%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1999-2012. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(trace_port_SUITE).
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
init_per_group/2,end_per_group/2,
init_per_testcase/2,end_per_testcase/2,
call_trace/1,
return_trace/1,
send/1,
receive_trace/1,
process_events/1,
schedule/1,
fake_schedule/1,
fake_schedule_after_register/1,
fake_schedule_after_getting_linked/1,
fake_schedule_after_getting_unlinked/1,
gc/1,
default_tracer/1,
tracer_port_crash/1]).
-include_lib("test_server/include/test_server.hrl").
test_cases() ->
[call_trace, return_trace, send, receive_trace,
process_events, schedule, fake_schedule,
fake_schedule_after_register,
fake_schedule_after_getting_linked,
fake_schedule_after_getting_unlinked, gc,
default_tracer, tracer_port_crash].
suite() -> [{ct_hooks,[ts_install_cth]}].
all() ->
test_cases().
groups() ->
[].
init_per_suite(Config) ->
Config.
end_per_suite(_Config) ->
ok.
init_per_group(_GroupName, Config) ->
Config.
end_per_group(_GroupName, Config) ->
Config.
init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
Dog = ?t:timetrap(?t:seconds(30)),
[{watchdog, Dog}|Config].
end_per_testcase(_Func, Config) ->
Dog = ?config(watchdog, Config),
?t:timetrap_cancel(Dog).
call_trace(doc) -> "Test sending call trace messages to a port.";
call_trace(Config) when is_list(Config) ->
case test_server:is_native(?MODULE) orelse
test_server:is_native(lists) of
true ->
{skip,"Native code"};
false ->
?line start_tracer(Config),
Self = self(),
?line trace_func({lists,reverse,1}, []),
?line trace_pid(Self, true, [call]),
?line trace_info(Self, flags),
?line trace_info(Self, tracer),
?line [b,a] = lists:reverse([a,b]),
?line expect({trace,Self,call,{lists,reverse,[[a,b]]}}),
?line trace_pid(Self, true, [timestamp]),
?line trace_info(Self, flags),
?line Huge = huge_data(),
?line lists:reverse(Huge),
?line expect({trace_ts,Self,call,{lists,reverse,[Huge]},ts}),
?line trace_pid(Self, true, [arity]),
?line trace_info(Self, flags),
?line [y,x] = lists:reverse([x,y]),
?line expect({trace_ts,Self,call,{lists,reverse,1},ts}),
?line trace_pid(Self, false, [timestamp]),
?line trace_info(Self, flags),
?line [z,y,x] = lists:reverse([x,y,z]),
?line expect({trace,Self,call,{lists,reverse,1}}),
%% OTP-7399. Delayed sub-binary creation optimization.
?line trace_pid(Self, false, [arity]),
?line trace_info(Self, flags),
?line trace_func({?MODULE,bs_sum_c,2}, [], [local]),
?line 26 = bs_sum_c(<<3:4,5:4,7:4,11:4>>, 0),
?line trace_func({?MODULE,bs_sum_c,2}, false, [local]),
?line expect({trace,Self,call,{?MODULE,bs_sum_c,[<<3:4,5:4,7:4,11:4>>,0]}}),
?line expect({trace,Self,call,{?MODULE,bs_sum_c,[<<5:4,7:4,11:4>>,3]}}),
?line expect({trace,Self,call,{?MODULE,bs_sum_c,[<<7:4,11:4>>,8]}}),
?line expect({trace,Self,call,{?MODULE,bs_sum_c,[<<11:4>>,15]}}),
?line expect({trace,Self,call,{?MODULE,bs_sum_c,[<<>>,26]}}),
?line trace_func({lists,reverse,1}, false),
ok
end.
bs_sum_c(<<H:4,T/bits>>, Acc) -> bs_sum_c(T, H+Acc);
bs_sum_c(<<>>, Acc) -> Acc.
return_trace(doc) -> "Test the new return trace.";
return_trace(Config) when is_list(Config) ->
case test_server:is_native(?MODULE) orelse
test_server:is_native(lists) of
true ->
{skip,"Native code"};
false ->
?line start_tracer(Config),
Self = self(),
MFA = {lists,reverse,1},
%% Plain (no timestamp, small data).
