services/inputflinger/InputClassifier.cpp - platform/frameworks/native - Git at Google

 /*
  * 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 "InputClassifierConverter.h"

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

 #include <android/hardware/input/classifier/1.0/IInputClassifier.h>

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

 using android::base::StringPrintf;
 using android::hardware::hidl_bitfield;
 using android::hardware::hidl_vec;
 using android::hardware::Return;
 using namespace android::hardware::input;

 namespace android {

 static constexpr bool DEBUG = false;

 // Category (=namespace) name for the input settings that are applied at boot time
 static const char* INPUT_NATIVE_BOOT = "input_native_boot";
 // Feature flag name for the deep press feature
 static const char* DEEP_PRESS_ENABLED = "deep_press_enabled";

 //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::V1_0::Classification classification) {
     static_assert(MotionClassification::NONE ==
             static_cast<MotionClassification>(common::V1_0::Classification::NONE));
     static_assert(MotionClassification::AMBIGUOUS_GESTURE ==
             static_cast<MotionClassification>(common::V1_0::Classification::AMBIGUOUS_GESTURE));
     static_assert(MotionClassification::DEEP_PRESS ==
             static_cast<MotionClassification>(common::V1_0::Classification::DEEP_PRESS));
     return static_cast<MotionClassification>(classification);
 }

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

 // Check if the "deep touch" feature is on.
 static bool deepPressEnabled() {
     std::string flag_value = server_configurable_flags::GetServerConfigurableFlag(
             INPUT_NATIVE_BOOT, DEEP_PRESS_ENABLED, "true");
     std::transform(flag_value.begin(), flag_value.end(), flag_value.begin(), ::tolower);
     if (flag_value == "1" || flag_value == "true") {
         ALOGI("Deep press feature enabled.");
         return true;
     }
     ALOGI("Deep press feature is not enabled.");
     return false;
 }


 // --- 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(sp<android::hardware::hidl_death_recipient> deathRecipient) :
         mDeathRecipient(deathRecipient), mEvents(MAX_EVENTS) {
     mHalThread = std::thread(&MotionClassifier::callInputClassifierHal, this);
 #if defined(__linux__)
     // Set the thread name for debugging
     pthread_setname_np(mHalThread.native_handle(), "InputClassifier");
 #endif
 }

 /**
  * This function may block for some time to initialize the HAL, so it should only be called
  * from the "InputClassifier HAL" thread.
  */
 bool MotionClassifier::init() {
     ensureHalThread(__func__);
     sp<android::hardware::input::classifier::V1_0::IInputClassifier> service =
             classifier::V1_0::IInputClassifier::getService();
     if (!service) {
         // Not really an error, maybe the device does not have this HAL,
         // but somehow the feature flag is flipped
         ALOGI("Could not obtain InputClassifier HAL");
         return false;
     }

     sp<android::hardware::hidl_death_recipient> recipient = mDeathRecipient.promote();
     if (recipient != nullptr) {
         const bool linked = service->linkToDeath(recipient, 0 /* cookie */).withDefault(false);
         if (!linked) {
             ALOGE("Could not link MotionClassifier to the HAL death");
             return false;
         }
     }

     // 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());

     {
         std::scoped_lock lock(mLock);
         if (mService) {
             ALOGE("MotionClassifier::%s should only be called once", __func__);
         }
         mService = service;
     }
     return true;
 }

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

 void MotionClassifier::ensureHalThread(const char* function) {
     if (DEBUG) {
         if (std::this_thread::get_id() != mHalThread.get_id()) {
             LOG_FATAL("Function %s should only be called from InputClassifier thread", function);
         }
     }
 }

 /**
  * 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::callInputClassifierHal() {
     ensureHalThread(__func__);
     const bool initialized = init();
     if (!initialized) {
         // MotionClassifier no longer useful.
         // Deliver death notification from a separate thread
         // because ~MotionClassifier may be invoked, which calls mHalThread.join()
         std::thread([deathRecipient = mDeathRecipient](){
                 sp<android::hardware::hidl_death_recipient> recipient = deathRecipient.promote();
                 if (recipient != nullptr) {
                     recipient->serviceDied(0 /*cookie*/, nullptr);
                 }
         }).detach();
         return;
     }
     // From this point on, mService is guaranteed to be non-null.

