| 1 | /* $Id: AutoStateDep.h 82968 2020-02-04 10:35:17Z vboxsync $ */
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| 2 |
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| 3 | #ifndef MAIN_INCLUDED_AutoStateDep_h
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| 4 | #define MAIN_INCLUDED_AutoStateDep_h
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| 5 | #ifndef RT_WITHOUT_PRAGMA_ONCE
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| 6 | # pragma once
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| 7 | #endif
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| 8 |
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| 9 | /** @file
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| 10 | *
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| 11 | * AutoStateDep template classes, formerly in MachineImpl.h. Use these if
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| 12 | * you need to ensure that the machine state does not change over a certain
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| 13 | * period of time.
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| 14 | */
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| 15 |
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| 16 | /*
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| 17 | * Copyright (C) 2006-2020 Oracle Corporation
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| 18 | *
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| 19 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 20 | * available from http://www.virtualbox.org. This file is free software;
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| 21 | * you can redistribute it and/or modify it under the terms of the GNU
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| 22 | * General Public License (GPL) as published by the Free Software
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| 23 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 24 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 25 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 26 | */
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| 27 |
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| 28 | /**
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| 29 | * Helper class that safely manages the machine state dependency by
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| 30 | * calling Machine::addStateDependency() on construction and
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| 31 | * Machine::releaseStateDependency() on destruction. Intended for Machine
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| 32 | * children. The usage pattern is:
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| 33 | *
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| 34 | * @code
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| 35 | * AutoCaller autoCaller(this);
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| 36 | * if (FAILED(autoCaller.rc())) return autoCaller.rc();
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| 37 | *
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| 38 | * Machine::AutoStateDependency<MutableStateDep> adep(mParent);
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| 39 | * if (FAILED(stateDep.rc())) return stateDep.rc();
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| 40 | * ...
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| 41 | * // code that depends on the particular machine state
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| 42 | * ...
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| 43 | * @endcode
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| 44 | *
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| 45 | * Note that it is more convenient to use the following individual
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| 46 | * shortcut classes instead of using this template directly:
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| 47 | * AutoAnyStateDependency, AutoMutableStateDependency,
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| 48 | * AutoMutableOrSavedStateDependency, AutoMutableOrRunningStateDependency
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| 49 | * or AutoMutableOrSavedOrRunningStateDependency. The usage pattern is
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| 50 | * exactly the same as above except that there is no need to specify the
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| 51 | * template argument because it is already done by the shortcut class.
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| 52 | *
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| 53 | * @param taDepType Dependency type to manage.
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| 54 | */
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| 55 | template <Machine::StateDependency taDepType = Machine::AnyStateDep>
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| 56 | class AutoStateDependency
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| 57 | {
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| 58 | public:
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| 59 |
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| 60 | AutoStateDependency(Machine *aThat)
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| 61 | : mThat(aThat), mRC(S_OK),
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| 62 | mMachineState(MachineState_Null),
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| 63 | mRegistered(FALSE)
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| 64 | {
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| 65 | Assert(aThat);
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| 66 | mRC = aThat->i_addStateDependency(taDepType, &mMachineState,
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| 67 | &mRegistered);
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| 68 | }
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| 69 | ~AutoStateDependency()
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| 70 | {
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| 71 | if (SUCCEEDED(mRC))
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| 72 | mThat->i_releaseStateDependency();
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| 73 | }
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| 74 |
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| 75 | /** Decreases the number of dependencies before the instance is
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| 76 | * destroyed. Note that will reset #rc() to E_FAIL. */
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| 77 | void release()
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| 78 | {
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| 79 | AssertReturnVoid(SUCCEEDED(mRC));
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| 80 | mThat->i_releaseStateDependency();
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| 81 | mRC = E_FAIL;
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| 82 | }
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| 83 |
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| 84 | /** Restores the number of callers after by #release(). #rc() will be
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| 85 | * reset to the result of calling addStateDependency() and must be
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| 86 | * rechecked to ensure the operation succeeded. */
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| 87 | void add()
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| 88 | {
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| 89 | AssertReturnVoid(!SUCCEEDED(mRC));
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| 90 | mRC = mThat->i_addStateDependency(taDepType, &mMachineState,
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| 91 | &mRegistered);
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| 92 | }
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| 93 |
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| 94 | /** Returns the result of Machine::addStateDependency(). */
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| 95 | HRESULT rc() const { return mRC; }
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| 96 |
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| 97 | /** Shortcut to SUCCEEDED(rc()). */
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| 98 | bool isOk() const { return SUCCEEDED(mRC); }
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| 99 |
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| 100 | /** Returns the machine state value as returned by
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| 101 | * Machine::addStateDependency(). */
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| 102 | MachineState_T machineState() const { return mMachineState; }
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| 103 |
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| 104 | /** Returns the machine state value as returned by
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| 105 | * Machine::addStateDependency(). */
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| 106 | BOOL machineRegistered() const { return mRegistered; }
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| 107 |
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| 108 | protected:
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| 109 |
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| 110 | Machine *mThat;
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| 111 | HRESULT mRC;
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| 112 | MachineState_T mMachineState;
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| 113 | BOOL mRegistered;
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| 114 |
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| 115 | private:
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| 116 |
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| 117 | DECLARE_CLS_COPY_CTOR_ASSIGN_NOOP(AutoStateDependency);
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| 118 | DECLARE_CLS_NEW_DELETE_NOOP(AutoStateDependency);
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| 119 | };
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| 120 |
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| 121 | /**
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| 122 | * Shortcut to AutoStateDependency<AnyStateDep>.
