Erlang tracing (nested and flat)

output

~/erlang_learning $ erl
Erlang R15B03 (erts-5.9.3.1) [source] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false] [dtrace]

Eshell V5.9.3.1  (abort with ^G)
(erlang_learning@127.0.0.1)1> trace(recursive). 
ok
(erlang_learning@127.0.0.1)2> recursive:fac(10).
call: <0.42.0> recursive:fac(10), level: 0
call: <0.42.0> recursive:fac(9), level: 1
call: <0.42.0> recursive:fac(8), level: 2
call: <0.42.0> recursive:fac(7), level: 3
call: <0.42.0> recursive:fac(6), level: 4
call: <0.42.0> recursive:fac(5), level: 5
call: <0.42.0> recursive:fac(4), level: 6
call: <0.42.0> recursive:fac(3), level: 7
call: <0.42.0> recursive:fac(2), level: 8
call: <0.42.0> recursive:fac(1), level: 9
call: <0.42.0> recursive:fac(0), level: 10
retn: <0.42.0> recursive:fac -> 1, level: 10
retn: <0.42.0> recursive:fac -> 1, level: 9
retn: <0.42.0> recursive:fac -> 2, level: 8
retn: <0.42.0> recursive:fac -> 6, level: 7
retn: <0.42.0> recursive:fac -> 24, level: 6
retn: <0.42.0> recursive:fac -> 120, level: 5
retn: <0.42.0> recursive:fac -> 720, level: 4
retn: <0.42.0> recursive:fac -> 5040, level: 3
retn: <0.42.0> recursive:fac -> 40320, level: 2
retn: <0.42.0> recursive:fac -> 362880, level: 1
retn: <0.42.0> recursive:fac -> 3628800, level: 0
3628800
(erlang_learning@127.0.0.1)3> trace_off().      
ok
(erlang_learning@127.0.0.1)4> tracen(recursive).
<0.42.0> recursive:module_info()
<0.42.0> [{exports,[{fac,1},{module_info,0},{module_info,1}]},
          {imports,[]},
          {attributes,[{vsn,[183699004504069682905172544172501704709]}]},
          {compile,[{options,[{outdir,"ebin"},debug_info,{i,"include"}]},
                    {version,"4.8.2"},
                    {time,{2013,9,12,7,4,16}},
                    {source,"/Users/andrzejsliwa/erlang_learning/apps/erlang_learning/src/recursive.erl"}]}]
ok
(erlang_learning@127.0.0.1)5> recursive:fac(10).
<0.42.0> recursive:fac(10)
<0.42.0> | recursive:fac(9)
<0.42.0> | | recursive:fac(8)
<0.42.0> | | | recursive:fac(7)
<0.42.0> | | | | recursive:fac(6)
<0.42.0> | | | | | recursive:fac(5)
<0.42.0> | | | | | | recursive:fac(4)
<0.42.0> | | | | | | | recursive:fac(3)
<0.42.0> | | | | | | | | recursive:fac(2)
<0.42.0> | | | | | | | | | recursive:fac(1)
<0.42.0> | | | | | | | | | | recursive:fac(0)
<0.42.0> | | | | | | | | | | 1
<0.42.0> | | | | | | | | | 1
<0.42.0> | | | | | | | | 2
<0.42.0> | | | | | | | 6
<0.42.0> | | | | | | 24
<0.42.0> | | | | | 120
<0.42.0> | | | | 720
<0.42.0> | | | 5040
<0.42.0> | | 40320
<0.42.0> | 362880
<0.42.0> 3628800
3628800

user_default.erl

-module(user_default).

-export([help/0]).

-export([p/1, p/2]).
-export([pn/1, pn/2]).
-export([yy/1, yp/1]).
-export([reloader/0]).

-export([trace/1, trace/2]).
-export([tracen/1, tracen/2]).
-export([trace_off/0]).
-export([untrace/1, untrace/2]).

%% output helpers for shell
p(String) -> io:format(String).
p(String, Args) -> io:format(String, Args).
pn(String) -> p(String ++ "~n").
pn(String, Args) -> p(String ++ "~n", Args).
yy(Term) -> pn("~w", [Term]).
yp(Term) -> pn("~p", [Term]).
reloader() -> sync:go().

