Document event.h (API)

[babeltrace.git] / include / babeltrace / ctf-ir / event.h

#ifndef BABELTRACE_CTF_IR_EVENT_H
#define BABELTRACE_CTF_IR_EVENT_H

/*
 * BabelTrace - CTF IR: Event
 *
 * Copyright 2013, 2014 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * The Common Trace Format (CTF) Specification is available at
 * http://www.efficios.com/ctf
 */

#include <stdint.h>
#include <stddef.h>
#include <babeltrace/values.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
@defgroup ctfirevent CTF IR event
@ingroup ctfir
@brief CTF IR event.

A CTF IR <strong><em>event</em></strong> is a container of event
fields:

- <strong>Stream event header</strong> field, described by the
  <em>stream event header field type</em> of a
  \link ctfirstreamclass CTF IR stream class\endlink.
- <strong>Stream event context</strong> field, described by the
  <em>stream event context field type</em> of a stream class.
- <strong>Event context</strong> field, described by the
  <em>event context field type</em> of a
  \link ctfireventclass CTF IR event class\endlink.
- <strong>Event payload</strong>, described by the
  <em>event payload field type</em> of an event class.

As a reminder, here's the structure of a CTF packet:

@imgpacketstructure

You can create a CTF IR event \em from a
\link ctfireventclass CTF IR event class\endlink with
bt_ctf_event_create(). The event class you use to create an event
object becomes its parent.

If the \link ctfirtraceclass CTF IR trace class\endlink of an event
object (parent of its \link ctfirstreamclass CTF IR stream class\endlink,
which is the parent of its event class) was created by a
\link ctfirwriter CTF IR writer\endlink object, then the only possible
action you can do with this event object is to append it to a
\link ctfirstream CTF IR stream\endlink with
bt_ctf_stream_append_event(). Otherwise, you can create an event
notification with bt_notification_event_create(). The event you pass
to this function \em must have an attached packet object first.

You can attach a \link ctfirpacket CTF IR packet object\endlink to an
event object with bt_ctf_event_set_packet().

A CTF IR event has a mapping of
\link ctfirclockvalue CTF IR clock values\endlink. A clock value is
an instance of a specific
\link ctfirclockclass CTF IR clock class\endlink when the event is
emitted. You can set an event object's clock value with
bt_ctf_event_set_clock_value().

As with any Babeltrace object, CTF IR event objects have
<a href="https://en.wikipedia.org/wiki/Reference_counting">reference
counts</a>. See \ref refs to learn more about the reference counting
management of Babeltrace objects.

bt_notification_event_create() \em freezes its event parameter on
success. You cannot modify a frozen event object: it is considered
immutable, except for \link refs reference counting\endlink.

@sa ctfireventclass
@sa ctfirpacket

@file
@brief CTF IR event type and functions.
@sa ctfirevent

@addtogroup ctfirevent
@{
*/

/**
@struct bt_ctf_event
@brief A CTF IR event.
@sa ctfirevent
*/
struct bt_ctf_event;
struct bt_ctf_clock;
struct bt_ctf_clock_value;
struct bt_ctf_event_class;
struct bt_ctf_field;
struct bt_ctf_field_type;
struct bt_ctf_stream_class;
struct bt_ctf_packet;

/**
@name Creation and parent access functions
@{
*/

/**
@brief  Creates a default CTF IR event from the CTF IR event class
	\p event_class.

\p event_class \em must have a parent
\link ctfirstreamclass CTF IR stream class\endlink.

On success, the four fields of the created event object are not set. You
can set them with bt_ctf_event_set_header(),
bt_ctf_event_set_stream_event_context(),
bt_ctf_event_set_event_context(), and bt_ctf_event_set_payload_field().

@param[in] event_class	CTF IR event class to use to create the
			CTF IR event.
@returns		Created event object, or \c NULL on error.

