evs/manager/1.1/HalCamera.cpp - platform/packages/services/Car - Gitiles

 /*
  * Copyright (C) 2019 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "HalCamera.h"
 #include "VirtualCamera.h"
 #include "Enumerator.h"

 #include <android-base/logging.h>
 #include <ui/GraphicBufferAllocator.h>
 #include <ui/GraphicBufferMapper.h>


 namespace android {
 namespace automotive {
 namespace evs {
 namespace V1_1 {
 namespace implementation {


 // TODO(changyeon):
 // We need to hook up death monitoring to detect stream death so we can attempt a reconnect


 sp<VirtualCamera> HalCamera::makeVirtualCamera() {

     // Create the client camera interface object
     std::vector<sp<HalCamera>> sourceCameras;
     sourceCameras.reserve(1);
     sourceCameras.emplace_back(this);
     sp<VirtualCamera> client = new VirtualCamera(sourceCameras);
     if (client == nullptr) {
         LOG(ERROR) << "Failed to create client camera object";
         return nullptr;
     }

     if (!ownVirtualCamera(client)) {
         LOG(ERROR) << "Failed to own a client camera object";
         client = nullptr;
     }

     return client;
 }


 bool HalCamera::ownVirtualCamera(sp<VirtualCamera> virtualCamera) {

     if (virtualCamera == nullptr) {
         LOG(ERROR) << "Failed to create virtualCamera camera object";
         return false;
     }

     // Make sure we have enough buffers available for all our clients
     if (!changeFramesInFlight(virtualCamera->getAllowedBuffers())) {
         // Gah!  We couldn't get enough buffers, so we can't support this virtualCamera
         // Null the pointer, dropping our reference, thus destroying the virtualCamera object
         return false;
     }

     // Create a timeline
     // TODO(b/146465074): EVS v1.1 client should use v1.0 frame delivery logic
     //                    when it fails to create a timeline.
     {
         std::lock_guard<std::mutex> lock(mFrameMutex);
         mTimelines[(uint64_t)virtualCamera.get()] = make_unique<UniqueTimeline>(0);
     }

     // Add this virtualCamera to our ownership list via weak pointer
     mClients.emplace_back(virtualCamera);
     return true;
 }


 void HalCamera::disownVirtualCamera(sp<VirtualCamera> virtualCamera) {
     // Ignore calls with null pointers
     if (virtualCamera.get() == nullptr) {
         LOG(WARNING) << "Ignoring disownVirtualCamera call with null pointer";
         return;
     }

     // Remove the virtual camera from our client list
     unsigned clientCount = mClients.size();
     mClients.remove(virtualCamera);
     if (clientCount != mClients.size() + 1) {
         LOG(ERROR) << "Couldn't find camera in our client list to remove it";
     }

     // Recompute the number of buffers required with the target camera removed from the list
     if (!changeFramesInFlight(0)) {
         LOG(ERROR) << "Error when trying to reduce the in flight buffer count";
     }
 }


 bool HalCamera::changeFramesInFlight(int delta) {
     // Walk all our clients and count their currently required frames
     unsigned bufferCount = 0;
     for (auto&& client :  mClients) {
         sp<VirtualCamera> virtCam = client.promote();
         if (virtCam != nullptr) {
             bufferCount += virtCam->getAllowedBuffers();
         }
     }

     // Add the requested delta
     bufferCount += delta;

     // Never drop below 1 buffer -- even if all client cameras get closed
     if (bufferCount < 1) {
         bufferCount = 1;
     }

     // Ask the hardware for the resulting buffer count
     Return<EvsResult> result = mHwCamera->setMaxFramesInFlight(bufferCount);
     bool success = (result.isOk() && result == EvsResult::OK);

     // Update the size of our array of outstanding frame records
     if (success) {
         std::vector<FrameRecord> newRecords;
         newRecords.reserve(bufferCount);

