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-rw-r--r--lib/dtrace/src/dtrace.erl216
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diff --git a/lib/dtrace/src/dtrace.erl b/lib/dtrace/src/dtrace.erl
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+-module(dtrace).
+
+%%% @doc The DTrace interface module
+%%%
+%%% This DTrace interface module, with the corresponding NIFs, should
+%%% work on any operating system platform where user-space DTrace
+%%% probes are supported.
+%%%
+%%% Use the `dtrace:init()' function to load the NIF shared library and
+%%% to initialize library's private state.
+%%%
+%%% It is recommended that you use the `dtrace:p()' function to add
+%%% DTrace probes to your Erlang code. This function can accept up to
+%%% four integer arguments and four string arguments; the integer
+%%% argument(s) must come before any string argument. For example:
+%%% ```
+%%% 1> put(dtrace_utag, "GGOOOAAALL!!!!!").
+%%% undefined
+%%% 2> dtrace:init().
+%%% ok
+%%%
+%%% % % % Enable the DTrace probe using the 'dtrace' command.
+%%%
+%%% 3> dtrace:p(7, 8, 9, "one", "four").
+%%% true
+%%% '''
+%%%
+%%% Output from the example D script `user-probe.d' looks like:
+%%% ```
+%%% <0.34.0> GGOOOAAALL!!!!! 7 8 9 0 'one' 'four' '' ''
+%%% '''
+%%%
+%%% If the expected type of variable is not present, e.g. integer when
+%%% integer() is expected, or an I/O list when iolist() is expected,
+%%% then the driver will ignore the user's input and use a default
+%%% value of 0 or NULL, respectively.
+
+-export([init/0, available/0,
+ user_trace_s1/1, % TODO: unify with pid & tag args like user_trace_i4s4
+ p/0, p/1, p/2, p/3, p/4, p/5, p/6, p/7, p/8]).
+-export([scaff/0]). % Development only
+-export([user_trace_i4s4/9]). % Know what you're doing!
+
+-type probe_arg() :: integer() | iolist().
+-type int_p_arg() :: integer() | iolist() | undef.
+%% The *_maybe() types use atom() instead of a stricter 'undef'
+%% because user_trace_i4s4/9 is exposed to the outside world, and
+%% because the driver will allow any atom to be used as a "not
+%% present" indication, we'll allow any atom in the types.
+-type integer_maybe() :: integer() | atom().
+-type iolist_maybe() :: iolist() | atom().
+
+-spec init() -> ok | {error, {term(), term()}}.
+
+init() ->
+ PrivDir = code:priv_dir(dtrace),
+ Lib = filename:join([PrivDir, "lib", "dtrace"]),
+ erlang:load_nif(Lib, 0).
+
+%%%
+%%% NIF placeholders
+%%%
+
+-spec available() -> true | false.
+
+available() ->
+ erlang:nif_error(nif_not_loaded).
+
+-spec user_trace_s1(iolist()) -> true | false | error | badarg.
+
+user_trace_s1(Message) ->
+ erlang:nif_error(nif_not_loaded).
+
+-spec user_trace_i4s4(iolist(),
+ integer_maybe(), integer_maybe(),
+ integer_maybe(), integer_maybe(),
+ iolist_maybe(), iolist_maybe(),
+ iolist_maybe(), iolist_maybe()) ->
+ true | false | error | badarg.
+
+user_trace_i4s4(_, _, _, _, _, _, _, _, _) ->
+ erlang:nif_error(nif_not_loaded).
+
+%%%
+%%% Erlang support functions
+%%%
+
+-spec p() -> true | false | error | badarg.
+
+p() ->
+ user_trace_int(undef, undef, undef, undef, undef, undef, undef, undef).
+
+-spec p(probe_arg()) -> true | false | error | badarg.
+
+p(I1) when is_integer(I1) ->
+ user_trace_int(I1, undef, undef, undef, undef, undef, undef, undef);
+p(S1) ->
+ user_trace_int(undef, undef, undef, undef, S1, undef, undef, undef).
+
+-spec p(probe_arg(), probe_arg()) -> true | false | error | badarg.
+
+p(I1, I2) when is_integer(I1), is_integer(I2) ->
+ user_trace_int(I1, I2, undef, undef, undef, undef, undef, undef);
+p(I1, S1) when is_integer(I1) ->
+ user_trace_int(I1, undef, undef, undef, S1, undef, undef, undef);
+p(S1, S2) ->
+ user_trace_int(undef, undef, undef, undef, S1, S2, undef, undef).
+
+-spec p(probe_arg(), probe_arg(), probe_arg()) -> true | false | error | badarg.
+
+p(I1, I2, I3) when is_integer(I1), is_integer(I2), is_integer(I3) ->
+ user_trace_int(I1, I2, I3, undef, undef, undef, undef, undef);
+p(I1, I2, S1) when is_integer(I1), is_integer(I2) ->
+ user_trace_int(I1, I2, undef, undef, S1, undef, undef, undef);
+p(I1, S1, S2) when is_integer(I1) ->
+ user_trace_int(I1, undef, undef, undef, S1, S2, undef, undef);
+p(S1, S2, S3) ->
+ user_trace_int(undef, undef, undef, undef, S1, S2, S3, undef).
+
+-spec p(probe_arg(), probe_arg(), probe_arg(), probe_arg()) ->
+ true | false | error | badarg.
