#ifndef V8_EXECUTION_MICROTASK_QUEUE_H_

#define V8_EXECUTION_MICROTASK_QUEUE_H_

#include <stdint.h>

#include <memory>

#include <vector>

#include "include/v8-internal.h" // For Address.

#include "include/v8-microtask-queue.h"

#include "src/base/macros.h"

namespace v8 {

namespace internal {

class Isolate;

class Microtask;

class Object;

class RootVisitor;

template <typename T>

class Tagged;

class V8_EXPORT_PRIVATE MicrotaskQueue final : public v8::MicrotaskQueue {

public:

static void SetUpDefaultMicrotaskQueue(Isolate* isolate);

static std::unique_ptr<MicrotaskQueue> New(Isolate* isolate);

~MicrotaskQueue() override;

// Uses raw Address values because it's called via ExternalReference.

// {raw_microtask} is a tagged Microtask pointer.

// Returns Smi::kZero due to CallCFunction.

static Address CallEnqueueMicrotask(Isolate* isolate,

intptr_t microtask_queue_pointer,

Address raw_microtask);

// v8::MicrotaskQueue implementations.

void EnqueueMicrotask(v8::Isolate* isolate,

v8::Local<Function> microtask) override;

void EnqueueMicrotask(v8::Isolate* isolate, v8::MicrotaskCallback callback,

void* data) override;

void PerformCheckpoint(v8::Isolate* isolate) override {

if (!ShouldPerfomCheckpoint()) return;

PerformCheckpointInternal(isolate);

}

bool ShouldPerfomCheckpoint() const {

return !IsRunningMicrotasks() && !GetMicrotasksScopeDepth() &&

!HasMicrotasksSuppressions();

}

void EnqueueMicrotask(Tagged<Microtask> microtask);

void AddMicrotasksCompletedCallback(

MicrotasksCompletedCallbackWithData callback, void* data) override;

void RemoveMicrotasksCompletedCallback(

MicrotasksCompletedCallbackWithData callback, void* data) override;

bool IsRunningMicrotasks() const override { return is_running_microtasks_; }

// Runs all queued Microtasks.

// Returns -1 if the execution is terminating, otherwise, returns the number

// of microtasks that ran in this round.

int RunMicrotasks(Isolate* isolate);

// Iterate all pending Microtasks in this queue as strong roots, so that

// builtins can update the queue directly without the write barrier.

void IterateMicrotasks(RootVisitor* visitor);

// Microtasks scope depth represents nested scopes controlling microtasks

// invocation, which happens when depth reaches zero.

void IncrementMicrotasksScopeDepth() { ++microtasks_depth_; }

void DecrementMicrotasksScopeDepth() { --microtasks_depth_; }

int GetMicrotasksScopeDepth() const override { return microtasks_depth_; }

// Possibly nested microtasks suppression scopes prevent microtasks

// from running.

void IncrementMicrotasksSuppressions() { ++microtasks_suppressions_; }

void DecrementMicrotasksSuppressions() { --microtasks_suppressions_; }

bool HasMicrotasksSuppressions() const {

return microtasks_suppressions_ != 0;

}

#ifdef DEBUG

// In debug we check that calls not intended to invoke microtasks are

// still correctly wrapped with microtask scopes.

void IncrementDebugMicrotasksScopeDepth() { ++debug_microtasks_depth_; }

void DecrementDebugMicrotasksScopeDepth() { --debug_microtasks_depth_; }

bool DebugMicrotasksScopeDepthIsZero() const {

return debug_microtasks_depth_ == 0;

}

#endif

void set_microtasks_policy(v8::MicrotasksPolicy microtasks_policy) {

microtasks_policy_ = microtasks_policy;

}

v8::MicrotasksPolicy microtasks_policy() const { return microtasks_policy_; }

intptr_t capacity() const { return capacity_; }

intptr_t size() const { return size_; }

intptr_t start() const { return start_; }

Tagged<Microtask> get(intptr_t index) const;

MicrotaskQueue* next() const { return next_; }

MicrotaskQueue* prev() const { return prev_; }

static const size_t kRingBufferOffset;

static const size_t kCapacityOffset;

static const size_t kSizeOffset;

static const size_t kStartOffset;

static const size_t kFinishedMicrotaskCountOffset;

static const intptr_t kMinimumCapacity;

private:

void PerformCheckpointInternal(v8::Isolate* v8_isolate);

void OnCompleted(Isolate* isolate) const;

MicrotaskQueue();

void ResizeBuffer(intptr_t new_capacity);

// A ring buffer to hold Microtask instances.

// ring_buffer_[(start_ + i) % capacity_] contains |i|th Microtask for each

// |i| in [0, size_).

intptr_t size_ = 0;

intptr_t capacity_ = 0;

intptr_t start_ = 0;

Address* ring_buffer_ = nullptr;

// The number of finished microtask.

intptr_t finished_microtask_count_ = 0;

// MicrotaskQueue instances form a doubly linked list loop, so that all

// instances are reachable through |next_|.

MicrotaskQueue* next_ = nullptr;

MicrotaskQueue* prev_ = nullptr;

int microtasks_depth_ = 0;

int microtasks_suppressions_ = 0;

#ifdef DEBUG

int debug_microtasks_depth_ = 0;

#endif

v8::MicrotasksPolicy microtasks_policy_ = v8::MicrotasksPolicy::kAuto;

bool is_running_microtasks_ = false;

using CallbackWithData =

std::pair<MicrotasksCompletedCallbackWithData, void*>;

std::vector<CallbackWithData> microtasks_completed_callbacks_;

};

} // namespace internal

} // namespace v8

#endif // V8_EXECUTION_MICROTASK_QUEUE_H_