зеркало из https://github.com/mozilla/gecko-dev.git
139 строки
3.6 KiB
C++
139 строки
3.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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 http://mozilla.org/MPL/2.0/. */
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#ifndef _mozilla_dom_ClientThing_h
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#define _mozilla_dom_ClientThing_h
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#include "nsTArray.h"
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namespace mozilla::dom {
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// Base class representing various Client "things" such as ClientHandle,
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// ClientSource, and ClientManager. Currently it provides a common set
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// of code for handling activation and shutdown of IPC actors.
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template <typename ActorType>
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class ClientThing {
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#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
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static const uint32_t kMagic1 = 0xC9FE2C9C;
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static const uint32_t kMagic2 = 0x832072D4;
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#endif
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ActorType* mActor;
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#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
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uint32_t mMagic1;
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uint32_t mMagic2;
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#endif
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bool mShutdown;
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protected:
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ClientThing()
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: mActor(nullptr)
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#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
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,
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mMagic1(kMagic1),
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mMagic2(kMagic2)
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#endif
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,
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mShutdown(false) {
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}
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~ClientThing() {
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AssertIsValid();
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ShutdownThing();
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#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
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mMagic1 = 0;
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mMagic2 = 0;
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#endif
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}
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void AssertIsValid() const {
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MOZ_DIAGNOSTIC_ASSERT(mMagic1 == kMagic1);
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MOZ_DIAGNOSTIC_ASSERT(mMagic2 == kMagic2);
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}
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// Return the current actor.
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ActorType* GetActor() const {
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AssertIsValid();
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return mActor;
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}
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// Returns true if ShutdownThing() has been called.
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bool IsShutdown() const {
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AssertIsValid();
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return mShutdown;
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}
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// Conditionally execute the given callable based on the current state.
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template <typename Callable>
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void MaybeExecute(
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const Callable& aSuccess, const std::function<void()>& aFailure = [] {}) {
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AssertIsValid();
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if (mShutdown) {
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aFailure();
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return;
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}
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MOZ_DIAGNOSTIC_ASSERT(mActor);
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aSuccess(mActor);
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}
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// Attach activate the thing by attaching its underlying IPC actor. This
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// will make the thing register as the actor's owner as well. The actor
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// must call RevokeActor() to clear this weak back reference before its
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// destroyed.
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void ActivateThing(ActorType* aActor) {
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AssertIsValid();
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MOZ_DIAGNOSTIC_ASSERT(aActor);
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MOZ_DIAGNOSTIC_ASSERT(!mActor);
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MOZ_DIAGNOSTIC_ASSERT(!mShutdown);
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mActor = aActor;
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mActor->SetOwner(this);
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}
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// Start destroying the underlying actor and disconnect the thing.
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void ShutdownThing() {
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AssertIsValid();
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if (mShutdown) {
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return;
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}
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mShutdown = true;
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// If we are shutdown before the actor, then clear the weak references
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// between the actor and the thing.
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if (mActor) {
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mActor->RevokeOwner(this);
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mActor->MaybeStartTeardown();
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mActor = nullptr;
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}
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OnShutdownThing();
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}
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// Allow extending classes to take action when shutdown.
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virtual void OnShutdownThing() {
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// by default do nothing
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}
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public:
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// Clear the weak references between the thing and its IPC actor.
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void RevokeActor(ActorType* aActor) {
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AssertIsValid();
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MOZ_DIAGNOSTIC_ASSERT(mActor);
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MOZ_DIAGNOSTIC_ASSERT(mActor == aActor);
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mActor->RevokeOwner(this);
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mActor = nullptr;
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// Also consider the ClientThing shutdown. We simply set the flag
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// instead of calling ShutdownThing() to avoid calling MaybeStartTeardown()
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// on the destroyed actor.
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mShutdown = true;
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OnShutdownThing();
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}
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};
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} // namespace mozilla::dom
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#endif // _mozilla_dom_ClientThing_h
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