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// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef INCLUDE_V8_MICROTASKS_QUEUE_H_
#define INCLUDE_V8_MICROTASKS_QUEUE_H_
#include <stddef.h>
#include <memory>
#include "v8-local-handle.h" // NOLINT(build/include_directory)
#include "v8-microtask.h" // NOLINT(build/include_directory)
#include "v8config.h" // NOLINT(build/include_directory)
namespace v8 {
class Function;
namespace internal {
class Isolate;
class MicrotaskQueue;
} // namespace internal
/**
* Represents the microtask queue, where microtasks are stored and processed.
* https://html.spec.whatwg.org/multipage/webappapis.html#microtask-queue
* https://html.spec.whatwg.org/multipage/webappapis.html#enqueuejob(queuename,-job,-arguments)
* https://html.spec.whatwg.org/multipage/webappapis.html#perform-a-microtask-checkpoint
*
* A MicrotaskQueue instance may be associated to multiple Contexts by passing
* it to Context::New(), and they can be detached by Context::DetachGlobal().
* The embedder must keep the MicrotaskQueue instance alive until all associated
* Contexts are gone or detached.
*
* Use the same instance of MicrotaskQueue for all Contexts that may access each
* other synchronously. E.g. for Web embedding, use the same instance for all
* origins that share the same URL scheme and eTLD+1.
*/
class V8_EXPORT MicrotaskQueue {
public:
/**
* Creates an empty MicrotaskQueue instance.
*/
static std::unique_ptr<MicrotaskQueue> New(
Isolate* isolate, MicrotasksPolicy policy = MicrotasksPolicy::kAuto);
virtual ~MicrotaskQueue() = default;
/**
* Enqueues the callback to the queue.
*/
virtual void EnqueueMicrotask(Isolate* isolate,
Local<Function> microtask) = 0;
/**
* Enqueues the callback to the queue.
*/
virtual void EnqueueMicrotask(v8::Isolate* isolate,
MicrotaskCallback callback,
void* data = nullptr) = 0;
/**
* Adds a callback to notify the embedder after microtasks were run. The
* callback is triggered by explicit RunMicrotasks call or automatic
* microtasks execution (see Isolate::SetMicrotasksPolicy).
*
* Callback will trigger even if microtasks were attempted to run,
* but the microtasks queue was empty and no single microtask was actually
* executed.
*
* Executing scripts inside the callback will not re-trigger microtasks and
* the callback.
*/
virtual void AddMicrotasksCompletedCallback(
MicrotasksCompletedCallbackWithData callback, void* data = nullptr) = 0;
/**
* Removes callback that was installed by AddMicrotasksCompletedCallback.
*/
virtual void RemoveMicrotasksCompletedCallback(
MicrotasksCompletedCallbackWithData callback, void* data = nullptr) = 0;
/**
* Runs microtasks if no microtask is running on this MicrotaskQueue instance.
*/
virtual void PerformCheckpoint(Isolate* isolate) = 0;
/**
* Returns true if a microtask is running on this MicrotaskQueue instance.
*/
virtual bool IsRunningMicrotasks() const = 0;
/**
* Returns the current depth of nested MicrotasksScope that has
* kRunMicrotasks.
*/
virtual int GetMicrotasksScopeDepth() const = 0;
MicrotaskQueue(const MicrotaskQueue&) = delete;
MicrotaskQueue& operator=(const MicrotaskQueue&) = delete;
private:
friend class internal::MicrotaskQueue;
MicrotaskQueue() = default;
};
/**
* This scope is used to control microtasks when MicrotasksPolicy::kScoped
* is used on Isolate. In this mode every non-primitive call to V8 should be
* done inside some MicrotasksScope.
* Microtasks are executed when topmost MicrotasksScope marked as kRunMicrotasks
* exits.
* kDoNotRunMicrotasks should be used to annotate calls not intended to trigger
* microtasks.
*/
class V8_EXPORT V8_NODISCARD MicrotasksScope {
public:
enum Type { kRunMicrotasks, kDoNotRunMicrotasks };
V8_DEPRECATE_SOON(
"May be incorrect if context was created with non-default microtask "
"queue")
MicrotasksScope(Isolate* isolate, Type type);
MicrotasksScope(Local<Context> context, Type type);
MicrotasksScope(Isolate* isolate, MicrotaskQueue* microtask_queue, Type type);
~MicrotasksScope();
/**
* Runs microtasks if no kRunMicrotasks scope is currently active.
*/
static void PerformCheckpoint(Isolate* isolate);
/**
* Returns current depth of nested kRunMicrotasks scopes.
*/
static int GetCurrentDepth(Isolate* isolate);
/**
* Returns true while microtasks are being executed.
*/
static bool IsRunningMicrotasks(Isolate* isolate);
// Prevent copying.
MicrotasksScope(const MicrotasksScope&) = delete;
MicrotasksScope& operator=(const MicrotasksScope&) = delete;
private:
internal::Isolate* const i_isolate_;
internal::MicrotaskQueue* const microtask_queue_;
bool run_;
};
} // namespace v8
#endif // INCLUDE_V8_MICROTASKS_QUEUE_H_