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32 lines
1.5 KiB
Plaintext
32 lines
1.5 KiB
Plaintext
"Finalize tree" to break XPCOM cycles and have clean shutdowns
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XMLterm class embedding hierarchy
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=================================
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mozXMLTermShell (or ../geckoterm/mozGeckoTerm)
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mozXMLTerminal
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+-----------------+----------------+
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mozXMLTermSession mozLineTermAux mozXMLTermListeners
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mozXMLTermStream... (lineterm)
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We would like to have clean shutdowns of an XMLterm, since we are using
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external resources, e.g., a shell process or an rlogin process. However, the
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XPCOM reference counting can hinder shutdowns, if there cycles. To avoid
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that, the XMLterm interfaces have a Finalize or Close method. A shutdown
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event triggers a call to the Finalize method of the root interface in the
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"Finalize tree". When the Finalize method of any interface is called, it
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first calls the Finalize methods of any child nodes in the Finalize tree, then
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releases all the XPCOM references it owns, de-initializes itself and quietly
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waits for its reference count to go to zero. In this "closed" state of the
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interface, any attempts use it result in an error return.
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The destructor of an object simply checks if all its interfaces have been
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finalized, and calls the Finalize methods for any that have not been.
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--
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