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authorJames Fish <[email protected]>2014-10-01 14:03:43 +0100
committerBjörn Gustavsson <[email protected]>2015-02-26 15:05:34 +0100
commit4a8f17aeccd950e4f76ea6ea6d9219a1e2c86df5 (patch)
treec10c8538c678af0cac99fbefaf7084e4ea794ba8
parentc9e36ab16034bb7fe71f772df6bba22070976bbf (diff)
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Ensure dbg tracer exits when dbg is stopped
Previously the tracer might receive an 'EXIT' message in the trace receive loop and treat it as garbage. Test uses a custom dbg process handler to reliably recreate the race condition, i.e. the message order {trace, ..}, {'EXIT, ..}.
-rw-r--r--lib/runtime_tools/src/dbg.erl60
-rw-r--r--lib/runtime_tools/test/dbg_SUITE.erl36
2 files changed, 64 insertions, 32 deletions
diff --git a/lib/runtime_tools/src/dbg.erl b/lib/runtime_tools/src/dbg.erl
index 186563ab74..c2de57d40b 100644
--- a/lib/runtime_tools/src/dbg.erl
+++ b/lib/runtime_tools/src/dbg.erl
@@ -778,50 +778,50 @@ tracer_init(Handler, HandlerData) ->
tracer_loop(Handler, HandlerData).
tracer_loop(Handler, Hdata) ->
- receive
- Msg ->
- %% Don't match in receive to avoid giving EXIT message higher
- %% priority than the trace messages.
- case Msg of
- {'EXIT',_Pid,_Reason} ->
- ok;
- Trace ->
- NewData = recv_all_traces(Trace, Handler, Hdata),
- tracer_loop(Handler, NewData)
- end
+ {State, Suspended, Traces} = recv_all_traces(),
+ NewHdata = handle_traces(Suspended, Traces, Handler, Hdata),
+ case State of
+ done ->
+ exit(normal);
+ loop ->
+ tracer_loop(Handler, NewHdata)
end.
-
-recv_all_traces(Trace, Handler, Hdata) ->
- Suspended = suspend(Trace, []),
- recv_all_traces(Suspended, Handler, Hdata, [Trace]).
-recv_all_traces(Suspended0, Handler, Hdata, Traces) ->
+recv_all_traces() ->
+ recv_all_traces([], [], infinity).
+
+recv_all_traces(Suspended0, Traces, Timeout) ->
receive
Trace when is_tuple(Trace), element(1, Trace) == trace ->
Suspended = suspend(Trace, Suspended0),
- recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
+ recv_all_traces(Suspended, [Trace|Traces], 0);
Trace when is_tuple(Trace), element(1, Trace) == trace_ts ->
Suspended = suspend(Trace, Suspended0),
- recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
+ recv_all_traces(Suspended, [Trace|Traces], 0);
Trace when is_tuple(Trace), element(1, Trace) == seq_trace ->
Suspended = suspend(Trace, Suspended0),
- recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
+ recv_all_traces(Suspended, [Trace|Traces], 0);
Trace when is_tuple(Trace), element(1, Trace) == drop ->
Suspended = suspend(Trace, Suspended0),
- recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
+ recv_all_traces(Suspended, [Trace|Traces], 0);
+ {'EXIT', _Pid, _Reason} ->
+ {done, Suspended0, Traces};
Other ->
%%% Is this really a good idea?
io:format(user,"** tracer received garbage: ~p~n", [Other]),
- recv_all_traces(Suspended0, Handler, Hdata, Traces)
- after 0 ->
- case catch invoke_handler(Traces, Handler, Hdata) of
- {'EXIT',Reason} ->
- resume(Suspended0),
- exit({trace_handler_crashed,Reason});
- NewHdata ->
- resume(Suspended0),
- NewHdata
- end
+ recv_all_traces(Suspended0, Traces, Timeout)
+ after Timeout ->
+ {loop, Suspended0, Traces}
+ end.
+
+handle_traces(Suspended, Traces, Handler, Hdata) ->
+ case catch invoke_handler(Traces, Handler, Hdata) of
+ {'EXIT',Reason} ->
+ resume(Suspended),
+ exit({trace_handler_crashed,Reason});
+ NewHdata ->
+ resume(Suspended),
+ NewHdata
end.
invoke_handler([Tr|Traces], Handler, Hdata0) ->
diff --git a/lib/runtime_tools/test/dbg_SUITE.erl b/lib/runtime_tools/test/dbg_SUITE.erl
index dfae52ed1d..0bcbd67d05 100644
--- a/lib/runtime_tools/test/dbg_SUITE.erl
+++ b/lib/runtime_tools/test/dbg_SUITE.erl
@@ -25,7 +25,7 @@
ip_port/1, file_port/1, file_port2/1, file_port_schedfix/1,
ip_port_busy/1, wrap_port/1, wrap_port_time/1,
with_seq_trace/1, dead_suspend/1, local_trace/1,
- saved_patterns/1]).
+ saved_patterns/1, tracer_exit_on_stop/1]).
-export([init_per_testcase/2, end_per_testcase/2]).
-export([tracee1/1, tracee2/1]).
-export([dummy/0, exported/1]).
@@ -47,7 +47,7 @@ all() ->
[big, tiny, simple, message, distributed, ip_port,
file_port, file_port2, file_port_schedfix, ip_port_busy,
wrap_port, wrap_port_time, with_seq_trace, dead_suspend,
- local_trace, saved_patterns].
+ local_trace, saved_patterns, tracer_exit_on_stop].
groups() ->
[].
@@ -742,6 +742,38 @@ run_dead_suspend() ->
dummy() ->
ok.
+%% Test that a tracer process does not ignore an exit signal message when it has
+%% received (but not handled) trace messages
+tracer_exit_on_stop(_) ->
+ %% Tracer blocks waiting for fun to complete so that the trace message and
+ %% the exit signal message from the dbg process are in its message queue.
+ Fun = fun() ->
+ ?MODULE:dummy(),
+ Ref = erlang:trace_delivered(self()),
+ receive {trace_delivered, _, Ref} -> stop() end
+ end,
+ {ok, _} = dbg:tracer(process, {fun spawn_once_handler/2, {self(), Fun}}),
+ {ok, Tracer} = dbg:get_tracer(),
+ MRef = monitor(process, Tracer),
+ {ok, _} = dbg:p(self(), [call]),
+ {ok, _} = dbg:p(new, [call]),
+ {ok, _} = dbg:tp(?MODULE, dummy, []),
+ ?MODULE:dummy(),
+ receive {'DOWN', MRef, _, _, normal} -> ok end,
+ [{trace,_,call,{?MODULE, dummy,[]}},
+ {trace,_,call,{?MODULE, dummy,[]}}] = flush(),
+ ok.
+
+spawn_once_handler(Event, {Pid, done} = State) ->
+ Pid ! Event,
+ State;
+spawn_once_handler(Event, {Pid, Fun}) ->
+ {_, Ref} = spawn_monitor(Fun),
+ receive
+ {'DOWN', Ref, _, _, _} ->
+ Pid ! Event,
+ {Pid, done}
+ end.
%%
%% Support functions