src/common/waiter.h

   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 <stdint.h>
  16 #include <urcu/wfstack.h>
  17 #include <stdbool.h>
  18 #include "macros.h"
  19
  20 struct lttng_waiter {
  21         struct cds_wfs_node wait_queue_node;
  22         int32_t state;
  23 };
  24
  25 struct lttng_wait_queue {
  26         struct cds_wfs_stack stack;
  27 };
  28
  29 LTTNG_HIDDEN
  30 void lttng_waiter_init(struct lttng_waiter *waiter);
  31
  32 LTTNG_HIDDEN
  33 void lttng_waiter_wait(struct lttng_waiter *waiter);
  34
  35 /*
  36  * lttng_waiter_wake must only be called by a single waker.
  37  * It is invalid for multiple "wake" operations to be invoked
  38  * on a single waiter without re-initializing it before.
  39  */
  40 LTTNG_HIDDEN
  41 void lttng_waiter_wake(struct lttng_waiter *waiter);
  42
  43 LTTNG_HIDDEN
  44 void lttng_wait_queue_init(struct lttng_wait_queue *queue);
  45
  46 /*
  47  * Atomically add a waiter to a wait queue.
  48  * A full memory barrier is issued before being added to the wait queue.
  49  */
  50 LTTNG_HIDDEN
  51 void lttng_wait_queue_add(struct lttng_wait_queue *queue,
  52                 struct lttng_waiter *waiter);
  53
  54 /*
  55  * Wake every waiter present in the wait queue and remove them from
  56  * the queue.
  57  */
  58 LTTNG_HIDDEN
  59 void lttng_wait_queue_wake_all(struct lttng_wait_queue *queue);
  60
  61 #endif /* LTTNG_WAITER_H */