@prenotnull{event_class}
@pre \p event_class has a parent stream class.
@postsuccessrefcountret1
*/
extern struct bt_ctf_event *bt_ctf_event_create(
		struct bt_ctf_event_class *event_class);

/**
@brief	Returns the parent CTF IR event class of the CTF IR event
	\p event.

This function returns a reference to the event class which was used to
create the event object in the first place with bt_ctf_event_create().

@param[in] event	Event of which to get the parent event class.
@returns		Parent event class of \p event,
			or \c NULL on error.

@prenotnull{event}
@postsuccessrefcountretinc
*/
extern struct bt_ctf_event_class *bt_ctf_event_get_class(
		struct bt_ctf_event *event);

/**
@brief	Returns the CTF IR packet associated to the CTF IR event
	\p event.

This function returns a reference to the event class which was set to
\p event in the first place with bt_ctf_event_set_packet().

@param[in] event	Event of which to get the associated packet.
@returns		Packet associated to \p event,
			or \c NULL if no packet is associated to
			\p event or on error.

@prenotnull{event}
@postsuccessrefcountretinc

@sa bt_ctf_event_set_packet(): Associates a given event to a given
	packet.
*/
extern struct bt_ctf_packet *bt_ctf_event_get_packet(
		struct bt_ctf_event *event);

/**
@brief	Associates the CTF IR event \p event to the CTF IR packet
	\p packet.

The \link ctfirstreamclass CTF IR stream class\endlink of the
parent \link ctfirstream CTF IR stream\endlink of \p packet \em must
be the same as the parent stream class of the
\link ctfireventclass CTF IR event class\endlink returned
by bt_ctf_event_get_class() for \p event.

You \em must call this function to create an event-packet association
before you call bt_notification_event_create() with \p event.

On success, this function also sets the parent stream object of
\p event to the parent stream of \p packet.

@param[in] event	Event to which to associate \p packet.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{packet}
@prehot{event}
@pre The parent stream class of \p packet is the same as the parent
	stream class of \p event.
@postsuccessrefcountretinc

@sa bt_ctf_event_get_packet(): Returns the associated packet of a
	given event object.
*/
extern int bt_ctf_event_set_packet(struct bt_ctf_event *event,
		struct bt_ctf_packet *packet);

/**
@brief	Returns the parent CTF IR stream associated to the CTF IR event
	\p event.

@param[in] event	Event of which to get the parent stream.
@returns		Parent stream of \p event, or \c NULL on error.

@prenotnull{event}
@postsuccessrefcountretinc
*/
extern struct bt_ctf_stream *bt_ctf_event_get_stream(
		struct bt_ctf_event *event);

/** @} */

/**
@name Contained fields functions
@{
*/

/**
@brief	Returns the stream event header field of the CTF IR event
	\p event.

@param[in] event	Event of which to get the stream event header
			field.
@returns		Stream event header field of \p event,
			or \c NULL if the stream event header
			field is not set or on error.

@prenotnull{event}
@postsuccessrefcountretinc

@sa bt_ctf_event_get_header(): Sets the stream event header
	field of a given event.
*/
extern struct bt_ctf_field *bt_ctf_event_get_header(
		struct bt_ctf_event *event);

/**
@brief	Sets the stream event header field of the CTF IR event
	\p event to \p header.

The field type of \p header, as returned by bt_ctf_field_get_type(),
\em must be equivalent to the field type returned by
bt_ctf_stream_class_get_event_header_type() for the parent stream class
of \p event.

@param[in] event	Event of which to set the stream event header
			field.
@param[in] header	Stream event header field.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{header}
@prehot{event}
@pre \p header has a field type equivalent to the field type returned by
	bt_ctf_stream_class_get_event_header_type() for the parent
	stream class of \p event.
@postrefcountsame{event}
@postsuccessrefcountinc{header}

@sa bt_ctf_event_get_header(): Returns the stream event header field
	of a given event.
*/
extern int bt_ctf_event_set_header(struct bt_ctf_event *event,
		struct bt_ctf_field *header);

/**
@brief	Returns the stream event context field of the CTF IR event
	\p event.

