AudioFlinger service 所在进程
frameworks/av/media/audioserver
? ?audioserver git:(0111) ? tree
.
├── Android.mk
├── audioserver.rc
├── main_audioserver.cpp
└── OWNERS
int main(int argc __unused, char **argv)
{
? ? ? ? android::hardware::configureRpcThreadpool(4, false /*callerWillJoin*/);
? ? ? ? sp<ProcessState> proc(ProcessState::self());
? ? ? ? sp<IServiceManager> sm = defaultServiceManager();
? ? ? ? ALOGI("ServiceManager: %p", sm.get());
? ? ? ? AudioFlinger::instantiate();
? ? ? ? ALOGI("ServiceManager: AudioFlinger instantiate done %p", sm.get());
? ? ? ? AudioPolicyService::instantiate();
? ? ? ? ALOGI("ServiceManager: AudioPolicyService instantiate done %p", sm.get());
? ? ? ? instantiateVRAudioServer();
? ? ? ? ALOGI("ServiceManager: VRAudioServer instantiate done %p", sm.get());
? ? ? ? ALOGI("ServiceManager: done %p", sm.get());
? ? ? ? ProcessState::self()->startThreadPool();
? ? ? ? IPCThreadState::self()->joinThreadPool();
}
?
AudioFlinger::instantiate的实现和AudioPolicyService::instantiate类似，AudioFiliger初始化的过程主要是mDevicesFactoryHal的赋值
AudioFlinger::AudioFlinger()
? ? : BnAudioFlinger(),
? ? ? mMediaLogNotifier(new AudioFlinger::MediaLogNotifier()),
? ? ? mVibratorMsgHandler(NULL),
? ? ? mPrimaryHardwareDev(NULL),
? ? ? mAudioHwDevs(NULL),
? ? ? mHardwareStatus(AUDIO_HW_IDLE),
? ? ? mMasterVolume(1.0f),
? ? ? mMasterMute(false),
? ? ? // mNextUniqueId(AUDIO_UNIQUE_ID_USE_MAX),
? ? ? mMode(AUDIO_MODE_INVALID),
? ? ? mBtNrecIsOff(false),
? ? ? mIsLowRamDevice(true),
? ? ? mIsDeviceTypeKnown(false),
? ? ? mTotalMemory(0),
? ? ? mClientSharedHeapSize(kMinimumClientSharedHeapSizeBytes),
? ? ? mGlobalEffectEnableTime(0),
? ? ? mPatchPanel(this),
? ? ? mDeviceEffectManager(this),
? ? ? mSystemReady(false)
{
? ? mDevicesFactoryHal = DevicesFactoryHalInterface::create();
? ? std::vector<pid_t> halPids;
? ? mDevicesFactoryHal->getHalPids(&halPids);
}
void AudioFlinger::onFirstRef()
{
? ? mMode = AUDIO_MODE_NORMAL;
? ? gAudioFlinger = this;
? ? // mDeviceFactoryHal: callback
? ? mDevicesFactoryHalCallback = new DevicesFactoryHalCallbackImpl;
? ? mDevicesFactoryHal->setCallbackOnce(mDevicesFactoryHalCallback);
}
mDeviceFactoryHal的创建
mDeviceFactoryHal的数据类型?DevicesFactoryHalInterface
frameworks/av/media/libaudiohal/include/media/audiohal/DevicesFactoryHalInterface.h
class DevicesFactoryHalCallback : public RefBase
{
? public:
? ? virtual void onNewDevicesAvailable() = 0;
};
class DevicesFactoryHalInterface : public RefBase
{
? public:
? ? // Opens a device with the specified name. To close the device, it is
? ? // necessary to release references to the returned object.
? ? virtual status_t openDevice(const char *name, sp<DeviceHalInterface> *device) = 0;
? ? virtual status_t getHalPids(std::vector<pid_t> *pids) = 0;
? ? // Sets a DevicesFactoryHalCallback to notify the client.
? ? // The callback can be only set once.
? ? virtual status_t setCallbackOnce(sp<DevicesFactoryHalCallback> callback) = 0;
? ? static sp<DevicesFactoryHalInterface> create();
? // openDevice的得到的DeviceHalInterface,而create得到是 DevicesFactoryHalInterface,两者什么关系？
? protected:
? ? // Subclasses can not be constructed directly by clients.
