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, 19 insertions, 7 deletions

diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 1d3704f0af..5c2e8bbd09 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -44,6 +44,8 @@
 #include "erl_port.h"
 #include "erl_gc.h"
 
+struct enif_func_t;
+
 struct enif_environment_t /* ErlNifEnv */
 {
     struct erl_module_nif* mod_nif;
@@ -54,6 +56,7 @@ struct enif_environment_t /* ErlNifEnv */
     int fpe_was_unmasked;
     struct enif_tmp_obj_t* tmp_obj_list;
     int exception_thrown; /* boolean */
+    Process *tracee;
 };
 extern void erts_pre_nif(struct enif_environment_t*, Process*,
 			 struct erl_module_nif*);
@@ -62,6 +65,12 @@ extern Eterm erts_nif_taints(Process* p);
 extern void erts_print_nif_taints(int to, void* to_arg);
 void erts_unload_nif(struct erl_module_nif* nif);
 extern void erl_nif_init(void);
+extern int erts_nif_get_funcs(struct erl_module_nif*,
+                              struct enif_func_t **funcs);
+extern Eterm erts_nif_call_function(Process *p, Process *tracee,
+                                    struct erl_module_nif*,
+                                    struct enif_func_t *,
+                                    int argc, Eterm *argv);
 
 /* Driver handle (wrapper for old plain handle) */
 #define ERL_DE_OK      0
@@ -1532,10 +1541,15 @@ ERTS_GLB_INLINE void dtrace_fun_decode(Process *process,
 ERTS_GLB_INLINE void
 dtrace_pid_str(Eterm pid, char *process_buf)
 {
-    erts_snprintf(process_buf, DTRACE_TERM_BUF_SIZE, "<%lu.%lu.%lu>",
-                  pid_channel_no(pid),
-                  pid_number(pid),
-                  pid_serial(pid));
+    if (is_pid(pid))
+        erts_snprintf(process_buf, DTRACE_TERM_BUF_SIZE, "<%lu.%lu.%lu>",
+                      pid_channel_no(pid),
+                      pid_number(pid),
+                      pid_serial(pid));
+    else if (is_port(pid))
+        erts_snprintf(process_buf, DTRACE_TERM_BUF_SIZE, "#Port<%lu.%lu>",
+                      port_channel_no(pid),
+                      port_number(pid));
 }
 
 ERTS_GLB_INLINE void
@@ -1547,9 +1561,7 @@ dtrace_proc_str(Process *process, char *process_buf)
 ERTS_GLB_INLINE void
 dtrace_port_str(Port *port, char *port_buf)
 {
-    erts_snprintf(port_buf, DTRACE_TERM_BUF_SIZE, "#Port<%lu.%lu>",
-                  port_channel_no(port->common.id),
-                  port_number(port->common.id));
+    dtrace_pid_str(port->common.id, port_buf);
 }
 
 ERTS_GLB_INLINE void