1.服务注册的路径
./frameworks/av/camera/cameraserver/main_cameraserver.cpp
#define LOG_TAG "cameraserver"
//#define LOG_NDEBUG 0
// from LOCAL_C_INCLUDES
#include "CameraService.h"
using namespace android;
int main(int argc __unused, char** argv __unused)
{
signal(SIGPIPE, SIG_IGN);
sp<ProcessState> proc(ProcessState::self());
sp<IServiceManager> sm = defaultServiceManager();
ALOGI("ServiceManager: %p", sm.get());
CameraService::instantiate();
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
}//下面分析CameraService::instantiate();
在frameworks/av/services/camera/libcameraservice/CameraService.cpp中没有找到instantiate函数，因此我们在他们的父类看一下有没有这个方法。
先列一下CameraService 的继承类
class CameraService :
public BinderService<CameraService>,
public ::android::hardware::BnCameraService,
public IBinder::DeathRecipient,
public camera_module_callbacks_t
果不其然，我们在./frameworks/native/include/binder/BinderService.h中发现了instantiate的踪影。
template<typename SERVICE>
class BinderService
{
public:
static status_t publish(bool allowIsolated = false) {
sp<IServiceManager> sm(defaultServiceManager());
return sm->addService(
String16(SERVICE::getServiceName()),
new SERVICE(), allowIsolated);
}
static void publishAndJoinThreadPool(bool allowIsolated = false) {
publish(allowIsolated);
joinThreadPool();
}
static void instantiate() { publish(); }
static status_t shutdown() { return NO_ERROR; }
private:
static void joinThreadPool() {
sp<ProcessState> ps(ProcessState::self());
ps->startThreadPool();
ps->giveThreadPoolName();
IPCThreadState::self()->joinThreadPool();
}
};static char const* getServiceName() { return "media.camera"; }CameraService::instantiate();static status_t publish(bool allowIsolated = false) {
sp<IServiceManager> sm(defaultServiceManager());
return sm->addService("media.camera", new CameraService(), allowIsolated);
}//注意这里等价做了两件事情
1.先new CameraService ，调用构造函数初始化对象
2.调用addService函数将它注册到SM中
frameworks/av/services/camera/libcameraservice/CameraService.cpp
static CameraService *gCameraService;
CameraService::CameraService() :
mEventLog(DEFAULT_EVENT_LOG_LENGTH),
mNumberOfCameras(0), mNumberOfNormalCameras(0),
mSoundRef(0), mModule(nullptr) {
ALOGI("CameraService started (pid=%d)", getpid());
gCameraService = this;
this->camera_device_status_change = android::camera_device_status_change;
this->torch_mode_status_change = android::torch_mode_status_change;
mServiceLockWrapper = std::make_shared<WaitableMutexWrapper>(&mServiceLock);
}1.实际binder通信的onTransact函数实现位于ICameraService.cpp
BnCameraService::onTransact(uint32_t _aidl_code, const ::android::Parcel& _aidl_data, ::android::Parcel* _aidl_reply, uint32_t _aidl_flags)
的代码路径为：
./out/target/product/msm8953_64/obj/SHARED_LIBRARIES/libcamera_client_intermediates/aidl-generated/src/aidl/android/hardware/ICameraService.cpp
2. CameraService::onFirstRef()函数的调用时机(这里才是camera的服务的开始)
参考网址：https://blog.csdn.net/bob_fly1984/article/details/77150263
在这个incStrong函数中，主要做了三件事情：
一是增加弱引用计数
二是增加强引用计数
三是如果发现是首次调用这个对象的incStrong函数，就会调用一个这个对象的onFirstRef函数，让对象有机会在对象被首次引用时做一些处理逻辑
//代码路径：frameworks/native/libs/binder/Binder.cpp
BpRefBase::BpRefBase(const sp<IBinder>& o) : mRemote(o.get()), mRefs(NULL), mState(0)//o.get()，这个是sp类的获取实际数据指针的一个方法，你只要知道它返回的是 sp<xxxx> 中 xxx* 指针就行
{
extendObjectLifetime(OBJECT_LIFETIME_WEAK);
if (mRemote) // mRemote 就是刚才的 BpBinder(0)
{
mRemote->incStrong(this); // Removed on first IncStrong(). //这个时候会去调用 onFirstRef函数
mRefs = mRemote->createWeak(this); // Held for our entire lifetime.
