services/inputflinger/reader/include/EventHub.h

/*
 * Copyright (C) 2005 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.
 */

#ifndef _RUNTIME_EVENT_HUB_H
#define _RUNTIME_EVENT_HUB_H

#include <bitset>
#include <climits>
#include <unordered_map>
#include <vector>

#include <input/Flags.h>
#include <filesystem>

#include <batteryservice/BatteryService.h>
#include <input/Input.h>
#include <input/InputDevice.h>
#include <input/KeyCharacterMap.h>
#include <input/KeyLayoutMap.h>
#include <input/Keyboard.h>
#include <input/PropertyMap.h>
#include <input/VirtualKeyMap.h>
#include <linux/input.h>
#include <sys/epoll.h>
#include <utils/BitSet.h>
#include <utils/Errors.h>
#include <utils/KeyedVector.h>
#include <utils/List.h>
#include <utils/Log.h>
#include <utils/Mutex.h>

#include "TouchVideoDevice.h"
#include "VibrationElement.h"

namespace android {

/* Number of colors : {red, green, blue} */
static constexpr size_t COLOR_NUM = 3;
/*
 * A raw event as retrieved from the EventHub.
 */
struct RawEvent {
    nsecs_t when;
    int32_t deviceId;
    int32_t type;
    int32_t code;
    int32_t value;
};

/* Describes an absolute axis. */
struct RawAbsoluteAxisInfo {
    bool valid; // true if the information is valid, false otherwise

    int32_t minValue;   // minimum value
    int32_t maxValue;   // maximum value
    int32_t flat;       // center flat position, eg. flat == 8 means center is between -8 and 8
    int32_t fuzz;       // error tolerance, eg. fuzz == 4 means value is +/- 4 due to noise
    int32_t resolution; // resolution in units per mm or radians per mm

    inline void clear() {
        valid = false;
        minValue = 0;
        maxValue = 0;
        flat = 0;
        fuzz = 0;
        resolution = 0;
    }
};

/*
 * Input device classes.
 */
enum class InputDeviceClass : uint32_t {
    /* The input device is a keyboard or has buttons. */
    KEYBOARD = 0x00000001,

    /* The input device is an alpha-numeric keyboard (not just a dial pad). */
    ALPHAKEY = 0x00000002,

    /* The input device is a touchscreen or a touchpad (either single-touch or multi-touch). */
    TOUCH = 0x00000004,

    /* The input device is a cursor device such as a trackball or mouse. */
    CURSOR = 0x00000008,

    /* The input device is a multi-touch touchscreen. */
    TOUCH_MT = 0x00000010,

    /* The input device is a directional pad (implies keyboard, has DPAD keys). */
    DPAD = 0x00000020,

    /* The input device is a gamepad (implies keyboard, has BUTTON keys). */
    GAMEPAD = 0x00000040,

    /* The input device has switches. */
    SWITCH = 0x00000080,

    /* The input device is a joystick (implies gamepad, has joystick absolute axes). */
    JOYSTICK = 0x00000100,

    /* The input device has a vibrator (supports FF_RUMBLE). */
    VIBRATOR = 0x00000200,

    /* The input device has a microphone. */
    MIC = 0x00000400,

    /* The input device is an external stylus (has data we want to fuse with touch data). */
    EXTERNAL_STYLUS = 0x00000800,

    /* The input device has a rotary encoder */
    ROTARY_ENCODER = 0x00001000,

    /* The input device has a sensor like accelerometer, gyro, etc */
    SENSOR = 0x00002000,

    /* The input device has a battery */
    BATTERY = 0x00004000,

    /* The input device has sysfs controllable lights */
    LIGHT = 0x00008000,

    /* The input device is virtual (not a real device, not part of UI configuration). */
    VIRTUAL = 0x40000000,