     while (true) {
         ClassifierEvent event = mEvents.pop();
         bool halResponseOk = true;
         switch (event.type) {
             case ClassifierEventType::MOTION: {
                 NotifyMotionArgs* motionArgs = static_cast<NotifyMotionArgs*>(event.args.get());
                 common::V1_0::MotionEvent motionEvent =
                         notifyMotionArgsToHalMotionEvent(*motionArgs);
                 Return<common::V1_0::Classification> response = mService->classify(motionEvent);
                 halResponseOk = response.isOk();
                 if (halResponseOk) {
                     common::V1_0::Classification halClassification = response;
                     updateClassification(motionArgs->deviceId, motionArgs->eventTime,
                             getMotionClassification(halClassification));
                 }
                 break;
             }
             case ClassifierEventType::DEVICE_RESET: {
                 const int32_t deviceId = *(event.getDeviceId());
                 halResponseOk = mService->resetDevice(deviceId).isOk();
                 setClassification(deviceId, MotionClassification::NONE);
                 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("Dropped event with eventTime %" PRId64, event.args->eventTime);
         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;
 }

 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 (mService->ping().isOk()) {
         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(const sp<InputListenerInterface>& listener) :
         mListener(listener) {
     // The rest of the initialization is done in onFirstRef, because we need to obtain
     // an sp to 'this' in order to register for HAL death notifications
 }

 void InputClassifier::onFirstRef() {
     if (!deepPressEnabled()) {
         // If feature is not enabled, MotionClassifier should stay null to avoid unnecessary work.
         // When MotionClassifier is null, InputClassifier will forward all events
         // to the next InputListener, unmodified.
         return;
     }
     std::scoped_lock lock(mLock);
     mMotionClassifier = std::make_unique<MotionClassifier>(this);
 }

 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::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::serviceDied(uint64_t /*cookie*/,
         const wp<android::hidl::base::V1_0::IBase>& who) {
     std::scoped_lock lock(mLock);
     ALOGE("InputClassifier HAL has died. Setting mMotionClassifier to null");
     mMotionClassifier = nullptr;
     sp<android::hidl::base::V1_0::IBase> service = who.promote();
     if (service) {
         service->unlinkToDeath(this);
     }
 }

 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";
 }

 } // 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.
	*/

	#define LOG_TAG "InputClassifier"

	#include "InputClassifier.h"
	#include "InputClassifierConverter.h"

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

	#include <android/hardware/input/classifier/1.0/IInputClassifier.h>

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

	using android::base::StringPrintf;
	using android::hardware::hidl_bitfield;
	using android::hardware::hidl_vec;
	using android::hardware::Return;
	using namespace android::hardware::input;

	namespace android {

	static constexpr bool DEBUG = false;

	// Category (=namespace) name for the input settings that are applied at boot time
	static const char* INPUT_NATIVE_BOOT = "input_native_boot";
	// Feature flag name for the deep press feature
	static const char* DEEP_PRESS_ENABLED = "deep_press_enabled";

	//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::V1_0::Classification classification) {
	static_assert(MotionClassification::NONE ==
	static_cast<MotionClassification>(common::V1_0::Classification::NONE));
	static_assert(MotionClassification::AMBIGUOUS_GESTURE ==
	static_cast<MotionClassification>(common::V1_0::Classification::AMBIGUOUS_GESTURE));
	static_assert(MotionClassification::DEEP_PRESS ==
	static_cast<MotionClassification>(common::V1_0::Classification::DEEP_PRESS));
	return static_cast<MotionClassification>(classification);
	}

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

	// Check if the "deep touch" feature is on.
	static bool deepPressEnabled() {
	std::string flag_value = server_configurable_flags::GetServerConfigurableFlag(
	INPUT_NATIVE_BOOT, DEEP_PRESS_ENABLED, "true");
	std::transform(flag_value.begin(), flag_value.end(), flag_value.begin(), ::tolower);
	if (flag_value == "1" \|\| flag_value == "true") {
	ALOGI("Deep press feature enabled.");
	return true;
	}
	ALOGI("Deep press feature is not enabled.");
	return false;
	}


	// --- 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(sp<android::hardware::hidl_death_recipient> deathRecipient) :
	mDeathRecipient(deathRecipient), mEvents(MAX_EVENTS) {
	mHalThread = std::thread(&MotionClassifier::callInputClassifierHal, this);
	#if defined(__linux__)
	// Set the thread name for debugging
	pthread_setname_np(mHalThread.native_handle(), "InputClassifier");
	#endif
	}

