157 lines
5.2 KiB
Plaintext
157 lines
5.2 KiB
Plaintext
libtraceevent(3)
|
|
================
|
|
|
|
NAME
|
|
----
|
|
tep_register_event_handler, tep_unregister_event_handler - Register /
|
|
unregisters a callback function to parse an event information.
|
|
|
|
SYNOPSIS
|
|
--------
|
|
[verse]
|
|
--
|
|
*#include <event-parse.h>*
|
|
|
|
enum *tep_reg_handler* {
|
|
_TEP_REGISTER_SUCCESS_,
|
|
_TEP_REGISTER_SUCCESS_OVERWRITE_,
|
|
};
|
|
|
|
int *tep_register_event_handler*(struct tep_handle pass:[*]_tep_, int _id_, const char pass:[*]_sys_name_, const char pass:[*]_event_name_, tep_event_handler_func _func_, void pass:[*]_context_);
|
|
int *tep_unregister_event_handler*(struct tep_handle pass:[*]tep, int id, const char pass:[*]sys_name, const char pass:[*]event_name, tep_event_handler_func func, void pass:[*]_context_);
|
|
|
|
typedef int (*pass:[*]tep_event_handler_func*)(struct trace_seq pass:[*]s, struct tep_record pass:[*]record, struct tep_event pass:[*]event, void pass:[*]context);
|
|
--
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
The _tep_register_event_handler()_ function registers a handler function,
|
|
which is going to be called to parse the information for a given event.
|
|
The _tep_ argument is the trace event parser context. The _id_ argument is
|
|
the id of the event. The _sys_name_ argument is the name of the system,
|
|
the event belongs to. The _event_name_ argument is the name of the event.
|
|
If _id_ is >= 0, it is used to find the event, otherwise _sys_name_ and
|
|
_event_name_ are used. The _func_ is a pointer to the function, which is going
|
|
to be called to parse the event information. The _context_ argument is a pointer
|
|
to the context data, which will be passed to the _func_. If a handler function
|
|
for the same event is already registered, it will be overridden with the new
|
|
one. This mechanism allows a developer to override the parsing of a given event.
|
|
If for some reason the default print format is not sufficient, the developer
|
|
can register a function for an event to be used to parse the data instead.
|
|
|
|
The _tep_unregister_event_handler()_ function unregisters the handler function,
|
|
previously registered with _tep_register_event_handler()_. The _tep_ argument
|
|
is the trace event parser context. The _id_, _sys_name_, _event_name_, _func_,
|
|
and _context_ are the same arguments, as when the callback function _func_ was
|
|
registered.
|
|
|
|
The _tep_event_handler_func_ is the type of the custom event handler
|
|
function. The _s_ argument is the trace sequence, it can be used to create a
|
|
custom string, describing the event. A _record_ to get the event from is passed
|
|
as input parameter and also the _event_ - the handle to the record's event. The
|
|
_context_ is custom context, set when the custom event handler is registered.
|
|
|
|
RETURN VALUE
|
|
------------
|
|
The _tep_register_event_handler()_ function returns _TEP_REGISTER_SUCCESS_
|
|
if the new handler is registered successfully or
|
|
_TEP_REGISTER_SUCCESS_OVERWRITE_ if an existing handler is overwritten.
|
|
If there is not enough memory to complete the registration,
|
|
TEP_ERRNO__MEM_ALLOC_FAILED is returned.
|
|
|
|
The _tep_unregister_event_handler()_ function returns 0 if _func_ was removed
|
|
successful or, -1 if the event was not found.
|
|
|
|
The _tep_event_handler_func_ should return -1 in case of an error,
|
|
or 0 otherwise.
|
|
|
|
EXAMPLE
|
|
-------
|
|
[source,c]
|
|
--
|
|
#include <event-parse.h>
|
|
#include <trace-seq.h>
|
|
...
|
|
struct tep_handle *tep = tep_alloc();
|
|
...
|
|
int timer_expire_handler(struct trace_seq *s, struct tep_record *record,
|
|
struct tep_event *event, void *context)
|
|
{
|
|
trace_seq_printf(s, "hrtimer=");
|
|
|
|
if (tep_print_num_field(s, "0x%llx", event, "timer", record, 0) == -1)
|
|
tep_print_num_field(s, "0x%llx", event, "hrtimer", record, 1);
|
|
|
|
trace_seq_printf(s, " now=");
|
|
|
|
tep_print_num_field(s, "%llu", event, "now", record, 1);
|
|
|
|
tep_print_func_field(s, " function=%s", event, "function", record, 0);
|
|
|
|
return 0;
|
|
}
|
|
...
|
|
int ret;
|
|
|
|
ret = tep_register_event_handler(tep, -1, "timer", "hrtimer_expire_entry",
|
|
timer_expire_handler, NULL);
|
|
if (ret < 0) {
|
|
char buf[32];
|
|
|
|
tep_strerror(tep, ret, buf, 32)
|
|
printf("Failed to register handler for hrtimer_expire_entry: %s\n", buf);
|
|
} else {
|
|
switch (ret) {
|
|
case TEP_REGISTER_SUCCESS:
|
|
printf ("Registered handler for hrtimer_expire_entry\n");
|
|
break;
|
|
case TEP_REGISTER_SUCCESS_OVERWRITE:
|
|
printf ("Overwrote handler for hrtimer_expire_entry\n");
|
|
break;
|
|
}
|
|
}
|
|
...
|
|
ret = tep_unregister_event_handler(tep, -1, "timer", "hrtimer_expire_entry",
|
|
timer_expire_handler, NULL);
|
|
if ( ret )
|
|
printf ("Failed to unregister handler for hrtimer_expire_entry\n");
|
|
|
|
--
|
|
|
|
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
|