?line trace_func(MFA, [{['$1'],[],[{return_trace},
{message,false}]}]),
?line trace_pid(Self, true, [call]),
?line trace_info(Self, flags),
?line trace_info(Self, tracer),
?line trace_info(MFA, match_spec),
?line {traced,global} = trace_info(MFA, traced),
?line [b,a] = lists:reverse([a,b]),
?line expect({trace,Self,return_from,MFA,[b,a]}),
%% Timestamp, huge data.
?line trace_pid(Self, true, [timestamp]),
?line Result = lists:reverse(huge_data()),
?line expect({trace_ts,Self,return_from,MFA,Result,ts}),
%% Turn off trace.
?line trace_func(MFA, false),
?line trace_info(MFA, match_spec),
?line {traced,false} = trace_info(MFA, traced),
ok
end.
send(doc) -> "Test sending send trace messages to a port.";
send(Config) when is_list(Config) ->
?line Tracer = start_tracer(Config),
Self = self(),
?line Sender = fun_spawn(fun sender/0),
?line trac(Sender, true, [send]),
%% Simple message, no timestamp.
?line Bin = list_to_binary(lists:seq(1, 10)),
?line Msg = {some_data,Bin},
Sender ! {send_please,self(),Msg},
receive Msg -> ok end,
?line expect({trace,Sender,send,Msg,Self}),
%% Timestamp.
BiggerMsg = {even_bigger,Msg},
?line trac(Sender, true, [send,timestamp]),
Sender ! {send_please,self(),BiggerMsg},
receive BiggerMsg -> ok end,
?line expect({trace_ts,Sender,send,BiggerMsg,Self,ts}),
%% Huge message.
?line HugeMsg = huge_data(),
Sender ! {send_please,self(),HugeMsg},
receive HugeMsg -> ok end,
?line expect({trace_ts,Sender,send,HugeMsg,Self,ts}),
%% Kill trace port and force a trace. The emulator should not crasch.
?line unlink(Tracer),
?line exit(Tracer, kill),
erlang:yield(), % Make sure that port gets killed.
Sender ! {send_please,Self,good_bye},
receive good_bye -> ok end,
ok.
receive_trace(doc) -> "Test sending receive traces to a port.";
receive_trace(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Receiver = fun_spawn(fun receiver/0),
?line trac(Receiver, true, ['receive']),
Receiver ! {hello,world},
?line expect({trace,Receiver,'receive',{hello,world}}),
?line trac(Receiver, true, ['receive',timestamp]),
Huge = {hello,huge_data()},
Receiver ! {hello,huge_data()},
?line expect({trace_ts,Receiver,'receive',Huge,ts}),
ok.
process_events(doc) -> "Tests a few process events (like getting linked).";
process_events(Config) when is_list(Config) ->
?line start_tracer(Config),
Self = self(),
?line Receiver = fun_spawn(fun receiver/0),
?line trac(Receiver, true, [procs]),
unlink(Receiver), %It is already linked.
?line expect({trace,Receiver,getting_unlinked,Self}),
link(Receiver),
?line expect({trace,Receiver,getting_linked,Self}),
?line trac(Receiver, true, [procs,timestamp]),
unlink(Receiver),
?line expect({trace_ts,Receiver,getting_unlinked,Self,ts}),
link(Receiver),
?line expect({trace_ts,Receiver,getting_linked,Self,ts}),
unlink(Receiver),
?line expect({trace_ts,Receiver,getting_unlinked,Self,ts}),
Huge = huge_data(),
exit(Receiver, Huge),
?line expect({trace_ts,Receiver,exit,Huge,ts}),
ok.
schedule(doc) -> "Test sending scheduling events to a port.";
schedule(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Receiver = fun_spawn(fun receiver/0),
?line trac(Receiver, true, [running]),
Receiver ! hi,
expect({trace,Receiver,in,{?MODULE,receiver,0}}),
expect({trace,Receiver,out,{?MODULE,receiver,0}}),
?line trac(Receiver, true, [running,timestamp]),
Receiver ! hi_again,
expect({trace_ts,Receiver,in,{?MODULE,receiver,0},ts}),
expect({trace_ts,Receiver,out,{?MODULE,receiver,0},ts}),
ok.
