examples/performance-thread/common/lthread_cond.c

/*
 * SPDX-License-Identifier: BSD-3-Clause
 * Copyright 2015 Intel Corporation.
 * Copyright 2012 Hasan Alayli <halayli@gmail.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stddef.h>
#include <limits.h>
#include <inttypes.h>
#include <unistd.h>
#include <pthread.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <errno.h>

#include <rte_log.h>
#include <rte_common.h>

#include "lthread_api.h"
#include "lthread_diag_api.h"
#include "lthread_diag.h"
#include "lthread_int.h"
#include "lthread_sched.h"
#include "lthread_queue.h"
#include "lthread_objcache.h"
#include "lthread_timer.h"
#include "lthread_mutex.h"
#include "lthread_cond.h"

/*
 * Create a condition variable
 */
int
lthread_cond_init(char *name, struct lthread_cond **cond,
          __rte_unused const struct lthread_condattr *attr)
{
    struct lthread_cond *c;

    if (cond == NULL)
        return POSIX_ERRNO(EINVAL);

    /* allocate a condition variable from cache */
    c = _lthread_objcache_alloc((THIS_SCHED)->cond_cache);

    if (c == NULL)
        return POSIX_ERRNO(EAGAIN);

    c->blocked = _lthread_queue_create("blocked");
    if (c->blocked == NULL) {
        _lthread_objcache_free((THIS_SCHED)->cond_cache, (void *)c);
        return POSIX_ERRNO(EAGAIN);
    }

    if (name == NULL)
        strncpy(c->name, "no name", sizeof(c->name));
    else
        strncpy(c->name, name, sizeof(c->name));
    c->name[sizeof(c->name)-1] = 0;

    c->root_sched = THIS_SCHED;

    (*cond) = c;
    DIAG_CREATE_EVENT((*cond), LT_DIAG_COND_CREATE);
    return 0;
}

/*
 * Destroy a condition variable
 */
int lthread_cond_destroy(struct lthread_cond *c)
{
    if (c == NULL) {
        DIAG_EVENT(c, LT_DIAG_COND_DESTROY, c, POSIX_ERRNO(EINVAL));
        return POSIX_ERRNO(EINVAL);
    }

    /* try to free it */
    if (_lthread_queue_destroy(c->blocked) < 0) {
        /* queue in use */
        DIAG_EVENT(c, LT_DIAG_COND_DESTROY, c, POSIX_ERRNO(EBUSY));
        return POSIX_ERRNO(EBUSY);
    }

    /* okay free it */
    _lthread_objcache_free(c->root_sched->cond_cache, c);
    DIAG_EVENT(c, LT_DIAG_COND_DESTROY, c, 0);
    return 0;
}

/*
 * Wait on a condition variable
 */
int lthread_cond_wait(struct lthread_cond *c, __rte_unused uint64_t reserved)
{
    struct lthread *lt = THIS_LTHREAD;

    if (c == NULL) {
        DIAG_EVENT(c, LT_DIAG_COND_WAIT, c, POSIX_ERRNO(EINVAL));
        return POSIX_ERRNO(EINVAL);
    }


    DIAG_EVENT(c, LT_DIAG_COND_WAIT, c, 0);

    /* queue the current thread in the blocked queue
     * this will be written when we return to the scheduler
     * to ensure that the current thread context is saved
     * before any signal could result in it being dequeued and
     * resumed
     */
    lt->pending_wr_queue = c->blocked;
    _suspend();

    /* the condition happened */
    return 0;
}

/*
 * Signal a condition variable
 * attempt to resume any blocked thread
 */
int lthread_cond_signal(struct lthread_cond *c)
{
    struct lthread *lt;

    if (c == NULL) {
        DIAG_EVENT(c, LT_DIAG_COND_SIGNAL, c, POSIX_ERRNO(EINVAL));
        return POSIX_ERRNO(EINVAL);
    }

    lt = _lthread_queue_remove(c->blocked);

    if (lt != NULL) {
        /* okay wake up this thread */
        DIAG_EVENT(c, LT_DIAG_COND_SIGNAL, c, lt);
        _ready_queue_insert((struct lthread_sched *)lt->sched, lt);
    }
    return 0;
}

/*
 * Broadcast a condition variable
 */
int lthread_cond_broadcast(struct lthread_cond *c)
{
    struct lthread *lt;

    if (c == NULL) {
        DIAG_EVENT(c, LT_DIAG_COND_BROADCAST, c, POSIX_ERRNO(EINVAL));
        return POSIX_ERRNO(EINVAL);
    }

    DIAG_EVENT(c, LT_DIAG_COND_BROADCAST, c, 0);
    do {
        /* drain the queue waking everybody */
        lt = _lthread_queue_remove(c->blocked);

        if (lt != NULL) {
            DIAG_EVENT(c, LT_DIAG_COND_BROADCAST, c, lt);
            /* wake up */
            _ready_queue_insert((struct lthread_sched *)lt->sched,
                        lt);
        }
    } while (!_lthread_queue_empty(c->blocked));
    _reschedule();
    DIAG_EVENT(c, LT_DIAG_COND_BROADCAST, c, 0);
    return 0;
}

/*
 * return the diagnostic ref val stored in a condition var
 */
uint64_t
lthread_cond_diag_ref(struct lthread_cond *c)
{
    if (c == NULL)
        return 0;
    return c->diag_ref;
}