it possible to have multiple nodes on a single machine listening
>> for
>> the same multicast packets at the same time? How can this be
>> accomplished within erts?
>>
>> Cheers,
>> Martin
>>
>
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| mlogan at futuresource.co |
| Posted: Fri Sep 03, 2004 2:46 pm |
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Guest
|
Reto, again thank you very much for the help. I am not sure what is
going on but on my machine, running Fedora Core 2 kernel 2.4.20-8, the
nodes eat eachothers packets.
received packet 1 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 2 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 3 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 4 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 5 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 6 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 7 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 8 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 9 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 10 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 1 from node 'foo_at_dhcp-lom-194-186.futuresource.com'
received packet 11 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 2 from node 'foo_at_dhcp-lom-194-186.futuresource.com'
received packet 12 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 3 from node 'foo_at_dhcp-lom-194-186.futuresource.com'
received packet 13 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
received packet 4 from node 'foo_at_dhcp-lom-194-186.futuresource.com'
received packet 14 from node 'bar_at_dhcp-lom-194-186.futuresource.com'
Once the second node foo starts receiving packets then bar stops.
Strange...
Martin
On Thu, 2004-09-02 at 20:58, Reto Kramer wrote:
> [ups, sent this from wrong account initially]
>
> Martin,
>
> Here's a complete testcase that you can run locally. It's a dumbed down
> version of a larget app.
>
> Compile this file and then run it in two terminals with:
>
> erl -sname foo -s discover_server run
> erl -sname bar -s discover_server run
>
> Each node (foo and bar) will send numbered heartbeats to the multicast
> address and each one will pick up it's own packets as well as packets
> send by the other node.
>
> (foo_at_yoghurt)1> Running for 5 minutes.
> received packet 1 from node foo_at_yoghurt
> received packet 2 from node foo_at_yoghurt
> received packet 1 from node bar_at_yoghurt
> received packet 3 from node foo_at_yoghurt
> received packet 2 from node bar_at_yoghurt
> received packet 4 from node foo_at_yoghurt
> received packet 3 from node bar_at_yoghurt
> received packet 5 from node foo_at_yoghurt
>
> (bar_at_yoghurt)1> Running for 5 minutes.
> received packet 2 from node foo_at_yoghurt
> received packet 1 from node bar_at_yoghurt
> received packet 3 from node foo_at_yoghurt
> received packet 2 from node bar_at_yoghurt
> received packet 4 from node foo_at_yoghurt
> received packet 3 from node bar_at_yoghurt
>
> This is running on one OSX box. E.g. foo picks up it's own heartbeat
> 2, and bar picks up that same packet (foo's heartbeat 2) as well. So
> here they are not eating each others packets, but each process sees the
> same packets.
>
> Run it to see what you'll get on your setup.
>
> cheers,
> - Reto
>
> %%%-------------------------------------------------------------------
> %%% File : discover_server.erl
> %%% Author : reto <kramer_at_acm.org>
> %%% Description : Basic multicast based heart-beating
> %%%-------------------------------------------------------------------
> -module(discover_server).
>
> -behaviour(gen_server).
> %%--------------------------------------------------------------------
> %% Include files
> %%--------------------------------------------------------------------
>
> %%--------------------------------------------------------------------
> %% External exports
> -export([start_link/0]).
>
> -export([run/0]).
>
> -export([trigger_heartbeat/0]).
>
> %% gen_server callbacks
> -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
> terminate/2, code_change/3]).
>
> -record(state, {socket, % multicast udp socket
> nodes, % set of nodes (atoms)
> send_timer, % timer used to send heartbeats
> counter
> }).
>
> -define(HB_PERIOD_MS, 1000). % (if not in .app) default hb interval
> -define(ADDR, {239,0,42,1}). % (if not in .app) default addr
> -define(PORT, 10042). % (if not in .app) default port
>
> -define(SERVER, ?MODULE).