}
}
相应的CameraService实例里面onFirstRef（）函数完成调用
下面是CameraService::onFirstRef()的部分解析
void CameraService::onFirstRef()
{
ALOGE("CameraService process starting");
BnCameraService::onFirstRef();
// Update battery life tracking if service is restarting
BatteryNotifier& notifier(BatteryNotifier::getInstance());
notifier.noteResetCamera();
notifier.noteResetFlashlight();
//1.jni 层获取 HAL 层的接口信息
camera_module_t *rawModule;
int err = hw_get_module(CAMERA_HARDWARE_MODULE_ID,(const hw_module_t **)&rawModule);
if (err < 0)
{
ALOGE("Could not load camera HAL module: %d (%s)", err, strerror(-err));
logServiceError("Could not load camera HAL module", err);
return;
}
//2.创建一个 CameraModule 类。构造函数中将 hw_get_module 得到的 HAL_MODULE_INFO_SYM 传入到 CameraModule 中的 mModule
// 初始化 mModule 调用 int CameraModule::init()
mModule = new CameraModule(rawModule);
err = mModule->init();
if (err != OK)
{
ALOGE("Could not initialize camera HAL module: %d (%s)", err, strerror(-err));
logServiceError("Could not initialize camera HAL module", err);
delete mModule;
mModule = nullptr;
return;
}
ALOGI("Loaded \"%s\" camera module", mModule->getModuleName());
//3.获取已经probe成功的camera的数量
mNumberOfCameras = mModule->getNumberOfCameras();
mNumberOfNormalCameras = mNumberOfCameras;
// Setup vendor tags before we call get_camera_info the first time because HAL might need to setup static vendor keys in get_camera_info
VendorTagDescriptor::clearGlobalVendorTagDescriptor();
if (mModule->getModuleApiVersion() >= CAMERA_MODULE_API_VERSION_2_2)
{
setUpVendorTags();
}
mFlashlight = new CameraFlashlight(*mModule, *this);
status_t res = mFlashlight->findFlashUnits();
if (res) {
// impossible because we haven't open any camera devices.
ALOGE("Failed to find flash units.");
}
int latestStrangeCameraId = INT_MAX;
for (int i = 0; i < mNumberOfCameras; i++)
{
String8 cameraId = String8::format("%d", i);
// Get camera info
struct camera_info info;
bool haveInfo = true;
//4.根据camera ID 去 得到camera的相关信息
status_t rc = mModule->getCameraInfo(i, &info);
if (rc != NO_ERROR) {
ALOGE("%s: Received error loading camera info for device %d, cost and"
" conflicting devices fields set to defaults for this device.",
__FUNCTION__, i);
haveInfo = false;
}
// Check for backwards-compatibility support
if (haveInfo)
{
if (checkCameraCapabilities(i, info, &latestStrangeCameraId) != OK) {
delete mModule;
mModule = nullptr;
return;
}
}
// Defaults to use for cost and conflicting devices
int cost = 100;
char** conflicting_devices = nullptr;
size_t conflicting_devices_length = 0;
// If using post-2.4 module version, query the cost + conflicting devices from the HAL
if (mModule->getModuleApiVersion() >= CAMERA_MODULE_API_VERSION_2_4 && haveInfo)
{
cost = info.resource_cost;
conflicting_devices = info.conflicting_devices;
conflicting_devices_length = info.conflicting_devices_length;
}
std::set<String8> conflicting;
for (size_t i = 0; i < conflicting_devices_length; i++)
{
conflicting.emplace(String8(conflicting_devices[i]));
}
// Initialize state for each camera device
{
Mutex::Autolock lock(mCameraStatesLock);
mCameraStates.emplace(cameraId, std::make_shared<CameraState>(cameraId, cost, conflicting));
}
if (mFlashlight->hasFlashUnit(cameraId))
{
mTorchStatusMap.add(cameraId, ICameraServiceListener::TORCH_STATUS_AVAILABLE_OFF);
}
}
if (mModule->getModuleApiVersion() >= CAMERA_MODULE_API_VERSION_2_1)
{
//5.设置回调函数
mModule->setCallbacks(this);
}
CameraService::pingCameraServiceProxy();
}/* 1.jni 层获取 HAL 层的接口信息
代码路径：hardware/qcom/camera/QCamera2/QCamera2Hal.cpp
