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authorErlang/OTP <otp@erlang.org>2009-11-20 14:54:40 +0000
committerErlang/OTP <otp@erlang.org>2009-11-20 14:54:40 +0000
commit84adefa331c4159d432d22840663c38f155cd4c1 (patch)
treebff9a9c66adda4df2106dfd0e5c053ab182a12bd /lib/pman/src/pman_relay.erl
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The R13B03 release.OTP_R13B03
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+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% 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.
+%%
+%% %CopyrightEnd%
+%%
+%%----------------------------------------------------------------------
+%% Purpose : Interface function to relay calls (esp. trace calls)
+%% to processes on other nodes. Some of the calls
+%% are conditionally relayed.
+%%----------------------------------------------------------------------
+
+-module(pman_relay).
+
+%%-compile(export_all).
+-export([start/1,
+ ok_to_trace/1,
+ trac/3]).
+
+
+-include("assert.hrl").
+
+%% --------------------------------------------------------------
+%% DISTRIBUTION
+%% --------------------------------------------------------------
+%% (???) Process dictionary alert!!!
+%%
+%% Since we are not allowed to do erlang:trace/3 on remote
+%% processe we create a help process at the remote node to
+%% do the job for us
+%% ---------------------------------------------------------------
+
+start(P) when is_pid(P), node(P)/=node() ->
+
+ %% Remote supervision, relaying necessary
+
+ put(relay, spawn_link(node(P), pman_relay_server, init, [self()]));
+
+
+start(_) ->
+
+ %% Local supervision, no relaying
+
+ ignore.
+
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% ok_to_trace/1 - Tests wheter we can actually start tracing
+%% a process.
+%%
+%% Arguments:
+%% Pid Pid of the process to trace (on local or remote node)
+%%
+%% Returns
+%% true If it is OK to trace the process
+%% false If the process is already traced, or some other
+%% condition prevents it from being traced.
+
+ok_to_trace(Pid) when node(Pid) == node()->
+
+ %% Local trace, no relaying
+
+ case catch erlang:trace(Pid, false, [send]) of
+ 1 ->
+ true;
+ _Otherwise ->
+ false
+ end;
+ok_to_trace(Pid) ->
+
+ %% Remote trace, relaying necessary
+
+ PidRelay = get(relay),
+ PidRelay ! {ok_to_trace, self(), Pid},
+ receive
+ {ok_to_trace, PidRelay} ->
+ true;
+ {not_ok_to_trace, PidRelay} ->
+ false;
+ _Otherwise ->
+ ?ALWAYS_ASSERT("Unexpected message from relay process")
+ after
+ 5000 ->
+ false
+ end.
+
+
+
+
+
+
+%% ---------------------------------------------------------------
+%% Possibly send a request to do tracing to a remote node.
+%% ---------------------------------------------------------------
+
+trac(Pid, How, Flag) when node(Pid) == node() ->
+
+ %% Local trace, no relaying necessary
+
+
+ case catch erlang:trace(Pid, How, Flag) of
+ 1 -> ok;
+ _ -> pman_win:format("** Illegal trace request ** \n", [])
+ end;
+
+trac(Pid, How, Flag) ->
+
+
+
+ %% Remote trace, relaying necessary
+
+ get(relay) ! {self(), erlang, trace, [Pid, How, Flag]}.
+