Fix: consumerd: slow metadata push slows down application registration

[lttng-tools.git] / src / common / waiter.h

/*
 * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 * This code is originally adapted from userspace-rcu's urcu-wait.h
 */

#ifndef LTTNG_WAITER_H
#define LTTNG_WAITER_H

#define _LGPL_SOURCE

#include <stdint.h>
#include <urcu/wfstack.h>
#include <stdbool.h>
#include "macros.h"

struct lttng_waiter {
	struct cds_wfs_node wait_queue_node;
	int32_t state;
};

struct lttng_wait_queue {
	struct cds_wfs_stack stack;
};

LTTNG_HIDDEN
void lttng_waiter_init(struct lttng_waiter *waiter);

LTTNG_HIDDEN
void lttng_waiter_wait(struct lttng_waiter *waiter);

/*
 * lttng_waiter_wake must only be called by a single waker.
 * It is invalid for multiple "wake" operations to be invoked
 * on a single waiter without re-initializing it before.
 */
LTTNG_HIDDEN
void lttng_waiter_wake(struct lttng_waiter *waiter);

LTTNG_HIDDEN
void lttng_wait_queue_init(struct lttng_wait_queue *queue);

/*
 * Atomically add a waiter to a wait queue.
 * A full memory barrier is issued before being added to the wait queue.
 */
LTTNG_HIDDEN
void lttng_wait_queue_add(struct lttng_wait_queue *queue,
		struct lttng_waiter *waiter);

/*
 * Wake every waiter present in the wait queue and remove them from
 * the queue.
 */
LTTNG_HIDDEN
void lttng_wait_queue_wake_all(struct lttng_wait_queue *queue);

#endif /* LTTNG_WAITER_H */