service_server.hpp

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/*
 * Copyright (C) 2014 Pavel Kirienko <pavel.kirienko@gmail.com>
 */
 
#ifndef UAVCAN_NODE_SERVICE_SERVER_HPP_INCLUDED
#define UAVCAN_NODE_SERVICE_SERVER_HPP_INCLUDED
 
#include <uavcan/build_config.hpp>
#include <uavcan/node/generic_publisher.hpp>
#include <uavcan/node/generic_subscriber.hpp>
 
#if !defined(UAVCAN_CPP_VERSION) || !defined(UAVCAN_CPP11)
# error UAVCAN_CPP_VERSION
#endif
 
#if UAVCAN_CPP_VERSION >= UAVCAN_CPP11
# include <functional>
#endif
 
namespace uavcan
{
template <typename ResponseDataType_>
class ServiceResponseDataStructure : public ResponseDataType_
{
    // Fields are weirdly named to avoid name clashing with the inherited data type
    bool _enabled_;
 
public:
    typedef ResponseDataType_ ResponseDataType;
 
    ServiceResponseDataStructure()
        : _enabled_(true)
    { }
 
    void setResponseEnabled(bool x) { _enabled_ = x; }
 
    bool isResponseEnabled() const { return _enabled_; }
};
 
template <typename DataType_,
#if UAVCAN_CPP_VERSION >= UAVCAN_CPP11
          typename Callback_ = std::function<void (const ReceivedDataStructure<typename DataType_::Request>&,
                                                   ServiceResponseDataStructure<typename DataType_::Response>&)>
#else
          typename Callback_ = void (*)(const ReceivedDataStructure<typename DataType_::Request>&,
                                        ServiceResponseDataStructure<typename DataType_::Response>&)
#endif
          >
class UAVCAN_EXPORT ServiceServer
    : public GenericSubscriber<DataType_, typename DataType_::Request, TransferListener>
{
public:
    typedef DataType_ DataType;
    typedef typename DataType::Request RequestType;
    typedef typename DataType::Response ResponseType;
    typedef Callback_ Callback;
 
private:
    typedef GenericSubscriber<DataType, RequestType, TransferListener> SubscriberType;
    typedef GenericPublisher<DataType, ResponseType> PublisherType;
 
    PublisherType publisher_;
    Callback callback_;
    uint32_t response_failure_count_;
 
    virtual void handleReceivedDataStruct(ReceivedDataStructure<RequestType>& request)
    {
        UAVCAN_ASSERT(request.getTransferType() == TransferTypeServiceRequest);
 
        ServiceResponseDataStructure<ResponseType> response;
 
        if (coerceOrFallback<bool>(callback_, true))
        {
            UAVCAN_ASSERT(response.isResponseEnabled());  // Enabled by default
            callback_(request, response);
        }
        else
        {
            handleFatalError("Srv serv clbk");
        }
 
        if (response.isResponseEnabled())
        {
            publisher_.setPriority(request.getPriority());      // Responding at the same priority.
 
            const int res = publisher_.publish(response, TransferTypeServiceResponse, request.getSrcNodeID(),
                                               request.getTransferID());
            if (res < 0)
            {
                UAVCAN_TRACE("ServiceServer", "Response publication failure: %i", res);
                publisher_.getNode().getDispatcher().getTransferPerfCounter().addError();
                response_failure_count_++;
            }
        }
        else
        {
            UAVCAN_TRACE("ServiceServer", "Response was suppressed by the application");
        }
    }
 
public:
    explicit ServiceServer(INode& node)
        : SubscriberType(node)
        , publisher_(node, getDefaultTxTimeout())
        , callback_()
        , response_failure_count_(0)
    {
        UAVCAN_ASSERT(getTxTimeout() == getDefaultTxTimeout());  // Making sure it is valid
 
        StaticAssert<DataTypeKind(DataType::DataTypeKind) == DataTypeKindService>::check();
    }
 
    int start(const Callback& callback)
    {
        stop();
 
        if (!coerceOrFallback<bool>(callback, true))
        {
            UAVCAN_TRACE("ServiceServer", "Invalid callback");
            return -ErrInvalidParam;
        }
        callback_ = callback;
 
        const int publisher_res = publisher_.init();
        if (publisher_res < 0)
        {
            UAVCAN_TRACE("ServiceServer", "Publisher initialization failure: %i", publisher_res);
            return publisher_res;
        }
        return SubscriberType::startAsServiceRequestListener();
    }
 
    using SubscriberType::stop;
 
    static MonotonicDuration getDefaultTxTimeout() { return MonotonicDuration::fromMSec(1000); }
    static MonotonicDuration getMinTxTimeout() { return PublisherType::getMinTxTimeout(); }
    static MonotonicDuration getMaxTxTimeout() { return PublisherType::getMaxTxTimeout(); }
 
    MonotonicDuration getTxTimeout() const { return publisher_.getTxTimeout(); }
    void setTxTimeout(MonotonicDuration tx_timeout) { publisher_.setTxTimeout(tx_timeout); }
 
    uint32_t getRequestFailureCount() const { return SubscriberType::getFailureCount(); }
    uint32_t getResponseFailureCount() const { return response_failure_count_; }
};
 
}
 
#endif // UAVCAN_NODE_SERVICE_SERVER_HPP_INCLUDED