/* $Id: ProgressImpl.cpp 33621 2010-10-29 16:15:40Z vboxsync $ */
/** @file
 *
 * VirtualBox Progress COM class implementation
 */

/*
 * Copyright (C) 2006-2010 Oracle Corporation
 *
 * 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.
 */

#include <iprt/types.h>

#if defined(VBOX_WITH_XPCOM)
#include <nsIServiceManager.h>
#include <nsIExceptionService.h>
#include <nsCOMPtr.h>
#endif /* defined(VBOX_WITH_XPCOM) */

#include "ProgressCombinedImpl.h"

#include "VirtualBoxImpl.h"
#include "VirtualBoxErrorInfoImpl.h"

#include "Logging.h"

#include <iprt/time.h>
#include <iprt/semaphore.h>
#include <iprt/cpp/utils.h>

#include <VBox/err.h>

////////////////////////////////////////////////////////////////////////////////
// ProgressBase class
////////////////////////////////////////////////////////////////////////////////

// constructor / destructor
////////////////////////////////////////////////////////////////////////////////

ProgressBase::ProgressBase()
#if !defined(VBOX_COM_INPROC)
    : mParent(NULL)
#endif
{
}

ProgressBase::~ProgressBase()
{
}


/**
 * Subclasses must call this method from their FinalConstruct() implementations.
 */
HRESULT ProgressBase::FinalConstruct()
{
    mCancelable = FALSE;
    mCompleted = FALSE;
    mCanceled = FALSE;
    mResultCode = S_OK;

    m_cOperations
        = m_ulTotalOperationsWeight
        = m_ulOperationsCompletedWeight
        = m_ulCurrentOperation
        = m_ulCurrentOperationWeight
        = m_ulOperationPercent
        = m_cMsTimeout
        = 0;

    // get creation timestamp
    m_ullTimestamp = RTTimeMilliTS();

    m_pfnCancelCallback = NULL;
    m_pvCancelUserArg = NULL;

    return S_OK;
}

// protected initializer/uninitializer for internal purposes only
////////////////////////////////////////////////////////////////////////////////

/**
 * Initializes the progress base object.
 *
 * Subclasses should call this or any other #protectedInit() method from their
 * init() implementations.
 *
 * @param aAutoInitSpan AutoInitSpan object instantiated by a subclass.
 * @param aParent       Parent object (only for server-side Progress objects).
 * @param aInitiator    Initiator of the task (for server-side objects. Can be
 *                      NULL which means initiator = parent, otherwise must not
 *                      be NULL).
 * @param aDescription  ask description.
 * @param aID           Address of result GUID structure (optional).
 *
 * @return              COM result indicator.
 */
HRESULT ProgressBase::protectedInit(AutoInitSpan &aAutoInitSpan,
#if !defined(VBOX_COM_INPROC)
                                    VirtualBox *aParent,
#endif
                                    IUnknown *aInitiator,
                                    CBSTR aDescription,
                                    OUT_GUID aId /* = NULL */)
{
    /* Guarantees subclasses call this method at the proper time */
    NOREF(aAutoInitSpan);

    AutoCaller autoCaller(this);
    AssertReturn(autoCaller.state() == InInit, E_FAIL);

#if !defined(VBOX_COM_INPROC)
    AssertReturn(aParent, E_INVALIDARG);
#else
    AssertReturn(aInitiator, E_INVALIDARG);
#endif

    AssertReturn(aDescription, E_INVALIDARG);

#if !defined(VBOX_COM_INPROC)
    /* share parent weakly */
    unconst(mParent) = aParent;
#endif

#if !defined(VBOX_COM_INPROC)
    /* assign (and therefore addref) initiator only if it is not VirtualBox
     * (to avoid cycling); otherwise mInitiator will remain null which means
     * that it is the same as the parent */
    if (aInitiator)
    {
        ComObjPtr<VirtualBox> pVirtualBox(mParent);
        if (!(pVirtualBox == aInitiator))
            unconst(mInitiator) = aInitiator;
    }
#else
    unconst(mInitiator) = aInitiator;
#endif

    unconst(mId).create();
    if (aId)
        mId.cloneTo(aId);

#if !defined(VBOX_COM_INPROC)
    /* add to the global collection of progress operations (note: after
     * creating mId) */
    mParent->addProgress(this);
#endif

    unconst(mDescription) = aDescription;

    return S_OK;
}

/**
 * Initializes the progress base object.
 *
 * This is a special initializer that doesn't initialize any field. Used by one
 * of the Progress::init() forms to create sub-progress operations combined
 * together using a CombinedProgress instance, so it doesn't require the parent,
 * initiator, description and doesn't create an ID.
 *
 * Subclasses should call this or any other #protectedInit() method from their
 * init() implementations.
 *
 * @param aAutoInitSpan AutoInitSpan object instantiated by a subclass.
 */
HRESULT ProgressBase::protectedInit(AutoInitSpan &aAutoInitSpan)
{
    /* Guarantees subclasses call this method at the proper time */
    NOREF(aAutoInitSpan);

    return S_OK;
}

/**
 * Uninitializes the instance.
 *
 * Subclasses should call this from their uninit() implementations.
 *
 * @param aAutoUninitSpan   AutoUninitSpan object instantiated by a subclass.
 *
 * @note Using the mParent member after this method returns is forbidden.
 */
void ProgressBase::protectedUninit(AutoUninitSpan &aAutoUninitSpan)
{
    /* release initiator (effective only if mInitiator has been assigned in
     * init()) */
    unconst(mInitiator).setNull();

#if !defined(VBOX_COM_INPROC)
    if (mParent)
    {
        /* remove the added progress on failure to complete the initialization */
        if (aAutoUninitSpan.initFailed() && !mId.isEmpty())
            mParent->removeProgress(mId.ref());

        unconst(mParent) = NULL;
    }
#endif
}

// IProgress properties
/////////////////////////////////////////////////////////////////////////////

STDMETHODIMP ProgressBase::COMGETTER(Id)(BSTR *aId)
{
    CheckComArgOutPointerValid(aId);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* mId is constant during life time, no need to lock */
    mId.toUtf16().cloneTo(aId);