run_fake_sched_test(Fun, Config) when is_function(Fun), is_list(Config) ->
?line case catch erlang:system_info(smp_support) of
true ->
?line {skipped,
"No need for faked schedule out/in trace messages "
"when smp support is enabled"};
_ ->
?line Fun(Config)
end.
fake_schedule(doc) -> "Tests time compensating fake out/in scheduling.";
fake_schedule(Config) when is_list(Config) ->
?line run_fake_sched_test(fun fake_schedule_test/1, Config).
fake_schedule_test(Config) when is_list(Config) ->
?line Tracer = start_tracer(Config),
?line Port = get(tracer_port),
?line General = fun_spawn(fun general/0),
%%
?line trac(General, true, [send, running]),
%%
%% Test that fake out/in scheduling is not generated unless
%% both 'running' and 'timestamp' is active.
?line [] = erlang:port_control(Port, $h, []),
?line General ! nop,
?line expect({trace, General, in, {?MODULE, general, 0}}),
?line expect({trace, General, out, {?MODULE, general, 0}}),
?line expect(),
%%
?line trac(General, false, [running]),
?line trac(General, true, [timestamp]),
%%
?line Ref1 = make_ref(),
?line Msg1 = {Port, {data, term_to_binary(Ref1)}},
?line [] = erlang:port_control(Port, $h, []),
?line General ! {send, Tracer, Msg1},
?line expect({trace_ts, General, send, Msg1, Tracer, ts}),
?line expect(Ref1),
?line expect(),
%%
?line trac(General, true, [running]),
%%
%% Test that fake out/in scheduling can be generated by the driver
?line Ref2 = make_ref(),
?line Msg2 = {Port, {data, term_to_binary(Ref2)}},
?line [] = erlang:port_control(Port, $h, []),
?line General ! {send, Tracer, Msg2},
?line {_,_,_,_,Ts} =
expect({trace_ts, General, in, {?MODULE, general, 0}, ts}),
?line expect({trace_ts, General, out, 0, Ts}),
?line expect({trace_ts, General, in, 0, ts}),
?line expect({trace_ts, General, send, Msg2, Tracer, ts}),
?line expect(Ref2),
?line expect({trace_ts, General, out, {?MODULE, general, 0}, ts}),
?line expect(),
%%
%% Test that fake out/in scheduling is not generated after an
%% 'out' scheduling event
?line Ref3 = make_ref(),
?line Msg3 = {Port, {data, term_to_binary(Ref3)}},
?line General ! {apply, {erlang, port_control, [Port, $h, []]}},
?line expect({trace_ts, General, in, {?MODULE, general, 0}, ts}),
?line expect({trace_ts, General, out, {?MODULE, general, 0}, ts}),
?line General ! {send, Tracer, Msg3},
?line expect({trace_ts, General, in, {?MODULE, general, 0}, ts}),
?line expect({trace_ts, General, send, Msg3, Tracer, ts}),
?line expect(Ref3),
?line expect({trace_ts, General, out, {?MODULE, general, 0}, ts}),
?line expect(),
%%
ok.
fake_schedule_after_register(doc) ->
"Tests fake out/in scheduling contents.";
fake_schedule_after_register(Config) when is_list(Config) ->
?line run_fake_sched_test(fun fake_schedule_after_register_test/1, Config).
fake_schedule_after_register_test(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Port = get(tracer_port),
?line G1 = fun_spawn(fun general/0),
?line G2 = fun_spawn(fun general/0),
%%
?line trac(G1, true, [running, timestamp, procs]),
?line trac(G2, true, [running, timestamp]),
%%
%% Test fake out/in scheduling after certain messages
?line erlang:yield(),
?line G2 ! {apply, {erlang, port_control, [Port, $h, []]}},
?line G2 ! {apply, {erlang, register, [fake_schedule_after_register, G1]}},
?line expect({trace_ts, G2, in, {?MODULE, general, 0}, ts}),
?line {_,_,_,_,Ts} =
expect({trace_ts, G1, register, fake_schedule_after_register, ts}),
?line expect({trace_ts, G2, out, 0, Ts}),
?line expect({trace_ts, G2, in, 0, ts}),
?line expect({trace_ts, G2, out, {?MODULE, general, 0}, ts}),
?line expect(),
%%
ok.
