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Bug 1931873 - Use WeakPtr in MIDIAccess, r=gsvelto a=RyanVM

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The WeakPtr type simplifies the situation if the `MIDIPort` object
outlives its `MIDIAccess`.

Differential Revision: https://phabricator.services.mozilla.com/D230812
This commit is contained in:
Nika Layzell 2024-12-04 17:35:56 +00:00
parent 533375dfdf
commit 8cb8da25a3
4 changed files with 9 additions and 46 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

8
dom/midi/MIDIAccess.cpp
View file

@ -45,6 +45,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(MIDIAccess,
NS_IMPL_CYCLE_COLLECTION_UNLINK(mOutputMap)
NS_IMPL_CYCLE_COLLECTION_UNLINK(mAccessPromise)
tmp->Shutdown();
NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_PTR
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MIDIAccess)
@ -74,7 +75,6 @@ void MIDIAccess::Shutdown() {
if (mHasShutdown) {
return;
}
mDestructionObservers.Broadcast(void_t());
if (MIDIAccessManager::IsRunning()) {
MIDIAccessManager::Get()->RemoveObserver(this);
}
@ -188,8 +188,6 @@ void MIDIAccess::MaybeCreateMIDIPort(const MIDIPortInfo& aInfo,
// That is bad.
MOZ_CRASH("We shouldn't be here!");
}
// Set up port to listen for destruction of this access object.
mDestructionObservers.AddObserver(port);
// If we haven't resolved the promise for handing the MIDIAccess object to
// content, this means we're still populating the list of already connected
@ -236,10 +234,6 @@ JSObject* MIDIAccess::WrapObject(JSContext* aCx,
return MIDIAccess_Binding::Wrap(aCx, this, aGivenProto);
}
void MIDIAccess::RemovePortListener(MIDIAccessDestructionObserver* aObs) {
mDestructionObservers.RemoveObserver(aObs);
}
void MIDIAccess::DisconnectFromOwner() {
IgnoreKeepAliveIfHasListenersFor(nsGkAtoms::onstatechange);

18
dom/midi/MIDIAccess.h
View file

@ -10,6 +10,7 @@
#include "mozilla/Attributes.h"
#include "mozilla/DOMEventTargetHelper.h"
#include "mozilla/Observer.h"
#include "mozilla/WeakPtr.h"
#include "nsCycleCollectionParticipant.h"
#include "nsWrapperCache.h"
@ -18,10 +19,6 @@ struct JSContext;
namespace mozilla {
class ErrorResult;
// Predeclare void_t here, as including IPCMessageUtils brings in windows.h and
// causes binding compilation problems.
struct void_t;
namespace dom {
class MIDIAccessManager;
@ -35,8 +32,6 @@ class MIDIPortInfo;
class MIDIPortList;
class Promise;
using MIDIAccessDestructionObserver = Observer<void_t>;
/**
* MIDIAccess is the DOM object that is handed to the user upon MIDI permissions
* being successfully granted. It manages access to MIDI ports, and fires events
@ -46,7 +41,8 @@ using MIDIAccessDestructionObserver = Observer<void_t>;
* MIDIAccess objects are managed via MIDIAccessManager.
*/
class MIDIAccess final : public DOMEventTargetHelper,
public Observer<MIDIPortList> {
public Observer<MIDIPortList>,
public SupportsWeakPtr {
// Use the Permission Request class in MIDIAccessManager for creating
// MIDIAccess objects.
friend class MIDIPermissionRequest;
@ -72,12 +68,6 @@ class MIDIAccess final : public DOMEventTargetHelper,
// Observer implementation for receiving port connection updates
void Notify(const MIDIPortList& aEvent) override;
// All MIDIPort objects observe destruction of the MIDIAccess object that
// created them, as the port object receives disconnection events which then
// must be passed up to the MIDIAccess object. If the Port object dies before
// the MIDIAccess object, it needs to be removed from the observer list.
void RemovePortListener(MIDIAccessDestructionObserver* aObs);
// Fires DOM event on port connection/disconnection
void FireConnectionEvent(MIDIPort* aPort);
@ -101,8 +91,6 @@ class MIDIAccess final : public DOMEventTargetHelper,
RefPtr<MIDIInputMap> mInputMap;
// Stores all known MIDIOutput Ports
RefPtr<MIDIOutputMap> mOutputMap;
// List of MIDIPort observers that need to be updated on destruction.
ObserverList<void_t> mDestructionObservers;
// True if user gave permissions for sysex usage to this object.
bool mSysexEnabled;
// Promise created by RequestMIDIAccess call, to be resolved after port

15
dom/midi/MIDIPort.cpp
View file

@ -48,10 +48,6 @@ MIDIPort::MIDIPort(nsPIDOMWindowInner* aWindow)
}
MIDIPort::~MIDIPort() {
if (mMIDIAccessParent) {
mMIDIAccessParent->RemovePortListener(this);
mMIDIAccessParent = nullptr;
}
if (Port()) {
// If the IPC port channel is still alive at this point, it means we're
// probably CC'ing this port object. Send the shutdown message to also clean
@ -191,13 +187,6 @@ already_AddRefed<Promise> MIDIPort::Close(ErrorResult& aError) {
return p.forget();
}
void MIDIPort::Notify(const void_t& aVoid) {
LOG("MIDIPort::notify MIDIAccess shutting down, dropping reference.");
// If we're getting notified, it means the MIDIAccess parent object is dead.
// Nullify our copy.
mMIDIAccessParent = nullptr;
}
void MIDIPort::FireStateChangeEvent() {
if (!GetOwner()) {
return; // Ignore changes once we've been disconnected from the owner
@ -238,8 +227,8 @@ void MIDIPort::FireStateChangeEvent() {
// Fire MIDIAccess events first so that the port is no longer in the port
// maps.
if (mMIDIAccessParent) {
mMIDIAccessParent->FireConnectionEvent(this);
if (RefPtr<MIDIAccess> access = mMIDIAccessParent.get()) {
access->FireConnectionEvent(this);
}
MIDIConnectionEventInit init;

14
dom/midi/MIDIPort.h
View file

@ -28,8 +28,7 @@ class MIDIMessage;
* and communication.
*
*/
class MIDIPort : public DOMEventTargetHelper,
public MIDIAccessDestructionObserver {
class MIDIPort : public DOMEventTargetHelper {
public:
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(MIDIPort,
@ -56,10 +55,6 @@ class MIDIPort : public DOMEventTargetHelper,
already_AddRefed<Promise> Open(ErrorResult& aError);
already_AddRefed<Promise> Close(ErrorResult& aError);
// MIDIPorts observe the death of their parent MIDIAccess object, and delete
// their reference accordingly.
virtual void Notify(const void_t& aVoid) override;
void FireStateChangeEvent();
virtual void StateChange();
@ -106,11 +101,8 @@ class MIDIPort : public DOMEventTargetHelper,
// MIDIAccess object that created this MIDIPort object, which we need for
// firing port connection events. There is a chance this MIDIPort object can
// outlive its parent MIDIAccess object, so this is a weak reference that must
// be handled properly. It is set on construction of the MIDIPort object, and
// set to null when the parent MIDIAccess object is destroyed, which fires an
// notification we observe.
MIDIAccess* mMIDIAccessParent;
// outlive its parent MIDIAccess object, so this is a weak pointer.
WeakPtr<MIDIAccess> mMIDIAccessParent;
// Promise object generated on Open() call, that needs to be resolved once the
// platform specific Open() function has completed.
RefPtr<Promise> mOpeningPromise;