services/inputflinger/InputClassifier.cpp

/*
 * 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.
 */

#define LOG_TAG "InputClassifier"

#include "InputClassifier.h"
#include "InputCommonConverter.h"

#include <android-base/stringprintf.h>
#include <android/binder_manager.h>
#include <android/binder_process.h>
#include <inttypes.h>
#include <log/log.h>
#include <algorithm>
#include <cmath>
#if defined(__linux__)
    #include <pthread.h>
#endif
#include <unordered_set>

#define INDENT1 "  "
#define INDENT2 "    "
#define INDENT3 "      "
#define INDENT4 "        "
#define INDENT5 "          "

using android::base::StringPrintf;
using namespace std::chrono_literals;
using namespace ::aidl::android::hardware::input;
using aidl::android::hardware::input::processor::IInputProcessor;

namespace android {

//Max number of elements to store in mEvents.
static constexpr size_t MAX_EVENTS = 5;

template<class K, class V>
static V getValueForKey(const std::unordered_map<K, V>& map, K key, V defaultValue) {
    auto it = map.find(key);
    if (it == map.end()) {
        return defaultValue;
    }
    return it->second;
}

static MotionClassification getMotionClassification(common::Classification classification) {
    static_assert(MotionClassification::NONE ==
                  static_cast<MotionClassification>(common::Classification::NONE));
    static_assert(MotionClassification::AMBIGUOUS_GESTURE ==
                  static_cast<MotionClassification>(common::Classification::AMBIGUOUS_GESTURE));
    static_assert(MotionClassification::DEEP_PRESS ==
                  static_cast<MotionClassification>(common::Classification::DEEP_PRESS));
    return static_cast<MotionClassification>(classification);
}

static bool isTouchEvent(const NotifyMotionArgs& args) {
    return isFromSource(args.source, AINPUT_SOURCE_TOUCHPAD) ||
            isFromSource(args.source, AINPUT_SOURCE_TOUCHSCREEN);
}

static void setCurrentThreadName(const char* name) {
#if defined(__linux__)
    // Set the thread name for debugging
    pthread_setname_np(pthread_self(), name);
#else
    (void*)(name); // prevent unused variable warning
#endif
}

static std::shared_ptr<IInputProcessor> getService() {
    const std::string aidl_instance_name = std::string(IInputProcessor::descriptor) + "/default";

    if (!AServiceManager_isDeclared(aidl_instance_name.c_str())) {
        ALOGI("HAL %s is not declared", aidl_instance_name.c_str());
        return nullptr;
    }

    ndk::SpAIBinder binder(AServiceManager_waitForService(aidl_instance_name.c_str()));
    return IInputProcessor::fromBinder(binder);
}

// Temporarily releases a held mutex for the lifetime of the instance.
// Named to match std::scoped_lock
class scoped_unlock {
public:
    explicit scoped_unlock(std::mutex& mutex) : mMutex(mutex) { mMutex.unlock(); }
    ~scoped_unlock() { mMutex.lock(); }

private:
    std::mutex& mMutex;
};

// --- ScopedDeathRecipient ---
ScopedDeathRecipient::ScopedDeathRecipient(AIBinder_DeathRecipient_onBinderDied onBinderDied,
                                           void* cookie)
      : mCookie(cookie) {
    mRecipient = AIBinder_DeathRecipient_new(onBinderDied);
}

void ScopedDeathRecipient::linkToDeath(AIBinder* binder) {
    binder_status_t linked = AIBinder_linkToDeath(binder, mRecipient, mCookie);
    if (linked != STATUS_OK) {
        ALOGE("Could not link death recipient to the HAL death");
    }
}

ScopedDeathRecipient::~ScopedDeathRecipient() {
    AIBinder_DeathRecipient_delete(mRecipient);
}

// --- ClassifierEvent ---

ClassifierEvent::ClassifierEvent(std::unique_ptr<NotifyMotionArgs> args) :
        type(ClassifierEventType::MOTION), args(std::move(args)) { };
ClassifierEvent::ClassifierEvent(std::unique_ptr<NotifyDeviceResetArgs> args) :
        type(ClassifierEventType::DEVICE_RESET), args(std::move(args)) { };
ClassifierEvent::ClassifierEvent(ClassifierEventType type, std::unique_ptr<NotifyArgs> args) :
        type(type), args(std::move(args)) { };

ClassifierEvent::ClassifierEvent(ClassifierEvent&& other) :
        type(other.type), args(std::move(other.args)) { };

