VulkanDeviceHolder.h

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef DOM_MEDIA_PLATFORMS_FFMPEG_VULKANDEVICEHOLDER_H_

#define DOM_MEDIA_PLATFORMS_FFMPEG_VULKANDEVICEHOLDER_H_

#include "mozilla/ThreadSafeWeakPtr.h"

#include "nsISupportsImpl.h"

struct AVBufferRef;

namespace mozilla {

struct FFmpegLibWrapper;

// Holds a shared AVHWDeviceContext (VkDevice) per FFmpegLibWrapper + device

// name in the RDD process. Mirrors VADisplayHolder for VA-API.

//

// The first decoder for a given lib+device pays vkCreateDevice; subsequent

// decoders on the same lib and name receive av_buffer_ref() on that context.

// System FFmpeg and ffvpx each keep their own cached device (layouts/buffer ops

// differ). A different physical device is a second cache entry. All entries

// are destroyed together when no decoder still holds any of them, under

// sDeviceHolders.

class VulkanDeviceHolder final

    : public SupportsThreadSafeWeakPtr<VulkanDeviceHolder> {

 public:

  MOZ_DECLARE_REFCOUNTED_TYPENAME(VulkanDeviceHolder)

  static RefPtr<VulkanDeviceHolder> GetOrCreate(const FFmpegLibWrapper* aLib,

                                                const char* aDeviceName,

                                                const char* aDeviceExtensions);

  // Releases a decoder's holder ref under sDeviceHolders. vkDestroyDevice runs

  // only if no decoder in the process still holds any cached holder.

  static void Drop(RefPtr<VulkanDeviceHolder>& aHolder);

  // Returns a new av_buffer_ref(); caller must av_buffer_unref() it.

  AVBufferRef* Ref() const;

  // Uniquely identifies this VkInstance/VkDevice pair, unlike the raw

  // VkInstance handle: once destroyed (see above), a later GetOrCreate()

  // could in principle get a new VkInstance at the same, just-freed

  // address (unconfirmed in practice; defensive measure). Callers caching

  // anything keyed by VkInstance (e.g. function pointers) should fold

  // this generation into the key to guard against that.

  uint64_t Generation() const { return mGeneration; }

  ~VulkanDeviceHolder();

 private:

  VulkanDeviceHolder(const FFmpegLibWrapper* aLib, AVBufferRef* aDeviceContext);

  const FFmpegLibWrapper* mLib;

  AVBufferRef* mDeviceContext;

  const uint64_t mGeneration;

};

}  // namespace mozilla

#endif  // DOM_MEDIA_PLATFORMS_FFMPEG_VULKANDEVICEHOLDER_H_