    /* The input device is external (not built-in). */
    EXTERNAL = 0x80000000,
};

enum class SysfsClass : uint32_t {
    POWER_SUPPLY = 0,
    LEDS = 1,
};

enum class LightColor : uint32_t {
    RED = 0,
    GREEN = 1,
    BLUE = 2,
};

enum class InputLightClass : uint32_t {
    /* The input light has brightness node. */
    BRIGHTNESS = 0x00000001,
    /* The input light has red name. */
    RED = 0x00000002,
    /* The input light has green name. */
    GREEN = 0x00000004,
    /* The input light has blue name. */
    BLUE = 0x00000008,
    /* The input light has global name. */
    GLOBAL = 0x00000010,
    /* The input light has multi index node. */
    MULTI_INDEX = 0x00000020,
    /* The input light has multi intensity node. */
    MULTI_INTENSITY = 0x00000040,
    /* The input light has max brightness node. */
    MAX_BRIGHTNESS = 0x00000080,
};

/* Describes a raw light. */
struct RawLightInfo {
    int32_t id;
    std::string name;
    std::optional<int32_t> maxBrightness;
    Flags<InputLightClass> flags;
    std::array<int32_t, COLOR_NUM> rgbIndex;
    std::filesystem::path path;
};

/*
 * Gets the class that owns an axis, in cases where multiple classes might claim
 * the same axis for different purposes.
 */
extern Flags<InputDeviceClass> getAbsAxisUsage(int32_t axis, Flags<InputDeviceClass> deviceClasses);

/*
 * Grand Central Station for events.
 *
 * The event hub aggregates input events received across all known input
 * devices on the system, including devices that may be emulated by the simulator
 * environment.  In addition, the event hub generates fake input events to indicate
 * when devices are added or removed.
 *
 * The event hub provides a stream of input events (via the getEvent function).
 * It also supports querying the current actual state of input devices such as identifying
 * which keys are currently down.  Finally, the event hub keeps track of the capabilities of
 * individual input devices, such as their class and the set of key codes that they support.
 */
class EventHubInterface {
public:
    EventHubInterface() {}
    virtual ~EventHubInterface() {}

    // Synthetic raw event type codes produced when devices are added or removed.
    enum {
        // Sent when a device is added.
        DEVICE_ADDED = 0x10000000,
        // Sent when a device is removed.
        DEVICE_REMOVED = 0x20000000,
        // Sent when all added/removed devices from the most recent scan have been reported.
        // This event is always sent at least once.
        FINISHED_DEVICE_SCAN = 0x30000000,

        FIRST_SYNTHETIC_EVENT = DEVICE_ADDED,
    };

    virtual Flags<InputDeviceClass> getDeviceClasses(int32_t deviceId) const = 0;

    virtual InputDeviceIdentifier getDeviceIdentifier(int32_t deviceId) const = 0;

    virtual int32_t getDeviceControllerNumber(int32_t deviceId) const = 0;

    virtual void getConfiguration(int32_t deviceId, PropertyMap* outConfiguration) const = 0;

    virtual status_t getAbsoluteAxisInfo(int32_t deviceId, int axis,
                                         RawAbsoluteAxisInfo* outAxisInfo) const = 0;

    virtual bool hasRelativeAxis(int32_t deviceId, int axis) const = 0;

    virtual bool hasInputProperty(int32_t deviceId, int property) const = 0;

    virtual bool hasMscEvent(int32_t deviceId, int mscEvent) const = 0;

    virtual status_t mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode,
                            int32_t metaState, int32_t* outKeycode, int32_t* outMetaState,
                            uint32_t* outFlags) const = 0;

    virtual status_t mapAxis(int32_t deviceId, int32_t scanCode, AxisInfo* outAxisInfo) const = 0;

    // Sets devices that are excluded from opening.
    // This can be used to ignore input devices for sensors.
    virtual void setExcludedDevices(const std::vector<std::string>& devices) = 0;

