erts: Implement tracer modules

Add the possibility to use modules as trace data receivers. The functions
in the module have to be nifs as otherwise complex trace probes will be
very hard to handle (complex means trace probes for ports for example).

This commit changes the way that the ptab->tracer field works from always
being an immediate, to now be NIL if no tracer is present or else be
the tuple {TracerModule, TracerState} where TracerModule is an atom that
is later used to lookup the appropriate tracer callbacks to call and
TracerState is just passed to the tracer callback. The default process and
port tracers have been rewritten to use the new API.

This commit also changes the order which trace messages are delivered to the
potential tracer process. Any enif_send done in a tracer module may be delayed
indefinitely because of lock order issues. If a message is delayed any other
trace message send from that process is also delayed so that order is preserved
for each traced entity. This means that for some trace events (i.e. send/receive)
the events may come in an unintuitive order (receive before send) to the
trace receiver. Timestamps are taken when the trace message is generated so
trace messages from differented processes may arrive with the timestamp
out of order.

Both the erlang:trace and seq_trace:set_system_tracer accept the new tracer
module tracers and also the backwards compatible arguments.

OTP-10267

1 files changed, 250 insertions, 0 deletions

diff --git a/erts/emulator/nifs/common/erl_tracer_nif.c b/erts/emulator/nifs/common/erl_tracer_nif.c
new file mode 100644
index 0000000000..a1e0e581a4
--- /dev/null
+++ b/erts/emulator/nifs/common/erl_tracer_nif.c
@@ -0,0 +1,250 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson 2015. 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%
+ */
+
+/*
+ * Purpose:  NIF library for process/port tracer
+ *
+ */
+
+
+#define STATIC_ERLANG_NIF 1
+
+#include "erl_nif.h"
+#include "config.h"
+#include "sys.h"
+
+#ifdef VALGRIND
+#  include <valgrind/memcheck.h>
+#endif
+
+/* NIF interface declarations */
+static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info);
+static int upgrade(ErlNifEnv* env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info);
+static void unload(ErlNifEnv* env, void* priv_data);
+
+/* The NIFs: */
+static ERL_NIF_TERM enabled(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM trace(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
+
+static ErlNifFunc nif_funcs[] = {
+    {"enabled", 3, enabled},
+    {"trace", 6, trace}
+};
+
+
+ERL_NIF_INIT(erl_tracer, nif_funcs, load, NULL, upgrade, unload)
+
+#define ATOMS                                      \
+    ATOM_DECL(call);                               \
+    ATOM_DECL(command);                            \
+    ATOM_DECL(cpu_timestamp);                      \
+    ATOM_DECL(discard);                            \
+    ATOM_DECL(exception_from);                     \
+    ATOM_DECL(match_spec_result);                  \
+    ATOM_DECL(monotonic);                          \
+    ATOM_DECL(ok);                                 \
+    ATOM_DECL(remove);                             \
+    ATOM_DECL(return_from);                        \
+    ATOM_DECL(scheduler_id);                       \
+    ATOM_DECL(send);                               \
+    ATOM_DECL(send_to_non_existing_process);       \
+    ATOM_DECL(seq_trace);                          \
+    ATOM_DECL(spawn);                              \
+    ATOM_DECL(strict_monotonic);                   \
+    ATOM_DECL(timestamp);                          \
+    ATOM_DECL(trace);                              \
+    ATOM_DECL(trace_ts);                           \
+    ATOM_DECL(true);                               \
+    ATOM_DECL(undefined);
+
+#define ATOM_DECL(A) static ERL_NIF_TERM atom_##A
+ATOMS
+#undef ATOM_DECL
+
+static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
+{
+
+#define ATOM_DECL(A) atom_##A = enif_make_atom(env, #A)
+ATOMS
+#undef ATOM_DECL
+
+    *priv_data = NULL;
+
+    return 0;
+}
+
+static void unload(ErlNifEnv* env, void* priv_data)
+{
+
+}
+
+static int upgrade(ErlNifEnv* env, void** priv_data, void** old_priv_data,
+		   ERL_NIF_TERM load_info)
+{
+    if (*old_priv_data != NULL) {
+	return -1; /* Don't know how to do that */
+    }
+    if (*priv_data != NULL) {
+	return -1; /* Don't know how to do that */
+    }
+    if (load(env, priv_data, load_info)) {
+	return -1;
+    }
+    return 0;
+}
+