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| 123 | * See AutoStateDependency to get the usage pattern.
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| 124 | *
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| 125 | * Accepts any machine state and guarantees the state won't change before
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| 126 | * this object is destroyed. If the machine state cannot be protected (as
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| 127 | * a result of the state change currently in progress), this instance's
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| 128 | * #rc() method will indicate a failure, and the caller is not allowed to
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| 129 | * rely on any particular machine state and should return the failed
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| 130 | * result code to the upper level.
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| 131 | */
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| 132 | typedef AutoStateDependency<Machine::AnyStateDep> AutoAnyStateDependency;
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| 133 |
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| 134 | /**
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| 135 | * Shortcut to AutoStateDependency<MutableStateDep>.
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| 136 | * See AutoStateDependency to get the usage pattern.
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| 137 | *
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| 138 | * Succeeds only if the machine state is in one of the mutable states, and
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| 139 | * guarantees the given mutable state won't change before this object is
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| 140 | * destroyed. If the machine is not mutable, this instance's #rc() method
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| 141 | * will indicate a failure, and the caller is not allowed to rely on any
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| 142 | * particular machine state and should return the failed result code to
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| 143 | * the upper level.
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| 144 | *
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| 145 | * Intended to be used within all setter methods of IMachine
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| 146 | * children objects (DVDDrive, NetworkAdapter, AudioAdapter, etc.) to
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| 147 | * provide data protection and consistency. There must be no VM process,
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| 148 | * i.e. use for settings changes which are valid when the VM is shut down.
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| 149 | */
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| 150 | typedef AutoStateDependency<Machine::MutableStateDep> AutoMutableStateDependency;
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| 151 |
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| 152 | /**
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| 153 | * Shortcut to AutoStateDependency<MutableOrSavedStateDep>.
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| 154 | * See AutoStateDependency to get the usage pattern.
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| 155 | *
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| 156 | * Succeeds only if the machine state is in one of the mutable states, or
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| 157 | * if the machine is in the Saved state, and guarantees the given mutable
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| 158 | * state won't change before this object is destroyed. If the machine is
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| 159 | * not mutable, this instance's #rc() method will indicate a failure, and
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| 160 | * the caller is not allowed to rely on any particular machine state and
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| 161 | * should return the failed result code to the upper level.
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| 162 | *
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| 163 | * Intended to be used within setter methods of IMachine
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| 164 | * children objects that may operate on shut down or Saved machines.
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| 165 | */
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| 166 | typedef AutoStateDependency<Machine::MutableOrSavedStateDep> AutoMutableOrSavedStateDependency;
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| 167 |
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| 168 | /**
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| 169 | * Shortcut to AutoStateDependency<MutableOrRunningStateDep>.
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| 170 | * See AutoStateDependency to get the usage pattern.
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| 171 | *
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| 172 | * Succeeds only if the machine state is in one of the mutable states, or
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| 173 | * if the machine is in the Running or Paused state, and guarantees the
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| 174 | * given mutable state won't change before this object is destroyed. If
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| 175 | * the machine is not mutable, this instance's #rc() method will indicate
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| 176 | * a failure, and the caller is not allowed to rely on any particular
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| 177 | * machine state and should return the failed result code to the upper
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| 178 | * level.
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| 179 | *
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| 180 | * Intended to be used within setter methods of IMachine
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| 181 | * children objects that may operate on shut down or running machines.
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| 182 | */
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| 183 | typedef AutoStateDependency<Machine::MutableOrRunningStateDep> AutoMutableOrRunningStateDependency;
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| 184 |
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| 185 | /**
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| 186 | * Shortcut to AutoStateDependency<MutableOrSavedOrRunningStateDep>.
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| 187 | * See AutoStateDependency to get the usage pattern.
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| 188 | *
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| 189 | * Succeeds only if the machine state is in one of the mutable states, or
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| 190 | * if the machine is in the Running, Paused or Saved state, and guarantees
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| 191 | * the given mutable state won't change before this object is destroyed.
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| 192 | * If the machine is not mutable, this instance's #rc() method will
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| 193 | * indicate a failure, and the caller is not allowed to rely on any
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| 194 | * particular machine state and should return the failed result code to
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| 195 | * the upper level.
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| 196 | *
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| 197 | * Intended to be used within setter methods of IMachine
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| 198 | * children objects that may operate on shut down, running or saved
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| 199 | * machines.
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| 200 | */
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| 201 | typedef AutoStateDependency<Machine::MutableOrSavedOrRunningStateDep> AutoMutableOrSavedOrRunningStateDependency;
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| 202 |
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| 203 | #endif /* !MAIN_INCLUDED_AutoStateDep_h */
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| 204 |
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