102 lines
2.1 KiB
C++
102 lines
2.1 KiB
C++
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// Copyright (c) 1997-1999 Microsoft Corporation
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//
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// DLL object instance and server lock utility class
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//
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// 8-19-97 sburns
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// concept stolen from DavidMun, who stole it from RaviR, who ...
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#ifndef __DLLREF_HPP_INCLUDED
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#define __DLLREF_HPP_INCLUDED
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// Maintains a instance counter and lock counter, with methods to manipulate
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// both in a thread-safe fashion. This is useful in implementing
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// DllCanUnloadNow.
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//
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// Each class that is instanciated and passed outside of the control of the
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// DLL should contain an instance of ComServerReference. This will automatically
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// increment and decrement the ComServerLockState instance counter in step with the
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// instance's lifetime. Typically, this includes all class factory instances,
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// and instances of classes that are created by those class factories.
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//
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// Calls to a class factory's LockServer method should be deferred to
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// this class.
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//
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// Calls to DllCanUnloadNow should defer to this class' CanUnloadNow method.
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class ComServerLockState
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{
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public:
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static
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void
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IncrementInstanceCounter()
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{
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::InterlockedIncrement(&instanceCount);
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}
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static
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void
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DecrementInstanceCounter()
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{
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::InterlockedDecrement(&instanceCount);
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}
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static
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void
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LockServer(bool lock)
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{
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lock
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? ::InterlockedIncrement(&lockCount)
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: ::InterlockedDecrement(&lockCount);
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}
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static
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bool
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CanUnloadNow()
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{
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return (instanceCount == 0 && lockCount == 0) ? true : false;
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}
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private:
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static long instanceCount;
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static long lockCount;
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// not implemented
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ComServerLockState();
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ComServerLockState(const ComServerLockState&);
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const ComServerLockState& operator=(const ComServerLockState&);
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};
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class ComServerReference
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{
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public:
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ComServerReference()
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{
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ComServerLockState::IncrementInstanceCounter();
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}
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~ComServerReference()
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{
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ComServerLockState::DecrementInstanceCounter();
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}
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private:
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// not implemented; no instance copying allowed.
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ComServerReference(const ComServerReference&);
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const ComServerReference& operator=(const ComServerReference&);
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};
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#endif // __DLLREF_HPP_INCLUDED
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