    /*
     * Wait for events to become available and returns them.
     * After returning, the EventHub holds onto a wake lock until the next call to getEvent.
     * This ensures that the device will not go to sleep while the event is being processed.
     * If the device needs to remain awake longer than that, then the caller is responsible
     * for taking care of it (say, by poking the power manager user activity timer).
     *
     * The timeout is advisory only.  If the device is asleep, it will not wake just to
     * service the timeout.
     *
     * Returns the number of events obtained, or 0 if the timeout expired.
     */
    virtual size_t getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) = 0;
    virtual std::vector<TouchVideoFrame> getVideoFrames(int32_t deviceId) = 0;
    virtual base::Result<std::pair<InputDeviceSensorType, int32_t>> mapSensor(int32_t deviceId,
                                                                              int32_t absCode) = 0;
    // Raw lights are sysfs led light nodes we found from the EventHub device sysfs node,
    // containing the raw info of the sysfs node structure.
    virtual const std::vector<int32_t> getRawLightIds(int32_t deviceId) = 0;
    virtual std::optional<RawLightInfo> getRawLightInfo(int32_t deviceId, int32_t lightId) = 0;
    virtual std::optional<int32_t> getLightBrightness(int32_t deviceId, int32_t lightId) = 0;
    virtual void setLightBrightness(int32_t deviceId, int32_t lightId, int32_t brightness) = 0;
    virtual std::optional<std::unordered_map<LightColor, int32_t>> getLightIntensities(
            int32_t deviceId, int32_t lightId) = 0;
    virtual void setLightIntensities(int32_t deviceId, int32_t lightId,
                                     std::unordered_map<LightColor, int32_t> intensities) = 0;
    /*
     * Query current input state.
     */
    virtual int32_t getScanCodeState(int32_t deviceId, int32_t scanCode) const = 0;
    virtual int32_t getKeyCodeState(int32_t deviceId, int32_t keyCode) const = 0;
    virtual int32_t getSwitchState(int32_t deviceId, int32_t sw) const = 0;
    virtual status_t getAbsoluteAxisValue(int32_t deviceId, int32_t axis,
                                          int32_t* outValue) const = 0;

    /*
     * Examine key input devices for specific framework keycode support
     */
    virtual bool markSupportedKeyCodes(int32_t deviceId, size_t numCodes, const int32_t* keyCodes,
                                       uint8_t* outFlags) const = 0;

    virtual bool hasScanCode(int32_t deviceId, int32_t scanCode) const = 0;

    /* LED related functions expect Android LED constants, not scan codes or HID usages */
    virtual bool hasLed(int32_t deviceId, int32_t led) const = 0;
    virtual void setLedState(int32_t deviceId, int32_t led, bool on) = 0;

    virtual void getVirtualKeyDefinitions(
            int32_t deviceId, std::vector<VirtualKeyDefinition>& outVirtualKeys) const = 0;

    virtual const std::shared_ptr<KeyCharacterMap> getKeyCharacterMap(int32_t deviceId) const = 0;
    virtual bool setKeyboardLayoutOverlay(int32_t deviceId,
                                          std::shared_ptr<KeyCharacterMap> map) = 0;

    /* Control the vibrator. */
    virtual void vibrate(int32_t deviceId, const VibrationElement& effect) = 0;
    virtual void cancelVibrate(int32_t deviceId) = 0;
    virtual std::vector<int32_t> getVibratorIds(int32_t deviceId) = 0;

    /* Query battery level. */
    virtual std::optional<int32_t> getBatteryCapacity(int32_t deviceId) const = 0;

    /* Query battery status. */
    virtual std::optional<int32_t> getBatteryStatus(int32_t deviceId) const = 0;

    /* Requests the EventHub to reopen all input devices on the next call to getEvents(). */
    virtual void requestReopenDevices() = 0;

    /* Wakes up getEvents() if it is blocked on a read. */
    virtual void wake() = 0;

    /* Dump EventHub state to a string. */
    virtual void dump(std::string& dump) = 0;

    /* Called by the heatbeat to ensures that the reader has not deadlocked. */
    virtual void monitor() = 0;

    /* Return true if the device is enabled. */
    virtual bool isDeviceEnabled(int32_t deviceId) = 0;

    /* Enable an input device */
    virtual status_t enableDevice(int32_t deviceId) = 0;

    /* Disable an input device. Closes file descriptor to that device. */
    virtual status_t disableDevice(int32_t deviceId) = 0;
};

template <std::size_t BITS>
class BitArray {
    /* Array element type and vector of element type. */
    using Element = std::uint32_t;
    /* Number of bits in each BitArray element. */
    static constexpr size_t WIDTH = sizeof(Element) * CHAR_BIT;
    /* Number of elements to represent a bit array of the specified size of bits. */
    static constexpr size_t COUNT = (BITS + WIDTH - 1) / WIDTH;