fake_schedule_after_getting_linked(doc) ->
"Tests fake out/in scheduling contents.";
fake_schedule_after_getting_linked(Config) when is_list(Config) ->
?line run_fake_sched_test(fun fake_schedule_after_getting_linked_test/1,
Config).
fake_schedule_after_getting_linked_test(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Port = get(tracer_port),
?line G1 = fun_spawn(fun general/0),
?line G2 = fun_spawn(fun general/0),
%%
?line trac(G1, true, [running, timestamp, procs]),
?line trac(G2, true, [running, timestamp]),
%%
%% Test fake out/in scheduling after certain messages
?line erlang:yield(),
?line G2 ! {apply, {erlang, port_control, [Port, $h, []]}},
?line G2 ! {apply, {erlang, link, [G1]}},
?line expect({trace_ts, G2, in, {?MODULE, general, 0}, ts}),
?line {_,_,_,_,Ts} =
expect({trace_ts, G1, getting_linked, G2, ts}),
?line expect({trace_ts, G2, out, 0, Ts}),
?line expect({trace_ts, G2, in, 0, ts}),
?line expect({trace_ts, G2, out, {?MODULE, general, 0}, ts}),
?line expect(),
%%
ok.
fake_schedule_after_getting_unlinked(doc) ->
"Tests fake out/in scheduling contents.";
fake_schedule_after_getting_unlinked(Config) when is_list(Config) ->
?line run_fake_sched_test(fun fake_schedule_after_getting_unlinked_test/1,
Config).
fake_schedule_after_getting_unlinked_test(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Port = get(tracer_port),
?line G1 = fun_spawn(fun general/0),
?line G2 = fun_spawn(fun general/0),
%%
?line trac(G1, true, [running, procs]),
?line trac(G2, true, [running, timestamp]),
%%
%% Test fake out/in scheduling after certain messages
?line erlang:yield(),
?line G2 ! {apply, {erlang, link, [G1]}},
?line G2 ! {apply, {erlang, port_control, [Port, $h, []]}},
?line G2 ! {apply, {erlang, unlink, [G1]}},
?line expect({trace_ts, G2, in, {?MODULE, general, 0}, ts}),
?line expect({trace, G1, getting_linked, G2}),
?line expect({trace, G1, getting_unlinked, G2}),
?line expect({trace_ts, G2, out, 0, ts}),
?line expect({trace_ts, G2, in, 0, ts}),
?line expect({trace_ts, G2, out, {?MODULE, general, 0}, ts}),
?line expect(),
%%
ok.
gc(doc) -> "Test sending garbage collection events to a port.";
gc(Config) when is_list(Config) ->
?line start_tracer(Config),
?line Garber = fun_spawn(fun garber/0, [{min_heap_size, 5000}]),
?line trac(Garber, true, [garbage_collection]),
?line trace_info(Garber, flags),
?line trace_info(Garber, flags),
Garber ! hi,
expect({trace,Garber,gc_start,info}),
expect({trace,Garber,gc_end,info}),
?line trac(Garber, true, [garbage_collection,timestamp]),
Garber ! hi,
expect({trace_ts,Garber,gc_start,info,ts}),
expect({trace_ts,Garber,gc_end,info,ts}),
ok.
default_tracer(doc) ->
"Test a port as default tracer.";
default_tracer(Config) when is_list(Config) ->
?line Tracer = start_tracer(Config),
?line TracerMonitor = erlang:monitor(process, Tracer),
?line Port = get(tracer_port),
%%
?line N = erlang:trace(all, true, [send, {tracer, Port}]),
?line {flags, [send]} = erlang:trace_info(self(), flags),
?line {tracer, Port} = erlang:trace_info(self(), tracer),
?line {flags, [send]} = erlang:trace_info(new, flags),
?line {tracer, Port} = erlang:trace_info(new, tracer),
?line G1 = fun_spawn(fun general/0),
?line {flags, [send]} = erlang:trace_info(G1, flags),
?line {tracer, Port} = erlang:trace_info(G1, tracer),
?line unlink(Tracer),
?line exit(Port, done),
?line receive
{'DOWN', TracerMonitor, process, Tracer, TracerExitReason} ->
?line done = TracerExitReason
end,
?line {flags, []} = erlang:trace_info(self(), flags),
?line {tracer, []} = erlang:trace_info(self(), tracer),
?line {flags, []} = erlang:trace_info(new, flags),
?line {tracer, []} = erlang:trace_info(new, tracer),
?line M = erlang:trace(all, false, [all]),
?line {flags, []} = erlang:trace_info(self(), flags),
?line {tracer, []} = erlang:trace_info(self(), tracer),
?line {flags, []} = erlang:trace_info(G1, flags),
?line {tracer, []} = erlang:trace_info(G1, tracer),
?line G1 ! {apply,{erlang,exit,[normal]}},
?line io:format("~p = ~p.~n", [M, N]),
?line M = N,
ok.
