abtd_futex.h

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/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 * See COPYRIGHT in top-level directory.
 */
 
#ifndef ABTD_FUTEX_H_INCLUDED
#define ABTD_FUTEX_H_INCLUDED
 
#ifndef ABT_CONFIG_ACTIVE_WAIT_POLICY
 
/* ABTD_futex_multiple supports a wait-broadcast pattern.  ABTD_futex_multiple
 * allows multiple waiters. */
typedef struct ABTD_futex_multiple ABTD_futex_multiple;
 
/* Initialize ABTD_futex_multiple. */
static inline void ABTD_futex_multiple_init(ABTD_futex_multiple *p_futex);
 
/* This routine unlocks p_lock and makes the underlying Pthread block on
 * p_futex.  Broadcast can wake up this waiter.  Spurious wakeup does not
 * happen. */
void ABTD_futex_wait_and_unlock(ABTD_futex_multiple *p_futex,
                                ABTD_spinlock *p_lock);
 
/* This routine unlocks p_lock and makes the underlying Pthread block on
 * p_futex.  Broadcast can wake up this waiter.  By nature, spurious wakeup
 * might happen, so the caller needs to check the current time if necessary. */
void ABTD_futex_timedwait_and_unlock(ABTD_futex_multiple *p_futex,
                                     ABTD_spinlock *p_lock,
                                     double wait_time_sec);
 
/* This routine wakes up waiters that are waiting on p_futex.  This function
 * must be called when a lock (p_lock above) is taken. */
void ABTD_futex_broadcast(ABTD_futex_multiple *p_futex);
 
/* ABTD_futex_single supports a suspend-resume pattern.  ABTD_futex_single
 * allows only a single waiter. */
typedef struct ABTD_futex_single ABTD_futex_single;
 
/* Initialize ABTD_futex_single. */
static inline void ABTD_futex_single_init(ABTD_futex_single *p_futex);
 
/* This routine suspends the underlying Pthread.  Only one thread can suspend
 * on a single p_futex.  This suspended thread must be woken up by
 * ABTD_futex_resume().  Spurious wakeup does not happen.
 *
 * p_futex must be new; it may not have been used after initialization. */
void ABTD_futex_suspend(ABTD_futex_single *p_futex);
 
/* This routine wakes up a Pthread suspended by ABTD_futex_suspend().  This
 * routine blocks if no Pthread is waiting on p_futex. */
void ABTD_futex_resume(ABTD_futex_single *p_futex);
 
#ifdef ABT_CONFIG_USE_LINUX_FUTEX
 
struct ABTD_futex_multiple {
    ABTD_atomic_int val;
};
 
static inline void ABTD_futex_multiple_init(ABTD_futex_multiple *p_futex)
{
    ABTD_atomic_relaxed_store_int(&p_futex->val, 0);
}
 
struct ABTD_futex_single {
    ABTD_atomic_int val;
};
 
static inline void ABTD_futex_single_init(ABTD_futex_single *p_futex)
{
    ABTD_atomic_relaxed_store_int(&p_futex->val, 0);
}
 
#else /* ABT_CONFIG_USE_LINUX_FUTEX */
 
struct ABTD_futex_multiple {
    void *p_next; /* pthread_sync */
};
 
static inline void ABTD_futex_multiple_init(ABTD_futex_multiple *p_futex)
{
    p_futex->p_next = NULL;
}
 
struct ABTD_futex_single {
    ABTD_atomic_ptr p_sync_obj;
};
 
static inline void ABTD_futex_single_init(ABTD_futex_single *p_futex)
{
    ABTD_atomic_relaxed_store_ptr(&p_futex->p_sync_obj, NULL);
}
 
#endif /* !ABT_CONFIG_USE_LINUX_FUTEX */
 
#endif /* !ABT_CONFIG_ACTIVE_WAIT_POLICY */
 
#endif /* ABTD_FUTEX_H_INCLUDED */