michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * vim: sw=2 ts=8 et :
michael@0:  */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: include protocol PLayerTransaction;
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace layers {
michael@0: 
michael@0: /**
michael@0:  * PLayer represents a layer shared across thread contexts.
michael@0:  */
michael@0: 
michael@0: async protocol PLayer {
michael@0:     manager PLayerTransaction;
michael@0: 
michael@0:     /**
michael@0:      * OWNERSHIP MODEL
michael@0:      *
michael@0:      * Roughly speaking, the child side "actually owns" a Layer.  This
michael@0:      * is because the parent side is the "shadow"; when the child
michael@0:      * releases a Layer, the parent's shadow is no longer meaningful.
michael@0:      *
michael@0:      * To implement this model, the concrete PLayerParent keeps a
michael@0:      * strong ref to its Layer, so the Layer's lifetime is bound to
michael@0:      * the PLayerParent's.  Then, when the Layer's refcount hits 0 on
michael@0:      * the child side, we send __delete__() from the child to parent.
michael@0:      * The parent then releases its Layer, which results in the Layer
michael@0:      * being deleted "soon" (usually immediately).
michael@0:      */
michael@0: parent:
michael@0:     async __delete__();
michael@0: };
michael@0: 
michael@0: } // layers
michael@0: } // mozilla