uORBFastRpcChannel.hpp

Go to the documentation of this file.

/****************************************************************************
 *
 * Copyright (C) 2015 Mark Charlebois. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/
#ifndef _uORBFastRpcChannel_hpp_
#define _uORBFastRpcChannel_hpp_

#include <stdint.h>
#include <string>
#include <list>
#include "uORB/uORBCommunicator.hpp"
#include <semaphore.h>
#include <set>
#include <px4_platform_common/sem.h>

namespace uORB
{
class FastRpcChannel;
}

class uORB::FastRpcChannel : public uORBCommunicator::IChannel
{
public:
    /**
     * static method to get the IChannel Implementor.
     */
    static uORB::FastRpcChannel *GetInstance()
    {
        return &(_Instance);
    }

    /**
     * @brief Interface to notify the remote entity of a topic being advertised.
     *
     * @param messageName
     *  This represents the uORB message name(aka topic); This message name should be
     *  globally unique.
     * @return
     *  0 = success; This means the messages is successfully sent to the receiver
     *      Note: This does not mean that the receiver as received it.
     *  otherwise = failure.
     */
    virtual int16_t topic_advertised(const char *messageName);

    /**
     * @brief Interface to notify the remote entity of a topic being unadvertised
     * and is no longer publishing messages.
     *
     * @param messageName
     *  This represents the uORB message name(aka topic); This message name should be
     *  globally unique.
     * @return
     *  0 = success; This means the messages is successfully sent to the receiver
     *      Note: This does not mean that the receiver as received it.
     *  otherwise = failure.
     */
    virtual int16_t topic_unadvertised(const char *messageName);

    /**
     * @brief Interface to notify the remote entity of interest of a
     * subscription for a message.
     *
     * @param messageName
     *  This represents the uORB message name; This message name should be
     *  globally unique.
     * @param msgRate
     *  The max rate at which the subscriber can accept the messages.
     * @return
     *  0 = success; This means the messages is successfully sent to the receiver
     *      Note: This does not mean that the receiver as received it.
     *  otherwise = failure.
     */
    virtual int16_t add_subscription(const char *messageName, int32_t msgRateInHz);


    /**
     * @brief Interface to notify the remote entity of removal of a subscription
     *
     * @param messageName
     *  This represents the uORB message name; This message name should be
     *  globally unique.
     * @return
     *  0 = success; This means the messages is successfully sent to the receiver
     *      Note: This does not necessarily mean that the receiver as received it.
     *  otherwise = failure.
     */
    virtual int16_t remove_subscription(const char *messageName);

    /**
     * Register Message Handler.  This is internal for the IChannel implementer*
     */
    virtual int16_t register_handler(uORBCommunicator::IChannelRxHandler *handler);


    //=========================================================================
    //     INTERFACES FOR Data messages
    //=========================================================================

    /**
     * @brief Sends the data message over the communication link.
     * @param messageName
     *  This represents the uORB message name; This message name should be
     *  globally unique.
     * @param length
     *  The length of the data buffer to be sent.
     * @param data
     *  The actual data to be sent.
     * @return
     *  0 = success; This means the messages is successfully sent to the receiver
     *      Note: This does not mean that the receiver as received it.
     *  otherwise = failure.
     */
    virtual int16_t send_message(const char *messageName, int32_t length, uint8_t *data);

    //Function to return the data to krait.
    int16_t get_data
    (
        int32_t *msg_type,
        char *topic_name,
        int32_t topic_name_len,
        uint8_t *data,
        int32_t data_len_in_bytes,
        int32_t *bytes_returned
    );

    int16_t get_bulk_data(uint8_t *buffer, int32_t max_size_in_bytes, int32_t *returned_bytes, int32_t *topic_count);

    // function to check if there are subscribers for a topic on adsp.
    int16_t is_subscriber_present(const char *messageName, int32_t *status);