hw_get_module(CAMERA_HARDWARE_MODULE_ID,(const hw_module_t **)&rawModule);
hw_get_module 是 jni 层获取 HAL 层 module 的接口函数
https://blog.csdn.net/computertechnology/article/details/17006107
*/
static hw_module_t camera_common = {
.tag = HARDWARE_MODULE_TAG,
.module_api_version = CAMERA_MODULE_API_VERSION_2_4,
.hal_api_version = HARDWARE_HAL_API_VERSION,
.id = CAMERA_HARDWARE_MODULE_ID,
.name = "QCamera Module",
.author = "Qualcomm Innovation Center Inc",
.methods = &qcamera::QCamera2Factory::mModuleMethods,
.dso = NULL,
.reserved = {0}
};
camera_module_t HAL_MODULE_INFO_SYM = {
.common = camera_common,
.get_number_of_cameras = qcamera::QCamera2Factory::get_number_of_cameras,
.get_camera_info = qcamera::QCamera2Factory::get_camera_info,
.set_callbacks = qcamera::QCamera2Factory::set_callbacks,
.get_vendor_tag_ops = qcamera::QCamera3VendorTags::get_vendor_tag_ops,
.open_legacy = qcamera::QCamera2Factory::open_legacy,
.set_torch_mode = qcamera::QCamera2Factory::set_torch_mode,
.init = NULL,
.reserved = {0}
};
/*
2.创建一个 CameraModule 类。构造函数中将 hw_get_module 得到的 HAL_MODULE_INFO_SYM 传入到 CameraModule 中的 mModule
代码路径：frameworks/av/services/camera/libcameraservice/common/CameraModule.cpp
创建一个 CameraModule 类。构造函数中将 hw_get_module 得到的 HAL_MODULE_INFO_SYM 传入到 CameraModule 中的 mModule
mModule = new CameraModule(rawModule); //camera_module_t *rawModule;
*/
CameraModule::CameraModule(camera_module_t *module)
{
if (module == NULL)
{
ALOGE("%s: camera hardware module must not be null", __FUNCTION__);
assert(0);
}
mModule = module;
}
int CameraModule::init()
{
ATRACE_CALL();
int res = OK;
if (getModuleApiVersion() >= CAMERA_MODULE_API_VERSION_2_4 && mModule->init != NULL)
{
ATRACE_BEGIN("camera_module->init");
res = mModule->init();//init = NULL 所以这个时候没有init的操作
ATRACE_END();
}
mCameraInfoMap.setCapacity(getNumberOfCameras());//这里获取的是整个的camera的数量
//https://blog.csdn.net/JIEJINQUANIL/article/details/51166154
return res;
}
/*
3.获取已经probe成功的camera的数量
代码路径：frameworks/av/services/camera/libcameraservice/common/CameraModule.cpp
hardware/qcom/camera/QCamera2/QCamera2Factory.cpp
*/
int CameraModule::getNumberOfCameras() {
int numCameras;
ATRACE_BEGIN("camera_module->get_number_of_cameras");
numCameras = mModule->get_number_of_cameras();
//这里的mModule 是来自hardware/qcom/camera/QCamera2/QCamera2Hal.cpp
ATRACE_END();
return numCameras;
}
int QCamera2Factory::get_number_of_cameras()
{
int numCameras = 0;
if (!gQCamera2Factory) {
gQCamera2Factory = new QCamera2Factory();//首先构造函数会去执行获取 mNumOfCameras
if (!gQCamera2Factory) {
LOGE("Failed to allocate Camera2Factory object");
return 0;
}
}
#ifdef QCAMERA_HAL1_SUPPORT
if(gQCameraMuxer)
numCameras = gQCameraMuxer->get_number_of_cameras();
else
#endif
numCameras = gQCamera2Factory->getNumberOfCameras();
// camera数量实际是在QCamera2Factory 的初始化中 去 确定 mNumOfCameras
// gQCamera2Factory = new QCamera2Factory();
// QCamera2Factory::QCamera2Factory();
LOGH("num of cameras: %d", numCameras);
return numCameras;
}
/*
//4.根据camera ID 去 得到camera的相关信息
代码路径：frameworks/av/services/camera/libcameraservice/common/CameraModule.cpp
*/
int CameraModule::getCameraInfo(int cameraId, struct camera_info *info)
{
ATRACE_CALL();
Mutex::Autolock lock(mCameraInfoLock);
if (cameraId < 0) {
ALOGE("%s: Invalid camera ID %d", __FUNCTION__, cameraId);
return -EINVAL;
}
// Only override static_camera_characteristics for API2 devices
int apiVersion = mModule->common.module_api_version; //8953 的是 CAMERA_MODULE_API_VERSION_2_4
if (apiVersion < CAMERA_MODULE_API_VERSION_2_0)
{
int ret;