? ? DevicesFactoryHalInterface() {}
? ? virtual ~DevicesFactoryHalInterface() {}
};
DevicesFactoryHalInterface static函数 create的实现
frameworks/av/media/libaudiohal/DevicesFactoryHalInterface.cpp
// static
sp<DevicesFactoryHalInterface> DevicesFactoryHalInterface::create() {
? ? return createPreferredImpl<DevicesFactoryHalInterface>(
? ? ? ? ? ? "android.hardware.audio", "IDevicesFactory");
}
create ->?createPreferredImpl
frameworks/av/media/libaudiohal/include/media/audiohal/FactoryHalHidl.h
namespace android {
namespace detail {
void* createPreferredImpl(const std::string& package, const std::string& interface);
} ?// namespace detail
/** @Return the preferred available implementation or nullptr if none are available. */
template <class Interface>
static sp<Interface> createPreferredImpl(const std::string& package, const std::string& interface) {
? ? return sp<Interface>{static_cast<Interface*>(detail::createPreferredImpl(package, interface))};
}
} // namespace android
createPreferredImpl 遍历 package:?android.hardware.audio的各个版本，寻找接口IDevicesFactory， 找到后就创建HalService:
frameworks/av/media/libaudiohal/FactoryHalHidl.cpp
void* createPreferredImpl(const std::string& package, const std::string& interface) {
? ? for (auto version = detail::sAudioHALVersions; version != nullptr; ++version) {
? ? ? ? void* rawInterface = nullptr;
? ? ? ? if (hasHalService(package, *version, interface)
? ? ? ? ? ? ? ? && createHalService(*version, interface, &rawInterface)) {
? ? ? ? ? ? return rawInterface;
? ? ? ? }
? ? }
? ? return nullptr;
}
const char* sAudioHALVersions[] = {
? ? "6.0",
? ? "5.0",
? ? "4.0",
? ? "2.0",
? ? nullptr
};
bool createHalService(const std::string& version, const std::string& interface,
? ? ? ? void** rawInterface) {
? ? const std::string libName = "libaudiohal@" + version + ".so";
? ? const std::string factoryFunctionName = "create" + interface;
? ? constexpr int dlMode = RTLD_LAZY;
? ? void* handle = nullptr;
? ? dlerror(); // clear
? ? handle = dlopen(libName.c_str(), dlMode); // libName = "libaudiohal@6.0.so"
? ? void* (*factoryFunction)();? ? ? ?// 函数 createIDevicesFactory
? ? *(void **)(&factoryFunction) = dlsym(handle, factoryFunctionName.c_str());
? ? *rawInterface = (*factoryFunction)();
? ? ALOGW_IF(!*rawInterface, "Factory function %s from %s returned nullptr",
? ? ? ? ? ? factoryFunctionName.c_str(), libName.c_str());
? ? return true;
}
createIDevicesFactory函数的实现在哪里
frameworks/av/media/libaudiohal/impl/Android.bp
cc_library_shared {
? ? name: "libaudiohal@6.0",
? ? defaults: ["libaudiohal_default"],
? ? shared_libs: [
? ? ? ? "android.hardware.audio.common@6.0",
? ? ? ? "android.hardware.audio.common@6.0-util",
? ? ? ? "android.hardware.audio.effect@6.0",
? ? ? ? "android.hardware.audio@6.0",
? ? ],
}
frameworks/av/media/libaudiohal/impl/DevicesFactoryHalHybrid.cpp
extern "C" __attribute__((visibility("default"))) void* createIDevicesFactory() {
? ? auto service = hardware::audio::CPP_VERSION::IDevicesFactory::getService();
? ? return service ? new CPP_VERSION::DevicesFactoryHalHybrid(service) : nullptr;
}
hardware::audio::CPP_VERSION::IDevicesFactory::getService
这里的getService是获得HIDL service, getService是个基类的接口
hardware/interfaces/audio/core/all-versions/vts/functional/DeviceManager.h
static sp<IDevicesFactory> createInterfaceInstance(const std::string& name) {
? ? ? ? return IDevicesFactory::getService(name);
}
hardware/interfaces/audio/core/all-versions/default/DevicesFactory.cpp
namespace android {
namespace hardware {
namespace audio {
namespace CPP_VERSION {? //从这里的命名空间也可以知道getService的实现在这里
namespace implementation {
} ?// namespace implementation
} ?// namespace CPP_VERSION
} ?// namespace audio
} ?// namespace hardware
} ?// namespace android
new CPP_VERSION::DevicesFactoryHalHybrid(service)
获得HIDL? service的代理 IDeviceFactory 后 创建DevicesFactoryHalHybrid
Hybrid是混合的意思，封装了 local/ hidl的两种实现方法，用户不用关心
DevicesFactoryHalHybrid继承通用接口DeviceFactoryHalInterfaces是DeviceFactoryHalInterface的一个实现，但其中没有 static create();?
