API : seek by timestamp

[babeltrace.git] / include / babeltrace / iterator.h

#ifndef _BABELTRACE_ITERATOR_H
#define _BABELTRACE_ITERATOR_H

/*
 * BabelTrace API Iterators
 *
 * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@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.
 */

#include <babeltrace/format.h>
#include <babeltrace/context.h>

/* Forward declarations */
struct bt_iter;
struct ctf_stream_event;
struct ctf_stream;
struct bt_saved_pos;

struct bt_iter_pos {
	enum {
		BT_SEEK_TIME,		/* uses u.seek_time */
		BT_SEEK_RESTORE,	/* uses u.restore */
		BT_SEEK_CUR,
		BT_SEEK_BEGIN,
		BT_SEEK_END,
	} type;
	union {
		uint64_t seek_time;
		struct bt_saved_pos *restore;
	} u;
};

/*
 * bt_iter_create - Allocate a trace collection iterator.
 *
 * begin_pos and end_pos are optional parameters to specify the position
 * at which the trace collection should be seeked upon iterator
 * creation, and the position at which iteration will start returning
 * "EOF".
 *
 * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
 * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
 * trace) is the EOF criterion.
 */
struct bt_iter *bt_iter_create(struct bt_context *ctx,
		struct bt_iter_pos *begin_pos,
		struct bt_iter_pos *end_pos);

/*
 * bt_iter_destroy - Free a trace collection iterator.
 */
void bt_iter_destroy(struct bt_iter *iter);

/*
 * bt_iter_next: Move trace collection position to the next event.
 *
 * Returns 0 on success, a negative value on error
 */
int bt_iter_next(struct bt_iter *iter);

/*
 * bt_iter_get_pos - Get the current iterator position.
 *
 * The position returned by this function needs to be freed by
 * bt_iter_free_pos after use.
 */
struct bt_iter_pos *
	bt_iter_get_pos(struct bt_iter *iter);

/*
 * bt_iter_free_pos - Free the position.
 */
void bt_iter_free_pos(struct bt_iter_pos *pos);

/*
 * bt_iter_set_pos: move the iterator to a given position.
 *
 * On error, the stream_heap is reinitialized and returned empty.
 *
 * Return 0 for success.
 *
 * Return EOF if the position requested is after the last event of the
 * trace collection.
 * Return -EINVAL when called with invalid parameter.
 * Return -ENOMEM if the stream_heap could not be properly initialized.
 */
int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);

/*
 * bt_iter_create_time_pos: create a position based on time
 *
 * This function allocates and returns a new bt_iter_pos (which must be freed
 * with bt_iter_free_pos) to be able to restore an iterator position based on a
 * timestamp.
 */
struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
		uint64_t timestamp);

/*
 * bt_iter_read_event: Read the iterator's current event data.
 *
 * @iter: trace collection iterator (input)
 * @stream: stream containing event at current position (output)
 * @event: current event (output)
 * Return 0 on success, negative error value on error.
 */
int bt_iter_read_event(struct bt_iter *iter,
		struct ctf_stream **stream,
		struct ctf_stream_event **event);

#endif /* _BABELTRACE_ITERATOR_H */