From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001
From: Erlang/OTP <otp@erlang.org>
Date: Fri, 20 Nov 2009 14:54:40 +0000
Subject: The R13B03 release.

---
 lib/pman/src/pman_relay.erl | 127 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 lib/pman/src/pman_relay.erl

(limited to 'lib/pman/src/pman_relay.erl')

diff --git a/lib/pman/src/pman_relay.erl b/lib/pman/src/pman_relay.erl
new file mode 100644
index 0000000000..289765492f
--- /dev/null
+++ b/lib/pman/src/pman_relay.erl
@@ -0,0 +1,127 @@
+%%
+%% %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]}.
+
-- 
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