frameworks/av/media/libaudiohal/impl/DevicesFactoryHalHybrid.h
using ::android::hardware::audio::CPP_VERSION::IDevicesFactory;
namespace android {
namespace CPP_VERSION {
class DevicesFactoryHalHybrid : public DevicesFactoryHalInterface
{
? public:
? ? DevicesFactoryHalHybrid(sp<IDevicesFactory> hidlFactory);
? ? // Opens a device with the specified name. To close the device, it is
? ? // necessary to release references to the returned object.
? ? virtual status_t openDevice(const char *name, sp<DeviceHalInterface> *device);
? ? ? ? ? ? status_t getHalPids(std::vector<pid_t> *pids) override;
? ? ? ? ? ? status_t setCallbackOnce(sp<DevicesFactoryHalCallback> callback) override;
? private:
? ? sp<DevicesFactoryHalInterface> mLocalFactory;
? ? sp<DevicesFactoryHalInterface> mHidlFactory;
};
} // namespace CPP_VERSION
} // namespace android
DevicesFactoryHalHybrid构造函数赋值了成员变量
DevicesFactoryHalHybrid::DevicesFactoryHalHybrid(sp<IDevicesFactory> hidlFactory)
? ? ? ? : mLocalFactory(new DevicesFactoryHalLocal()),
? ? ? ? ? mHidlFactory(new DevicesFactoryHalHidl(hidlFactory)) {
}
Local:
Local的意思是没有使用HIDL service， 直接local? 加载HAL的so
构造函数并没有什么
DevicesFactoryHalLocal() {}
HidlFactory:
DevicesFactoryHalHidl::DevicesFactoryHalHidl(sp<IDevicesFactory> devicesFactory) {
? ? ALOG_ASSERT(devicesFactory != nullptr, "Provided default IDevicesFactory service is NULL");
? ? addDeviceFactory(devicesFactory, false /*needToNotify*/);
}
void DevicesFactoryHalHidl::addDeviceFactory(sp<IDevicesFactory> factory, bool needToNotify) {
? ? // It is assumed that the DevicesFactoryHalInterface instance is owned
? ? // by AudioFlinger and thus have the same lifespan.
? ? factory->linkToDeath(HalDeathHandler::getInstance(), 0 /*cookie*/);
? ? sp<DevicesFactoryHalCallback> callback;
? ? {
? ? ? ? std::lock_guard<std::mutex> lock(mLock);
? ? ? ? mDeviceFactories.push_back(factory);
? ? ? ? if (needToNotify) {
? ? ? ? ? ? callback = mCallback.promote();
? ? ? ? ? ? if (!callback) {
? ? ? ? ? ? ? ? mHaveUndeliveredNotifications = true;
? ? ? ? ? ? }
? ? ? ? }
? ? }
? ? if (callback) {
? ? ? ? callback->onNewDevicesAvailable();
? ? }
}
从openDevice的实现可以看出Hybrid的意义所在
status_t DevicesFactoryHalHybrid::openDevice(const char *name, sp<DeviceHalInterface> *device) {
? ? if (mHidlFactory != 0 && strcmp(AUDIO_HARDWARE_MODULE_ID_A2DP, name) != 0 &&
? ? ? ? strcmp(AUDIO_HARDWARE_MODULE_ID_HEARING_AID, name) != 0) {
? ? ? ? return mHidlFactory->openDevice(name, device);
? ? }
? ? return mLocalFactory->openDevice(name, device);
}
总结
mDevicesFactoryHal 是访问Device HAL的接口,?mHidlFactory 还是mLocalFactory 是内部使用的成员变量 不用关心。AudioFlinger? service的初始化主要是和HAL、 HAL service的关联，得到访问 HAL device的接口mDeviceFactortyHAL