abort_signal_composition_manager.h | Explore in Territory

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ABORT_SIGNAL_COMPOSITION_MANAGER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ABORT_SIGNAL_COMPOSITION_MANAGER_H_

#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/dom/abort_signal_composition_type.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_linked_hash_set.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_vector.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/wtf/casting.h"

namespace blink {

class AbortSignal;

// `AbortSignalCompositionManager` maintains the relationships between source
// and dependent signals for AbortSignal.any() and TaskSignal.any(). The abort
// and priority components of a signal can be propagated separately and with
// different relationships, but the logic for maintaining the relationships is
// the same.
//
// There are two types of `AbortSignalManager`: one for source signals and one
// for dependents. New sources cannot be added to dependent signals after signal
// construction. When constructing a new composite signal that depends on
// another composite signal, this means the new signal can depend on the other
// composite signal's sources rather than directly on the directly on the
// composite signal itself. We can then represent each signal exclusively as a
// source or dependent, with composite signals being dependents and
// non-composite signals being sources.
//
// A signal is "settled" for a given event type (abort or prioritychange) when
// it can no longer emit that event, e.g. after abort or if a signal's
// controller is GCed. When all of a composite signal's sources are settled, it
// can be settled as well.
//
// Source signals are stored weakly and can be either associated with a
// controller or timeout. Sources are removed when they're settled.
//
// Dependent signals are stored weakly, with `AbortSignalRegistry` used to store
// strong references when needed. This, along with detecting settled signals,
// ensures we only hold strong references to signals when necessary.
class CORE_EXPORT AbortSignalCompositionManager
    : public GarbageCollected<AbortSignalCompositionManager> { … };

class DependentSignalCompositionManager;

// Manages composition for an `AbortSignal` that is a source for dependent
// signals.
class CORE_EXPORT SourceSignalCompositionManager
    : public AbortSignalCompositionManager { … };

// Manages composition for an `AbortSignal` that is dependent on zero or more
// source signals.
class CORE_EXPORT DependentSignalCompositionManager
    : public AbortSignalCompositionManager { … };

template <>
struct DowncastTraits<DependentSignalCompositionManager> { … };

template <>
struct DowncastTraits<SourceSignalCompositionManager> { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ABORT_SIGNAL_COMPOSITION_MANAGER_H_
chromium/third_party/blink/renderer/core/dom/abort_signal_composition_manager.h