@param[in] event	Event of which to get the stream event context
			field.
@returns		Stream event context field of \p event,
			or \c NULL if the stream event context
			field is not set or on error.

@prenotnull{event}
@postsuccessrefcountretinc

@sa bt_ctf_event_set_stream_event_context(): Sets the stream event
	context field of a given event.
*/
extern struct bt_ctf_field *bt_ctf_event_get_stream_event_context(
		struct bt_ctf_event *event);

/**
@brief	Sets the stream event context field of the CTF IR event
	\p event to \p context.

The field type of \p context, as returned by bt_ctf_field_get_type(),
\em must be equivalent to the field type returned by
bt_ctf_stream_class_get_event_context_type() for the parent stream class
of \p event.

@param[in] event	Event of which to set the stream event context
			field.
@param[in] context	Stream event context field.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{context}
@prehot{event}
@pre \p context has a field type equivalent to the field type returned
	by bt_ctf_stream_class_get_event_context_type() for the parent
	stream class of \p event.
@postrefcountsame{event}
@postsuccessrefcountinc{context}

@sa bt_ctf_event_get_stream_event_context(): Returns the stream event
	context field of a given event.
*/
extern int bt_ctf_event_set_stream_event_context(struct bt_ctf_event *event,
		struct bt_ctf_field *context);

/**
@brief	Returns the event context field of the CTF IR event
	\p event.

@param[in] event	Event of which to get the event context
			field.
@returns                Event context field of \p event, or \c NULL if
			the event context field is not set or on error.

@prenotnull{event}
@postsuccessrefcountretinc

@sa bt_ctf_event_set_event_context(): Sets the event context field of a
	given event.
*/
extern struct bt_ctf_field *bt_ctf_event_get_event_context(
		struct bt_ctf_event *event);

/**
@brief	Sets the event context field of the CTF IR event
	\p event to \p context.

The field type of \p context, as returned by bt_ctf_field_get_type(),
\em must be equivalent to the field type returned by
bt_ctf_event_class_get_context_type() for the parent event class
of \p event.

@param[in] event	Event of which to set the event context field.
@param[in] context	Event context field.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{context}
@prehot{event}
@pre \p context has a field type equivalent to the field type returned
	by bt_ctf_event_class_get_context_type() for the parent
	event class of \p event.
@postrefcountsame{event}
@postsuccessrefcountinc{context}

@sa bt_ctf_event_get_event_context(): Returns the event context field of
	a given event.
*/
extern int bt_ctf_event_set_event_context(struct bt_ctf_event *event,
		struct bt_ctf_field *context);

/**
@brief	Returns the event payload field of the CTF IR event
	\p event.

@param[in] event	Event of which to get the event payload
			field.
@returns                Event payload field of \p event, or \c NULL if
			the event payload field is not set or on error.

@prenotnull{event}
@postsuccessrefcountretinc

@sa bt_ctf_event_set_payload_field(): Sets the event payload field of a
	given event.
*/
extern struct bt_ctf_field *bt_ctf_event_get_payload_field(
		struct bt_ctf_event *event);

/**
@brief	Sets the event payload field of the CTF IR event
	\p event to \p payload.

The field type of \p payload, as returned by bt_ctf_field_get_type(),
\em must be equivalent to the field type returned by
bt_ctf_event_class_get_payload_type() for the parent event class
of \p event.

