xref: /aosp_15_r20/external/libtraceevent/Documentation/libtraceevent-handle.txt (revision 436bf2bcd5202612ffffe471bbcc1f277cc8d28e)

libtraceevent(3)
================

NAME
----
tep_alloc, tep_free,tep_ref, tep_unref,tep_get_ref, tep_kbuffer - Create, destroy, manage
references of trace event parser context.

SYNOPSIS
--------
[verse]
--
*#include <event-parse.h>*

struct tep_handle pass:[*]*tep_alloc*(void);
void *tep_free*(struct tep_handle pass:[*]_tep_);
void *tep_ref*(struct tep_handle pass:[*]_tep_);
void *tep_unref*(struct tep_handle pass:[*]_tep_);
int *tep_get_ref*(struct tep_handle pass:[*]_tep_);
struct kbuffer pass:[*]*tep_kbuffer*(struct tep_handle pass:[*]_tep_);
--

DESCRIPTION
-----------
These are the main functions to create and destroy tep_handle - the main
structure, representing the trace event parser context. This context is used as
the input parameter of most library APIs.

The *tep_alloc()* function allocates and initializes the tep context.

The *tep_free()* function will decrement the reference of the _tep_ handler.
When there is no more references, then it will free the handler, as well
as clean up all its resources that it had used. The argument _tep_ is
the pointer to the trace event parser context.

The *tep_ref()* function adds a reference to the _tep_ handler.

The *tep_unref()* function removes a reference from the _tep_ handler. When
the last reference is removed, the _tep_ is destroyed, and all resources that
it had used are cleaned up.

The *tep_ref_get()* functions gets the current references of the _tep_ handler.

The *tep_kbuffer()* function allocates a kbuffer descriptor that can be used to
parse raw data that is represented by the _tep_ handle descriptor. It must be freed
with *kbuf_free(3)*.

RETURN VALUE
------------
*tep_alloc()* returns a pointer to a newly created tep_handle structure.
NULL is returned in case there is not enough free memory to allocate it.

*tep_ref_get()* returns the current references of _tep_.
If _tep_ is NULL, 0 is returned.

*tep_kbuffer()* returns a kbuffer descriptor that can parse the raw data that
represents the tep handle. Must be freed with *kbuf_free(3)*.

EXAMPLE
-------
[source,c]
--
#include <event-parse.h>

...
struct tep_handle *tep = tep_alloc();
...
int ref = tep_get_ref(tep);
tep_ref(tep);
if ( (ref+1) != tep_get_ref(tep)) {
	/* Something wrong happened, the counter is not incremented by 1 */
}
tep_unref(tep);
...
tep_free(tep);
...
--
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* <[email protected]>, author of *libtraceevent*.
*Tzvetomir Stoyanov* <[email protected]>, author of this man page.
--
REPORTING BUGS
--------------
Report bugs to  <[email protected]>

LICENSE
-------
libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES
---------
https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/