ClassifierEvent& ClassifierEvent::operator=(ClassifierEvent&& other) {
    type = other.type;
    args = std::move(other.args);
    return *this;
}

ClassifierEvent ClassifierEvent::createHalResetEvent() {
    return ClassifierEvent(ClassifierEventType::HAL_RESET, nullptr);
}

ClassifierEvent ClassifierEvent::createExitEvent() {
    return ClassifierEvent(ClassifierEventType::EXIT, nullptr);
}

std::optional<int32_t> ClassifierEvent::getDeviceId() const {
    switch (type) {
        case ClassifierEventType::MOTION: {
            NotifyMotionArgs* motionArgs = static_cast<NotifyMotionArgs*>(args.get());
            return motionArgs->deviceId;
        }
        case ClassifierEventType::DEVICE_RESET: {
            NotifyDeviceResetArgs* deviceResetArgs =
                    static_cast<NotifyDeviceResetArgs*>(args.get());
            return deviceResetArgs->deviceId;
        }
        case ClassifierEventType::HAL_RESET: {
            return std::nullopt;
        }
        case ClassifierEventType::EXIT: {
            return std::nullopt;
        }
    }
}

// --- MotionClassifier ---

MotionClassifier::MotionClassifier(std::shared_ptr<IInputProcessor> service)
      : mEvents(MAX_EVENTS), mService(std::move(service)) {
    // Under normal operation, we do not need to reset the HAL here. But in the case where system
    // crashed, but HAL didn't, we may be connecting to an existing HAL process that might already
    // have received events in the past. That means, that HAL could be in an inconsistent state
    // once it receives events from the newly created MotionClassifier.
    mEvents.push(ClassifierEvent::createHalResetEvent());

    mHalThread = std::thread(&MotionClassifier::processEvents, this);
#if defined(__linux__)
    // Set the thread name for debugging
    pthread_setname_np(mHalThread.native_handle(), "InputClassifier");
#endif
}

std::unique_ptr<MotionClassifierInterface> MotionClassifier::create(
        std::shared_ptr<IInputProcessor> service) {
    LOG_ALWAYS_FATAL_IF(service == nullptr);
    // Using 'new' to access a non-public constructor
    return std::unique_ptr<MotionClassifier>(new MotionClassifier(std::move(service)));
}

MotionClassifier::~MotionClassifier() {
    requestExit();
    mHalThread.join();
}

/**
 * Obtain the classification from the HAL for a given MotionEvent.
 * Should only be called from the InputClassifier thread (mHalThread).
 * Should not be called from the thread that notifyMotion runs on.
 *
 * There is no way to provide a timeout for a HAL call. So if the HAL takes too long
 * to return a classification, this would directly impact the touch latency.
 * To remove any possibility of negatively affecting the touch latency, the HAL
 * is called from a dedicated thread.
 */
void MotionClassifier::processEvents() {
    while (true) {
        ClassifierEvent event = mEvents.pop();
        bool halResponseOk = true;
        switch (event.type) {
            case ClassifierEventType::MOTION: {
                NotifyMotionArgs* motionArgs = static_cast<NotifyMotionArgs*>(event.args.get());
                common::MotionEvent motionEvent = notifyMotionArgsToHalMotionEvent(*motionArgs);
                common::Classification classification;
                ndk::ScopedAStatus response = mService->classify(motionEvent, &classification);
                if (response.isOk()) {
                    updateClassification(motionArgs->deviceId, motionArgs->eventTime,
                                         getMotionClassification(classification));
                }
                break;
            }
            case ClassifierEventType::DEVICE_RESET: {
                const int32_t deviceId = *(event.getDeviceId());
                halResponseOk = mService->resetDevice(deviceId).isOk();
                clearDeviceState(deviceId);
                break;
            }
            case ClassifierEventType::HAL_RESET: {
                halResponseOk = mService->reset().isOk();
                clearClassifications();
                break;
            }
            case ClassifierEventType::EXIT: {
                clearClassifications();
                return;
            }
        }
        if (!halResponseOk) {
            ALOGE("Error communicating with InputClassifier HAL. "
                    "Exiting MotionClassifier HAL thread");
            clearClassifications();
            return;
        }
    }
}

void MotionClassifier::enqueueEvent(ClassifierEvent&& event) {
    bool eventAdded = mEvents.push(std::move(event));
    if (!eventAdded) {
        // If the queue is full, suspect the HAL is slow in processing the events.
        ALOGE("Could not add the event to the queue. Resetting");
        reset();
    }
}

void MotionClassifier::requestExit() {
    reset();
    mEvents.push(ClassifierEvent::createExitEvent());
}

