/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2002-2003, Network Appliance, Inc. All rights reserved.
 */

/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 *
 * MODULE: dapl_cno_wait.c
 *
 * PURPOSE: Wait for a consumer notification event
 * Description: Interfaces in this file are completely described in
 *              the DAPL 1.1 API, Chapter 6, section 3.2.3
 *
 * $Id: dapl_cno_wait.c,v 1.6 2003/06/16 17:53:32 sjs2 Exp $
 */

#include "dapl.h"
#include "dapl_adapter_util.h"
#include "dapl_ring_buffer_util.h"

/*
 * dapl_cno_wait
 *
 * DAPL Requirements Version xxx, 6.3.2.3
 *
 * Wait for a consumer notification event
 *
 * Input:
 *      cno_handle
 *      timeout
 *      evd_handle
 *
 * Output:
 *      evd_handle
 *
 * Returns:
 *      DAT_SUCCESS
 *      DAT_INVALID_HANDLE
 *      DAT_QUEUE_EMPTY
 *      DAT_INVALID_PARAMETER
 */
DAT_RETURN
dapl_cno_wait(
        IN      DAT_CNO_HANDLE          cno_handle,     /* cno_handle */
        IN      DAT_TIMEOUT             timeout,        /* agent */
        OUT     DAT_EVD_HANDLE          *evd_handle)    /* evd_handle */
{
        DAPL_CNO        *cno_ptr;
        DAPL_EVD        *evd_ptr, *head_evd_ptr;
        DAT_RETURN      dat_status;
        int             nevents;

        if (DAPL_BAD_HANDLE(cno_handle, DAPL_MAGIC_CNO)) {
                dat_status = DAT_INVALID_HANDLE | DAT_INVALID_HANDLE_CNO;
                goto bail;
        }

        dat_status = DAT_SUCCESS;
        cno_ptr = (DAPL_CNO *) cno_handle;

        if (cno_ptr->cno_state == DAPL_CNO_STATE_DEAD) {
                dat_status = DAT_ERROR(DAT_INVALID_STATE,
                    DAT_INVALID_STATE_CNO_DEAD);
                goto bail;
        }

        dapl_os_lock(&cno_ptr->header.lock);
        if (dapl_llist_is_empty(&cno_ptr->evd_list_head)) {
                dapl_os_unlock(&cno_ptr->header.lock);
                return (DAT_ERROR(DAT_QUEUE_EMPTY, 0));
        }

        /* scan evd list */
        evd_ptr = (DAPL_EVD *)
            dapl_llist_next_entry(&cno_ptr->evd_list_head, NULL);

        for (;;) {
                /*
                 * Check the evd ring buffer for events, if nothing is found
                 * peek into the CQ to see if there are events
                 */
                if (dapls_rbuf_count(&evd_ptr->pending_event_queue) > 0) {
                        break;
                }

                nevents = 0;
                dapls_ib_cq_peek(evd_ptr, &nevents);
                if (nevents > 0) {
                        break;
                }

                evd_ptr = (DAPL_EVD *)
                    dapl_llist_next_entry(&cno_ptr->evd_list_head,
                    &evd_ptr->cno_list_entry);
                if (evd_ptr == NULL) {
                        break;
                }
        }

        /* shift list by one to simulate round-robin */
        head_evd_ptr = (DAPL_EVD *)
            dapl_llist_remove_head(&cno_ptr->evd_list_head);
        dapl_os_assert(head_evd_ptr != NULL);
        dapl_llist_add_tail(&cno_ptr->evd_list_head,
            &head_evd_ptr->cno_list_entry, head_evd_ptr);

        if (evd_ptr != NULL) {
                *evd_handle = evd_ptr;
                dapl_os_unlock(&cno_ptr->header.lock);
                return (DAT_SUCCESS);
        }

        cno_ptr->cno_waiters++;
        dapl_os_unlock(&cno_ptr->header.lock);

        dat_status = dapls_ib_cno_wait(cno_ptr, timeout, &evd_ptr);

        dapl_os_lock(&cno_ptr->header.lock);
        cno_ptr->cno_waiters--;

        /* verify that evd_ptr is still in the list */
        head_evd_ptr = dapl_llist_next_entry(&cno_ptr->evd_list_head, NULL);
        for (;;) {
                if (head_evd_ptr == NULL || head_evd_ptr == evd_ptr) {
                        break;
                }
                head_evd_ptr = (DAPL_EVD *)
                    dapl_llist_next_entry(&cno_ptr->evd_list_head,
                    &head_evd_ptr->cno_list_entry);
        }

        if (cno_ptr->cno_state == DAPL_CNO_STATE_DEAD) {
                dat_status = DAT_ERROR(DAT_INVALID_STATE,
                    DAT_INVALID_STATE_CNO_DEAD);
        } else if (dat_status == DAT_SUCCESS) {
                /*
                 * After the first triggering, this will be a valid handle.
                 * If we're racing with wakeups of other CNO waiters,
                 * that's ok.
                 */
                if (head_evd_ptr == evd_ptr && evd_ptr != NULL) {
                        *evd_handle = evd_ptr;
                } else {
                        dat_status = DAT_ERROR(DAT_QUEUE_EMPTY, 0);
                }
        }
        /*
         * The only other reason we could have made it out of
         * the loop is a timeout.
         */
        dapl_os_unlock(&cno_ptr->header.lock);
bail:
        return (dat_status);
}