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Description)(BSTR *aDescription)
{
    CheckComArgOutPointerValid(aDescription);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* mDescription is constant during life time, no need to lock */
    mDescription.cloneTo(aDescription);

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Initiator)(IUnknown **aInitiator)
{
    CheckComArgOutPointerValid(aInitiator);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* mInitiator/mParent are constant during life time, no need to lock */

#if !defined(VBOX_COM_INPROC)
    if (mInitiator)
        mInitiator.queryInterfaceTo(aInitiator);
    else
    {
        ComObjPtr<VirtualBox> pVirtualBox(mParent);
        pVirtualBox.queryInterfaceTo(aInitiator);
    }
#else
    mInitiator.queryInterfaceTo(aInitiator);
#endif

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Cancelable)(BOOL *aCancelable)
{
    CheckComArgOutPointerValid(aCancelable);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aCancelable = mCancelable;

    return S_OK;
}

/**
 * Internal helper to compute the total percent value based on the member values and
 * returns it as a "double". This is used both by GetPercent (which returns it as a
 * rounded ULONG) and GetTimeRemaining().
 *
 * Requires locking by the caller!
 *
 * @return fractional percentage as a double value.
 */
double ProgressBase::calcTotalPercent()
{
    // avoid division by zero
    if (m_ulTotalOperationsWeight == 0)
        return 0;

    double dPercent = (    (double)m_ulOperationsCompletedWeight                                              // weight of operations that have been completed
                         + ((double)m_ulOperationPercent * (double)m_ulCurrentOperationWeight / (double)100)  // plus partial weight of the current operation
                      ) * (double)100 / (double)m_ulTotalOperationsWeight;

    return dPercent;
}

/**
 * Internal helper for automatically timing out the operation.
 *
 * The caller should hold the object write lock.
 */
void ProgressBase::checkForAutomaticTimeout(void)
{
    if (   m_cMsTimeout
        && mCancelable
        && !mCanceled
        && RTTimeMilliTS() - m_ullTimestamp > m_cMsTimeout
       )
        Cancel();
}


STDMETHODIMP ProgressBase::COMGETTER(TimeRemaining)(LONG *aTimeRemaining)
{
    CheckComArgOutPointerValid(aTimeRemaining);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCompleted)
        *aTimeRemaining = 0;
    else
    {
        double dPercentDone = calcTotalPercent();
        if (dPercentDone < 1)
            *aTimeRemaining = -1;       // unreliable, or avoid division by 0 below
        else
        {
            uint64_t ullTimeNow = RTTimeMilliTS();
            uint64_t ullTimeElapsed = ullTimeNow - m_ullTimestamp;
            uint64_t ullTimeTotal = (uint64_t)(ullTimeElapsed * 100 / dPercentDone);
            uint64_t ullTimeRemaining = ullTimeTotal - ullTimeElapsed;

//             Log(("ProgressBase::GetTimeRemaining: dPercentDone %RI32, ullTimeNow = %RI64, ullTimeElapsed = %RI64, ullTimeTotal = %RI64, ullTimeRemaining = %RI64\n",
//                         (uint32_t)dPercentDone, ullTimeNow, ullTimeElapsed, ullTimeTotal, ullTimeRemaining));

            *aTimeRemaining = (LONG)(ullTimeRemaining / 1000);
        }
    }

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Percent)(ULONG *aPercent)
{
    CheckComArgOutPointerValid(aPercent);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    checkForAutomaticTimeout();

    /* checkForAutomaticTimeout requires a write lock. */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCompleted && SUCCEEDED(mResultCode))
        *aPercent = 100;
    else
    {
        ULONG ulPercent = (ULONG)calcTotalPercent();
        // do not report 100% until we're really really done with everything as the Qt GUI dismisses progress dialogs in that case
        if (    ulPercent == 100
             && (    m_ulOperationPercent < 100
                  || (m_ulCurrentOperation < m_cOperations -1)
                )
           )
            *aPercent = 99;
        else
            *aPercent = ulPercent;
    }

    checkForAutomaticTimeout();

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Completed)(BOOL *aCompleted)
{
    CheckComArgOutPointerValid(aCompleted);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aCompleted = mCompleted;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Canceled)(BOOL *aCanceled)
{
    CheckComArgOutPointerValid(aCanceled);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aCanceled = mCanceled;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(ResultCode)(LONG *aResultCode)
{
    CheckComArgOutPointerValid(aResultCode);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (!mCompleted)
        return setError(E_FAIL,
                        tr("Result code is not available, operation is still in progress"));

    *aResultCode = mResultCode;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(ErrorInfo)(IVirtualBoxErrorInfo **aErrorInfo)
{
    CheckComArgOutPointerValid(aErrorInfo);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (!mCompleted)
        return setError(E_FAIL,
                        tr("Error info is not available, operation is still in progress"));

    mErrorInfo.queryInterfaceTo(aErrorInfo);

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(OperationCount)(ULONG *aOperationCount)
{
    CheckComArgOutPointerValid(aOperationCount);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aOperationCount = m_cOperations;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Operation)(ULONG *aOperation)
{
    CheckComArgOutPointerValid(aOperation);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aOperation = m_ulCurrentOperation;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(OperationDescription)(BSTR *aOperationDescription)
{
    CheckComArgOutPointerValid(aOperationDescription);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    m_bstrOperationDescription.cloneTo(aOperationDescription);

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(OperationPercent)(ULONG *aOperationPercent)
{
    CheckComArgOutPointerValid(aOperationPercent);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCompleted && SUCCEEDED(mResultCode))
        *aOperationPercent = 100;
    else
        *aOperationPercent = m_ulOperationPercent;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(OperationWeight)(ULONG *aOperationWeight)
{
    CheckComArgOutPointerValid(aOperationWeight);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aOperationWeight = m_ulCurrentOperationWeight;

    return S_OK;
}

STDMETHODIMP ProgressBase::COMSETTER(Timeout)(ULONG aTimeout)
{
    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (!mCancelable)
        return setError(VBOX_E_INVALID_OBJECT_STATE,
                        tr("Operation cannot be canceled"));

    LogThisFunc(("%#x => %#x\n", m_cMsTimeout, aTimeout));
    m_cMsTimeout = aTimeout;
    return S_OK;
}

