futures.c

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/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 * See COPYRIGHT in top-level directory.
 */
 
#include "abti.h"
 
int ABT_future_create(uint32_t num_compartments, void (*cb_func)(void **arg),
                      ABT_future *newfuture)
{
    int abt_errno;
    ABTI_future *p_future;
    size_t arg_num_compartments = num_compartments;
 
    abt_errno = ABTU_malloc(sizeof(ABTI_future), (void **)&p_future);
    ABTI_CHECK_ERROR(abt_errno);
    ABTD_spinlock_clear(&p_future->lock);
    ABTD_atomic_relaxed_store_size(&p_future->counter, 0);
    p_future->num_compartments = arg_num_compartments;
    if (arg_num_compartments > 0) {
        abt_errno = ABTU_malloc(arg_num_compartments * sizeof(void *),
                                (void **)&p_future->array);
        if (ABTI_IS_ERROR_CHECK_ENABLED && abt_errno != ABT_SUCCESS) {
            ABTU_free(p_future);
            ABTI_HANDLE_ERROR(abt_errno);
        }
    } else {
        p_future->array = NULL;
    }
    p_future->p_callback = cb_func;
    ABTI_waitlist_init(&p_future->waitlist);
 
    *newfuture = ABTI_future_get_handle(p_future);
    return ABT_SUCCESS;
}
 
int ABT_future_free(ABT_future *future)
{
    ABTI_future *p_future = ABTI_future_get_ptr(*future);
    ABTI_CHECK_NULL_FUTURE_PTR(p_future);
 
    /* The lock needs to be acquired to safely free the future structure.
     * However, we do not have to unlock it because the entire structure is
     * freed here. */
    ABTD_spinlock_acquire(&p_future->lock);
 
    ABTU_free(p_future->array);
    ABTU_free(p_future);
 
    *future = ABT_FUTURE_NULL;
    return ABT_SUCCESS;
}
 
int ABT_future_wait(ABT_future future)
{
    ABTI_local *p_local = ABTI_local_get_local();
    ABTI_future *p_future = ABTI_future_get_ptr(future);
    ABTI_CHECK_NULL_FUTURE_PTR(p_future);
 
#ifndef ABT_CONFIG_ENABLE_VER_20_API
    /* Calling this routine on a tasklet is not allowed. */
    if (ABTI_IS_ERROR_CHECK_ENABLED && p_local) {
        ABTI_xstream *p_local_xstream = ABTI_local_get_xstream(p_local);
        ABTI_CHECK_TRUE(p_local_xstream->p_thread->type &
                            ABTI_THREAD_TYPE_YIELDABLE,
                        ABT_ERR_FUTURE);
    }
#endif
 
    ABTD_spinlock_acquire(&p_future->lock);
    if (ABTD_atomic_relaxed_load_size(&p_future->counter) <
        p_future->num_compartments) {
        ABTI_waitlist_wait_and_unlock(&p_local, &p_future->waitlist,
                                      &p_future->lock,
                                      ABT_SYNC_EVENT_TYPE_FUTURE,
                                      (void *)p_future);
    } else {
        ABTD_spinlock_release(&p_future->lock);
    }
    return ABT_SUCCESS;
}
 
int ABT_future_test(ABT_future future, ABT_bool *is_ready)
{
    ABTI_future *p_future = ABTI_future_get_ptr(future);
    ABTI_CHECK_NULL_FUTURE_PTR(p_future);
 
    size_t counter = ABTD_atomic_acquire_load_size(&p_future->counter);
    *is_ready = (counter == p_future->num_compartments) ? ABT_TRUE : ABT_FALSE;
    return ABT_SUCCESS;
}
 
int ABT_future_set(ABT_future future, void *value)
{
    ABTI_local *p_local = ABTI_local_get_local();
    ABTI_future *p_future = ABTI_future_get_ptr(future);
    ABTI_CHECK_NULL_FUTURE_PTR(p_future);
 
    ABTD_spinlock_acquire(&p_future->lock);
 
    size_t counter = ABTD_atomic_relaxed_load_size(&p_future->counter);
    size_t num_compartments = p_future->num_compartments;
#ifndef ABT_CONFIG_DISABLE_ERROR_CHECK
    /* If num_compartments is 0, this routine always returns ABT_ERR_FUTURE */
    if (counter >= num_compartments) {
        ABTD_spinlock_release(&p_future->lock);
        ABTI_HANDLE_ERROR(ABT_ERR_FUTURE);
    }
#endif
    p_future->array[counter] = value;
    counter++;
    /* Call a callback function before setting the counter. */
    if (counter == num_compartments && p_future->p_callback != NULL) {
        (*p_future->p_callback)(p_future->array);
    }
 
    ABTD_atomic_release_store_size(&p_future->counter, counter);
 
    if (counter == num_compartments) {
        ABTI_waitlist_broadcast(p_local, &p_future->waitlist);
    }
 
    ABTD_spinlock_release(&p_future->lock);
    return ABT_SUCCESS;
}
 
int ABT_future_reset(ABT_future future)
{
    ABTI_future *p_future = ABTI_future_get_ptr(future);
    ABTI_CHECK_NULL_FUTURE_PTR(p_future);
 
    ABTD_spinlock_acquire(&p_future->lock);
    ABTD_atomic_release_store_size(&p_future->counter, 0);
    ABTD_spinlock_release(&p_future->lock);
    return ABT_SUCCESS;
}