    // function to release the blocking semaphore for get_data method.
    int16_t unblock_get_data_method();

    uORBCommunicator::IChannelRxHandler *GetRxHandler()
    {
        return _RxHandler;
    }

    void AddRemoteSubscriber(const std::string &messageName)
    {
        _RemoteSubscribers.insert(messageName);
    }
    void RemoveRemoteSubscriber(const std::string &messageName)
    {
        _RemoteSubscribers.erase(messageName);
    }

private: // data members
    static uORB::FastRpcChannel _Instance;
    uORBCommunicator::IChannelRxHandler *_RxHandler;

    /// data structure to store the messages to be retrived by Krait.
    static const int32_t _MAX_MSG_QUEUE_SIZE = 100;
    static const int32_t _CONTROL_MSG_TYPE_ADD_SUBSCRIBER = 1;
    static const int32_t _CONTROL_MSG_TYPE_REMOVE_SUBSCRIBER = 2;
    static const int32_t _DATA_MSG_TYPE = 3;
    static const int32_t _CONTROL_MSG_TYPE_ADVERTISE = 4;
    static const int32_t _CONTROL_MSG_TYPE_UNADVERTISE = 5;

    static const int32_t _PACKET_FIELD_TOPIC_NAME_LEN_SIZE_IN_BYTES = 2;
    static const int32_t _PACKET_FIELD_DATA_LEN_IN_BYTES = 2;
    static const int32_t _PACKET_HEADER_SIZE = 1 + //first byte is the MSG Type
            _PACKET_FIELD_TOPIC_NAME_LEN_SIZE_IN_BYTES + _PACKET_FIELD_DATA_LEN_IN_BYTES;

    struct FastRpcDataMsg {
        int32_t     _MaxBufferSize;
        int32_t     _Length;
        uint8_t    *_Buffer;
        std::string _MsgName;
    };

    struct FastRpcControlMsg {
        int32_t _Type;
        std::string _MsgName;
    };

    struct BulkTransferHeader {
        uint16_t _MsgType;
        uint16_t _MsgNameLen;
        uint16_t _DataLen;
    };


    struct FastRpcDataMsg _DataMsgQueue[ _MAX_MSG_QUEUE_SIZE ];
    int32_t _DataQInIndex;
    int32_t _DataQOutIndex;

    struct FastRpcControlMsg _ControlMsgQueue[ _MAX_MSG_QUEUE_SIZE ];
    int32_t _ControlQInIndex;
    int32_t _ControlQOutIndex;

    std::list<std::string> _Subscribers;

    //utility classes
    class Mutex
    {
    public:
        Mutex()
        {
            sem_init(&_Sem, 0, 1);
        }
        ~Mutex()
        {
            sem_destroy(&_Sem);
        }
        void lock()
        {
            sem_wait(&_Sem);
        }
        void unlock()
        {
            sem_post(&_Sem);
        }
    private:
        sem_t _Sem;

        Mutex(const Mutex &);

        Mutex &operator=(const Mutex &);
    };

    class Semaphore
    {
    public:
        Semaphore()
        {
            sem_init(&_Sem, 0, 0);
            /* _Sem use case is a signal */
            px4_sem_setprotocol(&_Sem, SEM_PRIO_NONE);
        }
        ~Semaphore()
        {
            sem_destroy(&_Sem);
        }
        void post()
        {
            sem_post(&_Sem);
        }
        void wait()
        {
            sem_wait(&_Sem);
        }
    private:
        sem_t _Sem;
        Semaphore(const Semaphore &);
        Semaphore &operator=(const Semaphore &);

    };

    Mutex _QueueMutex;
    Semaphore _DataAvailableSemaphore;

private://class members.
    /// constructor.
    FastRpcChannel();

    void check_and_expand_data_buffer(int32_t index, int32_t length);

    bool IsControlQFull();
    bool IsControlQEmpty();
    bool IsDataQFull();
    bool IsDataQEmpty();
    int32_t DataQSize();
    int32_t ControlQSize();

    int32_t get_msg_size_at(bool isData, int32_t index);
    int32_t copy_msg_to_buffer(bool isData, int32_t src_index, uint8_t *dst_buffer, int32_t offset, int32_t dst_buffer_len);
    int16_t control_msg_queue_add(int32_t msgtype, const char *messageName);

    std::set<std::string> _RemoteSubscribers;
};

#endif /* _uORBFastRpcChannel_hpp_ */