STDMETHODIMP ProgressBase::COMGETTER(Timeout)(ULONG *aTimeout)
{
    CheckComArgOutPointerValid(aTimeout);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoReadLock alock(this COMMA_LOCKVAL_SRC_POS);

    *aTimeout = m_cMsTimeout;
    return S_OK;
}

// public methods only for internal purposes
////////////////////////////////////////////////////////////////////////////////

/**
 * Sets the cancelation callback, checking for cancelation first.
 *
 * @returns Success indicator.
 * @retval  true on success.
 * @retval  false if the progress object has already been canceled or is in an
 *          invalid state
 *
 * @param   pfnCallback     The function to be called upon cancelation.
 * @param   pvUser          The callback argument.
 */
bool ProgressBase::setCancelCallback(void (*pfnCallback)(void *), void *pvUser)
{
    AutoCaller autoCaller(this);
    AssertComRCReturn(autoCaller.rc(), false);

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    checkForAutomaticTimeout();
    if (mCanceled)
        return false;

    m_pvCancelUserArg   = pvUser;
    m_pfnCancelCallback = pfnCallback;
    return true;
}

////////////////////////////////////////////////////////////////////////////////
// Progress class
////////////////////////////////////////////////////////////////////////////////

HRESULT Progress::FinalConstruct()
{
    HRESULT rc = ProgressBase::FinalConstruct();
    if (FAILED(rc)) return rc;

    mCompletedSem = NIL_RTSEMEVENTMULTI;
    mWaitersCount = 0;

    return S_OK;
}

void Progress::FinalRelease()
{
    uninit();
}

// public initializer/uninitializer for internal purposes only
////////////////////////////////////////////////////////////////////////////////

/**
 * Initializes the normal progress object. With this variant, one can have
 * an arbitrary number of sub-operation which IProgress can analyze to
 * have a weighted progress computed.
 *
 * For example, say that one IProgress is supposed to track the cloning
 * of two hard disk images, which are 100 MB and 1000 MB in size, respectively,
 * and each of these hard disks should be one sub-operation of the IProgress.
 *
 * Obviously the progress would be misleading if the progress displayed 50%
 * after the smaller image was cloned and would then take much longer for
 * the second half.
 *
 * With weighted progress, one can invoke the following calls:
 *
 * 1) create progress object with cOperations = 2 and ulTotalOperationsWeight =
 *    1100 (100 MB plus 1100, but really the weights can be any ULONG); pass
 *    in ulFirstOperationWeight = 100 for the first sub-operation
 *
 * 2) Then keep calling setCurrentOperationProgress() with a percentage
 *    for the first image; the total progress will increase up to a value
 *    of 9% (100MB / 1100MB * 100%).
 *
 * 3) Then call setNextOperation with the second weight (1000 for the megabytes
 *    of the second disk).
 *
 * 4) Then keep calling setCurrentOperationProgress() with a percentage for
 *    the second image, where 100% of the operation will then yield a 100%
 *    progress of the entire task.
 *
 * Weighting is optional; you can simply assign a weight of 1 to each operation
 * and pass ulTotalOperationsWeight == cOperations to this constructor (but
 * for that variant and for backwards-compatibility a simpler constructor exists
 * in ProgressImpl.h as well).
 *
 * Even simpler, if you need no sub-operations at all, pass in cOperations =
 * ulTotalOperationsWeight = ulFirstOperationWeight = 1.
 *
 * @param aParent           See ProgressBase::init().
 * @param aInitiator        See ProgressBase::init().
 * @param aDescription      See ProgressBase::init().
 * @param aCancelable       Flag whether the task maybe canceled.
 * @param cOperations       Number of operations within this task (at least 1).
 * @param ulTotalOperationsWeight Total weight of operations; must be the sum of ulFirstOperationWeight and
 *                          what is later passed with each subsequent setNextOperation() call.
 * @param bstrFirstOperationDescription Description of the first operation.
 * @param ulFirstOperationWeight Weight of first sub-operation.
 * @param aId               See ProgressBase::init().
 */
HRESULT Progress::init(
#if !defined(VBOX_COM_INPROC)
                       VirtualBox *aParent,
#endif
                       IUnknown *aInitiator,
                       CBSTR aDescription,
                       BOOL aCancelable,
                       ULONG cOperations,
                       ULONG ulTotalOperationsWeight,
                       CBSTR bstrFirstOperationDescription,
                       ULONG ulFirstOperationWeight,
                       OUT_GUID aId /* = NULL */)
{
    LogFlowThisFunc(("aDescription=\"%ls\", cOperations=%d, ulTotalOperationsWeight=%d, bstrFirstOperationDescription=\"%ls\", ulFirstOperationWeight=%d\n",
                     aDescription,
                     cOperations,
                     ulTotalOperationsWeight,
                     bstrFirstOperationDescription,
                     ulFirstOperationWeight));

    AssertReturn(bstrFirstOperationDescription, E_INVALIDARG);
    AssertReturn(ulTotalOperationsWeight >= 1, E_INVALIDARG);

    /* Enclose the state transition NotReady->InInit->Ready */
    AutoInitSpan autoInitSpan(this);
    AssertReturn(autoInitSpan.isOk(), E_FAIL);

    HRESULT rc = S_OK;

    rc = ProgressBase::protectedInit(autoInitSpan,
#if !defined(VBOX_COM_INPROC)
                                     aParent,
#endif
                                     aInitiator, aDescription, aId);
    if (FAILED(rc)) return rc;

    mCancelable = aCancelable;

    m_cOperations = cOperations;
    m_ulTotalOperationsWeight = ulTotalOperationsWeight;
    m_ulOperationsCompletedWeight = 0;
    m_ulCurrentOperation = 0;
    m_bstrOperationDescription = bstrFirstOperationDescription;
    m_ulCurrentOperationWeight = ulFirstOperationWeight;
    m_ulOperationPercent = 0;

    int vrc = RTSemEventMultiCreate(&mCompletedSem);
    ComAssertRCRet(vrc, E_FAIL);

    RTSemEventMultiReset(mCompletedSem);