         // Copy and compact the old records that are still active
         for (const auto& rec : mFrames) {
             if (rec.refCount > 0) {
                 newRecords.emplace_back(rec);
             }
         }
         if (newRecords.size() > (unsigned)bufferCount) {
             LOG(WARNING) << "We found more frames in use than requested.";
         }

         mFrames.swap(newRecords);
     }

     return success;
 }


 UniqueFence HalCamera::requestNewFrame(sp<VirtualCamera> client,
                                        const int64_t lastTimestamp) {
     FrameRequest req;
     req.client = client;
     req.timestamp = lastTimestamp;

     const uint64_t id = (uint64_t)client.get();

     std::lock_guard<std::mutex> lock(mFrameMutex);

     mTimelines[id]->BumpFenceEventCounter();
     UniqueFence fence = mTimelines[id]->CreateFence("FrameFence");

     mNextRequests->push_back(req);

     return fence.Dup();
 }


 Return<EvsResult> HalCamera::clientStreamStarting() {
     Return<EvsResult> result = EvsResult::OK;

     if (mStreamState == STOPPED) {
         mStreamState = RUNNING;
         result = mHwCamera->startVideoStream(this);
     }

     return result;
 }


 void HalCamera::clientStreamEnding(sp<VirtualCamera> client) {
     {
         std::lock_guard<std::mutex> lock(mFrameMutex);
         auto itReq = mNextRequests->begin();
         while (itReq != mNextRequests->end()) {
             if (itReq->client == client) {
                 break;
             } else {
                 ++itReq;
             }
         }

         const uint64_t clientId = reinterpret_cast<const uint64_t>(client.get());
         if (itReq != mNextRequests->end()) {
             mNextRequests->erase(itReq);

             // Signal a pending fence and delete associated timeline.
             mTimelines[clientId]->BumpTimelineEventCounter();
             mTimelines.erase(clientId);
         }

         auto itCam = mClients.begin();
         while (itCam != mClients.end()) {
             if (itCam->promote() == client.get()) {
                 break;
             } else {
                 ++itCam;
             }
         }

         if (itCam != mClients.end()) {
             // Remove a client, which requested to stop, from the list.
             mClients.erase(itCam);
         }
     }

     // Do we still have a running client?
     bool stillRunning = false;
     for (auto&& client : mClients) {
         sp<VirtualCamera> virtCam = client.promote();
         if (virtCam != nullptr) {
             stillRunning |= virtCam->isStreaming();
         }
     }

     // If not, then stop the hardware stream
     if (!stillRunning) {
         mStreamState = STOPPING;
         mHwCamera->stopVideoStream();
     }
 }


 Return<void> HalCamera::doneWithFrame(const BufferDesc_1_0& buffer) {
     // Find this frame in our list of outstanding frames
     unsigned i;
     for (i = 0; i < mFrames.size(); i++) {
         if (mFrames[i].frameId == buffer.bufferId) {
             break;
         }
     }
     if (i == mFrames.size()) {
         LOG(ERROR) << "We got a frame back with an ID we don't recognize!";
     } else {
         // Are there still clients using this buffer?
         mFrames[i].refCount--;
         if (mFrames[i].refCount <= 0) {
             // Since all our clients are done with this buffer, return it to the device layer
             mHwCamera->doneWithFrame(buffer);
         }
     }

     return Void();
 }


 Return<void> HalCamera::doneWithFrame(const BufferDesc_1_1& buffer) {
     // Find this frame in our list of outstanding frames
     unsigned i;
     for (i = 0; i < mFrames.size(); i++) {
         if (mFrames[i].frameId == buffer.bufferId) {
             break;
         }
     }
     if (i == mFrames.size()) {
         LOG(ERROR) << "We got a frame back with an ID we don't recognize!";
     } else {
         // Are there still clients using this buffer?
         mFrames[i].refCount--;
         if (mFrames[i].refCount <= 0) {
             // Since all our clients are done with this buffer, return it to the device layer
             hardware::hidl_vec<BufferDesc_1_1> returnedBuffers;
             returnedBuffers.resize(1);
             returnedBuffers[0] = buffer;
             mHwCamera->doneWithFrame_1_1(returnedBuffers);
         }
     }