tracer_port_crash(Config) when is_list(Config) ->
case test_server:is_native(?MODULE) orelse
test_server:is_native(lists) of
true ->
{skip,"Native code"};
false ->
Tr = start_tracer(Config),
Port = get(tracer_port),
Tracee = spawn(fun () ->
register(trace_port_linker, self()),
link(Port),
receive go -> ok end,
lists:reverse([1,b,c]),
receive die -> ok end
end),
Tr ! {unlink_tracer_port, self()},
receive {unlinked_tracer_port, Tr} -> ok end,
port_control(Port, $c, []), %% Make port commands crash tracer port...
trace_func({lists,reverse,1}, []),
trace_pid(Tracee, true, [call]),
trace_info(Tracee, flags),
trace_info(self(), tracer),
Tracee ! go,
receive after 1000 -> ok end,
case whereis(trace_port_linker) of
undefined ->
ok;
Id ->
% erts_debug:set_internal_state(available_internal_state, true),
% erts_debug:set_internal_state(abort, {trace_port_linker, Id})
?t:fail({trace_port_linker, Id})
end,
undefined = process_info(Tracee),
ok
end.
%%% Help functions.
huge_data() -> huge_data(16384).
huge_data(0) -> [];
huge_data(N) when N rem 2 == 0 ->
P = huge_data(N div 2),
[P|P];
huge_data(N) ->
P = huge_data(N div 2),
[16#1234566,P|P].
expect() ->
receive
Other ->
ok = io:format("Unexpected; got ~p", [Other]),
test_server:fail({unexpected, Other})
after 200 ->
ok
end.
expect({trace_ts,E1,E2,info,ts}=Message) ->
receive
{trace_ts,E1,E2,_Info,_Ts}=MessageTs ->
ok = io:format("Expected and got ~p", [MessageTs]),
MessageTs;
Other ->
io:format("Expected ~p; got ~p", [Message,Other]),
test_server:fail({unexpected,Other})
after 5000 ->
io:format("Expected ~p; got nothing", [Message]),
test_server:fail(no_trace_message)
end;
expect({trace,E1,E2,info}=Message) ->
receive
{trace,E1,E2,_Info}=MessageTs ->
ok = io:format("Expected and got ~p", [MessageTs]),
MessageTs;
Other ->
io:format("Expected ~p; got ~p", [Message,Other]),
test_server:fail({unexpected,Other})
after 5000 ->
io:format("Expected ~p; got nothing", [Message]),
test_server:fail(no_trace_message)
end;
expect({trace_ts,E1,E2,E3,ts}=Message) ->
receive
{trace_ts,E1,E2,E3,_Ts}=MessageTs ->
ok = io:format("Expected and got ~p", [MessageTs]),
MessageTs;
Other ->
io:format("Expected ~p; got ~p", [Message,Other]),
test_server:fail({unexpected,Other})
after 5000 ->
io:format("Expected ~p; got nothing", [Message]),
test_server:fail(no_trace_message)
end;
expect({trace_ts,E1,E2,E3,E4,ts}=Message) ->
receive
{trace_ts,E1,E2,E3,E4,_Ts}=MessageTs ->
ok = io:format("Expected and got ~p", [MessageTs]),
MessageTs;
Other ->
io:format("Expected ~p; got ~p", [Message,Other]),
test_server:fail({unexpected,Other})
after 5000 ->
io:format("Expected ~p; got nothing", [Message]),
test_server:fail(no_trace_message)
end;
expect(Message) ->
receive
Message ->
ok = io:format("Expected and got ~p", [Message]),
Message;
Other ->
io:format("Expected ~p; got ~p", [Message,Other]),
test_server:fail({unexpected,Other})
after 5000 ->
io:format("Expected ~p; got nothing", [Message]),
test_server:fail(no_trace_message)
end.