@param[in] event	Event of which to set the event payload field.
@param[in] payload	Event payload field.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{payload}
@prehot{event}
@pre \p payload has a field type equivalent to the field type returned
	by bt_ctf_event_class_get_payload_type() for the parent
	event class of \p event.
@postrefcountsame{event}
@postsuccessrefcountinc{payload}

@sa bt_ctf_event_get_payload_field(): Returns the event payload field of
	a given event.
*/
extern int bt_ctf_event_set_payload_field(struct bt_ctf_event *event,
		struct bt_ctf_field *payload);

/**
@cond DOCUMENT
*/

/*
 * TODO: Doxygenize.
 *
 * bt_ctf_event_get_payload: get an event's field.
 *
 * Returns the field matching "name". bt_put() must be called on the
 * returned value.
 *
 * @param event Event instance.
 * @param name Event field name, see notes.
 *
 * Returns a field instance on success, NULL on error.
 *
 * Note: Passing a name will cause the function to perform a look-up by
 *	name assuming the event's payload is a structure. This will return
 *	the raw payload instance if name is NULL.
 */
extern struct bt_ctf_field *bt_ctf_event_get_payload(struct bt_ctf_event *event,
		const char *name);

/*
 * TODO: Doxygenize.
 *
 * bt_ctf_event_get_payload_by_index: Get event's field by index.
 *
 * Returns the field associated with the provided index. bt_put()
 * must be called on the returned value. The indexes to be provided are
 * the same as can be retrieved from the event class.
 *
 * @param event Event.
 * @param index Index of field.
 *
 * Returns the event's field, NULL on error.
 *
 * Note: Will return an error if the payload's type is not a structure.
 */
extern struct bt_ctf_field *bt_ctf_event_get_payload_by_index(
		struct bt_ctf_event *event, int index);

/*
 * TODO: Doxygenize.
 *
 * bt_ctf_event_set_payload: set an event's field.
 *
 * Set a manually allocated field as an event's payload. The event will share
 * the field's ownership by using its reference count.
 * bt_put() must be called on the returned value.
 *
 * @param event Event instance.
 * @param name Event field name, see notes.
 * @param value Instance of a field whose type corresponds to the event's field.
 *
 * Returns 0 on success, a negative value on error.
 *
 * Note: The function will return an error if a name is provided and the payload
 *	type is not a structure. If name is NULL, the payload field will be set
 *	directly and must match the event class' payload's type.
 */
extern int bt_ctf_event_set_payload(struct bt_ctf_event *event,
		const char *name,
		struct bt_ctf_field *value);

/**
@endcond
*/

/** @} */

/**
@name Clock value functions
@{
*/

/**
@brief	Returns the value, as of the CTF IR event \p event, of the
	clock described by the
	\link ctfirclockclass CTF IR clock class\endlink \p clock_class.

@param[in] event	Event of which to get the value of the clock
			described by \p clock_class.
@param[in] clock_class	Class of the clock of which to get the value.
@returns		Value of the clock described by \p clock_class
			as of \p event.

@prenotnull{event}
@prenotnull{clock_class}
@postrefcountsame{event}
@postrefcountsame{clock_class}
@postsuccessrefcountretinc

@sa bt_ctf_event_set_clock_value(): Sets the clock value of a given event.
*/
extern struct bt_ctf_clock_value *bt_ctf_event_get_clock_value(
		struct bt_ctf_event *event, struct bt_ctf_clock *clock_class);

/**
@brief	Sets the value, as of the CTF IR event \p event, of the
	clock described by the
	\link ctfirclockclass CTF IR clock class\endlink \p clock_class.

@param[in] event	Event of which to set the value of the clock
			described by \p clock_class.
@param[in] clock_class	Class of the clock of which to set the value
			for \p event.
@param[in] clock_value	Value of the clock described by \p clock_class
			as of \p event.
@returns		0 on success, or a negative value on error.

@prenotnull{event}
@prenotnull{clock_class}
@prenotnull{clock_value}
@prehot{event}
@postrefcountsame{event}
@postrefcountsame{clock_class}

@sa bt_ctf_event_get_clock_value(): Returns the clock value of
	a given event.
*/
extern int bt_ctf_event_set_clock_value(
		struct bt_ctf_event *event, struct bt_ctf_clock *clock_class,
		struct bt_ctf_clock_value *clock_value);

/** @} */

/** @} */

#ifdef __cplusplus
}
#endif

#endif /* BABELTRACE_CTF_IR_EVENT_H */