     return Void();
 }


 // Methods from ::android::hardware::automotive::evs::V1_0::IEvsCameraStream follow.
 Return<void> HalCamera::deliverFrame(const BufferDesc_1_0& buffer) {
     /* Frames are delivered via deliverFrame_1_1 callback for clients that implement
      * IEvsCameraStream v1.1 interfaces and therefore this method must not be
      * used.
      */
     LOG(INFO) << "A delivered frame from EVS v1.0 HW module is rejected.";
     mHwCamera->doneWithFrame(buffer);

     return Void();
 }


 // Methods from ::android::hardware::automotive::evs::V1_1::IEvsCameraStream follow.
 Return<void> HalCamera::deliverFrame_1_1(const hardware::hidl_vec<BufferDesc_1_1>& buffer) {
     LOG(VERBOSE) << "Received a frame";
     // Frames are being forwarded to v1.1 clients only who requested new frame.
     const auto timestamp = buffer[0].timestamp;
     // TODO(b/145750636): For now, we are using a approximately half of 1 seconds / 30 frames = 33ms
     //           but this must be derived from current framerate.
     constexpr int64_t kThreshold = 16 * 1e+3; // ms
     unsigned frameDeliveriesV1 = 0;
     {
         std::lock_guard<std::mutex> lock(mFrameMutex);
         std::swap(mCurrentRequests, mNextRequests);
         while (!mCurrentRequests->empty()) {
             auto req = mCurrentRequests->front(); mCurrentRequests->pop_front();
             sp<VirtualCamera> vCam = req.client.promote();
             if (vCam == nullptr) {
                 // Ignore a client already dead.
                 continue;
             } else if (timestamp - req.timestamp < kThreshold) {
                 // Skip current frame because it arrives too soon.
                 LOG(DEBUG) << "Skips a frame from " << getId();
                 mNextRequests->push_back(req);
             } else if (vCam != nullptr && vCam->deliverFrame(buffer[0])) {
                 // Forward a frame and move a timeline.
                 LOG(DEBUG) << getId() << " forwarded the buffer #" << buffer[0].bufferId;
                 mTimelines[(uint64_t)vCam.get()]->BumpTimelineEventCounter();
                 ++frameDeliveriesV1;
             }
         }
     }

     // Frames are being forwarded to v1.0 clients always.
     unsigned frameDeliveries = 0;
     for (auto&& client : mClients) {
         sp<VirtualCamera> vCam = client.promote();
         if (vCam == nullptr || vCam->getVersion() > 0) {
             continue;
         }

         if (vCam->deliverFrame(buffer[0])) {
             ++frameDeliveries;
         }
     }

     frameDeliveries += frameDeliveriesV1;
     if (frameDeliveries < 1) {
         // If none of our clients could accept the frame, then return it
         // right away.
         LOG(INFO) << "Trivially rejecting frame (" << buffer[0].bufferId
                   << ") from " << getId() << " with no acceptance";
         mHwCamera->doneWithFrame_1_1(buffer);
     } else {
         // Add an entry for this frame in our tracking list.
         unsigned i;
         for (i = 0; i < mFrames.size(); ++i) {
             if (mFrames[i].refCount == 0) {
                 break;
             }
         }

         if (i == mFrames.size()) {
             mFrames.emplace_back(buffer[0].bufferId);
         } else {
             mFrames[i].frameId = buffer[0].bufferId;
         }
         mFrames[i].refCount = frameDeliveries;
     }

     return Void();
 }


 Return<void> HalCamera::notify(const EvsEventDesc& event) {
     LOG(DEBUG) << "Received an event id: " << static_cast<int32_t>(event.aType);
     if(event.aType == EvsEventType::STREAM_STOPPED) {
         // This event happens only when there is no more active client.
         if (mStreamState != STOPPING) {
             LOG(WARNING) << "Stream stopped unexpectedly";
         }

