第14讲 cameraserver进程启动之LogicalDeviceStatusChange详解 - And

本讲是Android Camera Native Framework专题的第14讲，我们介绍cameraserver进程启动之LogicalDeviceStatusChange。

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Process Cache Status Callbacks

本讲我们介绍Logical CameraDevice的Status Callback是逻辑。

cameraDeviceStatusChangeLocked

上述流程图来自Android 13：

status_t CameraProviderManager::ProviderInfo::cameraDeviceStatusChangeLocked(
        std::string* id, const std::string& cameraDeviceName,
        CameraDeviceStatus newStatus) {
    bool known = false;
    std::string cameraId;
    for (auto& deviceInfo : mDevices) {
        if (deviceInfo->mName == cameraDeviceName) {
            Mutex::Autolock l(deviceInfo->mDeviceAvailableLock);
            ALOGI("Camera device %s status is now %s, was %s", cameraDeviceName.c_str(),
                    FrameworkDeviceStatusToString(newStatus),
                    FrameworkDeviceStatusToString(deviceInfo->mStatus));
            deviceInfo->mStatus = newStatus;
            // TODO: Handle device removal (NOT_PRESENT)
            cameraId = deviceInfo->mId;
            known = true;
            deviceInfo->mIsDeviceAvailable =
                (newStatus == CameraDeviceStatus::PRESENT);
            deviceInfo->mDeviceAvailableSignal.signal();
            break;
        }
    }
    // Previously unseen device; status must not be NOT_PRESENT
    if (!known) {
        if (newStatus == CameraDeviceStatus::NOT_PRESENT) {
            ALOGW("Camera provider %s says an unknown camera device %s is not present. Curious.",
                mProviderName.c_str(), cameraDeviceName.c_str());
            return BAD_VALUE;
        }
        addDevice(cameraDeviceName, newStatus, &cameraId);
    } else if (newStatus == CameraDeviceStatus::NOT_PRESENT) {
        removeDevice(cameraId);
    } else if (isExternalLazyHAL()) {
        // Do not notify CameraService for PRESENT->PRESENT (lazy HAL restart)
        // because NOT_AVAILABLE is set on CameraService::connect and a PRESENT
        // notif. would overwrite it
        return BAD_VALUE;
    }

    if (reCacheConcurrentStreamingCameraIdsLocked() != OK) {
        ALOGE("%s: CameraProvider %s could not re-cache concurrent streaming camera id list ",
                  __FUNCTION__, mProviderName.c_str());
    }
    *id = cameraId;
    return OK;
}

Logical onCameraDeviceChanged

上述流程图来自Android 13：

void CameraService::onDeviceStatusChanged(const String8& id,
        CameraDeviceStatus newHalStatus) {
    ALOGI("%s: Status changed for cameraId=%s, newStatus=%d", __FUNCTION__,
            id.string(), newHalStatus);

    StatusInternal newStatus = mapToInternal(newHalStatus);

    std::shared_ptr state = getCameraState(id);

    if (state == nullptr) {
        if (newStatus == StatusInternal::PRESENT) {
            ALOGI("%s: Unknown camera ID %s, a new camera is added",
                    __FUNCTION__, id.string());

            // First add as absent to make sure clients are notified below
            addStates(id);

            updateStatus(newStatus, id);
        } else {
            ALOGE("%s: Bad camera ID %s", __FUNCTION__, id.string());
        }
        return;
    }

    StatusInternal oldStatus = state->getStatus();

    if (oldStatus == newStatus) {
        ALOGE("%s: State transition to the same status %#x not allowed", __FUNCTION__, newStatus);
        return;
    }

    if (newStatus == StatusInternal::NOT_PRESENT) {
        logDeviceRemoved(id, String8::format("Device status changed from %d to %d", oldStatus,
                newStatus));

        // Set the device status to NOT_PRESENT, clients will no longer be able to connect
        // to this device until the status changes
        updateStatus(StatusInternal::NOT_PRESENT, id);

        sp clientToDisconnectOnline, clientToDisconnectOffline;
        {
            // Don't do this in updateStatus to avoid deadlock over mServiceLock
            Mutex::Autolock lock(mServiceLock);

            // Remove cached shim parameters
            state->setShimParams(CameraParameters());

            // Remove online as well as offline client from the list of active clients,
            // if they are present
            clientToDisconnectOnline = removeClientLocked(id);
            clientToDisconnectOffline = removeClientLocked(kOfflineDevice + id);
        }

        disconnectClient(id, clientToDisconnectOnline);
        disconnectClient(kOfflineDevice + id, clientToDisconnectOffline);

        removeStates(id);
    } else {
        if (oldStatus == StatusInternal::NOT_PRESENT) {
            logDeviceAdded(id, String8::format("Device status changed from %d to %d", oldStatus,
                    newStatus));
        }
        updateStatus(newStatus, id);
    }
}