trac(What, On, Flags0) ->
Flags = [{tracer,get(tracer_port)}|Flags0],
get(tracer) ! {apply,self(),{erlang,trace,[What,On,Flags]}},
Res = receive
{apply_result,Result} -> Result
end,
ok = io:format("erlang:trace(~p, ~p, ~p) -> ~p",
[What,On,Flags,Res]),
Res.
trace_info(What, Key) ->
get(tracer) ! {apply,self(),{erlang,trace_info,[What,Key]}},
Res = receive
{apply_result,Result} -> Result
end,
ok = io:format("erlang:trace_info(~p, ~p) -> ~p",
[What,Key,Res]),
Res.
trace_func(MFA, MatchProg) ->
get(tracer) ! {apply,self(),{erlang,trace_pattern,[MFA,MatchProg]}},
Res = receive
{apply_result,Result} -> Result
end,
ok = io:format("erlang:trace_pattern(~p, ~p) -> ~p", [MFA,MatchProg,Res]),
Res.
trace_func(MFA, MatchProg, Flags) ->
get(tracer) ! {apply,self(),{erlang,trace_pattern,[MFA,MatchProg,Flags]}},
Res = receive
{apply_result,Result} -> Result
end,
ok = io:format("erlang:trace_pattern(~p, ~p) -> ~p", [MFA,MatchProg,Res]),
Res.
trace_pid(Pid, On, Flags0) ->
Flags = [{tracer,get(tracer_port)}|Flags0],
get(tracer) ! {apply,self(),{erlang,trace,[Pid,On,Flags]}},
Res = receive
{apply_result,Result} -> Result
end,
ok = io:format("erlang:trace(~p, ~p, ~p) -> ~p",
[Pid,On,Flags,Res]),
Res.
start_tracer(Config) ->
Path = ?config(data_dir, Config),
ok = load_driver(Path, echo_drv),
Self = self(),
put(tracer, fun_spawn(fun() -> tracer(Self) end)),
receive
{started,Port} ->
put(tracer_port, Port)
end,
get(tracer).
load_driver(Dir, Driver) ->
case erl_ddll:load_driver(Dir, Driver) of
ok -> ok;
{error, Error} = Res ->
io:format("~s\n", [erl_ddll:format_error(Error)]),
Res
end.
tracer(RelayTo) ->
Port = open_port({spawn,echo_drv}, [eof,binary]),
RelayTo ! {started,Port},
tracer_loop(RelayTo, Port).
tracer_loop(RelayTo, Port) ->
receive
{apply,From,{M,F,A}} ->
From ! {apply_result,apply(M, F, A)},
tracer_loop(RelayTo, Port);
{Port,{data,Msg}} ->
RelayTo ! binary_to_term(Msg),
tracer_loop(RelayTo, Port);
{unlink_tracer_port, From} ->
unlink(Port),
From ! {unlinked_tracer_port, self()},
tracer_loop(RelayTo, Port);
Other ->
exit({bad_message,Other})
end.
fun_spawn(Fun) ->
spawn_link(erlang, apply, [Fun,[]]).
fun_spawn(Fun, Opts) ->
spawn_opt(erlang, apply, [Fun,[]], [link | Opts]).
% flush() ->
% receive
% X ->
% [X | flush()]
% after 2000 ->
% []
% end.
%%% Models for various kinds of processes.
%% Sends messages when ordered to.
sender() ->
receive
{send_please, To, What} ->
To ! What,
sender()
end.
%% Just consumes messages from its message queue.
receiver() ->
receive
_Any -> receiver()
end.
%% Does a garbage collection when it receives a message.
garber() ->
receive
_Any ->
lists:seq(1, 100),
erlang:garbage_collect(),
garber()
end.
%% All-purpose process
general() ->
receive
{apply, {M, F, Args}} ->
erlang:apply(M, F, Args),
general();
{send, Dest, Msg} ->
Dest ! Msg,
general();
{call_f_1, Arg} ->
f(Arg),
general();
nop ->
general()
end.
f(Arg) ->
Arg.