>
> %%====================================================================
> %% External functions
> %%====================================================================
> %%--------------------------------------------------------------------
> %% Function: start_link/0
> %% Description: Starts the server
> %%--------------------------------------------------------------------
> start_link() ->
> gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
>
> %%====================================================================
> %% Server functions
> %%====================================================================
>
> %%--------------------------------------------------------------------
> %% Function: init/1
> %% Description: Initiates the server
> %% Returns: {ok, State} |
> %% {ok, State, Timeout} |
> %% ignore |
> %% {stop, Reason}
> %%--------------------------------------------------------------------
> init([]) ->
> process_flag(trap_exit, true),
> {ok, Socket} = gen_udp:open(get_port(), [binary,
> {reuseaddr,true},
> {ip,get_addr()},
> {multicast_loop,true},
> {add_membership,{get_addr(),
> {0,0,0,0}}}]),
> % net_kernel:monitor_nodes(true),
> {ok, TRef} = timer:apply_interval(get_period(),
> ?MODULE, trigger_heartbeat, []),
> {ok, #state{socket=Socket,
> nodes=sets:new(),
> send_timer=TRef,
> counter=1}}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_call/3
> %% Description: Handling call messages
> %% Returns: {reply, Reply, State} |
> %% {reply, Reply, State, Timeout} |
> %% {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, Reply, State} | (terminate/2 is called)
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_call(Request, From, State) ->
> Reply = ok,
> {reply, Reply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_cast/2
> %% Description: Handling cast messages
> %% Returns: {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_cast({send_heartbeat}, State) ->
> send_heartbeat(State),
> NewState = State#state{counter = State#state.counter + 1},
> {noreply, NewState};
> handle_cast(Msg, State) ->
> {noreply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_info/2
> %% Description: Handling all non call/cast messages
> %% Returns: {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_info({udp, Socket, IP, InPortNo, Packet}, State) ->
> {node_name, Node,
> counter, Counter} = binary_to_term(Packet),
> io:format("received packet ~p from node ~p~n",[Counter, Node]),
> {noreply, State};
> handle_info(Info, State) ->
> {noreply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: terminate/2
> %% Description: Shutdown the server
> %% Returns: any (ignored by gen_server)
> %%--------------------------------------------------------------------
> terminate(Reason, State) ->
> ok.
>
> %%--------------------------------------------------------------------
> %% Func: code_change/3
> %% Purpose: Convert process state when code is changed
> %% Returns: {ok, NewState}
> %%--------------------------------------------------------------------
> code_change(OldVsn, State, Extra) ->
> {ok, State}.
>
> %%--------------------------------------------------------------------
> %%% Internal functions
> %%--------------------------------------------------------------------
> trigger_heartbeat() ->
> gen_server:cast(?SERVER, {send_heartbeat}).
>
> send_heartbeat(State) ->
> Packet = {node_name, node(),
> counter, State#state.counter},
> ok = gen_udp:send(State#state.socket,
> get_addr(),
> get_port(),
> term_to_binary(Packet)).
>
> get_addr() ->
> case application:get_application() of
> undefined ->
> ?ADDR;
> {ok, App} ->
> case application:get_env(App, addr) of
> undefined ->
> ?ADDR;
> {ok, Val} ->
> Val
> end
> end.
>
> get_port() ->
> case application:get_application() of
> undefined ->
> ?PORT;
> {ok, App} ->
> case application:get_env(App, port) of
> undefined ->
> ?PORT;
> {ok, Val} ->
> Val
> end
> end.
>
> get_period() ->
> case application:get_application() of
> undefined ->
> ?HB_PERIOD_MS;
> {ok, App} ->
> case application:get_env(App, period) of
> undefined ->
> ?HB_PERIOD_MS;
> {ok, Val} ->
> Val
> end
> end.
>
>
> %%--------------------------------------------------------------------
> %%% debug functions
> %%--------------------------------------------------------------------
> run() ->
> {ok, Pid} = ?MODULE:start_link(),
> io:format("Running for 5 minutes.~n",[]),
> timer:sleep(5*60*1000),
> io:format("done.~n",[]).
>
> #
>
> On Sep 2, 2004, at 12:39 PM, Reto Kramer wrote:
>
> > The following works on the OSX and Linux for me. I had trouble
> > opening the multicast socket on WinXP, but no patience to figure out
> > the cause.
> >
> > cheers,
> > - Reto
> >
> > Open a multicast port with:
> > Res = gen_udp:open(get_port(), [binary,
> > {reuseaddr,true},
> > {ip,get_addr()},
> > {multicast_loop,true},
> > {add_membership,{get_addr(),
> > {0,0,0,0}}}]),
> >
> > where
> > get_addr() ->
> > {ok, App} = application:get_application(),
> > case application:get_env(App, addr) of
> > {ok, Val} ->
> > Val;
> > undefined ->
> > ?ADDR
> > end.
> > get_port() -> ...
> >
> > and the env key of the .app file is
> > {env, [{addr, {239,0,0,1}}, % the multicast ip addr
> > {port, 10042}, % the port we multicast at
> > {period, 1000}]}, % heartbeat interval in ms
> >
> > Send packets with
> > Packet = {node_name, node()},
> > ok = gen_udp:send(State#state.socket,
> > get_addr(),
> > get_port(),
> > term_to_binary(Packet)),
> >
> > and receive packets like this:
> > receive
> > {udp, Socket, IP, InPortNo, Packet} ->
> > {node_name, Node} = binary_to_term(Packet),
> >
> > #
> >
> > On Sep 2, 2004, at 12:03 PM, Martin J. Logan wrote:
> >
> >> Is it possible to have multiple nodes on a single machine listening
> >> for
> >> the same multicast packets at the same time? How can this be
> >> accomplished within erts?