CameraService::updateStatus

上述流程图来自Android 13：

void CameraService::updateStatus(StatusInternal status, const String8& cameraId,
        std::initializer_list rejectSourceStates) {
    // Do not lock mServiceLock here or can get into a deadlock from
    // connect() -> disconnect -> updateStatus

    auto state = getCameraState(cameraId);

    if (state == nullptr) {
        ALOGW("%s: Could not update the status for %s, no such device exists", __FUNCTION__,
                cameraId.string());
        return;
    }

    // Avoid calling getSystemCameraKind() with mStatusListenerLock held (b/141756275)
    SystemCameraKind deviceKind = SystemCameraKind::PUBLIC;
    if (getSystemCameraKind(cameraId, &deviceKind) != OK) {
        ALOGE("%s: Invalid camera id %s, skipping", __FUNCTION__, cameraId.string());
        return;
    }

    // Collect the logical cameras without holding mStatusLock in updateStatus
    // as that can lead to a deadlock(b/162192331).
    auto logicalCameraIds = getLogicalCameras(cameraId);
    // Update the status for this camera state, then send the onStatusChangedCallbacks to each
    // of the listeners with both the mStatusLock and mStatusListenerLock held
    state->updateStatus(status, cameraId, rejectSourceStates, [this, &deviceKind,
                        &logicalCameraIds]
            (const String8& cameraId, StatusInternal status) {

            if (status != StatusInternal::ENUMERATING) {
                // Update torch status if it has a flash unit.
                Mutex::Autolock al(mTorchStatusMutex);
                TorchModeStatus torchStatus;
                if (getTorchStatusLocked(cameraId, &torchStatus) !=
                        NAME_NOT_FOUND) {
                    TorchModeStatus newTorchStatus =
                            status == StatusInternal::PRESENT ?
                            TorchModeStatus::AVAILABLE_OFF :
                            TorchModeStatus::NOT_AVAILABLE;
                    if (torchStatus != newTorchStatus) {
                        onTorchStatusChangedLocked(cameraId, newTorchStatus, deviceKind);
                    }
                }
            }

            Mutex::Autolock lock(mStatusListenerLock);
            notifyPhysicalCameraStatusLocked(mapToInterface(status), String16(cameraId),
                    logicalCameraIds, deviceKind);

            for (auto& listener : mListenerList) {
                bool isVendorListener = listener->isVendorListener();
                if (shouldSkipStatusUpdates(deviceKind, isVendorListener,
                        listener->getListenerPid(), listener->getListenerUid()) ||
                        isVendorListener) {
                    ALOGV("Skipping discovery callback for system-only camera device %s",
                            cameraId.c_str());
                    continue;
                }
                listener->getListener()->onStatusChanged(mapToInterface(status),
                        String16(cameraId));
            }
        });
}

CameraService::addStates

上述流程图来自Android 13：

void CameraService::addStates(const String8 id) {
    std::string cameraId(id.c_str());
    CameraResourceCost cost;
    status_t res = mCameraProviderManager->getResourceCost(cameraId, &cost);
    if (res != OK) {
        ALOGE("Failed to query device resource cost: %s (%d)", strerror(-res), res);
        return;
    }
    SystemCameraKind deviceKind = SystemCameraKind::PUBLIC;
    res = mCameraProviderManager->getSystemCameraKind(cameraId, &deviceKind);
    if (res != OK) {
        ALOGE("Failed to query device kind: %s (%d)", strerror(-res), res);
        return;
    }
    std::vector physicalCameraIds;
    mCameraProviderManager->isLogicalCamera(cameraId, &physicalCameraIds);
    std::set conflicting;
    for (size_t i = 0; i < cost.conflictingDevices.size(); i++) {
        conflicting.emplace(String8(cost.conflictingDevices[i].c_str()));
    }

    {
        Mutex::Autolock lock(mCameraStatesLock);
        mCameraStates.emplace(id, std::make_shared(id, cost.resourceCost,
                conflicting, deviceKind, physicalCameraIds));
    }

    if (mFlashlight->hasFlashUnit(id)) {
        Mutex::Autolock al(mTorchStatusMutex);
        mTorchStatusMap.add(id, TorchModeStatus::AVAILABLE_OFF);

        broadcastTorchModeStatus(id, TorchModeStatus::AVAILABLE_OFF, deviceKind);
    }

    updateCameraNumAndIds();
    logDeviceAdded(id, "Device added");
}

CameraService::removeStates

上述流程图来自Android 13：

void CameraService::removeStates(const String8 id) {
    updateCameraNumAndIds();
    if (mFlashlight->hasFlashUnit(id)) {
        Mutex::Autolock al(mTorchStatusMutex);
        mTorchStatusMap.removeItem(id);
    }

    {
        Mutex::Autolock lock(mCameraStatesLock);
        mCameraStates.erase(id);
    }
}

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