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, 27 insertions, 5 deletions

diff --git a/erts/emulator/beam/erl_process_lock.h b/erts/emulator/beam/erl_process_lock.h
index ac324c6f3e..d81ef63af2 100644
--- a/erts/emulator/beam/erl_process_lock.h
+++ b/erts/emulator/beam/erl_process_lock.h
@@ -66,7 +66,7 @@
 
 #endif
 
-#define ERTS_PROC_LOCK_MAX_BIT 4
+#define ERTS_PROC_LOCK_MAX_BIT 5
 
 typedef erts_aint32_t ErtsProcLocks;
 
@@ -84,6 +84,7 @@ typedef struct erts_proc_lock_t_ {
     erts_lcnt_lock_t lcnt_msgq;
     erts_lcnt_lock_t lcnt_btm;
     erts_lcnt_lock_t lcnt_status;
+    erts_lcnt_lock_t lcnt_trace;
 #endif
 #elif ERTS_PROC_LOCK_RAW_MUTEX_IMPL
     erts_mtx_t main;
@@ -91,6 +92,7 @@ typedef struct erts_proc_lock_t_ {
     erts_mtx_t msgq;
     erts_mtx_t btm;
     erts_mtx_t status;
+    erts_mtx_t trace;
 #else
 #  error "no implementation"
 #endif
@@ -137,9 +139,18 @@ typedef struct erts_proc_lock_t_ {
  *   Protects the following fields in the process structure:
  *   * pending_suspenders
  *   * suspendee
+ *   * sys_tasks
  *   * ...
  */
-#define ERTS_PROC_LOCK_STATUS		(((ErtsProcLocks) 1) << ERTS_PROC_LOCK_MAX_BIT)
+#define ERTS_PROC_LOCK_STATUS		(((ErtsProcLocks) 1) << 4)
+
+/*
+ * Trace message lock:
+ *   Protects the order in which messages are sent
+ *   from trace nifs. This lock is taken inside enif_send.
+ *
+ */
+#define ERTS_PROC_LOCK_TRACE            (((ErtsProcLocks) 1) << ERTS_PROC_LOCK_MAX_BIT)
 
 /*
  * Special fields:
@@ -154,8 +165,8 @@ typedef struct erts_proc_lock_t_ {
  *   all process locks are held, and are allowed to be read if
  *   at least one process lock (whichever one doesn't matter)
  *   is held:
- *     * tracer_proc
- *     * tracer_flags
+ *     * common.tracer
+ *     * common.trace_flags
  *
  *   The following fields are only allowed to be accessed if
  *   both the schedule queue lock and at least one process lock
@@ -208,7 +219,7 @@ typedef struct erts_proc_lock_t_ {
   ((((ErtsProcLocks) 1) << (ERTS_PROC_LOCK_MAX_BIT + 1)) - 1)
 
 #define ERTS_PROC_LOCKS_ALL_MINOR	(ERTS_PROC_LOCKS_ALL \
-					 & ~ERTS_PROC_LOCK_MAIN)
+                                         & ~ERTS_PROC_LOCK_MAIN)
 
 
 #define ERTS_PIX_LOCKS_BITS		10
@@ -260,6 +271,7 @@ void erts_proc_lc_might_unlock(Process *p, ErtsProcLocks locks);
 void erts_proc_lc_chk_have_proc_locks(Process *p, ErtsProcLocks locks);
 void erts_proc_lc_chk_proc_locks(Process *p, ErtsProcLocks locks);
 void erts_proc_lc_chk_only_proc_main(Process *p);
+void erts_proc_lc_chk_only_proc(Process *p, ErtsProcLocks locks);
 void erts_proc_lc_chk_no_proc_locks(char *file, int line);
 ErtsProcLocks erts_proc_lc_my_proc_locks(Process *p);
 int erts_proc_lc_trylock_force_busy(Process *p, ErtsProcLocks locks);
@@ -477,9 +489,15 @@ erts_smp_proc_raw_trylock__(Process *p, ErtsProcLocks locks)
     if (locks & ERTS_PROC_LOCK_STATUS)
 	if (erts_mtx_trylock(&p->lock.status) == EBUSY)
 	    goto busy_status;
+    if (locks & ERTS_PROC_LOCK_TRACE)
+	if (erts_mtx_trylock(&p->lock.trace) == EBUSY)
+	    goto busy_trace;
 
     return 0;
 
+busy_trace:
+    if (locks & ERTS_PROC_LOCK_TRACE)
+	erts_mtx_unlock(&p->lock.trace);
 busy_status:
     if (locks & ERTS_PROC_LOCK_BTM)
 	erts_mtx_unlock(&p->lock.btm);
@@ -568,6 +586,8 @@ erts_smp_proc_lock__(Process *p,
 	erts_mtx_lock(&p->lock.btm);
     if (locks & ERTS_PROC_LOCK_STATUS)
 	erts_mtx_lock(&p->lock.status);
+    if (locks & ERTS_PROC_LOCK_TRACE)
+	erts_mtx_lock(&p->lock.trace);
 
 #ifdef ERTS_PROC_LOCK_DEBUG
     erts_proc_lock_op_debug(p, locks, 1);
@@ -653,6 +673,8 @@ erts_smp_proc_unlock__(Process *p,
     erts_proc_lock_op_debug(p, locks, 0);
 #endif
 
+    if (locks & ERTS_PROC_LOCK_TRACE)
+	erts_mtx_unlock(&p->lock.trace);
     if (locks & ERTS_PROC_LOCK_STATUS)
 	erts_mtx_unlock(&p->lock.status);
     if (locks & ERTS_PROC_LOCK_BTM)