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/* $Id$ */
#ifndef MAIN_INCLUDED_AutoStateDep_h
#define MAIN_INCLUDED_AutoStateDep_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
/** @file
*
* AutoStateDep template classes, formerly in MachineImpl.h. Use these if
* you need to ensure that the machine state does not change over a certain
* period of time.
*/
/*
* Copyright (C) 2006-2019 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.
*/
/**
* Helper class that safely manages the machine state dependency by
* calling Machine::addStateDependency() on construction and
* Machine::releaseStateDependency() on destruction. Intended for Machine
* children. The usage pattern is:
*
* @code
* AutoCaller autoCaller(this);
* if (FAILED(autoCaller.rc())) return autoCaller.rc();
*
* Machine::AutoStateDependency<MutableStateDep> adep(mParent);
* if (FAILED(stateDep.rc())) return stateDep.rc();
* ...
* // code that depends on the particular machine state
* ...
* @endcode
*
* Note that it is more convenient to use the following individual
* shortcut classes instead of using this template directly:
* AutoAnyStateDependency, AutoMutableStateDependency,
* AutoMutableOrSavedStateDependency, AutoMutableOrRunningStateDependency
* or AutoMutableOrSavedOrRunningStateDependency. The usage pattern is
* exactly the same as above except that there is no need to specify the
* template argument because it is already done by the shortcut class.
*
* @param taDepType Dependency type to manage.
*/
template <Machine::StateDependency taDepType = Machine::AnyStateDep>
class AutoStateDependency
{
public:
AutoStateDependency(Machine *aThat)
: mThat(aThat), mRC(S_OK),
mMachineState(MachineState_Null),
mRegistered(FALSE)
{
Assert(aThat);
mRC = aThat->i_addStateDependency(taDepType, &mMachineState,
&mRegistered);
}
~AutoStateDependency()
{
if (SUCCEEDED(mRC))
mThat->i_releaseStateDependency();
}
/** Decreases the number of dependencies before the instance is
* destroyed. Note that will reset #rc() to E_FAIL. */
void release()
{
AssertReturnVoid(SUCCEEDED(mRC));
mThat->i_releaseStateDependency();
mRC = E_FAIL;
}
/** Restores the number of callers after by #release(). #rc() will be
* reset to the result of calling addStateDependency() and must be
* rechecked to ensure the operation succeeded. */
void add()
{
AssertReturnVoid(!SUCCEEDED(mRC));
mRC = mThat->i_addStateDependency(taDepType, &mMachineState,
&mRegistered);
}
/** Returns the result of Machine::addStateDependency(). */
HRESULT rc() const { return mRC; }
/** Shortcut to SUCCEEDED(rc()). */
bool isOk() const { return SUCCEEDED(mRC); }
/** Returns the machine state value as returned by
* Machine::addStateDependency(). */
MachineState_T machineState() const { return mMachineState; }
/** Returns the machine state value as returned by
* Machine::addStateDependency(). */
BOOL machineRegistered() const { return mRegistered; }
protected:
Machine *mThat;
HRESULT mRC;
MachineState_T mMachineState;
BOOL mRegistered;
private:
DECLARE_CLS_COPY_CTOR_ASSIGN_NOOP(AutoStateDependency);
DECLARE_CLS_NEW_DELETE_NOOP(AutoStateDependency);
};
/**
* Shortcut to AutoStateDependency<AnyStateDep>.
* See AutoStateDependency to get the usage pattern.
*
* Accepts any machine state and guarantees the state won't change before
* this object is destroyed. If the machine state cannot be protected (as
* a result of the state change currently in progress), this instance's
* #rc() method will indicate a failure, and the caller is not allowed to
* rely on any particular machine state and should return the failed
* result code to the upper level.
*/
typedef AutoStateDependency<Machine::AnyStateDep> AutoAnyStateDependency;
/**
* Shortcut to AutoStateDependency<MutableStateDep>.
* See AutoStateDependency to get the usage pattern.
*
* Succeeds only if the machine state is in one of the mutable states, and
* guarantees the given mutable state won't change before this object is
* destroyed. If the machine is not mutable, this instance's #rc() method
* will indicate a failure, and the caller is not allowed to rely on any
* particular machine state and should return the failed result code to
* the upper level.
*
* Intended to be used within all setter methods of IMachine
* children objects (DVDDrive, NetworkAdapter, AudioAdapter, etc.) to
* provide data protection and consistency. There must be no VM process,
* i.e. use for settings changes which are valid when the VM is shut down.
*/
typedef AutoStateDependency<Machine::MutableStateDep> AutoMutableStateDependency;
/**
* Shortcut to AutoStateDependency<MutableOrSavedStateDep>.
* See AutoStateDependency to get the usage pattern.
*
* Succeeds only if the machine state is in one of the mutable states, or
* if the machine is in the Saved state, and guarantees the given mutable
* state won't change before this object is destroyed. If the machine is
* not mutable, this instance's #rc() method will indicate a failure, and
* the caller is not allowed to rely on any particular machine state and
* should return the failed result code to the upper level.
*
* Intended to be used within setter methods of IMachine
* children objects that may operate on shut down or Saved machines.
*/
typedef AutoStateDependency<Machine::MutableOrSavedStateDep> AutoMutableOrSavedStateDependency;
/**
* Shortcut to AutoStateDependency<MutableOrRunningStateDep>.
* See AutoStateDependency to get the usage pattern.
*
* Succeeds only if the machine state is in one of the mutable states, or
* if the machine is in the Running or Paused state, and guarantees the
* given mutable state won't change before this object is destroyed. If
* the machine is not mutable, this instance's #rc() method will indicate
* a failure, and the caller is not allowed to rely on any particular
* machine state and should return the failed result code to the upper
* level.
*
* Intended to be used within setter methods of IMachine
* children objects that may operate on shut down or running machines.
*/
typedef AutoStateDependency<Machine::MutableOrRunningStateDep> AutoMutableOrRunningStateDependency;
/**
* Shortcut to AutoStateDependency<MutableOrSavedOrRunningStateDep>.
* See AutoStateDependency to get the usage pattern.
*
* Succeeds only if the machine state is in one of the mutable states, or
* if the machine is in the Running, Paused or Saved state, and guarantees
* the given mutable state won't change before this object is destroyed.
* If the machine is not mutable, this instance's #rc() method will
* indicate a failure, and the caller is not allowed to rely on any
* particular machine state and should return the failed result code to
* the upper level.
*
* Intended to be used within setter methods of IMachine
* children objects that may operate on shut down, running or saved
* machines.
*/
typedef AutoStateDependency<Machine::MutableOrSavedOrRunningStateDep> AutoMutableOrSavedOrRunningStateDependency;
#endif /* !MAIN_INCLUDED_AutoStateDep_h */
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