src/dawn/native/metal/QueueMTL.h

// Copyright 2018 The Dawn & Tint Authors
//
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#ifndef SRC_DAWN_NATIVE_METAL_QUEUEMTL_H_
#define SRC_DAWN_NATIVE_METAL_QUEUEMTL_H_

#import <Metal/Metal.h>
#include <map>

#include "dawn/common/MutexProtected.h"
#include "dawn/common/SerialMap.h"
#include "dawn/native/EventManager.h"
#include "dawn/native/Queue.h"
#include "dawn/native/WaitListEvent.h"
#include "dawn/native/metal/CommandRecordingContext.h"
#include "dawn/native/metal/SharedFenceMTL.h"

namespace dawn::native::metal {

class Device;

class Queue final : public QueueBase {
  public:
    static ResultOrError<Ref<Queue>> Create(Device* device, const QueueDescriptor* descriptor);

    CommandRecordingContext* GetPendingCommandContext(SubmitMode submitMode = SubmitMode::Normal);
    MaybeError SubmitPendingCommandBuffer();

    // TODO(crbug.com/444702048): Remove after migrating Chromium to commands scheduled futures.
    void WaitForCommandsToBeScheduled();

    FutureID GetCommandsScheduledFuture();

    id<MTLSharedEvent> GetMTLSharedEvent() const;
    ResultOrError<Ref<SharedFence>> GetOrCreateSharedFence();

    ResultOrError<ExecutionSerial> WaitForQueueSerialImpl(ExecutionSerial waitSerial,
                                                          Nanoseconds timeout) override;

  private:
    Queue(Device* device, const QueueDescriptor* descriptor);
    ~Queue() override;

    MaybeError Initialize();
    void UpdateCommandsScheduledEvents(ExecutionSerial scheduledSerial);
    void UpdateCommandsCompletedEvents(ExecutionSerial completedSerial);

    MaybeError SubmitImpl(uint32_t commandCount, CommandBufferBase* const* commands) override;
    bool HasPendingCommands() const override;
    MaybeError SubmitPendingCommandsImpl() override;
    ResultOrError<ExecutionSerial> CheckAndUpdateCompletedSerials() override;
    void ForceEventualFlushOfCommands() override;
    MaybeError WaitForIdleForDestructionImpl() override;
    void DestroyImpl() override;

    NSPRef<id<MTLCommandQueue>> mCommandQueue;
    CommandRecordingContext mCommandContext{this};

    // The following fields will be accessed in an async Metal command buffer handler that can be
    // fired on a different thread so we guard access to them with mutexes.
    // We need to keep the last submitted command buffer around to call waitUntilScheduled on it
    // for WaitForCommandsToBeScheduled. Note that what's mutex protected is just the pointer to the
    // last submitted command buffer; the command buffer itself is safe to use across threads.
    MutexProtected<NSPRef<id<MTLCommandBuffer>>> mLastSubmittedCommands;
    MutexProtected<SerialMap<ExecutionSerial, Ref<EventManager::TrackedEvent>>>
        mCommandsScheduledEvents;
    // TODO(crbug.com/dawn/2065): If we atomically knew a conservative lower bound on the
    // mCommandsCompletedEvents serials, we could avoid taking this lock sometimes. Optimize if
    // needed. See old draft code: https://dawn-review.googlesource.com/c/dawn/+/137502/29
    MutexProtected<SerialMap<ExecutionSerial, Ref<WaitListEvent>>> mCommandsCompletedEvents;

    // A shared event that can be exported for synchronization with other users of Metal.
    // MTLSharedEvent is not available until macOS 10.14+ so use just `id`.
    NSPRef<id> mMtlSharedEvent;
    // The shared event wrapped as a SharedFence object.
    Ref<SharedFence> mSharedFence;
};

}  // namespace dawn::native::metal

#endif  // SRC_DAWN_NATIVE_METAL_QUEUEMTL_H_