	/**
	* This function may block for some time to initialize the HAL, so it should only be called
	* from the "InputClassifier HAL" thread.
	*/
	bool MotionClassifier::init() {
	ensureHalThread(__func__);
	sp<android::hardware::input::classifier::V1_0::IInputClassifier> service =
	classifier::V1_0::IInputClassifier::getService();
	if (!service) {
	// Not really an error, maybe the device does not have this HAL,
	// but somehow the feature flag is flipped
	ALOGI("Could not obtain InputClassifier HAL");
	return false;
	}

	sp<android::hardware::hidl_death_recipient> recipient = mDeathRecipient.promote();
	if (recipient != nullptr) {
	const bool linked = service->linkToDeath(recipient, 0 /* cookie */).withDefault(false);
	if (!linked) {
	ALOGE("Could not link MotionClassifier to the HAL death");
	return false;
	}
	}

	// 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());

	{
	std::scoped_lock lock(mLock);
	if (mService) {
	ALOGE("MotionClassifier::%s should only be called once", __func__);
	}
	mService = service;
	}
	return true;
	}

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

	void MotionClassifier::ensureHalThread(const char* function) {
	if (DEBUG) {
	if (std::this_thread::get_id() != mHalThread.get_id()) {
	LOG_FATAL("Function %s should only be called from InputClassifier thread", function);
	}
	}
	}

	/**
	* 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::callInputClassifierHal() {
	ensureHalThread(__func__);
	const bool initialized = init();
	if (!initialized) {
	// MotionClassifier no longer useful.
	// Deliver death notification from a separate thread
	// because ~MotionClassifier may be invoked, which calls mHalThread.join()
	std::thread([deathRecipient = mDeathRecipient](){
	sp<android::hardware::hidl_death_recipient> recipient = deathRecipient.promote();
	if (recipient != nullptr) {
	recipient->serviceDied(0 /cookie/, nullptr);
	}
	}).detach();
	return;
	}
	// From this point on, mService is guaranteed to be non-null.

	while (true) {
	ClassifierEvent event = mEvents.pop();
	bool halResponseOk = true;
	switch (event.type) {
	case ClassifierEventType::MOTION: {
	NotifyMotionArgs* motionArgs = static_cast<NotifyMotionArgs*>(event.args.get());
	common::V1_0::MotionEvent motionEvent =
	notifyMotionArgsToHalMotionEvent(*motionArgs);
	Return<common::V1_0::Classification> response = mService->classify(motionEvent);
	halResponseOk = response.isOk();
	if (halResponseOk) {
	common::V1_0::Classification halClassification = response;
	updateClassification(motionArgs->deviceId, motionArgs->eventTime,
	getMotionClassification(halClassification));
	}
	break;
	}
	case ClassifierEventType::DEVICE_RESET: {
	const int32_t deviceId = *(event.getDeviceId());
	halResponseOk = mService->resetDevice(deviceId).isOk();
	setClassification(deviceId, MotionClassification::NONE);
	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("Dropped event with eventTime %" PRId64, event.args->eventTime);
	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;
	}

	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 (mService->ping().isOk()) {
	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(const sp<InputListenerInterface>& listener) :
	mListener(listener) {
	// The rest of the initialization is done in onFirstRef, because we need to obtain
	// an sp to 'this' in order to register for HAL death notifications
	}

	void InputClassifier::onFirstRef() {
	if (!deepPressEnabled()) {
	// If feature is not enabled, MotionClassifier should stay null to avoid unnecessary work.
	// When MotionClassifier is null, InputClassifier will forward all events
	// to the next InputListener, unmodified.
	return;
	}
	std::scoped_lock lock(mLock);
	mMotionClassifier = std::make_unique<MotionClassifier>(this);
	}

	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::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::serviceDied(uint64_t /cookie/,
	const wp<android::hidl::base::V1_0::IBase>& who) {
	std::scoped_lock lock(mLock);
	ALOGE("InputClassifier HAL has died. Setting mMotionClassifier to null");
	mMotionClassifier = nullptr;
	sp<android::hidl::base::V1_0::IBase> service = who.promote();
	if (service) {
	service->unlinkToDeath(this);
	}
	}

	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";
	}

	} // namespace android