         mStreamState = STOPPED;
     }

     // Forward all other events to the clients
     for (auto&& client : mClients) {
         sp<VirtualCamera> vCam = client.promote();
         if (vCam != nullptr) {
             if (!vCam->notify(event)) {
                 LOG(INFO) << "Failed to forward an event";
             }
         }
     }

     return Void();
 }


 Return<EvsResult> HalCamera::setMaster(sp<VirtualCamera> virtualCamera) {
     if (mMaster == nullptr) {
         LOG(DEBUG) << __FUNCTION__
                    << ": " << virtualCamera.get() << " becomes a master.";
         mMaster = virtualCamera;
         return EvsResult::OK;
     } else {
         LOG(INFO) << "This camera already has a master client.";
         return EvsResult::OWNERSHIP_LOST;
     }
 }


 Return<EvsResult> HalCamera::forceMaster(sp<VirtualCamera> virtualCamera) {
     sp<VirtualCamera> prevMaster = mMaster.promote();
     if (prevMaster == virtualCamera) {
         LOG(DEBUG) << "Client " << virtualCamera.get()
                    << " is already a master client";
     } else {
         mMaster = virtualCamera;
         if (prevMaster != nullptr) {
             LOG(INFO) << "High priority client " << virtualCamera.get()
                       << " steals a master role from " << prevMaster.get();

             /* Notify a previous master client the loss of a master role */
             EvsEventDesc event;
             event.aType = EvsEventType::MASTER_RELEASED;
             if (!prevMaster->notify(event)) {
                 LOG(ERROR) << "Fail to deliver a master role lost notification";
             }
         }
     }

     return EvsResult::OK;
 }


 Return<EvsResult> HalCamera::unsetMaster(sp<VirtualCamera> virtualCamera) {
     if (mMaster.promote() != virtualCamera) {
         return EvsResult::INVALID_ARG;
     } else {
         LOG(INFO) << "Unset a master camera client";
         mMaster = nullptr;

         /* Notify other clients that a master role becomes available. */
         EvsEventDesc event;
         event.aType = EvsEventType::MASTER_RELEASED;
         auto cbResult = this->notify(event);
         if (!cbResult.isOk()) {
             LOG(ERROR) << "Fail to deliver a parameter change notification";
         }

         return EvsResult::OK;
     }
 }


 Return<EvsResult> HalCamera::setParameter(sp<VirtualCamera> virtualCamera,
                                           CameraParam id, int32_t& value) {
     EvsResult result = EvsResult::INVALID_ARG;
     if (virtualCamera == mMaster.promote()) {
         mHwCamera->setIntParameter(id, value,
                                    [&result, &value](auto status, auto readValue) {
                                        result = status;
                                        value = readValue[0];
                                    });

         if (result == EvsResult::OK) {
             /* Notify a parameter change */
             EvsEventDesc event;
             event.aType = EvsEventType::PARAMETER_CHANGED;
             event.payload[0] = static_cast<uint32_t>(id);
             event.payload[1] = static_cast<uint32_t>(value);
             auto cbResult = this->notify(event);
             if (!cbResult.isOk()) {
                 LOG(ERROR) << "Fail to deliver a parameter change notification";
             }
         }
     } else {
         LOG(WARNING) << "A parameter change request from a non-master client is declined.";

         /* Read a current value of a requested camera parameter */
         getParameter(id, value);
     }

     return result;
 }


 Return<EvsResult> HalCamera::getParameter(CameraParam id, int32_t& value) {
     EvsResult result = EvsResult::OK;
     mHwCamera->getIntParameter(id, [&result, &value](auto status, auto readValue) {
                                        result = status;
                                        if (result == EvsResult::OK) {
                                            value = readValue[0];
                                        }
     });

     return result;
 }


 } // namespace implementation
 } // namespace V1_1
 } // namespace evs
 } // namespace automotive
 } // namespace android
	/*
	* Copyright (C) 2019 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "HalCamera.h"
	#include "VirtualCamera.h"
	#include "Enumerator.h"