> >>
> >> Cheers,
> >> Martin
> >>
> >
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| mlogan at futuresource.co |
| Posted: Fri Sep 03, 2004 2:51 pm |
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Guest
|
Disregard the last email - In my eagerness to try this last example I
plugged in the wrong IP for the multicast. I was using the localhost IP
addr which of course explains the round robin in the last case. Thanks
for the help - it works perfectly.
On Thu, 2004-09-02 at 20:58, Reto Kramer wrote:
> [ups, sent this from wrong account initially]
>
> Martin,
>
> Here's a complete testcase that you can run locally. It's a dumbed down
> version of a larget app.
>
> Compile this file and then run it in two terminals with:
>
> erl -sname foo -s discover_server run
> erl -sname bar -s discover_server run
>
> Each node (foo and bar) will send numbered heartbeats to the multicast
> address and each one will pick up it's own packets as well as packets
> send by the other node.
>
> (foo_at_yoghurt)1> Running for 5 minutes.
> received packet 1 from node foo_at_yoghurt
> received packet 2 from node foo_at_yoghurt
> received packet 1 from node bar_at_yoghurt
> received packet 3 from node foo_at_yoghurt
> received packet 2 from node bar_at_yoghurt
> received packet 4 from node foo_at_yoghurt
> received packet 3 from node bar_at_yoghurt
> received packet 5 from node foo_at_yoghurt
>
> (bar_at_yoghurt)1> Running for 5 minutes.
> received packet 2 from node foo_at_yoghurt
> received packet 1 from node bar_at_yoghurt
> received packet 3 from node foo_at_yoghurt
> received packet 2 from node bar_at_yoghurt
> received packet 4 from node foo_at_yoghurt
> received packet 3 from node bar_at_yoghurt
>
> This is running on one OSX box. E.g. foo picks up it's own heartbeat
> 2, and bar picks up that same packet (foo's heartbeat 2) as well. So
> here they are not eating each others packets, but each process sees the
> same packets.
>
> Run it to see what you'll get on your setup.
>
> cheers,
> - Reto
>
> %%%-------------------------------------------------------------------
> %%% File : discover_server.erl
> %%% Author : reto <kramer_at_acm.org>
> %%% Description : Basic multicast based heart-beating
> %%%-------------------------------------------------------------------
> -module(discover_server).
>
> -behaviour(gen_server).
> %%--------------------------------------------------------------------
> %% Include files
> %%--------------------------------------------------------------------
>
> %%--------------------------------------------------------------------
> %% External exports
> -export([start_link/0]).
>
> -export([run/0]).
>
> -export([trigger_heartbeat/0]).
>
> %% gen_server callbacks
> -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
> terminate/2, code_change/3]).
>
> -record(state, {socket, % multicast udp socket
> nodes, % set of nodes (atoms)
> send_timer, % timer used to send heartbeats
> counter
> }).
>
> -define(HB_PERIOD_MS, 1000). % (if not in .app) default hb interval
> -define(ADDR, {239,0,42,1}). % (if not in .app) default addr
> -define(PORT, 10042). % (if not in .app) default port
>
> -define(SERVER, ?MODULE).
>
> %%====================================================================
> %% External functions
> %%====================================================================
> %%--------------------------------------------------------------------
> %% Function: start_link/0
> %% Description: Starts the server
> %%--------------------------------------------------------------------
> start_link() ->
> gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
>
> %%====================================================================
> %% Server functions
> %%====================================================================
>
> %%--------------------------------------------------------------------
> %% Function: init/1
> %% Description: Initiates the server
> %% Returns: {ok, State} |
> %% {ok, State, Timeout} |
> %% ignore |
> %% {stop, Reason}
> %%--------------------------------------------------------------------
> init([]) ->
> process_flag(trap_exit, true),
> {ok, Socket} = gen_udp:open(get_port(), [binary,
> {reuseaddr,true},
> {ip,get_addr()},
> {multicast_loop,true},
> {add_membership,{get_addr(),
> {0,0,0,0}}}]),
> % net_kernel:monitor_nodes(true),
> {ok, TRef} = timer:apply_interval(get_period(),
> ?MODULE, trigger_heartbeat, []),
> {ok, #state{socket=Socket,
> nodes=sets:new(),
> send_timer=TRef,
> counter=1}}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_call/3
> %% Description: Handling call messages
> %% Returns: {reply, Reply, State} |
> %% {reply, Reply, State, Timeout} |
> %% {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, Reply, State} | (terminate/2 is called)
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_call(Request, From, State) ->
> Reply = ok,
> {reply, Reply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_cast/2
> %% Description: Handling cast messages
> %% Returns: {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_cast({send_heartbeat}, State) ->
> send_heartbeat(State),
> NewState = State#state{counter = State#state.counter + 1},
> {noreply, NewState};
> handle_cast(Msg, State) ->
> {noreply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: handle_info/2
> %% Description: Handling all non call/cast messages
> %% Returns: {noreply, State} |
> %% {noreply, State, Timeout} |
> %% {stop, Reason, State} (terminate/2 is called)
> %%--------------------------------------------------------------------
> handle_info({udp, Socket, IP, InPortNo, Packet}, State) ->
> {node_name, Node,
> counter, Counter} = binary_to_term(Packet),
> io:format("received packet ~p from node ~p~n",[Counter, Node]),
> {noreply, State};
> handle_info(Info, State) ->
> {noreply, State}.
