Commit 6dfe6849 authored by Tzvetomir Stoyanov's avatar Tzvetomir Stoyanov Committed by Arnaldo Carvalho de Melo

tools lib traceevent: Man pages for print field APIs

Create man pages for libtraceevent APIs:

  tep_print_field(),
  tep_print_fields(),
  tep_print_num_field(),
  tep_print_func_field()
Signed-off-by: default avatarTzvetomir 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/20190503091119.23399-20-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200109.054708419@goodmis.orgSigned-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 96e75ef9
libtraceevent(3)
================
NAME
----
tep_print_field, tep_print_fields, tep_print_num_field, tep_print_func_field -
Print the field content.
SYNOPSIS
--------
[verse]
--
*#include <event-parse.h>*
*#include <trace-seq.h>*
void *tep_print_field*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, struct tep_format_field pass:[*]_field_);
void *tep_print_fields*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, int _size_, struct tep_event pass:[*]_event_);
int *tep_print_num_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_);
int *tep_print_func_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_);
--
DESCRIPTION
-----------
These functions print recorded field's data, according to the field's type.
The _tep_print_field()_ function extracts from the recorded raw _data_ value of
the _field_ and prints it into _s_, according to the field type.
The _tep_print_fields()_ prints each field name followed by the record's field
value according to the field's type:
[verse]
--
"field1_name=field1_value field2_name=field2_value ..."
--
It iterates all fields of the _event_, and calls _tep_print_field()_ for each of
them.
The _tep_print_num_field()_ function prints a numeric field with given format
string. A search is performed in the _event_ for a field with _name_. If such
field is found, its value is extracted from the _record_ and is printed in the
_s_, according to the given format string _fmt_. If the argument _err_ is
non-zero, and an error occures - it is printed in the _s_.
The _tep_print_func_field()_ function prints a function field with given format
string. A search is performed in the _event_ for a field with _name_. If such
field is found, its value is extracted from the _record_. The value is assumed
to be a function address, and a search is perform to find the name of this
function. The function name (if found) and its address are printed in the _s_,
according to the given format string _fmt_. If the argument _err_ is non-zero,
and an error occures - it is printed in _s_.
RETURN VALUE
------------
The _tep_print_num_field()_ and _tep_print_func_field()_ functions return 1
on success, -1 in case of an error or 0 if the print buffer _s_ is full.
EXAMPLE
-------
[source,c]
--
#include <event-parse.h>
#include <trace-seq.h>
...
struct tep_handle *tep = tep_alloc();
...
struct trace_seq seq;
trace_seq_init(&seq);
struct tep_event *event = tep_find_event_by_name(tep, "timer", "hrtimer_start");
...
void process_record(struct tep_record *record)
{
struct tep_format_field *field_pid = tep_find_common_field(event, "common_pid");
trace_seq_reset(&seq);
/* Print the value of "common_pid" */
tep_print_field(&seq, record->data, field_pid);
/* Print all fields of the "hrtimer_start" event */
tep_print_fields(&seq, record->data, record->size, event);
/* Print the value of "expires" field with custom format string */
tep_print_num_field(&seq, " timer expires in %llu ", event, "expires", record, 0);
/* Print the address and the name of "function" field with custom format string */
tep_print_func_field(&seq, " timer function is %s ", event, "function", record, 0);
}
...
--
FILES
-----
[verse]
--
*event-parse.h*
Header file to include in order to have access to the library APIs.
*trace-seq.h*
Header file to include in order to have access to trace sequences related APIs.
Trace sequences are used to allow a function to call several other functions
to create a string of data to use.
*-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
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