	#include <android-base/logging.h>
	#include <ui/GraphicBufferAllocator.h>
	#include <ui/GraphicBufferMapper.h>


	namespace android {
	namespace automotive {
	namespace evs {
	namespace V1_1 {
	namespace implementation {


	// TODO(changyeon):
	// We need to hook up death monitoring to detect stream death so we can attempt a reconnect


	sp<VirtualCamera> HalCamera::makeVirtualCamera() {

	// Create the client camera interface object
	std::vector<sp<HalCamera>> sourceCameras;
	sourceCameras.reserve(1);
	sourceCameras.emplace_back(this);
	sp<VirtualCamera> client = new VirtualCamera(sourceCameras);
	if (client == nullptr) {
	LOG(ERROR) << "Failed to create client camera object";
	return nullptr;
	}

	if (!ownVirtualCamera(client)) {
	LOG(ERROR) << "Failed to own a client camera object";
	client = nullptr;
	}

	return client;
	}


	bool HalCamera::ownVirtualCamera(sp<VirtualCamera> virtualCamera) {

	if (virtualCamera == nullptr) {
	LOG(ERROR) << "Failed to create virtualCamera camera object";
	return false;
	}

	// Make sure we have enough buffers available for all our clients
	if (!changeFramesInFlight(virtualCamera->getAllowedBuffers())) {
	// Gah! We couldn't get enough buffers, so we can't support this virtualCamera
	// Null the pointer, dropping our reference, thus destroying the virtualCamera object
	return false;
	}

	// Create a timeline
	// TODO(b/146465074): EVS v1.1 client should use v1.0 frame delivery logic
	// when it fails to create a timeline.
	{
	std::lock_guard<std::mutex> lock(mFrameMutex);
	mTimelines[(uint64_t)virtualCamera.get()] = make_unique<UniqueTimeline>(0);
	}

	// Add this virtualCamera to our ownership list via weak pointer
	mClients.emplace_back(virtualCamera);
	return true;
	}


	void HalCamera::disownVirtualCamera(sp<VirtualCamera> virtualCamera) {
	// Ignore calls with null pointers
	if (virtualCamera.get() == nullptr) {
	LOG(WARNING) << "Ignoring disownVirtualCamera call with null pointer";
	return;
	}

	// Remove the virtual camera from our client list
	unsigned clientCount = mClients.size();
	mClients.remove(virtualCamera);
	if (clientCount != mClients.size() + 1) {
	LOG(ERROR) << "Couldn't find camera in our client list to remove it";
	}

	// Recompute the number of buffers required with the target camera removed from the list
	if (!changeFramesInFlight(0)) {
	LOG(ERROR) << "Error when trying to reduce the in flight buffer count";
	}
	}


	bool HalCamera::changeFramesInFlight(int delta) {
	// Walk all our clients and count their currently required frames
	unsigned bufferCount = 0;
	for (auto&& client : mClients) {
	sp<VirtualCamera> virtCam = client.promote();
	if (virtCam != nullptr) {
	bufferCount += virtCam->getAllowedBuffers();
	}
	}

	// Add the requested delta
	bufferCount += delta;

	// Never drop below 1 buffer -- even if all client cameras get closed
	if (bufferCount < 1) {
	bufferCount = 1;
	}

	// Ask the hardware for the resulting buffer count
	Return<EvsResult> result = mHwCamera->setMaxFramesInFlight(bufferCount);
	bool success = (result.isOk() && result == EvsResult::OK);

	// Update the size of our array of outstanding frame records
	if (success) {
	std::vector<FrameRecord> newRecords;
	newRecords.reserve(bufferCount);