>
> %%--------------------------------------------------------------------
> %% Function: terminate/2
> %% Description: Shutdown the server
> %% Returns: any (ignored by gen_server)
> %%--------------------------------------------------------------------
> terminate(Reason, State) ->
> ok.
>
> %%--------------------------------------------------------------------
> %% Func: code_change/3
> %% Purpose: Convert process state when code is changed
> %% Returns: {ok, NewState}
> %%--------------------------------------------------------------------
> code_change(OldVsn, State, Extra) ->
> {ok, State}.
>
> %%--------------------------------------------------------------------
> %%% Internal functions
> %%--------------------------------------------------------------------
> trigger_heartbeat() ->
> gen_server:cast(?SERVER, {send_heartbeat}).
>
> send_heartbeat(State) ->
> Packet = {node_name, node(),
> counter, State#state.counter},
> ok = gen_udp:send(State#state.socket,
> get_addr(),
> get_port(),
> term_to_binary(Packet)).
>
> get_addr() ->
> case application:get_application() of
> undefined ->
> ?ADDR;
> {ok, App} ->
> case application:get_env(App, addr) of
> undefined ->
> ?ADDR;
> {ok, Val} ->
> Val
> end
> end.
>
> get_port() ->
> case application:get_application() of
> undefined ->
> ?PORT;
> {ok, App} ->
> case application:get_env(App, port) of
> undefined ->
> ?PORT;
> {ok, Val} ->
> Val
> end
> end.
>
> get_period() ->
> case application:get_application() of
> undefined ->
> ?HB_PERIOD_MS;
> {ok, App} ->
> case application:get_env(App, period) of
> undefined ->
> ?HB_PERIOD_MS;
> {ok, Val} ->
> Val
> end
> end.
>
>
> %%--------------------------------------------------------------------
> %%% debug functions
> %%--------------------------------------------------------------------
> run() ->
> {ok, Pid} = ?MODULE:start_link(),
> io:format("Running for 5 minutes.~n",[]),
> timer:sleep(5*60*1000),
> io:format("done.~n",[]).
>
> #
>
> On Sep 2, 2004, at 12:39 PM, Reto Kramer wrote:
>
> > The following works on the OSX and Linux for me. I had trouble
> > opening the multicast socket on WinXP, but no patience to figure out
> > the cause.
> >
> > cheers,
> > - Reto
> >
> > Open a multicast port with:
> > Res = gen_udp:open(get_port(), [binary,
> > {reuseaddr,true},
> > {ip,get_addr()},
> > {multicast_loop,true},
> > {add_membership,{get_addr(),
> > {0,0,0,0}}}]),
> >
> > where
> > get_addr() ->
> > {ok, App} = application:get_application(),
> > case application:get_env(App, addr) of
> > {ok, Val} ->
> > Val;
> > undefined ->
> > ?ADDR
> > end.
> > get_port() -> ...
> >
> > and the env key of the .app file is
> > {env, [{addr, {239,0,0,1}}, % the multicast ip addr
> > {port, 10042}, % the port we multicast at
> > {period, 1000}]}, % heartbeat interval in ms
> >
> > Send packets with
> > Packet = {node_name, node()},
> > ok = gen_udp:send(State#state.socket,
> > get_addr(),
> > get_port(),
> > term_to_binary(Packet)),
> >
> > and receive packets like this:
> > receive
> > {udp, Socket, IP, InPortNo, Packet} ->
> > {node_name, Node} = binary_to_term(Packet),
> >
> > #
> >
> > On Sep 2, 2004, at 12:03 PM, Martin J. Logan wrote:
> >
> >> Is it possible to have multiple nodes on a single machine listening
> >> for
> >> the same multicast packets at the same time? How can this be
> >> accomplished within erts?
> >>
> >> Cheers,
> >> Martin
> >>
> >
Post generated using Mail2Forum (http://m2f.sourceforge.net) |
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