POSIX_TRACE_EVENT(P)					     POSIX Programmer's Manual					      POSIX_TRACE_EVENT(P)

NAME

       posix_trace_event, posix_trace_eventid_open - trace functions for instrumenting application code (TRACING)

SYNOPSIS

       #include <sys/types.h>
       #include <trace.h>

       void posix_trace_event(trace_event_id_t event_id,
	      const void *restrictdata_ptr, size_t data_len);
       int posix_trace_eventid_open(const char *restrict event_name,
	      trace_event_id_t *restrict event_id);

DESCRIPTION

       The  posix_trace_event()  function  shall  record  the event_id and the user data pointed to by data_ptr in the trace stream into which the
       calling process is being traced and in which event_id is not filtered out. If the total size of the user trace event  data  represented	by
       data_len  is  not greater than the declared maximum size for user trace event data, then the truncation-status attribute of the trace event
       recorded is POSIX_TRACE_NOT_TRUNCATED. Otherwise, the user trace event data is truncated to this declared maximum size and the  truncation-
       status attribute of the trace event recorded is POSIX_TRACE_TRUNCATED_RECORD.

       If  there  is  no  trace  stream  created for the process or if the created trace stream is not running, or if the trace event specified by
       event_id is filtered out in the trace stream, the posix_trace_event() function shall have no effect.

       The posix_trace_eventid_open() function shall associate a user trace event name with a trace event type identifier for the calling process.
       The  trace  event  name	is  the string pointed to by the argument event_name. It shall have a maximum of {TRACE_EVENT_NAME_MAX} characters
       (which has the minimum value {_POSIX_TRACE_EVENT_NAME_MAX}).  The number of user trace event type identifiers that can be defined  for  any
       given process is limited by the maximum value {TRACE_USER_EVENT_MAX}, which has the minimum value {POSIX_TRACE_USER_EVENT_MAX}.

       If  the Trace Inherit option is not supported, the posix_trace_eventid_open() function shall associate the user trace event name pointed to
       by the event_name argument with a trace event type identifier that is unique for the traced  process,  and  is  returned  in  the  variable
       pointed	to  by	the  event_id  argument.  If the user trace event name has already been mapped for the traced process, then the previously
       assigned  trace	event  type  identifier  shall	be  returned.  If  the	per-process  user  trace   event   name   limit   represented	by
       {TRACE_USER_EVENT_MAX}  has  been  reached,  the pre-defined POSIX_TRACE_UNNAMED_USEREVENT (see Trace Option: User Trace Event ) user trace
       event shall be returned.

       If the Trace Inherit option is supported, the posix_trace_eventid_open() function shall associate the user trace event name pointed  to	by
       the event_name argument with a trace event type identifier that is unique for all the processes being traced in this same trace stream, and
       is returned in the variable pointed to by the event_id argument. If the user trace event name has already been mapped for the  traced  pro-
       cesses,	then  the previously assigned trace event type identifier shall be returned. If the per-process user trace event name limit repre-
       sented by {TRACE_USER_EVENT_MAX} has been reached, the pre-defined POSIX_TRACE_UNNAMED_USEREVENT ( Trace Option: User Trace  Event  )  user
       trace event shall be returned.

       Note:  The  above  procedure,  together with the fact that multiple processes can only be traced into the same trace stream by inheritance,
	      ensure that all the processes that are traced into a trace stream have the same mapping of trace event names  to	trace  event  type
	      identifiers.

       If  there is no trace stream created, the posix_trace_eventid_open() function shall store this information for future trace streams created
       for this process.

RETURN VALUE

       No return value is defined for the posix_trace_event() function.

       Upon successful completion, the posix_trace_eventid_open() function shall return a value of zero. Otherwise, it	shall  return  the  corre-
       sponding  error	number.  The  posix_trace_eventid_open() function stores the trace event type identifier value in the object pointed to by
       event_id, if successful.

ERRORS

       The posix_trace_eventid_open() function shall fail if:

       ENAMETOOLONG
	      The size of the name pointed to by the event_name argument was longer than the implementation-defined value {TRACE_EVENT_NAME_MAX}.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Trace  Option:  User  Trace  Event  ,  posix_trace_start()  ,  posix_trace_trid_eventid_open()	,   the   Base	 Definitions   volume	of
       IEEE Std 1003.1-2001, <sys/types.h>, <trace.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003						      POSIX_TRACE_EVENT(P)