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<task id="GUID-E3A80D62-09A5-502D-AB55-6AB2A5623465" xml:lang="en"><title>Cleaning-up

Memory</title><shortdesc>To ensure the plug-in framework unloads the plug-in DLLs when they

are no longer required and releases associated memory, the clients should

follow an explicit memory cleanup procedure. The main purpose is to release

memory and close handles held on unused plug-in implementations and their

associated DLLs. The memory clean-up should be performed after all instantiated

interface objects have been deleted. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context><p>The plug-in framework client-side library implements a deferred

cleanup mechanism in the client process to handle destroyed plug-ins. Following

a call to <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-8BA69111-0451-34CA-A1E8-C83513C4D29D"><apiname>REComSession::DestroyedImplementation()</apiname></xref> in the

destructor, the plug-in’s reference count is decremented to zero and the client-side

library has a “last destroyed last plug-in” garbage pointer. The internal

framework memory associated with the garbage plug-in is released. The handles

on the DLL are closed at the beginning of the next call to <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-8BA69111-0451-34CA-A1E8-C83513C4D29D"><apiname>REComSession::DestroyedImplementation()</apiname></xref>.

This chain of deferred cleanup in the client thread requires the final plug-in

in the garbage queue to be released. Hence there is a requirement for explicit

memory clean-up. The memory clean-up is performed by the clients of the plug-in

framework. <note> The destructor of the interface implementation deletes the

instantiated objects obtained from an interface when they are no longer required

by calling the static function <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-8BA69111-0451-34CA-A1E8-C83513C4D29D"><apiname>REComSession::DestroyedImplementation()</apiname></xref>. <codeblock xml:space="preserve">inline CExampleInterfaceDefinition::~CExampleInterfaceDefinition()

    {

    REComSession::DestroyedImplementation(iDtor_ID_Key);

    }</codeblock></note></p> </context>

<steps id="GUID-31FD83CA-3EC3-5EA2-8297-21165CC16335">

<step id="GUID-BB4A525E-4D43-59F0-8D45-136D31258FDA"><cmd/>

<info>Call <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-1AACEF53-2CAD-34EC-A485-CE49BC8B9BD8"><apiname>REComSession::FinalClose()</apiname></xref> before shut down

to ensure the plug-in framework executes the final cleanup steps. </info>

<info> Note:  <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-1AACEF53-2CAD-34EC-A485-CE49BC8B9BD8"><apiname>REComSession::FinalClose()</apiname></xref> should not be

called from a plug-in implementation class destructor, especially following

a <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-8BA69111-0451-34CA-A1E8-C83513C4D29D"><apiname>REComSession::DestroyedImplementation()</apiname></xref>. There is a risk

that the plug-in's supporting DLL may immediately be unloaded by the Kernel

due to the closure of RLibrary handles. It can result in a KERN-EXEC if the

destructor call stack is still inside the DLL that is unloaded. </info>

</step>

<step id="GUID-AA4796C3-0F56-5AE2-A278-08CA615C4157"><cmd/>

<info>If the plug-in framework is used in a library, then <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-1AACEF53-2CAD-34EC-A485-CE49BC8B9BD8"><apiname>REComSession::FinalClose()</apiname></xref> should

be invoked within the library's shutdown function. This makes the library's

use of plug-in framework transparent to the clients. </info>

<info>It is not an error if both the library and client call <xref href="GUID-1344F049-81C4-3D17-AF46-8B5584680ADB.dita#GUID-1344F049-81C4-3D17-AF46-8B5584680ADB/GUID-1AACEF53-2CAD-34EC-A485-CE49BC8B9BD8"><apiname>REComSession::FinalClose()</apiname></xref>. </info>

</step>

</steps>