    /* Confirm a successful initialization when it's the case */
    if (SUCCEEDED(rc))
        autoInitSpan.setSucceeded();

    return rc;
}

/**
 * Initializes the sub-progress object that represents a specific operation of
 * the whole task.
 *
 * Objects initialized with this method are then combined together into the
 * single task using a CombinedProgress instance, so it doesn't require the
 * parent, initiator, description and doesn't create an ID. Note that calling
 * respective getter methods on an object initialized with this method is
 * useless. Such objects are used only to provide a separate wait semaphore and
 * store individual operation descriptions.
 *
 * @param aCancelable       Flag whether the task maybe canceled.
 * @param aOperationCount   Number of sub-operations within this task (at least 1).
 * @param aOperationDescription Description of the individual operation.
 */
HRESULT Progress::init(BOOL aCancelable,
                       ULONG aOperationCount,
                       CBSTR aOperationDescription)
{
    LogFlowThisFunc(("aOperationDescription=\"%ls\"\n", aOperationDescription));

    /* Enclose the state transition NotReady->InInit->Ready */
    AutoInitSpan autoInitSpan(this);
    AssertReturn(autoInitSpan.isOk(), E_FAIL);

    HRESULT rc = S_OK;

    rc = ProgressBase::protectedInit(autoInitSpan);
    if (FAILED(rc)) return rc;

    mCancelable = aCancelable;

    // for this variant we assume for now that all operations are weighed "1"
    // and equal total weight = operation count
    m_cOperations = aOperationCount;
    m_ulTotalOperationsWeight = aOperationCount;
    m_ulOperationsCompletedWeight = 0;
    m_ulCurrentOperation = 0;
    m_bstrOperationDescription = aOperationDescription;
    m_ulCurrentOperationWeight = 1;
    m_ulOperationPercent = 0;

    int vrc = RTSemEventMultiCreate(&mCompletedSem);
    ComAssertRCRet(vrc, E_FAIL);

    RTSemEventMultiReset(mCompletedSem);

    /* Confirm a successful initialization when it's the case */
    if (SUCCEEDED(rc))
        autoInitSpan.setSucceeded();

    return rc;
}

/**
 * Uninitializes the instance and sets the ready flag to FALSE.
 *
 * Called either from FinalRelease() or by the parent when it gets destroyed.
 */
void Progress::uninit()
{
    LogFlowThisFunc(("\n"));

    /* Enclose the state transition Ready->InUninit->NotReady */
    AutoUninitSpan autoUninitSpan(this);
    if (autoUninitSpan.uninitDone())
        return;

    /* wake up all threads still waiting on occasion */
    if (mWaitersCount > 0)
    {
        LogFlow(("WARNING: There are still %d threads waiting for '%ls' completion!\n",
                 mWaitersCount, mDescription.raw()));
        RTSemEventMultiSignal(mCompletedSem);
    }

    RTSemEventMultiDestroy(mCompletedSem);

    ProgressBase::protectedUninit(autoUninitSpan);
}

// IProgress properties
/////////////////////////////////////////////////////////////////////////////

// IProgress methods
/////////////////////////////////////////////////////////////////////////////

/**
 * @note XPCOM: when this method is not called on the main XPCOM thread, it
 *       simply blocks the thread until mCompletedSem is signalled. If the
 *       thread has its own event queue (hmm, what for?) that it must run, then
 *       calling this method will definitely freeze event processing.
 */
STDMETHODIMP Progress::WaitForCompletion(LONG aTimeout)
{
    LogFlowThisFuncEnter();
    LogFlowThisFunc(("aTimeout=%d\n", aTimeout));

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    /* if we're already completed, take a shortcut */
    if (!mCompleted)
    {
        int vrc = VINF_SUCCESS;
        bool fForever = aTimeout < 0;
        int64_t timeLeft = aTimeout;
        int64_t lastTime = RTTimeMilliTS();

        while (!mCompleted && (fForever || timeLeft > 0))
        {
            mWaitersCount++;
            alock.leave();
            vrc = RTSemEventMultiWait(mCompletedSem,
                                      fForever ? RT_INDEFINITE_WAIT : (RTMSINTERVAL)timeLeft);
            alock.enter();
            mWaitersCount--;

            /* the last waiter resets the semaphore */
            if (mWaitersCount == 0)
                RTSemEventMultiReset(mCompletedSem);

            if (RT_FAILURE(vrc) && vrc != VERR_TIMEOUT)
                break;

            if (!fForever)
            {
                int64_t now = RTTimeMilliTS();
                timeLeft -= now - lastTime;
                lastTime = now;
            }
        }

        if (RT_FAILURE(vrc) && vrc != VERR_TIMEOUT)
            return setError(VBOX_E_IPRT_ERROR,
                            tr("Failed to wait for the task completion (%Rrc)"),
                            vrc);
    }

    LogFlowThisFuncLeave();

    return S_OK;
}

/**
 * @note XPCOM: when this method is not called on the main XPCOM thread, it
 *       simply blocks the thread until mCompletedSem is signalled. If the
 *       thread has its own event queue (hmm, what for?) that it must run, then
 *       calling this method will definitely freeze event processing.
 */
STDMETHODIMP Progress::WaitForOperationCompletion(ULONG aOperation, LONG aTimeout)
{
    LogFlowThisFuncEnter();
    LogFlowThisFunc(("aOperation=%d, aTimeout=%d\n", aOperation, aTimeout));

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    CheckComArgExpr(aOperation, aOperation < m_cOperations);

    /* if we're already completed or if the given operation is already done,
     * then take a shortcut */
    if (    !mCompleted
         && aOperation >= m_ulCurrentOperation)
    {
        int vrc = VINF_SUCCESS;
        bool fForever = aTimeout < 0;
        int64_t timeLeft = aTimeout;
        int64_t lastTime = RTTimeMilliTS();

        while (    !mCompleted && aOperation >= m_ulCurrentOperation
                && (fForever || timeLeft > 0))
        {
            mWaitersCount ++;
            alock.leave();
            vrc = RTSemEventMultiWait(mCompletedSem,
                                      fForever ? RT_INDEFINITE_WAIT : (unsigned) timeLeft);
            alock.enter();
            mWaitersCount--;