	// Copy and compact the old records that are still active
	for (const auto& rec : mFrames) {
	if (rec.refCount > 0) {
	newRecords.emplace_back(rec);
	}
	}
	if (newRecords.size() > (unsigned)bufferCount) {
	LOG(WARNING) << "We found more frames in use than requested.";
	}

	mFrames.swap(newRecords);
	}

	return success;
	}


	UniqueFence HalCamera::requestNewFrame(sp<VirtualCamera> client,
	const int64_t lastTimestamp) {
	FrameRequest req;
	req.client = client;
	req.timestamp = lastTimestamp;

	const uint64_t id = (uint64_t)client.get();

	std::lock_guard<std::mutex> lock(mFrameMutex);

	mTimelines[id]->BumpFenceEventCounter();
	UniqueFence fence = mTimelines[id]->CreateFence("FrameFence");

	mNextRequests->push_back(req);

	return fence.Dup();
	}


	Return<EvsResult> HalCamera::clientStreamStarting() {
	Return<EvsResult> result = EvsResult::OK;

	if (mStreamState == STOPPED) {
	mStreamState = RUNNING;
	result = mHwCamera->startVideoStream(this);
	}

	return result;
	}


	void HalCamera::clientStreamEnding(sp<VirtualCamera> client) {
	{
	std::lock_guard<std::mutex> lock(mFrameMutex);
	auto itReq = mNextRequests->begin();
	while (itReq != mNextRequests->end()) {
	if (itReq->client == client) {
	break;
	} else {
	++itReq;
	}
	}

	const uint64_t clientId = reinterpret_cast<const uint64_t>(client.get());
	if (itReq != mNextRequests->end()) {
	mNextRequests->erase(itReq);

	// Signal a pending fence and delete associated timeline.
	mTimelines[clientId]->BumpTimelineEventCounter();
	mTimelines.erase(clientId);
	}

	auto itCam = mClients.begin();
	while (itCam != mClients.end()) {
	if (itCam->promote() == client.get()) {
	break;
	} else {
	++itCam;
	}
	}

	if (itCam != mClients.end()) {
	// Remove a client, which requested to stop, from the list.
	mClients.erase(itCam);
	}
	}

	// Do we still have a running client?
	bool stillRunning = false;
	for (auto&& client : mClients) {
	sp<VirtualCamera> virtCam = client.promote();
	if (virtCam != nullptr) {
	stillRunning \|= virtCam->isStreaming();
	}
	}

	// If not, then stop the hardware stream
	if (!stillRunning) {
	mStreamState = STOPPING;
	mHwCamera->stopVideoStream();
	}
	}


	Return<void> HalCamera::doneWithFrame(const BufferDesc_1_0& buffer) {
	// Find this frame in our list of outstanding frames
	unsigned i;
	for (i = 0; i < mFrames.size(); i++) {
	if (mFrames[i].frameId == buffer.bufferId) {
	break;
	}
	}
	if (i == mFrames.size()) {
	LOG(ERROR) << "We got a frame back with an ID we don't recognize!";
	} else {
	// Are there still clients using this buffer?
	mFrames[i].refCount--;
	if (mFrames[i].refCount <= 0) {
	// Since all our clients are done with this buffer, return it to the device layer
	mHwCamera->doneWithFrame(buffer);
	}
	}

	return Void();
	}


	Return<void> HalCamera::doneWithFrame(const BufferDesc_1_1& buffer) {
	// Find this frame in our list of outstanding frames
	unsigned i;
	for (i = 0; i < mFrames.size(); i++) {
	if (mFrames[i].frameId == buffer.bufferId) {
	break;
	}
	}
	if (i == mFrames.size()) {
	LOG(ERROR) << "We got a frame back with an ID we don't recognize!";
	} else {
	// Are there still clients using this buffer?
	mFrames[i].refCount--;
	if (mFrames[i].refCount <= 0) {
	// Since all our clients are done with this buffer, return it to the device layer
	hardware::hidl_vec<BufferDesc_1_1> returnedBuffers;
	returnedBuffers.resize(1);
	returnedBuffers[0] = buffer;
	mHwCamera->doneWithFrame_1_1(returnedBuffers);
	}
	}