public:
    /* BUFFER type declaration for BitArray */
    using Buffer = std::array<Element, COUNT>;
    /* To tell if a bit is set in array, it selects an element from the array, and test
     * if the relevant bit set.
     * Note the parameter "bit" is an index to the bit, 0 <= bit < BITS.
     */
    inline bool test(size_t bit) const {
        return (bit < BITS) ? mData[bit / WIDTH].test(bit % WIDTH) : false;
    }
    /* Returns total number of bytes needed for the array */
    inline size_t bytes() { return (BITS + CHAR_BIT - 1) / CHAR_BIT; }
    /* Returns true if array contains any non-zero bit from the range defined by start and end
     * bit index [startIndex, endIndex).
     */
    bool any(size_t startIndex, size_t endIndex) {
        if (startIndex >= endIndex || startIndex > BITS || endIndex > BITS + 1) {
            ALOGE("Invalid start/end index. start = %zu, end = %zu, total bits = %zu", startIndex,
                  endIndex, BITS);
            return false;
        }
        size_t se = startIndex / WIDTH; // Start of element
        size_t ee = endIndex / WIDTH;   // End of element
        size_t si = startIndex % WIDTH; // Start index in start element
        size_t ei = endIndex % WIDTH;   // End index in end element
        // Need to check first unaligned bitset for any non zero bit
        if (si > 0) {
            size_t nBits = se == ee ? ei - si : WIDTH - si;
            // Generate the mask of interested bit range
            Element mask = ((1 << nBits) - 1) << si;
            if (mData[se++].to_ulong() & mask) {
                return true;
            }
        }
        // Check whole bitset for any bit set
        for (; se < ee; se++) {
            if (mData[se].any()) {
                return true;
            }
        }
        // Need to check last unaligned bitset for any non zero bit
        if (ei > 0 && se <= ee) {
            // Generate the mask of interested bit range
            Element mask = (1 << ei) - 1;
            if (mData[se].to_ulong() & mask) {
                return true;
            }
        }
        return false;
    }
    /* Load bit array values from buffer */
    void loadFromBuffer(const Buffer& buffer) {
        for (size_t i = 0; i < COUNT; i++) {
            mData[i] = std::bitset<WIDTH>(buffer[i]);
        }
    }

private:
    std::array<std::bitset<WIDTH>, COUNT> mData;
};

class EventHub : public EventHubInterface {
public:
    EventHub();

    Flags<InputDeviceClass> getDeviceClasses(int32_t deviceId) const override final;

    InputDeviceIdentifier getDeviceIdentifier(int32_t deviceId) const override final;

    int32_t getDeviceControllerNumber(int32_t deviceId) const override final;

    void getConfiguration(int32_t deviceId, PropertyMap* outConfiguration) const override final;

    status_t getAbsoluteAxisInfo(int32_t deviceId, int axis,
                                 RawAbsoluteAxisInfo* outAxisInfo) const override final;

    bool hasRelativeAxis(int32_t deviceId, int axis) const override final;

    bool hasInputProperty(int32_t deviceId, int property) const override final;

    bool hasMscEvent(int32_t deviceId, int mscEvent) const override final;

    status_t mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode, int32_t metaState,
                    int32_t* outKeycode, int32_t* outMetaState,
                    uint32_t* outFlags) const override final;

    status_t mapAxis(int32_t deviceId, int32_t scanCode,
                     AxisInfo* outAxisInfo) const override final;

    base::Result<std::pair<InputDeviceSensorType, int32_t>> mapSensor(
            int32_t deviceId, int32_t absCode) override final;

    const std::vector<int32_t> getRawLightIds(int32_t deviceId) override final;

    std::optional<RawLightInfo> getRawLightInfo(int32_t deviceId, int32_t lightId) override final;

    std::optional<int32_t> getLightBrightness(int32_t deviceId, int32_t lightId) override final;
    void setLightBrightness(int32_t deviceId, int32_t lightId, int32_t brightness) override final;
    std::optional<std::unordered_map<LightColor, int32_t>> getLightIntensities(
            int32_t deviceId, int32_t lightId) override final;
    void setLightIntensities(int32_t deviceId, int32_t lightId,
                             std::unordered_map<LightColor, int32_t> intensities) override final;

    void setExcludedDevices(const std::vector<std::string>& devices) override final;