            /* the last waiter resets the semaphore */
            if (mWaitersCount == 0)
                RTSemEventMultiReset(mCompletedSem);

            if (RT_FAILURE(vrc) && vrc != VERR_TIMEOUT)
                break;

            if (!fForever)
            {
                int64_t now = RTTimeMilliTS();
                timeLeft -= now - lastTime;
                lastTime = now;
            }
        }

        if (RT_FAILURE(vrc) && vrc != VERR_TIMEOUT)
            return setError(E_FAIL,
                            tr("Failed to wait for the operation completion (%Rrc)"),
                            vrc);
    }

    LogFlowThisFuncLeave();

    return S_OK;
}

STDMETHODIMP Progress::Cancel()
{
    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (!mCancelable)
        return setError(VBOX_E_INVALID_OBJECT_STATE,
                        tr("Operation cannot be canceled"));

    if (!mCanceled)
    {
        LogThisFunc(("Canceling\n"));
        mCanceled = TRUE;
        if (m_pfnCancelCallback)
            m_pfnCancelCallback(m_pvCancelUserArg);

    }
    else
        LogThisFunc(("Already canceled\n"));

    return S_OK;
}

/**
 * Updates the percentage value of the current operation.
 *
 * @param aPercent  New percentage value of the operation in progress
 *                  (in range [0, 100]).
 */
STDMETHODIMP Progress::SetCurrentOperationProgress(ULONG aPercent)
{
    AutoCaller autoCaller(this);
    AssertComRCReturnRC(autoCaller.rc());

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    AssertMsgReturn(aPercent <= 100, ("%u\n", aPercent), E_INVALIDARG);

    checkForAutomaticTimeout();
    if (mCancelable && mCanceled)
    {
        Assert(!mCompleted);
        return E_FAIL;
    }
    AssertReturn(!mCompleted && !mCanceled, E_FAIL);

    m_ulOperationPercent = aPercent;

    return S_OK;
}

/**
 * Signals that the current operation is successfully completed and advances to
 * the next operation. The operation percentage is reset to 0.
 *
 * @param aOperationDescription     Description of the next operation.
 *
 * @note The current operation must not be the last one.
 */
STDMETHODIMP Progress::SetNextOperation(IN_BSTR bstrNextOperationDescription, ULONG ulNextOperationsWeight)
{
    AssertReturn(bstrNextOperationDescription, E_INVALIDARG);

    AutoCaller autoCaller(this);
    AssertComRCReturnRC(autoCaller.rc());

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCanceled)
        return E_FAIL;
    AssertReturn(!mCompleted, E_FAIL);
    AssertReturn(m_ulCurrentOperation + 1 < m_cOperations, E_FAIL);

    ++m_ulCurrentOperation;
    m_ulOperationsCompletedWeight += m_ulCurrentOperationWeight;

    m_bstrOperationDescription = bstrNextOperationDescription;
    m_ulCurrentOperationWeight = ulNextOperationsWeight;
    m_ulOperationPercent = 0;

    Log(("Progress::setNextOperation(%ls): ulNextOperationsWeight = %d; m_ulCurrentOperation is now %d, m_ulOperationsCompletedWeight is now %d\n",
         m_bstrOperationDescription.raw(), ulNextOperationsWeight, m_ulCurrentOperation, m_ulOperationsCompletedWeight));

    /* wake up all waiting threads */
    if (mWaitersCount > 0)
        RTSemEventMultiSignal(mCompletedSem);

    return S_OK;
}

// public methods only for internal purposes
/////////////////////////////////////////////////////////////////////////////

/**
 * Sets the internal result code and attempts to retrieve additional error
 * info from the current thread. Gets called from Progress::notifyComplete(),
 * but can be called again to override a previous result set with
 * notifyComplete().
 *
 * @param aResultCode
 */
HRESULT Progress::setResultCode(HRESULT aResultCode)
{
    AutoCaller autoCaller(this);
    AssertComRCReturnRC(autoCaller.rc());

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    mResultCode = aResultCode;

    HRESULT rc = S_OK;

    if (FAILED(aResultCode))
    {
        /* try to import error info from the current thread */

#if !defined(VBOX_WITH_XPCOM)

        ComPtr<IErrorInfo> err;
        rc = ::GetErrorInfo(0, err.asOutParam());
        if (rc == S_OK && err)
        {
            rc = err.queryInterfaceTo(mErrorInfo.asOutParam());
            if (SUCCEEDED(rc) && !mErrorInfo)
                rc = E_FAIL;
        }

#else /* !defined(VBOX_WITH_XPCOM) */

        nsCOMPtr<nsIExceptionService> es;
        es = do_GetService(NS_EXCEPTIONSERVICE_CONTRACTID, &rc);
        if (NS_SUCCEEDED(rc))
        {
            nsCOMPtr <nsIExceptionManager> em;
            rc = es->GetCurrentExceptionManager(getter_AddRefs(em));
            if (NS_SUCCEEDED(rc))
            {
                ComPtr<nsIException> ex;
                rc = em->GetCurrentException(ex.asOutParam());
                if (NS_SUCCEEDED(rc) && ex)
                {
                    rc = ex.queryInterfaceTo(mErrorInfo.asOutParam());
                    if (NS_SUCCEEDED(rc) && !mErrorInfo)
                        rc = E_FAIL;
                }
            }
        }
#endif /* !defined(VBOX_WITH_XPCOM) */

        AssertMsg(rc == S_OK, ("Couldn't get error info (rc=%08X) while trying to set a failed result (%08X)!\n",
                               rc, aResultCode));
    }

    return rc;
}

/**
 * Marks the whole task as complete and sets the result code.
 *
 * If the result code indicates a failure (|FAILED(@a aResultCode)|) then this
 * method will import the error info from the current thread and assign it to
 * the errorInfo attribute (it will return an error if no info is available in
 * such case).
 *
 * If the result code indicates a success (|SUCCEEDED(@a aResultCode)|) then
 * the current operation is set to the last.
 *
 * Note that this method may be called only once for the given Progress object.
 * Subsequent calls will assert.
 *
 * @param aResultCode   Operation result code.
 */
HRESULT Progress::notifyComplete(HRESULT aResultCode)
{
    AutoCaller autoCaller(this);
    AssertComRCReturnRC(autoCaller.rc());

