/*

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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")

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*

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* This Source Code Form is subject to the terms of the Mozilla Public

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* License, v. 2.0. If a copy of the MPL was not distributed with this

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* file, you can obtain one at https://mozilla.org/MPL/2.0/.

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*

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* See the COPYRIGHT file distributed with this work for additional

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* information regarding copyright ownership.

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*/

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#ifndef ISC_ONDESTROY_H

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#define ISC_ONDESTROY_H 1

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#include <isc/lang.h>

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#include <isc/types.h>

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ISC_LANG_BEGINDECLS

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/*! \file isc/ondestroy.h

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* ondestroy handling.

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*

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* Any class ``X'' of objects that wants to send out notifications

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* on its destruction should declare a field of type isc_ondestroy_t

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* (call it 'ondest').

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*

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* \code

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* typedef struct {

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* ...

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* isc_ondestroy_t ondest;

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* ...

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* } X;

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* \endcode

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*

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* When an object ``A'' of type X is created

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* it must initialize the field ondest with a call to

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*

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* \code

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* isc_ondestroy_init(&A->ondest).

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* \endcode

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*

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* X should also provide a registration function for third-party

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* objects to call to register their interest in being told about

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* the destruction of a particular instance of X.

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*

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* \code

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* isc_result_t

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* X_ondestroy(X *instance, isc_task_t *task,

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* isc_event_t **eventp) {

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* return(isc_ondestroy_register(&instance->ondest, task,eventp));

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* }

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* \endcode

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*

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* Note: locking of the ondestory structure embedded inside of X, is

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* X's responsibility.

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*

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* When an instance of X is destroyed, a call to isc_ondestroy_notify()

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* sends the notifications:

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*

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* \code

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* X *instance;

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* isc_ondestroy_t ondest = instance->ondest;

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*

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* ... completely cleanup 'instance' here...

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*

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* isc_ondestroy_notify(&ondest, instance);

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* \endcode

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*

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*

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* see lib/dns/zone.c for an ifdef'd-out example.

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*/

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struct isc_ondestroy {

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unsigned int magic;

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isc_eventlist_t events;

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};

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void

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isc_ondestroy_init(isc_ondestroy_t *ondest);

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/*%<

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* Initialize the on ondest structure. *must* be called before first call

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* to isc_ondestroy_register().

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*/

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isc_result_t

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isc_ondestroy_register(isc_ondestroy_t *ondest, isc_task_t *task,

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isc_event_t **eventp);

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/*%<

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* Stores task and *eventp away inside *ondest. Ownership of **event is

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* taken from the caller (and *eventp is set to NULL). The task is attached

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* to.

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*/

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void

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isc_ondestroy_notify(isc_ondestroy_t *ondest, void *sender);

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/*%<

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* Dispatches the event(s) to the task(s) that were given in

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* isc_ondestroy_register call(s) (done via calls to

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* isc_task_sendanddetach()). Before dispatch, the sender value of each

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* event structure is set to the value of the sender parameter. The

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* internal structures of the ondest parameter are cleaned out, so no other

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* cleanup is needed.

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*/

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ISC_LANG_ENDDECLS

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#endif /* ISC_ONDESTROY_H */

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