ATRACE_BEGIN("camera_module->get_camera_info");
ret = mModule->get_camera_info(cameraId, info);
// Fill in this so CameraService won't be confused by
// possibly 0 device_version
info->device_version = CAMERA_DEVICE_API_VERSION_1_0;
ATRACE_END();
return ret;
}
ssize_t index = mCameraInfoMap.indexOfKey(cameraId);
if (index == NAME_NOT_FOUND)
{
// Get camera info from raw module and cache it
camera_info rawInfo, cameraInfo;
ATRACE_BEGIN("camera_module->get_camera_info");
//通过这里调用hardware/qcom/camera/QCamera2/QCamera2Factory.cpp
int ret = mModule->get_camera_info(cameraId, &rawInfo);
ATRACE_END();
if (ret != 0) {
return ret;
}
int deviceVersion = rawInfo.device_version;
if (deviceVersion < CAMERA_DEVICE_API_VERSION_3_0)
{
// static_camera_characteristics is invalid
*info = rawInfo;
return ret;
}
CameraMetadata m;
m = rawInfo.static_camera_characteristics;
deriveCameraCharacteristicsKeys(rawInfo.device_version, m);
cameraInfo = rawInfo;
cameraInfo.static_camera_characteristics = m.release();
index = mCameraInfoMap.add(cameraId, cameraInfo);
}
assert(index != NAME_NOT_FOUND);
// return the cached camera info
*info = mCameraInfoMap[index];
return OK;
}
int QCamera2Factory::get_camera_info(int camera_id, struct camera_info *info)
{
int rc = NO_ERROR;
#ifdef QCAMERA_HAL1_SUPPORT
if(gQCameraMuxer)
rc = gQCameraMuxer->get_camera_info(camera_id, info);
else
#endif
rc = gQCamera2Factory->getCameraInfo(camera_id, info);
return rc;
}
//这里会根据ID 判断为 USBCamera 还是MIPI camera 来选择不同的实现方式。
int QCamera2Factory::getCameraInfo(int camera_id, struct camera_info *info)
{
int rc;
ALOGI("getCameraInfo camera_id==%d",camera_id);
if(camera_id >= mNumOfCSICamera) {
return usbcam_get_camera_info(camera_id, info);
}
if (!mNumOfCameras || camera_id >= mNumOfCameras || !info || (camera_id < 0))
{
LOGE("Error getting camera info!! mNumOfCameras = %d," "camera_id = %d, info = %p", mNumOfCameras, camera_id, info);
return -ENODEV;
}
if ( NULL == mHalDescriptors )
{
LOGE("Hal descriptor table is not initialized!");
return NO_INIT;
}
LOGI("Camera id %d API version %d", amera_id, mHalDescriptors[camera_id].device_version);
// Need ANDROID_FLASH_INFO_AVAILABLE property for flashlight widget to
// work and so get the static data regardless of HAL version
rc = QCamera3HardwareInterface::getCamInfo( mHalDescriptors[camera_id].cameraId, info);
if (mHalDescriptors[camera_id].device_version == CAMERA_DEVICE_API_VERSION_1_0)
{
info->device_version = CAMERA_DEVICE_API_VERSION_1_0;
}
return rc;
}
/*
//5.设置回调函数
代码路径：frameworks/av/services/camera/libcameraservice/CameraService.h
class CameraService : public BinderService<CameraService>, public ::android::hardware::BnCameraService, public IBinder::DeathRecipient, public camera_module_callbacks_t
hardware/qcom/camera/QCamera2/QCamera2Factory.cpp
hardware/qcom/camera/QCamera2/util/QCameraFlash.cpp
*/
CameraService::CameraService() : mEventLog(DEFAULT_EVENT_LOG_LENGTH), mNumberOfCameras(0), mNumberOfNormalCameras(0), mSoundRef(0), mModule(nullptr)
{
ALOGI("CameraService started (pid=%d)", getpid());
gCameraService = this;
//这里填充的是mModule->setCallbacks(this); 的callbacks
this->camera_device_status_change = android::camera_device_status_change;
this->torch_mode_status_change = android::torch_mode_status_change;
mServiceLockWrapper = std::make_shared<WaitableMutexWrapper>(&mServiceLock);
}参考文档：
1. Android 5.1 Camera 架构学习（一）——Camera初始化
https://blog.csdn.net/u012248972/article/details/50763441
2.Android系统进程间通信（IPC）机制Binder中的Server启动过程源代码分析
https://blog.csdn.net/u012248972/article/details/50763441