linux/tools/lib/traceevent/Documentation/libtraceevent-field_find.txt
Tzvetomir Stoyanov 0b51220ee0 tools lib traceevent: Man pages for find field APIs
Create man pages for libtraceevent APIs:

  tep_find_common_field(),
  tep_find_field()
  tep_find_any_field()

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190503091119.23399-18-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200108.721589427@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-05-15 16:36:48 -03:00

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libtraceevent(3)
================
NAME
----
tep_find_common_field, tep_find_field, tep_find_any_field -
Search for a field in an event.
SYNOPSIS
--------
[verse]
--
*#include <event-parse.h>*
struct tep_format_field pass:[*]*tep_find_common_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_);
struct tep_format_field pass:[*]*tep_find_field*(struct tep_event_ormat pass:[*]_event_, const char pass:[*]_name_);
struct tep_format_field pass:[*]*tep_find_any_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_);
--
DESCRIPTION
-----------
These functions search for a field with given name in an event. The field
returned can be used to find the field content from within a data record.
The _tep_find_common_field()_ function searches for a common field with _name_
in the _event_.
The _tep_find_field()_ function searches for an event specific field with
_name_ in the _event_.
The _tep_find_any_field()_ function searches for any field with _name_ in the
_event_.
RETURN VALUE
------------
The _tep_find_common_field(), _tep_find_field()_ and _tep_find_any_field()_
functions return a pointer to the found field, or NULL in case there is no field
with the requested name.
EXAMPLE
-------
[source,c]
--
#include <event-parse.h>
...
void get_htimer_info(struct tep_handle *tep, struct tep_record *record)
{
struct tep_format_field *field;
struct tep_event *event;
long long softexpires;
int mode;
int pid;
event = tep_find_event_by_name(tep, "timer", "hrtimer_start");
field = tep_find_common_field(event, "common_pid");
if (field == NULL) {
/* Cannot find "common_pid" field in the event */
} else {
/* Get pid from the data record */
pid = tep_read_number(tep, record->data + field->offset,
field->size);
}
field = tep_find_field(event, "softexpires");
if (field == NULL) {
/* Cannot find "softexpires" event specific field in the event */
} else {
/* Get softexpires parameter from the data record */
softexpires = tep_read_number(tep, record->data + field->offset,
field->size);
}
field = tep_find_any_field(event, "mode");
if (field == NULL) {
/* Cannot find "mode" field in the event */
} else
{
/* Get mode parameter from the data record */
mode = tep_read_number(tep, record->data + field->offset,
field->size);
}
}
...
--
FILES
-----
[verse]
--
*event-parse.h*
Header file to include in order to have access to the library APIs.
*-ltraceevent*
Linker switch to add when building a program that uses the library.
--
SEE ALSO
--------
_libtraceevent(3)_, _trace-cmd(1)_
AUTHOR
------
[verse]
--
*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
--
REPORTING BUGS
--------------
Report bugs to <linux-trace-devel@vger.kernel.org>
LICENSE
-------
libtraceevent is Free Software licensed under the GNU LGPL 2.1
RESOURCES
---------
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git