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    AssertReturn(mCompleted == FALSE, E_FAIL);

    LogFunc(("aResultCode=%d\n", aResultCode));

    if (mCanceled && SUCCEEDED(aResultCode))
        aResultCode = E_FAIL;

    HRESULT rc = setResultCode(aResultCode);

    mCompleted = TRUE;

    if (!FAILED(aResultCode))
    {
        m_ulCurrentOperation = m_cOperations - 1; /* last operation */
        m_ulOperationPercent = 100;
    }

#if !defined VBOX_COM_INPROC
    /* remove from the global collection of pending progress operations */
    if (mParent)
        mParent->removeProgress(mId.ref());
#endif

    /* wake up all waiting threads */
    if (mWaitersCount > 0)
        RTSemEventMultiSignal(mCompletedSem);

    return rc;
}

/**
 * Wrapper around Progress:notifyCompleteV.
 */
HRESULT Progress::notifyComplete(HRESULT aResultCode,
                                 const GUID &aIID,
                                 const char *pcszComponent,
                                 const char *aText,
                                 ...)
{
    va_list va;
    va_start(va, aText);
    HRESULT hrc = notifyCompleteV(aResultCode, aIID, pcszComponent, aText, va);
    va_end(va);
    return hrc;
}

/**
 * Marks the operation as complete and attaches full error info.
 *
 * See com::SupportErrorInfoImpl::setError(HRESULT, const GUID &, const wchar_t
 * *, const char *, ...) for more info.
 *
 * @param aResultCode   Operation result (error) code, must not be S_OK.
 * @param aIID          IID of the interface that defines the error.
 * @param aComponent    Name of the component that generates the error.
 * @param aText         Error message (must not be null), an RTStrPrintf-like
 *                      format string in UTF-8 encoding.
 * @param va            List of arguments for the format string.
 */
HRESULT Progress::notifyCompleteV(HRESULT aResultCode,
                                  const GUID &aIID,
                                  const char *pcszComponent,
                                  const char *aText,
                                  va_list va)
{
    Utf8Str text(aText, va);

    AutoCaller autoCaller(this);
    AssertComRCReturnRC(autoCaller.rc());

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    AssertReturn(mCompleted == FALSE, E_FAIL);

    if (mCanceled && SUCCEEDED(aResultCode))
        aResultCode = E_FAIL;

    mCompleted = TRUE;
    mResultCode = aResultCode;

    AssertReturn(FAILED(aResultCode), E_FAIL);

    ComObjPtr<VirtualBoxErrorInfo> errorInfo;
    HRESULT rc = errorInfo.createObject();
    AssertComRC(rc);
    if (SUCCEEDED(rc))
    {
        errorInfo->init(aResultCode, aIID, pcszComponent, text);
        errorInfo.queryInterfaceTo(mErrorInfo.asOutParam());
    }

#if !defined VBOX_COM_INPROC
    /* remove from the global collection of pending progress operations */
    if (mParent)
        mParent->removeProgress(mId.ref());
#endif

    /* wake up all waiting threads */
    if (mWaitersCount > 0)
        RTSemEventMultiSignal(mCompletedSem);

    return rc;
}

/**
 * Notify the progress object that we're almost at the point of no return.
 *
 * This atomically checks for and disables cancelation.  Calls to
 * IProgress::Cancel() made after a successful call to this method will fail
 * and the user can be told.  While this isn't entirely clean behavior, it
 * prevents issues with an irreversible actually operation succeeding while the
 * user believe it was rolled back.
 *
 * @returns Success indicator.
 * @retval  true on success.
 * @retval  false if the progress object has already been canceled or is in an
 *          invalid state
 */
bool Progress::notifyPointOfNoReturn(void)
{
    AutoCaller autoCaller(this);
    AssertComRCReturn(autoCaller.rc(), false);

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCanceled)
    {
        LogThisFunc(("returns false\n"));
        return false;
    }

    mCancelable = FALSE;
    LogThisFunc(("returns true\n"));
    return true;
}

////////////////////////////////////////////////////////////////////////////////
// CombinedProgress class
////////////////////////////////////////////////////////////////////////////////

HRESULT CombinedProgress::FinalConstruct()
{
    HRESULT rc = ProgressBase::FinalConstruct();
    if (FAILED(rc)) return rc;

    mProgress = 0;
    mCompletedOperations = 0;

    return S_OK;
}

void CombinedProgress::FinalRelease()
{
    uninit();
}

// public initializer/uninitializer for internal purposes only
////////////////////////////////////////////////////////////////////////////////

/**
 * Initializes this object based on individual combined progresses.
 * Must be called only from #init()!
 *
 * @param aAutoInitSpan AutoInitSpan object instantiated by a subclass.
 * @param aParent       See ProgressBase::init().
 * @param aInitiator    See ProgressBase::init().
 * @param aDescription  See ProgressBase::init().
 * @param aId           See ProgressBase::init().
 */
HRESULT CombinedProgress::protectedInit(AutoInitSpan &aAutoInitSpan,
#if !defined(VBOX_COM_INPROC)
                                        VirtualBox *aParent,
#endif
                                        IUnknown *aInitiator,
                                        CBSTR aDescription, OUT_GUID aId)
{
    LogFlowThisFunc(("aDescription={%ls} mProgresses.size()=%d\n",
                      aDescription, mProgresses.size()));