+
+p(I1, I2, I3, I4) when is_integer(I1), is_integer(I2), is_integer(I3), is_integer(I4) ->
+ user_trace_int(I1, I2, I3, I4, undef, undef, undef, undef);
+p(I1, I2, I3, S1) when is_integer(I1), is_integer(I2), is_integer(I3) ->
+ user_trace_int(I1, I2, I3, undef, S1, undef, undef, undef);
+p(I1, I2, S1, S2) when is_integer(I1), is_integer(I2) ->
+ user_trace_int(I1, I2, undef, undef, S1, S2, undef, undef);
+p(I1, S1, S2, S3) when is_integer(I1) ->
+ user_trace_int(I1, undef, undef, undef, S1, S2, S3, undef);
+p(S1, S2, S3, S4) ->
+ user_trace_int(undef, undef, undef, undef, S1, S2, S3, S4).
+
+-spec p(probe_arg(), probe_arg(), probe_arg(), probe_arg(),
+ probe_arg()) ->
+ true | false | error | badarg.
+
+p(I1, I2, I3, I4, S1) when is_integer(I1), is_integer(I2), is_integer(I3), is_integer(I4) ->
+ user_trace_int(I1, I2, I3, I4, S1, undef, undef, undef);
+p(I1, I2, I3, S1, S2) when is_integer(I1), is_integer(I2), is_integer(I3) ->
+ user_trace_int(I1, I2, I3, undef, S1, S2, undef, undef);
+p(I1, I2, S1, S2, S3) when is_integer(I1), is_integer(I2) ->
+ user_trace_int(I1, I2, undef, undef, S1, S2, S3, undef);
+p(I1, S1, S2, S3, S4) when is_integer(I1) ->
+ user_trace_int(I1, undef, undef, undef, S1, S2, S3, S4).
+
+-spec p(probe_arg(), probe_arg(), probe_arg(), probe_arg(),
+ probe_arg(), probe_arg()) ->
+ true | false | error | badarg.
+
+p(I1, I2, I3, I4, S1, S2) when is_integer(I1), is_integer(I2), is_integer(I3), is_integer(I4) ->
+ user_trace_int(I1, I2, I3, I4, S1, S2, undef, undef);
+p(I1, I2, I3, S1, S2, S3) when is_integer(I1), is_integer(I2), is_integer(I3) ->
+ user_trace_int(I1, I2, I3, undef, S1, S2, S3, undef);
+p(I1, I2, S1, S2, S3, S4) when is_integer(I1), is_integer(I2) ->
+ user_trace_int(I1, I2, undef, undef, S1, S2, S3, S4).
+
+-spec p(probe_arg(), probe_arg(), probe_arg(), probe_arg(),
+ probe_arg(), probe_arg(), probe_arg()) ->
+ true | false | error | badarg.
+
+p(I1, I2, I3, I4, S1, S2, S3) when is_integer(I1), is_integer(I2), is_integer(I3), is_integer(I4) ->
+ user_trace_int(I1, I2, I3, I4, S1, S2, S3, undef);
+p(I1, I2, I3, S1, S2, S3, S4) when is_integer(I1), is_integer(I2), is_integer(I3) ->
+ user_trace_int(I1, I2, I3, undef, S1, S2, S3, S4).
+
+-spec p(probe_arg(), probe_arg(), probe_arg(), probe_arg(),
+ probe_arg(), probe_arg(), probe_arg(), probe_arg()) ->
+ true | false | error | badarg.
+
+p(I1, I2, I3, I4, S1, S2, S3, S4) when is_integer(I1), is_integer(I2), is_integer(I3), is_integer(I4) ->
+ user_trace_int(I1, I2, I3, I4, S1, S2, S3, S4).
+
+-spec user_trace_int(int_p_arg(), int_p_arg(), int_p_arg(), int_p_arg(),
+ int_p_arg(), int_p_arg(), int_p_arg(), int_p_arg()) ->
+ true | false | error | badarg.
+
+user_trace_int(I1, I2, I3, I4, S1, S2, S3, S4) ->
+ UTag = prim_file:get_dtrace_utag(),
+ user_trace_i4s4(UTag, I1, I2, I3, I4, S1, S2, S3, S4).
+
+%% Scaffolding to write tedious code: quick brute force and not 100% correct.
+
+scaff_int_args(N) ->
+ L = lists:sublist(["I1", "I2", "I3", "I4"], N),
+ [string:join(L, ", ")].
+
+scaff_int_guards(N) ->
+ L = lists:sublist(["is_integer(I1)", "is_integer(I2)", "is_integer(I3)",
+ "is_integer(I4)"], N),
+ lists:flatten(string:join(L, ", ")).
+
+scaff_char_args(N) ->
+ L = lists:sublist(["S1", "S2", "S3", "S4"], N),
+ [string:join(L, ", ")].
+
+scaff_fill(N) ->
+ [string:join(lists:duplicate(N, "undef"), ", ")].
+
+scaff() ->
+ L = [begin
+ IntArgs = scaff_int_args(N_int),
+ IntGuards = scaff_int_guards(N_int),
+ IntFill = scaff_fill(4 - N_int),
+ CharArgs = scaff_char_args(N_char),
+ CharFill = scaff_fill(4 - N_char),
+ InArgs = string:join(IntArgs ++ CharArgs, ", "),
+ OutArgs = string:join(IntArgs ++ IntFill ++ CharArgs ++ CharFill,
+ ", "),
+ {N_int + N_char,
+ lists:flatten([io_lib:format("p(~s) when ~s ->\n",
+ [InArgs, IntGuards]),
+ io_lib:format(" user_trace_int(~s);\n", [OutArgs])
+ ])}
+ end || N_int <- [0,1,2,3,4], N_char <- [0,1,2,3,4]],
+ [io:format("%%~p\n~s", [N, Str]) || {N, Str} <- lists:sort(L)].
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