    int32_t getScanCodeState(int32_t deviceId, int32_t scanCode) const override final;
    int32_t getKeyCodeState(int32_t deviceId, int32_t keyCode) const override final;
    int32_t getSwitchState(int32_t deviceId, int32_t sw) const override final;
    status_t getAbsoluteAxisValue(int32_t deviceId, int32_t axis,
                                  int32_t* outValue) const override final;

    bool markSupportedKeyCodes(int32_t deviceId, size_t numCodes, const int32_t* keyCodes,
                               uint8_t* outFlags) const override final;

    size_t getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) override final;
    std::vector<TouchVideoFrame> getVideoFrames(int32_t deviceId) override final;

    bool hasScanCode(int32_t deviceId, int32_t scanCode) const override final;
    bool hasLed(int32_t deviceId, int32_t led) const override final;
    void setLedState(int32_t deviceId, int32_t led, bool on) override final;

    void getVirtualKeyDefinitions(
            int32_t deviceId,
            std::vector<VirtualKeyDefinition>& outVirtualKeys) const override final;

    const std::shared_ptr<KeyCharacterMap> getKeyCharacterMap(
            int32_t deviceId) const override final;
    bool setKeyboardLayoutOverlay(int32_t deviceId,
                                  std::shared_ptr<KeyCharacterMap> map) override final;

    void vibrate(int32_t deviceId, const VibrationElement& effect) override final;
    void cancelVibrate(int32_t deviceId) override final;
    std::vector<int32_t> getVibratorIds(int32_t deviceId) override final;

    void requestReopenDevices() override final;

    void wake() override final;

    void dump(std::string& dump) override final;

    void monitor() override final;

    std::optional<int32_t> getBatteryCapacity(int32_t deviceId) const override final;

    std::optional<int32_t> getBatteryStatus(int32_t deviceId) const override final;

    bool isDeviceEnabled(int32_t deviceId) override final;

    status_t enableDevice(int32_t deviceId) override final;

    status_t disableDevice(int32_t deviceId) override final;

    ~EventHub() override;

private:
    struct Device {
        int fd; // may be -1 if device is closed
        const int32_t id;
        const std::string path;
        const InputDeviceIdentifier identifier;

        std::unique_ptr<TouchVideoDevice> videoDevice;

        Flags<InputDeviceClass> classes;

        BitArray<KEY_MAX> keyBitmask;
        BitArray<KEY_MAX> keyState;
        BitArray<ABS_MAX> absBitmask;
        BitArray<REL_MAX> relBitmask;
        BitArray<SW_MAX> swBitmask;
        BitArray<SW_MAX> swState;
        BitArray<LED_MAX> ledBitmask;
        BitArray<FF_MAX> ffBitmask;
        BitArray<INPUT_PROP_MAX> propBitmask;
        BitArray<MSC_MAX> mscBitmask;

        std::string configurationFile;
        std::unique_ptr<PropertyMap> configuration;
        std::unique_ptr<VirtualKeyMap> virtualKeyMap;
        KeyMap keyMap;

        bool ffEffectPlaying;
        int16_t ffEffectId; // initially -1

        // The paths are invalid when they're std::nullopt
        std::optional<std::filesystem::path> sysfsRootPath;
        std::optional<std::filesystem::path> sysfsBatteryPath;
        // maps from light id to light info
        std::unordered_map<int32_t, RawLightInfo> lightInfos;
        int32_t nextLightId;

        int32_t controllerNumber;

        Device(int fd, int32_t id, const std::string& path,
               const InputDeviceIdentifier& identifier);
        ~Device();

        void close();

        bool enabled; // initially true
        status_t enable();
        status_t disable();
        bool hasValidFd() const;
        const bool isVirtual; // set if fd < 0 is passed to constructor

        const std::shared_ptr<KeyCharacterMap> getKeyCharacterMap() const;

        template <std::size_t N>
        status_t readDeviceBitMask(unsigned long ioctlCode, BitArray<N>& bitArray);