void MotionClassifier::updateClassification(int32_t deviceId, nsecs_t eventTime,
        MotionClassification classification) {
    std::scoped_lock lock(mLock);
    const nsecs_t lastDownTime = getValueForKey(mLastDownTimes, deviceId, static_cast<nsecs_t>(0));
    if (eventTime < lastDownTime) {
        // HAL just finished processing an event that belonged to an earlier gesture,
        // but new gesture is already in progress. Drop this classification.
        ALOGW("Received late classification. Late by at least %" PRId64 " ms.",
                nanoseconds_to_milliseconds(lastDownTime - eventTime));
        return;
    }
    mClassifications[deviceId] = classification;
}

void MotionClassifier::setClassification(int32_t deviceId, MotionClassification classification) {
    std::scoped_lock lock(mLock);
    mClassifications[deviceId] = classification;
}

void MotionClassifier::clearClassifications() {
    std::scoped_lock lock(mLock);
    mClassifications.clear();
}

MotionClassification MotionClassifier::getClassification(int32_t deviceId) {
    std::scoped_lock lock(mLock);
    return getValueForKey(mClassifications, deviceId, MotionClassification::NONE);
}

void MotionClassifier::updateLastDownTime(int32_t deviceId, nsecs_t downTime) {
    std::scoped_lock lock(mLock);
    mLastDownTimes[deviceId] = downTime;
    mClassifications[deviceId] = MotionClassification::NONE;
}

void MotionClassifier::clearDeviceState(int32_t deviceId) {
    std::scoped_lock lock(mLock);
    mClassifications.erase(deviceId);
    mLastDownTimes.erase(deviceId);
}

MotionClassification MotionClassifier::classify(const NotifyMotionArgs& args) {
    if ((args.action & AMOTION_EVENT_ACTION_MASK) == AMOTION_EVENT_ACTION_DOWN) {
        updateLastDownTime(args.deviceId, args.downTime);
    }

    ClassifierEvent event(std::make_unique<NotifyMotionArgs>(args));
    enqueueEvent(std::move(event));
    return getClassification(args.deviceId);
}

void MotionClassifier::reset() {
    mEvents.clear();
    mEvents.push(ClassifierEvent::createHalResetEvent());
}

/**
 * Per-device reset. Clear the outstanding events that are going to be sent to HAL.
 * Request InputClassifier thread to call resetDevice for this particular device.
 */
void MotionClassifier::reset(const NotifyDeviceResetArgs& args) {
    int32_t deviceId = args.deviceId;
    // Clear the pending events right away, to avoid unnecessary work done by the HAL.
    mEvents.erase([deviceId](const ClassifierEvent& event) {
            std::optional<int32_t> eventDeviceId = event.getDeviceId();
            return eventDeviceId && (*eventDeviceId == deviceId);
    });
    enqueueEvent(std::make_unique<NotifyDeviceResetArgs>(args));
}

const char* MotionClassifier::getServiceStatus() REQUIRES(mLock) {
    if (!mService) {
        return "null";
    }

    if (AIBinder_ping(mService->asBinder().get()) == STATUS_OK) {
        return "running";
    }
    return "not responding";
}

void MotionClassifier::dump(std::string& dump) {
    std::scoped_lock lock(mLock);
    dump += StringPrintf(INDENT2 "mService status: %s\n", getServiceStatus());
    dump += StringPrintf(INDENT2 "mEvents: %zu element(s) (max=%zu)\n",
            mEvents.size(), MAX_EVENTS);
    dump += INDENT2 "mClassifications, mLastDownTimes:\n";
    dump += INDENT3 "Device Id\tClassification\tLast down time";
    // Combine mClassifications and mLastDownTimes into a single table.
    // Create a superset of device ids.
    std::unordered_set<int32_t> deviceIds;
    std::for_each(mClassifications.begin(), mClassifications.end(),
            [&deviceIds](auto pair){ deviceIds.insert(pair.first); });
    std::for_each(mLastDownTimes.begin(), mLastDownTimes.end(),
            [&deviceIds](auto pair){ deviceIds.insert(pair.first); });
    for(int32_t deviceId : deviceIds) {
        const MotionClassification classification =
                getValueForKey(mClassifications, deviceId, MotionClassification::NONE);
        const nsecs_t downTime = getValueForKey(mLastDownTimes, deviceId, static_cast<nsecs_t>(0));
        dump += StringPrintf("\n" INDENT4 "%" PRId32 "\t%s\t%" PRId64,
                deviceId, motionClassificationToString(classification), downTime);
    }
}