	return Void();
	}


	// Methods from ::android::hardware::automotive::evs::V1_0::IEvsCameraStream follow.
	Return<void> HalCamera::deliverFrame(const BufferDesc_1_0& buffer) {
	/* Frames are delivered via deliverFrame_1_1 callback for clients that implement
	* IEvsCameraStream v1.1 interfaces and therefore this method must not be
	* used.
	*/
	LOG(INFO) << "A delivered frame from EVS v1.0 HW module is rejected.";
	mHwCamera->doneWithFrame(buffer);

	return Void();
	}


	// Methods from ::android::hardware::automotive::evs::V1_1::IEvsCameraStream follow.
	Return<void> HalCamera::deliverFrame_1_1(const hardware::hidl_vec<BufferDesc_1_1>& buffer) {
	LOG(VERBOSE) << "Received a frame";
	// Frames are being forwarded to v1.1 clients only who requested new frame.
	const auto timestamp = buffer[0].timestamp;
	// TODO(b/145750636): For now, we are using a approximately half of 1 seconds / 30 frames = 33ms
	// but this must be derived from current framerate.
	constexpr int64_t kThreshold = 16 * 1e+3; // ms
	unsigned frameDeliveriesV1 = 0;
	{
	std::lock_guard<std::mutex> lock(mFrameMutex);
	std::swap(mCurrentRequests, mNextRequests);
	while (!mCurrentRequests->empty()) {
	auto req = mCurrentRequests->front(); mCurrentRequests->pop_front();
	sp<VirtualCamera> vCam = req.client.promote();
	if (vCam == nullptr) {
	// Ignore a client already dead.
	continue;
	} else if (timestamp - req.timestamp < kThreshold) {
	// Skip current frame because it arrives too soon.
	LOG(DEBUG) << "Skips a frame from " << getId();
	mNextRequests->push_back(req);
	} else if (vCam != nullptr && vCam->deliverFrame(buffer[0])) {
	// Forward a frame and move a timeline.
	LOG(DEBUG) << getId() << " forwarded the buffer #" << buffer[0].bufferId;
	mTimelines[(uint64_t)vCam.get()]->BumpTimelineEventCounter();
	++frameDeliveriesV1;
	}
	}
	}

	// Frames are being forwarded to v1.0 clients always.
	unsigned frameDeliveries = 0;
	for (auto&& client : mClients) {
	sp<VirtualCamera> vCam = client.promote();
	if (vCam == nullptr \|\| vCam->getVersion() > 0) {
	continue;
	}

	if (vCam->deliverFrame(buffer[0])) {
	++frameDeliveries;
	}
	}

	frameDeliveries += frameDeliveriesV1;
	if (frameDeliveries < 1) {
	// If none of our clients could accept the frame, then return it
	// right away.
	LOG(INFO) << "Trivially rejecting frame (" << buffer[0].bufferId
	<< ") from " << getId() << " with no acceptance";
	mHwCamera->doneWithFrame_1_1(buffer);
	} else {
	// Add an entry for this frame in our tracking list.
	unsigned i;
	for (i = 0; i < mFrames.size(); ++i) {
	if (mFrames[i].refCount == 0) {
	break;
	}
	}

	if (i == mFrames.size()) {
	mFrames.emplace_back(buffer[0].bufferId);
	} else {
	mFrames[i].frameId = buffer[0].bufferId;
	}
	mFrames[i].refCount = frameDeliveries;
	}

	return Void();
	}


	Return<void> HalCamera::notify(const EvsEventDesc& event) {
	LOG(DEBUG) << "Received an event id: " << static_cast<int32_t>(event.aType);
	if(event.aType == EvsEventType::STREAM_STOPPED) {
	// This event happens only when there is no more active client.
	if (mStreamState != STOPPING) {
	LOG(WARNING) << "Stream stopped unexpectedly";
	}