+static ERL_NIF_TERM enabled(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    ErlNifPid to_pid;
+    ErlNifPort to_port;
+    ASSERT(argc == 3);
+
+    if (enif_get_local_pid(env, argv[1], &to_pid)) {
+        if (!enif_is_process_alive(env, &to_pid))
+            /* tracer is dead so we should remove this trace point */
+            return atom_remove;
+    } else if (enif_get_local_port(env, argv[1], &to_port)) {
+        if (!enif_is_port_alive(env, &to_port))
+            /* tracer is dead so we should remove this trace point */
+            return atom_remove;
+    }
+
+    /* Only generate trace for when tracer != tracee */
+    if (enif_is_identical(argv[1], argv[2])) {
+        return atom_discard;
+    }
+
+    return atom_trace;
+}
+
+/*
+  -spec trace(seq_trace, TracerState :: pid() | port(),
+              Label :: non_neg_integer(),
+              Msg :: term(),
+              Opts :: map()) -> ignored();
+        trace(Tag :: atom(), TracerState :: pid() | port(),
+              Tracee :: pid() || port() || undefined,
+              Msg :: term(),
+              Opts :: map()) -> ignored().
+   -spec trace(Tag :: atom(), TracerState :: pid() | port(),
+              Tracee :: pid() || port() || undefined,
+              Msg :: term(),
+              Extra :: term(),
+              Opts :: map()) -> ignored().
+*/
+static ERL_NIF_TERM trace(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    ERL_NIF_TERM value, msg, tt[8], opts;
+    ErlNifPid to_pid;
+    ErlNifPort to_port;
+    size_t tt_sz = 0;
+    int is_port = 0;
+    ASSERT(argc == 6);
+
+    if (!enif_get_local_pid(env, argv[1], &to_pid)) {
+        if (!enif_get_local_port(env, argv[1], &to_port)) {
+            /* This only fails if argv[1] is a not a local port/pid
+               which should not happen as it is checked in enabled */
+            ASSERT(0);
+            return atom_ok;
+        }
+        is_port = 1;
+    }
+
+    if (!enif_is_identical(argv[4], atom_undefined)) {
+        tt[tt_sz++] = atom_trace;
+        tt[tt_sz++] = argv[2];
+        tt[tt_sz++] = argv[0];
+        tt[tt_sz++] = argv[3];
+        tt[tt_sz++] = argv[4];
+    } else {
+        if (enif_is_identical(argv[0], atom_seq_trace)) {
+            tt[tt_sz++] = atom_seq_trace;
+            tt[tt_sz++] = argv[2];
+            tt[tt_sz++] = argv[3];
+        } else {
+            tt[tt_sz++] = atom_trace;
+            tt[tt_sz++] = argv[2];
+            tt[tt_sz++] = argv[0];
+            tt[tt_sz++] = argv[3];
+        }
+    }
+
+    opts = argv[5];
+
+    if (enif_get_map_value(env, opts, atom_match_spec_result,
+                           &value)
+        && !enif_is_identical(value, atom_true)) {
+        tt[tt_sz++] = value;
+    }
+
+    if (enif_get_map_value(env, opts, atom_scheduler_id, &value)
+        && !enif_is_identical(value, atom_undefined)) {
+        tt[tt_sz++] = value;
+    }
+
+    if (enif_get_map_value(env, opts, atom_timestamp, &value)
+        && !enif_is_identical(value, atom_undefined)) {
+        ERL_NIF_TERM ts;
+        if (enif_is_identical(value, atom_monotonic)) {
+            ErlNifTime mon = enif_monotonic_time(ERL_NIF_NSEC);
+            ts = enif_make_int64(env, mon);
+        } else if (enif_is_identical(value, atom_strict_monotonic)) {
+            ErlNifTime mon = enif_monotonic_time(ERL_NIF_NSEC);
+            ERL_NIF_TERM unique = enif_make_unique_integer(
+                env, ERL_NIF_UNIQUE_MONOTONIC);
+            ts = enif_make_tuple2(env, enif_make_int64(env, mon), unique);
+        } else if (enif_is_identical(value, atom_timestamp)) {
+            ts = enif_now_time(env);
+        } else if (enif_is_identical(value, atom_cpu_timestamp)) {
+            ts = enif_cpu_time(env);
+        } else {
+            ASSERT(0);
+            goto error;
+        }
+        tt[tt_sz++] = ts;
+        if (tt[0] == atom_trace)
+            tt[0] = atom_trace_ts;
+    }
+
+    msg = enif_make_tuple_from_array(env, tt, tt_sz);
+
+    if (is_port) {
+        ErlNifBinary bin;
+
+        if (!enif_term_to_binary(env, msg, &bin))
+            goto error;
+
+        msg = enif_make_binary(env, &bin);
+
+        if (!enif_port_command(env, &to_port, NULL, msg))
+            /* port has probably died, enabled will clean up */;
+
+        enif_release_binary(&bin);
+    } else {
+
+        if (!enif_send(env, &to_pid, NULL, msg))
+            /* process has probably died, enabled will clean up */;
+    }
+
+error:
+
+    return atom_ok;
+}