    HRESULT rc = S_OK;

    rc = ProgressBase::protectedInit(aAutoInitSpan,
#if !defined(VBOX_COM_INPROC)
                                     aParent,
#endif
                                     aInitiator, aDescription, aId);
    if (FAILED(rc)) return rc;

    mProgress = 0; /* the first object */
    mCompletedOperations = 0;

    mCompleted = FALSE;
    mCancelable = TRUE; /* until any progress returns FALSE */
    mCanceled = FALSE;

    m_cOperations = 0; /* will be calculated later */

    m_ulCurrentOperation = 0;
    rc = mProgresses[0]->COMGETTER(OperationDescription)(m_bstrOperationDescription.asOutParam());
    if (FAILED(rc)) return rc;

    for (size_t i = 0; i < mProgresses.size(); i ++)
    {
        if (mCancelable)
        {
            BOOL cancelable = FALSE;
            rc = mProgresses[i]->COMGETTER(Cancelable)(&cancelable);
            if (FAILED(rc)) return rc;

            if (!cancelable)
                mCancelable = FALSE;
        }

        {
            ULONG opCount = 0;
            rc = mProgresses[i]->COMGETTER(OperationCount)(&opCount);
            if (FAILED(rc)) return rc;

            m_cOperations += opCount;
        }
    }

    rc =  checkProgress();
    if (FAILED(rc)) return rc;

    return rc;
}

/**
 * Initializes the combined progress object given two normal progress
 * objects.
 *
 * @param aParent       See ProgressBase::init().
 * @param aInitiator    See ProgressBase::init().
 * @param aDescription  See ProgressBase::init().
 * @param aProgress1    First normal progress object.
 * @param aProgress2    Second normal progress object.
 * @param aId           See ProgressBase::init().
 */
HRESULT CombinedProgress::init(
#if !defined(VBOX_COM_INPROC)
                               VirtualBox *aParent,
#endif
                               IUnknown *aInitiator,
                               CBSTR aDescription,
                               IProgress *aProgress1,
                               IProgress *aProgress2,
                               OUT_GUID aId /* = NULL */)
{
    /* Enclose the state transition NotReady->InInit->Ready */
    AutoInitSpan autoInitSpan(this);
    AssertReturn(autoInitSpan.isOk(), E_FAIL);

    mProgresses.resize(2);
    mProgresses[0] = aProgress1;
    mProgresses[1] = aProgress2;

    HRESULT rc =  protectedInit(autoInitSpan,
#if !defined(VBOX_COM_INPROC)
                                aParent,
#endif
                                aInitiator,
                                aDescription,
                                aId);

    /* Confirm a successful initialization when it's the case */
    if (SUCCEEDED(rc))
        autoInitSpan.setSucceeded();

    return rc;
}

/**
 * Uninitializes the instance and sets the ready flag to FALSE.
 *
 * Called either from FinalRelease() or by the parent when it gets destroyed.
 */
void CombinedProgress::uninit()
{
    LogFlowThisFunc(("\n"));

    /* Enclose the state transition Ready->InUninit->NotReady */
    AutoUninitSpan autoUninitSpan(this);
    if (autoUninitSpan.uninitDone())
        return;

    mProgress = 0;
    mProgresses.clear();

    ProgressBase::protectedUninit(autoUninitSpan);
}

// IProgress properties
////////////////////////////////////////////////////////////////////////////////

STDMETHODIMP CombinedProgress::COMGETTER(Percent)(ULONG *aPercent)
{
    CheckComArgOutPointerValid(aPercent);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (mCompleted && SUCCEEDED(mResultCode))
        *aPercent = 100;
    else
    {
        HRESULT rc = checkProgress();
        if (FAILED(rc)) return rc;

        /* global percent =
         *      (100 / m_cOperations) * mOperation +
         *      ((100 / m_cOperations) / 100) * m_ulOperationPercent */
        *aPercent = (100 * m_ulCurrentOperation + m_ulOperationPercent) / m_cOperations;
    }

    return S_OK;
}

STDMETHODIMP CombinedProgress::COMGETTER(Completed)(BOOL *aCompleted)
{
    CheckComArgOutPointerValid(aCompleted);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(Completed)(aCompleted);
}

STDMETHODIMP CombinedProgress::COMGETTER(Canceled)(BOOL *aCanceled)
{
    CheckComArgOutPointerValid(aCanceled);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(Canceled)(aCanceled);
}

STDMETHODIMP CombinedProgress::COMGETTER(ResultCode)(LONG *aResultCode)
{
    CheckComArgOutPointerValid(aResultCode);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(ResultCode)(aResultCode);
}

STDMETHODIMP CombinedProgress::COMGETTER(ErrorInfo)(IVirtualBoxErrorInfo **aErrorInfo)
{
    CheckComArgOutPointerValid(aErrorInfo);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(ErrorInfo)(aErrorInfo);
}

STDMETHODIMP CombinedProgress::COMGETTER(Operation)(ULONG *aOperation)
{
    CheckComArgOutPointerValid(aOperation);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(Operation)(aOperation);
}

STDMETHODIMP CombinedProgress::COMGETTER(OperationDescription)(BSTR *aOperationDescription)
{
    CheckComArgOutPointerValid(aOperationDescription);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(OperationDescription)(aOperationDescription);
}

STDMETHODIMP CombinedProgress::COMGETTER(OperationPercent)(ULONG *aOperationPercent)
{
    CheckComArgOutPointerValid(aOperationPercent);

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    /* checkProgress needs a write lock */
    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    HRESULT rc = checkProgress();
    if (FAILED(rc)) return rc;

    return ProgressBase::COMGETTER(OperationPercent)(aOperationPercent);
}

STDMETHODIMP CombinedProgress::COMSETTER(Timeout)(ULONG aTimeout)
{
    NOREF(aTimeout);
    AssertFailed();
    return E_NOTIMPL;
}

STDMETHODIMP CombinedProgress::COMGETTER(Timeout)(ULONG *aTimeout)
{
    CheckComArgOutPointerValid(aTimeout);

    AssertFailed();
    return E_NOTIMPL;
}

// IProgress methods
/////////////////////////////////////////////////////////////////////////////

/**
 * @note XPCOM: when this method is called not on the main XPCOM thread, it
 *       simply blocks the thread until mCompletedSem is signalled. If the
 *       thread has its own event queue (hmm, what for?) that it must run, then
 *       calling this method will definitely freeze event processing.
 */
STDMETHODIMP CombinedProgress::WaitForCompletion(LONG aTimeout)
{
    LogFlowThisFuncEnter();
    LogFlowThisFunc(("aTtimeout=%d\n", aTimeout));