%% +-----------------------------------------------------------------+
%% | NESTED TRACER                                                   |
%% +-----------------------------------------------------------------+

nested_tracer() ->
    dbg:tracer(process, {fun nested_trace/2, 0}).

nested_trace({trace, Pid, call, {Mod, Fun, Args}}, Level) ->
    pn("~p ~s~p:~p~s", [Pid, fill_spaces(Level), Mod, Fun, format_args(Args)]),
    Level + 1;
nested_trace({trace, Pid, return_from, {_, _, _}, ReturnValue}, Level) ->
    NewLevel = Level - 1,
    pn("~p ~s~p", [Pid, fill_spaces(NewLevel), ReturnValue]),
    NewLevel;
nested_trace(Any, Level) ->
    pn("trace_msg: ~p", [Any]),
    Level.

tracer() ->
    dbg:tracer(process, {fun flat_trace/2, 0}).

flat_trace({trace, Pid, call, {Mod, Fun, Args}}, Level) ->
    pn("call: ~p ~p:~p~s, level: ~w", [Pid, Mod, Fun, format_args(Args), Level]),
    Level + 1;
flat_trace({trace, Pid, return_from, {Mod, Fun, _}, ReturnValue}, Level) ->
    NewLevel = Level - 1,
    pn("retn: ~p ~p:~p -> ~p, level: ~w", [Pid, Mod, Fun, ReturnValue, NewLevel]),
    NewLevel;
flat_trace(Any, Level) ->
    pn("trace_msg: ~p", [Any]),
    Level.

fill_spaces(Level) ->
    lists:duplicate(Level, "| ").

format_args(Args) ->
    Args1 = io_lib:format("~w", [Args]),
    Opts = [global, {return, list}],
    Args2 = re:replace(Args1, "^\\[", "(", Opts),
    Args3 = re:replace(Args2, "\\]$", ")", Opts),
    re:replace(Args3, "\\,", ", ", Opts).

%% +-----------------------------------------------------------------+
%% | TRACING HELPERS                                                 |
%% +-----------------------------------------------------------------+

trace(Module) ->
    tracer(), setup_tracing(Module).
trace(Module, Function) ->
    tracer(), setup_tracing(Module, Function).
tracen(Module) ->
    nested_tracer(), setup_tracing(Module).
tracen(Module, Function) ->
    nested_tracer(), setup_tracing(Module, Function).

trace_off() -> dbg:stop().

untrace(Module) ->
    {ok, _} = dbg:ctpl(Module), ok.
untrace(Module, Function) ->
    {ok, _} = dbg:ctpl(Module, Function), ok.

setup_tracing(Module)
  when is_atom(Module) ->
    {ok, _} = dbg:p(all, call),
    {ok, _} = dbg:tpl(Module, tracing_options()),
    ok.
setup_tracing(Module, Function)
  when is_atom(Module),
       is_atom(Function) ->
    {ok, _} = dbg:p(all, call),
    {ok, _} = dbg:tpl(Module, Function, tracing_options()),
    ok.

tracing_options() ->
    [{'_', [], [{return_trace}, {exception_trace}]}].

%% +-----------------------------------------------------------------+
%% | HELP MENU                                                       |
%% +-----------------------------------------------------------------+

help() ->
    shell_default:help(),
    pn("~n** commands in module ~s (user helpers) **~n", [?MODULE]),
    pn("reloader()                -- run code reloader"),
    pn("trace(Module)             -- run tracing for 'Module'"),
    pn("trace(Module, Function)   -- run tracing for 'Function' of 'Module'"),
    pn("tracen(Module)            -- run tracing for 'Module' - nested way"),
    pn("tracen(Module, Function)  -- run tracing for 'Function' of 'Module' - nasted way"),
    pn("trace_off()               -- disable tracing"),
    pn("untrace(Module)           -- stop tracing 'Module'"),
    pn("untrace(Module, Function) -- stop tracing 'Function' of 'Module'"),
    pn("p(String)                 -- print string"),
    pn("p(String, Args)           -- print string with format"),
    pn("pn(String)                -- print string with ~~n"),
    pn("pn(String, Args)          -- print string with ~~n and format"),
    pn("yy(Term)                  -- print raw term"),
    pn("yp(Term)                  -- print term").