gecko-dev/gfx/vr/VRShMem.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 GFX_VR_VRSHMEM_H
#define GFX_VR_VRSHMEM_H
// This file declares VRShMem, which is used for cross-platform, cross-process
// communication between VR components.
// A shared memory handle is opened for the struct of type VRExternalShmem, and
// different processes write or read members of it to share data. Note that no
// process should be reading or writing to the same members, except for the
// versioning members used for synchronization.
#include "moz_external_vr.h"
#include "base/process.h" // for base::ProcessHandle
#include <functional>
namespace mozilla {
namespace gfx {
class VRShMem final {
public:
VRShMem(volatile VRExternalShmem* aShmem, bool aRequiresMutex);
~VRShMem() = default;
void CreateShMem(bool aCreateOnSharedMemory);
void CreateShMemForAndroid();
void ClearShMem();
void CloseShMem();
bool JoinShMem();
void LeaveShMem();
void PushBrowserState(VRBrowserState& aBrowserState, bool aNotifyCond);
void PullBrowserState(mozilla::gfx::VRBrowserState& aState);
void PushSystemState(const mozilla::gfx::VRSystemState& aState);
void PullSystemState(
VRDisplayState& aDisplayState, VRHMDSensorState& aSensorState,
VRControllerState (&aControllerState)[kVRControllerMaxCount],
bool& aEnumerationCompleted,
const std::function<bool()>& aWaitCondition = nullptr);
void PushWindowState(VRWindowState& aState);
void PullWindowState(VRWindowState& aState);
bool HasExternalShmem() const { return mExternalShmem != nullptr; }
bool IsSharedExternalShmem() const { return mIsSharedExternalShmem; }
volatile VRExternalShmem* GetExternalShmem() const;
bool IsDisplayStateShutdown() const;
private:
bool IsCreatedOnSharedMemory() const;
// mExternalShmem can have one of three sources:
// - Allocated outside of this class on the heap and passed in via
// constructor, or acquired via GeckoVRManager (for GeckoView scenario).
// This is usually for scenarios where there is no VR process for cross-
// proc communication, and VRService is receiving the object.
// --> mIsSharedExternalShmem == true, IsCreatedOnSharedMemory() == false
// --> [Windows 7, Mac, Android, Linux]
// - Allocated inside this class on the heap. This is usually for scenarios
// where there is no VR process, and VRManager is creating the object.
// --> mIsSharedExternalShmem == false, IsCreatedOnSharedMemory() == false
// --> [Windows 7, Mac, Linux]
// - Allocated inside this class on shared memory. This is usually for
// scenarios where there is a VR process and cross-process communication
// is necessary
// --> mIsSharedExternalShmem == false, IsCreatedOnSharedMemory() == true
// --> [Windows 10 with VR process enabled]
volatile VRExternalShmem* mExternalShmem = nullptr;
// This member is true when mExternalShmem was allocated externally, via
// being passed into the constructor or accessed via GeckoVRManager
bool mIsSharedExternalShmem;
#if defined(XP_WIN)
bool mRequiresMutex;
#endif
#if defined(XP_MACOSX)
int mShmemFD;
#elif defined(XP_WIN)
base::ProcessHandle mShmemFile;
base::ProcessHandle mMutex;
#endif
#if !defined(MOZ_WIDGET_ANDROID)
int64_t mBrowserGeneration = 0;
#endif
};
} // namespace gfx
} // namespace mozilla
#endif