src/common/waiter.hpp

   1 /*
   2  * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-only
   6  *
   7  * This code is originally adapted from userspace-rcu's urcu-wait.h
   8  */
   9
  10 #ifndef LTTNG_WAITER_H
  11 #define LTTNG_WAITER_H
  12
  13 #define _LGPL_SOURCE
  14
  15 #include "macros.hpp"
  16
  17 #include <stdbool.h>
  18 #include <stdint.h>
  19 #include <urcu/wfstack.h>
  20
  21 struct lttng_waiter {
  22         struct cds_wfs_node wait_queue_node;
  23         int32_t state;
  24 };
  25
  26 struct lttng_wait_queue {
  27         struct cds_wfs_stack stack;
  28 };
  29
  30 void lttng_waiter_init(struct lttng_waiter *waiter);
  31
  32 void lttng_waiter_wait(struct lttng_waiter *waiter);
  33
  34 /*
  35  * lttng_waiter_wake must only be called by a single waker.
  36  * It is invalid for multiple "wake" operations to be invoked
  37  * on a single waiter without re-initializing it before.
  38  */
  39 void lttng_waiter_wake(struct lttng_waiter *waiter);
  40
  41 void lttng_wait_queue_init(struct lttng_wait_queue *queue);
  42
  43 /*
  44  * Atomically add a waiter to a wait queue.
  45  * A full memory barrier is issued before being added to the wait queue.
  46  */
  47 void lttng_wait_queue_add(struct lttng_wait_queue *queue, struct lttng_waiter *waiter);
  48
  49 /*
  50  * Wake every waiter present in the wait queue and remove them from
  51  * the queue.
  52  */
  53 void lttng_wait_queue_wake_all(struct lttng_wait_queue *queue);
  54
  55 #endif /* LTTNG_WAITER_H */