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, 4 insertions, 4 deletions

diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index c2303eea49..8261ae28f8 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1041,6 +1041,7 @@ struct process {
 
 #ifdef ERTS_SMP
     ErlMessageInQueue msg_inq;
+    ErlTraceMessageQueue *trace_msg_q;
     ErtsPendExit pending_exit;
     erts_proc_lock_t lock;
     ErtsSchedulerData *scheduler_data;
@@ -1358,7 +1359,6 @@ extern int erts_system_profile_ts_type;
 #define F_TRACE_FLAG(N)      (1 << (ERTS_TRACE_TS_TYPE_BITS + (N)))
 
 /* process trace_flags */
-
 #define F_NOW_TS             (ERTS_TRACE_FLG_NOW_TIMESTAMP \
 			      << ERTS_TRACE_FLAGS_TS_TYPE_SHIFT)
 #define F_STRICT_MON_TS      (ERTS_TRACE_FLG_STRICT_MONOTONIC_TIMESTAMP \
@@ -1380,8 +1380,7 @@ extern int erts_system_profile_ts_type;
 #define F_TRACE_ARITY_ONLY   F_TRACE_FLAG(12)
 #define F_TRACE_RETURN_TO    F_TRACE_FLAG(13) /* Return_to trace when breakpoint tracing */
 #define F_TRACE_SILENT       F_TRACE_FLAG(14) /* No call trace msg suppress */
-#define F_TRACER             F_TRACE_FLAG(15) /* May be (has been) tracer */
-#define F_EXCEPTION_TRACE    F_TRACE_FLAG(16) /* May have exception trace on stack */
+#define F_EXCEPTION_TRACE    F_TRACE_FLAG(15) /* May have exception trace on stack */
 
 /* port trace flags, currently the same as process trace flags */
 #define F_TRACE_SCHED_PORTS  F_TRACE_FLAG(17) /* Trace of port scheduling */
@@ -1717,6 +1716,8 @@ void erts_schedule_thr_prgr_later_cleanup_op(void (*)(void *),
 					     ErtsThrPrgrLaterOp *,
 					     UWord);
 void erts_schedule_complete_off_heap_message_queue_change(Eterm pid);
+void erts_schedule_flush_trace_messages(Eterm pid);
+int erts_flush_trace_messages(Process *c_p, ErtsProcLocks locks);
 
 #if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
 int erts_dbg_check_halloc_lock(Process *p);
@@ -1996,7 +1997,6 @@ erts_psd_set(Process *p, int ix, void *data)
 #define ERTS_PROC_SET_NIF_TRAP_EXPORT(P, NTE) \
     erts_psd_set((P), ERTS_PSD_NIF_TRAP_EXPORT, (void *) (NTE))
 
-
 ERTS_GLB_INLINE Eterm erts_proc_get_error_handler(Process *p);
 ERTS_GLB_INLINE Eterm erts_proc_set_error_handler(Process *p, Eterm handler);