// --- InputClassifier ---

InputClassifier::InputClassifier(InputListenerInterface& listener) : mListener(listener) {}

void InputClassifier::onBinderDied(void* cookie) {
    InputClassifier* classifier = static_cast<InputClassifier*>(cookie);
    if (classifier == nullptr) {
        LOG_ALWAYS_FATAL("Cookie is not valid");
        return;
    }
    classifier->setMotionClassifierEnabled(false);
}

void InputClassifier::setMotionClassifierEnabled(bool enabled) {
    std::scoped_lock lock(mLock);
    if (enabled) {
        ALOGI("Enabling motion classifier");
        if (mInitializeMotionClassifier.valid()) {
            scoped_unlock unlock(mLock);
            std::future_status status = mInitializeMotionClassifier.wait_for(5s);
            if (status != std::future_status::ready) {
                /**
                 * We don't have a better option here than to crash. We can't stop the thread,
                 * and we can't continue because 'mInitializeMotionClassifier' will block in its
                 * destructor.
                 */
                LOG_ALWAYS_FATAL("The thread to load IInputClassifier is stuck!");
            }
        }
        mInitializeMotionClassifier = std::async(std::launch::async, [this] {
            setCurrentThreadName("Create MotionClassifier");
            std::shared_ptr<IInputProcessor> service = getService();
            if (service == nullptr) {
                // Keep the MotionClassifier null, no service was found
                return;
            }
            { // acquire lock
                std::scoped_lock threadLock(mLock);
                mHalDeathRecipient =
                        std::make_unique<ScopedDeathRecipient>(onBinderDied, this /*cookie*/);
                mHalDeathRecipient->linkToDeath(service->asBinder().get());
                setMotionClassifierLocked(MotionClassifier::create(std::move(service)));
            } // release lock
        });
    } else {
        ALOGI("Disabling motion classifier");
        setMotionClassifierLocked(nullptr);
    }
}

void InputClassifier::notifyConfigurationChanged(const NotifyConfigurationChangedArgs* args) {
    // pass through
    mListener.notifyConfigurationChanged(args);
}

void InputClassifier::notifyKey(const NotifyKeyArgs* args) {
    // pass through
    mListener.notifyKey(args);
}

void InputClassifier::notifyMotion(const NotifyMotionArgs* args) {
    std::scoped_lock lock(mLock);
    // MotionClassifier is only used for touch events, for now
    const bool sendToMotionClassifier = mMotionClassifier && isTouchEvent(*args);
    if (!sendToMotionClassifier) {
        mListener.notifyMotion(args);
        return;
    }

    NotifyMotionArgs newArgs(*args);
    newArgs.classification = mMotionClassifier->classify(newArgs);
    mListener.notifyMotion(&newArgs);
}

void InputClassifier::notifySensor(const NotifySensorArgs* args) {
    // pass through
    mListener.notifySensor(args);
}

void InputClassifier::notifyVibratorState(const NotifyVibratorStateArgs* args) {
    // pass through
    mListener.notifyVibratorState(args);
}

void InputClassifier::notifySwitch(const NotifySwitchArgs* args) {
    // pass through
    mListener.notifySwitch(args);
}

void InputClassifier::notifyDeviceReset(const NotifyDeviceResetArgs* args) {
    std::scoped_lock lock(mLock);
    if (mMotionClassifier) {
        mMotionClassifier->reset(*args);
    }
    // continue to next stage
    mListener.notifyDeviceReset(args);
}

void InputClassifier::notifyPointerCaptureChanged(const NotifyPointerCaptureChangedArgs* args) {
    // pass through
    mListener.notifyPointerCaptureChanged(args);
}

void InputClassifier::setMotionClassifierLocked(
        std::unique_ptr<MotionClassifierInterface> motionClassifier) REQUIRES(mLock) {
    if (motionClassifier == nullptr) {
        // Destroy the ScopedDeathRecipient object, which will cause it to unlinkToDeath.
        // We can't call 'unlink' here because we don't have the binder handle.
        mHalDeathRecipient = nullptr;
    }
    mMotionClassifier = std::move(motionClassifier);
}

void InputClassifier::dump(std::string& dump) {
    std::scoped_lock lock(mLock);
    dump += "Input Classifier State:\n";
    dump += INDENT1 "Motion Classifier:\n";
    if (mMotionClassifier) {
        mMotionClassifier->dump(dump);
    } else {
        dump += INDENT2 "<nullptr>";
    }
    dump += "\n";
}

InputClassifier::~InputClassifier() {
}

} // namespace android