Re: [PATCH v4 22/46] tools/lib/traceevent: Man pages tep_find_common_field(), tep_find_field() and tep_find_any_field()

[Steven Rostedt <rostedt@goodmis.org>]

On Fri,  8 Mar 2019 15:36:30 +0200
Tzvetomir Stoyanov <tstoyanov@vmware.com> wrote:

> Create man pages for tep_find_common_field(), tep_find_field()
> and tep_find_any_field() as part of the libtraceevent APIs.
> 
> Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
> ---
>  .../libtraceevent-field_find.txt              | 98 +++++++++++++++++++
>  1 file changed, 98 insertions(+)
>  create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-field_find.txt
> 
> diff --git a/tools/lib/traceevent/Documentation/libtraceevent-field_find.txt b/tools/lib/traceevent/Documentation/libtraceevent-field_find.txt
> new file mode 100644
> index 000000000000..b941988429a0
> --- /dev/null
> +++ b/tools/lib/traceevent/Documentation/libtraceevent-field_find.txt
> @@ -0,0 +1,98 @@
> +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 _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_.
> +

I would state also how these fields can be used. Something like:

"The field returned can then be used to find the field content from
within a data record."


> +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>
> +...
> +struct tep_handle *tep = tep_alloc();
> +...
> +struct tep_event *event = tep_find_event_by_name(tep, "timer", "hrtimer_start");
> +...
> +	struct tep_format_field *field;
> +
> +	field = tep_find_common_field(event, "common_pid");
> +	if (field == NULL) {
> +		/* Cannot find "common_pid" common field in the event */
> +	}

Perhaps add what to do with this:

	pid = tep_read_number(tep, record->data + field->offset, field->size);

-- Steve

 
> +
> +	field = tep_find_field(event, "softexpires");
> +	if (field == NULL) {
> +		/* Cannot find "softexpires" event specific field in the event */
> +	}
> +
> +	field = tep_find_any_field(event, "mode");
> +	if (field == NULL) {
> +		/* Cannot find "mode" field in the event */
> +	}
> +...
> +--
> +
> +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