	mStreamState = STOPPED;
	}

	// Forward all other events to the clients
	for (auto&& client : mClients) {
	sp<VirtualCamera> vCam = client.promote();
	if (vCam != nullptr) {
	if (!vCam->notify(event)) {
	LOG(INFO) << "Failed to forward an event";
	}
	}
	}

	return Void();
	}


	Return<EvsResult> HalCamera::setMaster(sp<VirtualCamera> virtualCamera) {
	if (mMaster == nullptr) {
	LOG(DEBUG) << __FUNCTION__
	<< ": " << virtualCamera.get() << " becomes a master.";
	mMaster = virtualCamera;
	return EvsResult::OK;
	} else {
	LOG(INFO) << "This camera already has a master client.";
	return EvsResult::OWNERSHIP_LOST;
	}
	}


	Return<EvsResult> HalCamera::forceMaster(sp<VirtualCamera> virtualCamera) {
	sp<VirtualCamera> prevMaster = mMaster.promote();
	if (prevMaster == virtualCamera) {
	LOG(DEBUG) << "Client " << virtualCamera.get()
	<< " is already a master client";
	} else {
	mMaster = virtualCamera;
	if (prevMaster != nullptr) {
	LOG(INFO) << "High priority client " << virtualCamera.get()
	<< " steals a master role from " << prevMaster.get();

	/* Notify a previous master client the loss of a master role */
	EvsEventDesc event;
	event.aType = EvsEventType::MASTER_RELEASED;
	if (!prevMaster->notify(event)) {
	LOG(ERROR) << "Fail to deliver a master role lost notification";
	}
	}
	}

	return EvsResult::OK;
	}


	Return<EvsResult> HalCamera::unsetMaster(sp<VirtualCamera> virtualCamera) {
	if (mMaster.promote() != virtualCamera) {
	return EvsResult::INVALID_ARG;
	} else {
	LOG(INFO) << "Unset a master camera client";
	mMaster = nullptr;

	/* Notify other clients that a master role becomes available. */
	EvsEventDesc event;
	event.aType = EvsEventType::MASTER_RELEASED;
	auto cbResult = this->notify(event);
	if (!cbResult.isOk()) {
	LOG(ERROR) << "Fail to deliver a parameter change notification";
	}

	return EvsResult::OK;
	}
	}


	Return<EvsResult> HalCamera::setParameter(sp<VirtualCamera> virtualCamera,
	CameraParam id, int32_t& value) {
	EvsResult result = EvsResult::INVALID_ARG;
	if (virtualCamera == mMaster.promote()) {
	mHwCamera->setIntParameter(id, value,
	[&result, &value](auto status, auto readValue) {
	result = status;
	value = readValue[0];
	});

	if (result == EvsResult::OK) {
	/* Notify a parameter change */
	EvsEventDesc event;
	event.aType = EvsEventType::PARAMETER_CHANGED;
	event.payload[0] = static_cast<uint32_t>(id);
	event.payload[1] = static_cast<uint32_t>(value);
	auto cbResult = this->notify(event);
	if (!cbResult.isOk()) {
	LOG(ERROR) << "Fail to deliver a parameter change notification";
	}
	}
	} else {
	LOG(WARNING) << "A parameter change request from a non-master client is declined.";

	/* Read a current value of a requested camera parameter */
	getParameter(id, value);
	}

	return result;
	}


	Return<EvsResult> HalCamera::getParameter(CameraParam id, int32_t& value) {
	EvsResult result = EvsResult::OK;
	mHwCamera->getIntParameter(id, [&result, &value](auto status, auto readValue) {
	result = status;
	if (result == EvsResult::OK) {
	value = readValue[0];
	}
	});

	return result;
	}


	} // namespace implementation
	} // namespace V1_1
	} // namespace evs
	} // namespace automotive
	} // namespace android