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    /* if we're already completed, take a shortcut */
    if (!mCompleted)
    {
        HRESULT rc = S_OK;
        bool forever = aTimeout < 0;
        int64_t timeLeft = aTimeout;
        int64_t lastTime = RTTimeMilliTS();

        while (!mCompleted && (forever || timeLeft > 0))
        {
            alock.leave();
            rc = mProgresses.back()->WaitForCompletion(forever ? -1 : (LONG) timeLeft);
            alock.enter();

            if (SUCCEEDED(rc))
                rc = checkProgress();

            if (FAILED(rc)) break;

            if (!forever)
            {
                int64_t now = RTTimeMilliTS();
                timeLeft -= now - lastTime;
                lastTime = now;
            }
        }

        if (FAILED(rc)) return rc;
    }

    LogFlowThisFuncLeave();

    return S_OK;
}

/**
 * @note XPCOM: when this method is called not on the main XPCOM thread, it
 *       simply blocks the thread until mCompletedSem is signalled. If the
 *       thread has its own event queue (hmm, what for?) that it must run, then
 *       calling this method will definitely freeze event processing.
 */
STDMETHODIMP CombinedProgress::WaitForOperationCompletion(ULONG aOperation, LONG aTimeout)
{
    LogFlowThisFuncEnter();
    LogFlowThisFunc(("aOperation=%d, aTimeout=%d\n", aOperation, aTimeout));

    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (aOperation >= m_cOperations)
        return setError(E_FAIL,
                        tr("Operation number must be in range [0, %d]"), m_ulCurrentOperation - 1);

    /* if we're already completed or if the given operation is already done,
     * then take a shortcut */
    if (!mCompleted && aOperation >= m_ulCurrentOperation)
    {
        HRESULT rc = S_OK;

        /* find the right progress object to wait for */
        size_t progress = mProgress;
        ULONG operation = 0, completedOps = mCompletedOperations;
        do
        {
            ULONG opCount = 0;
            rc = mProgresses[progress]->COMGETTER(OperationCount)(&opCount);
            if (FAILED(rc))
                return rc;

            if (completedOps + opCount > aOperation)
            {
                /* found the right progress object */
                operation = aOperation - completedOps;
                break;
            }

            completedOps += opCount;
            progress ++;
            ComAssertRet(progress < mProgresses.size(), E_FAIL);
        }
        while (1);

        LogFlowThisFunc(("will wait for mProgresses [%d] (%d)\n",
                          progress, operation));

        bool forever = aTimeout < 0;
        int64_t timeLeft = aTimeout;
        int64_t lastTime = RTTimeMilliTS();

        while (!mCompleted && aOperation >= m_ulCurrentOperation &&
               (forever || timeLeft > 0))
        {
            alock.leave();
            /* wait for the appropriate progress operation completion */
            rc = mProgresses[progress]-> WaitForOperationCompletion(operation,
                                                                    forever ? -1 : (LONG) timeLeft);
            alock.enter();

            if (SUCCEEDED(rc))
                rc = checkProgress();

            if (FAILED(rc)) break;

            if (!forever)
            {
                int64_t now = RTTimeMilliTS();
                timeLeft -= now - lastTime;
                lastTime = now;
            }
        }

        if (FAILED(rc)) return rc;
    }

    LogFlowThisFuncLeave();

    return S_OK;
}

STDMETHODIMP CombinedProgress::Cancel()
{
    AutoCaller autoCaller(this);
    if (FAILED(autoCaller.rc())) return autoCaller.rc();

    AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);

    if (!mCancelable)
        return setError(E_FAIL, tr("Operation cannot be canceled"));

    if (!mCanceled)
    {
        LogThisFunc(("Canceling\n"));
        mCanceled = TRUE;
/** @todo Teleportation: Shouldn't this be propagated to mProgresses? If
 *        powerUp creates passes a combined progress object to the client, I
 *        won't get called back since I'm only getting the powerupProgress ...
 *        Or what? */
        if (m_pfnCancelCallback)
            m_pfnCancelCallback(m_pvCancelUserArg);

    }
    else
        LogThisFunc(("Already canceled\n"));

    return S_OK;
}

// private methods
////////////////////////////////////////////////////////////////////////////////

/**
 * Fetches the properties of the current progress object and, if it is
 * successfully completed, advances to the next uncompleted or unsuccessfully
 * completed object in the vector of combined progress objects.
 *
 * @note Must be called from under this object's write lock!
 */
HRESULT CombinedProgress::checkProgress()
{
    /* do nothing if we're already marked ourselves as completed */
    if (mCompleted)
        return S_OK;

    AssertReturn(mProgress < mProgresses.size(), E_FAIL);

    ComPtr<IProgress> progress = mProgresses[mProgress];
    ComAssertRet(!progress.isNull(), E_FAIL);

    HRESULT rc = S_OK;
    BOOL fCompleted = FALSE;

    do
    {
        rc = progress->COMGETTER(Completed)(&fCompleted);
        if (FAILED(rc))
            return rc;

        if (fCompleted)
        {
            rc = progress->COMGETTER(Canceled)(&mCanceled);
            if (FAILED(rc))
                return rc;

            LONG iRc;
            rc = progress->COMGETTER(ResultCode)(&iRc);
            if (FAILED(rc))
                return rc;
            mResultCode = iRc;

            if (FAILED(mResultCode))
            {
                rc = progress->COMGETTER(ErrorInfo)(mErrorInfo.asOutParam());
                if (FAILED(rc))
                    return rc;
            }

            if (FAILED(mResultCode) || mCanceled)
            {
                mCompleted = TRUE;
            }
            else
            {
                ULONG opCount = 0;
                rc = progress->COMGETTER(OperationCount)(&opCount);
                if (FAILED(rc))
                    return rc;

                mCompletedOperations += opCount;
                mProgress ++;

                if (mProgress < mProgresses.size())
                    progress = mProgresses[mProgress];
                else
                    mCompleted = TRUE;
            }
        }
    }
    while (fCompleted && !mCompleted);

    rc = progress->COMGETTER(OperationPercent)(&m_ulOperationPercent);
    if (SUCCEEDED(rc))
    {
        ULONG operation = 0;
        rc = progress->COMGETTER(Operation)(&operation);
        if (SUCCEEDED(rc) && mCompletedOperations + operation > m_ulCurrentOperation)
        {
            m_ulCurrentOperation = mCompletedOperations + operation;
            rc = progress->COMGETTER(OperationDescription)(m_bstrOperationDescription.asOutParam());
        }
    }

    return rc;
}
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