        void configureFd();
        bool hasKeycodeLocked(int keycode) const;
        void loadConfigurationLocked();
        bool loadVirtualKeyMapLocked();
        status_t loadKeyMapLocked();
        bool isExternalDeviceLocked();
        bool deviceHasMicLocked();
        void setLedForControllerLocked();
        status_t mapLed(int32_t led, int32_t* outScanCode) const;
        void setLedStateLocked(int32_t led, bool on);
        bool configureBatteryLocked();
        bool configureLightsLocked();
    };

    status_t openDeviceLocked(const std::string& devicePath);
    void openVideoDeviceLocked(const std::string& devicePath);
    /**
     * Try to associate a video device with an input device. If the association succeeds,
     * the videoDevice is moved into the input device. 'videoDevice' will become null if this
     * happens.
     * Return true if the association succeeds.
     * Return false otherwise.
     */
    bool tryAddVideoDevice(Device& device, std::unique_ptr<TouchVideoDevice>& videoDevice);
    void createVirtualKeyboardLocked();
    void addDeviceLocked(std::unique_ptr<Device> device);
    void assignDescriptorLocked(InputDeviceIdentifier& identifier);

    void closeDeviceByPathLocked(const std::string& devicePath);
    void closeVideoDeviceByPathLocked(const std::string& devicePath);
    void closeDeviceLocked(Device& device);
    void closeAllDevicesLocked();

    status_t registerFdForEpoll(int fd);
    status_t unregisterFdFromEpoll(int fd);
    status_t registerDeviceForEpollLocked(Device& device);
    void registerVideoDeviceForEpollLocked(const TouchVideoDevice& videoDevice);
    status_t unregisterDeviceFromEpollLocked(Device& device);
    void unregisterVideoDeviceFromEpollLocked(const TouchVideoDevice& videoDevice);

    status_t scanDirLocked(const std::string& dirname);
    status_t scanVideoDirLocked(const std::string& dirname);
    void scanDevicesLocked();
    status_t readNotifyLocked();

    Device* getDeviceByDescriptorLocked(const std::string& descriptor) const;
    Device* getDeviceLocked(int32_t deviceId) const;
    Device* getDeviceByPathLocked(const std::string& devicePath) const;
    /**
     * Look through all available fd's (both for input devices and for video devices),
     * and return the device pointer.
     */
    Device* getDeviceByFdLocked(int fd) const;

    int32_t getNextControllerNumberLocked(const std::string& name);
    void releaseControllerNumberLocked(int32_t num);

    // Protect all internal state.
    mutable std::mutex mLock;

    // The actual id of the built-in keyboard, or NO_BUILT_IN_KEYBOARD if none.
    // EventHub remaps the built-in keyboard to id 0 externally as required by the API.
    enum {
        // Must not conflict with any other assigned device ids, including
        // the virtual keyboard id (-1).
        NO_BUILT_IN_KEYBOARD = -2,
    };
    int32_t mBuiltInKeyboardId;

    int32_t mNextDeviceId;

    BitSet32 mControllerNumbers;

    std::unordered_map<int32_t, std::unique_ptr<Device>> mDevices;
    /**
     * Video devices that report touchscreen heatmap, but have not (yet) been paired
     * with a specific input device. Video device discovery is independent from input device
     * discovery, so the two types of devices could be found in any order.
     * Ideally, video devices in this queue do not have an open fd, or at least aren't
     * actively streaming.
     */
    std::vector<std::unique_ptr<TouchVideoDevice>> mUnattachedVideoDevices;

    std::vector<std::unique_ptr<Device>> mOpeningDevices;
    std::vector<std::unique_ptr<Device>> mClosingDevices;

    bool mNeedToSendFinishedDeviceScan;
    bool mNeedToReopenDevices;
    bool mNeedToScanDevices;
    std::vector<std::string> mExcludedDevices;

    int mEpollFd;
    int mINotifyFd;
    int mWakeReadPipeFd;
    int mWakeWritePipeFd;

    int mInputWd;
    int mVideoWd;

    // Maximum number of signalled FDs to handle at a time.
    static const int EPOLL_MAX_EVENTS = 16;

    // The array of pending epoll events and the index of the next event to be handled.
    struct epoll_event mPendingEventItems[EPOLL_MAX_EVENTS];
    size_t mPendingEventCount;
    size_t mPendingEventIndex;
    bool mPendingINotify;
};

}; // namespace android

#endif // _RUNTIME_EVENT_HUB_H