/* $Id: PDMAsyncCompletionFileFailsafe.cpp 21496 2009-07-10 20:16:09Z vboxsync $ */
/** @file
 * PDM Async I/O - Transport data asynchronous in R3 using EMT.
 * Failsafe File I/O manager.
 */

/*
 * Copyright (C) 2006-2008 Sun Microsystems, Inc.
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 USA or visit http://www.sun.com if you need
 * additional information or have any questions.
 */
#define LOG_GROUP LOG_GROUP_PDM_ASYNC_COMPLETION
#include <iprt/types.h>
#include <VBox/log.h>

#include "PDMAsyncCompletionFileInternal.h"

static int pdmacFileAioMgrFailsafeProcessEndpoint(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint)
{
    int rc = VINF_SUCCESS;
    PPDMASYNCCOMPLETIONTASK pTasks = pdmacFileEpGetNewTasks(pEndpoint);

    while (pTasks)
    {
        PPDMASYNCCOMPLETIONTASKFILE pTaskFile = (PPDMASYNCCOMPLETIONTASKFILE)pTasks;

        if (pTasks->pNext)
            AssertMsg(pTasks->uTaskId < pTasks->pNext->uTaskId,
                      ("The task IDs are not ordered Curr=%u Next=%u\n", pTasks->uTaskId, pTasks->pNext->uTaskId));

        switch (pTaskFile->enmTransferType)
        {
            case PDMACTASKFILETRANSFER_FLUSH:
            {
                rc = RTFileFlush(pEndpoint->File);
                break;
            }
            case PDMACTASKFILETRANSFER_READ:
            case PDMACTASKFILETRANSFER_WRITE:
            {
                PPDMACTASKFILESEG pSeg = pTaskFile->u.DataTransfer.pSegmentsHead;
                RTFOFF offCurr = pTaskFile->u.DataTransfer.off;

                do
                {
                    if (pTaskFile->enmTransferType == PDMACTASKFILETRANSFER_READ)
                    {
                        rc = RTFileReadAt(pEndpoint->File, offCurr,
                                          pSeg->DataSeg.pvSeg,
                                          pSeg->DataSeg.cbSeg,
                                          NULL);
                    }
                    else
                    {
                        rc = RTFileWriteAt(pEndpoint->File, offCurr,
                                          pSeg->DataSeg.pvSeg,
                                          pSeg->DataSeg.cbSeg,
                                          NULL);
                    }

                    /* Free the segment. */
                    PPDMACTASKFILESEG pCur = pSeg;
                    pSeg = pSeg->pNext;

                    offCurr += pCur->DataSeg.cbSeg;

                    pdmacFileSegmentFree(pEndpoint, pCur);
                } while(pSeg && RT_SUCCESS(rc));

                AssertMsg(offCurr == (pTaskFile->u.DataTransfer.off + (RTFOFF)pTaskFile->u.DataTransfer.cbTransfer),
                          ("Incomplete transfer %llu bytes requested offCurr=%llu rc=%Rrc\n",
                           pTaskFile->u.DataTransfer.cbTransfer,
                           offCurr, rc));

                break;
            }
            default:
                AssertMsgFailed(("Invalid transfer type %d\n", pTaskFile->enmTransferType));
        }

        AssertRC(rc);
        pTasks = pTasks->pNext;

        /* Notify task owner */
        pdmR3AsyncCompletionCompleteTask(&pTaskFile->Core);
    }

    return rc;
}

/**
 * A fallback method in case something goes wrong with the normal
 * I/O manager.
 */
int pdmacFileAioMgrFailsafe(RTTHREAD ThreadSelf, void *pvUser)
{
    int rc = VINF_SUCCESS;
    PPDMACEPFILEMGR pAioMgr = (PPDMACEPFILEMGR)pvUser;

    while (!pAioMgr->fShutdown)
    {
        if (!ASMAtomicReadBool(&pAioMgr->fWokenUp))
        {
            ASMAtomicWriteBool(&pAioMgr->fWaitingEventSem, true);
            rc = RTSemEventWait(pAioMgr->EventSem, RT_INDEFINITE_WAIT);
            ASMAtomicWriteBool(&pAioMgr->fWaitingEventSem, false);
            AssertRC(rc);
        }
        ASMAtomicXchgBool(&pAioMgr->fWokenUp, false);

        /* Process endpoint events first. */
        PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint = pAioMgr->pEndpointsHead;
        while (pEndpoint)
        {
            rc = pdmacFileAioMgrFailsafeProcessEndpoint(pEndpoint);
            AssertRC(rc);
            pEndpoint = pEndpoint->AioMgr.pEndpointNext;
        }

        /* Now check for an external blocking event. */
        if (pAioMgr->fBlockingEventPending)
        {
            switch (pAioMgr->enmBlockingEvent)
            {
                case PDMACEPFILEAIOMGRBLOCKINGEVENT_ADD_ENDPOINT:
                {
                    PPDMASYNCCOMPLETIONENDPOINTFILE pEndpointNew = pAioMgr->BlockingEventData.AddEndpoint.pEndpoint;
                    AssertMsg(VALID_PTR(pEndpointNew), ("Adding endpoint event without a endpoint to add\n"));

                    pEndpointNew->AioMgr.pEndpointNext = pAioMgr->pEndpointsHead;
                    pEndpointNew->AioMgr.pEndpointPrev = NULL;
                    if (pAioMgr->pEndpointsHead)
                        pAioMgr->pEndpointsHead->AioMgr.pEndpointPrev = pEndpointNew;
                    pAioMgr->pEndpointsHead = pEndpointNew;
                    break;
                }
                case PDMACEPFILEAIOMGRBLOCKINGEVENT_REMOVE_ENDPOINT:
                {
                    PPDMASYNCCOMPLETIONENDPOINTFILE pEndpointRemove = pAioMgr->BlockingEventData.RemoveEndpoint.pEndpoint;
                    AssertMsg(VALID_PTR(pEndpointRemove), ("Removing endpoint event without a endpoint to remove\n"));

                    PPDMASYNCCOMPLETIONENDPOINTFILE pPrev = pEndpointRemove->AioMgr.pEndpointPrev;
                    PPDMASYNCCOMPLETIONENDPOINTFILE pNext = pEndpointRemove->AioMgr.pEndpointNext;

                    if (pPrev)
                        pPrev->AioMgr.pEndpointNext = pNext;
                    else
                        pAioMgr->pEndpointsHead = pNext;

                    if (pNext)
                        pNext->AioMgr.pEndpointPrev = pPrev;
                    break;
                }
                case PDMACEPFILEAIOMGRBLOCKINGEVENT_CLOSE_ENDPOINT:
                {
                    PPDMASYNCCOMPLETIONENDPOINTFILE pEndpointClose = pAioMgr->BlockingEventData.CloseEndpoint.pEndpoint;
                    AssertMsg(VALID_PTR(pEndpointClose), ("Close endpoint event without a endpoint to Close\n"));

                    /* Make sure all tasks finished. */
                    rc = pdmacFileAioMgrFailsafeProcessEndpoint(pEndpointClose);
                    AssertRC(rc);
                }
                case PDMACEPFILEAIOMGRBLOCKINGEVENT_SHUTDOWN:
                    break;
                case PDMACEPFILEAIOMGRBLOCKINGEVENT_SUSPEND:
                    break;
                default:
                    AssertMsgFailed(("Invalid event type %d\n", pAioMgr->enmBlockingEvent));
            }

            /* Release the waiting thread. */
            rc = RTSemEventSignal(pAioMgr->EventSemBlock);
            AssertRC(rc);
        }
    }

    return rc;
}