service_client.hpp

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/*
 * Copyright (C) 2014 Pavel Kirienko <pavel.kirienko@gmail.com>
 */
 
#ifndef UAVCAN_NODE_SERVICE_CLIENT_HPP_INCLUDED
#define UAVCAN_NODE_SERVICE_CLIENT_HPP_INCLUDED
 
#include <uavcan/build_config.hpp>
#include <uavcan/util/multiset.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
{
struct ServiceCallID
{
    NodeID server_node_id;
    TransferID transfer_id;
 
    ServiceCallID() { }
 
    ServiceCallID(NodeID arg_server_node_id, TransferID arg_transfer_id)
        : server_node_id(arg_server_node_id)
        , transfer_id(arg_transfer_id)
    { }
 
    bool operator==(const ServiceCallID rhs) const
    {
        return (rhs.server_node_id == server_node_id) &&
               (rhs.transfer_id == transfer_id);
    }
 
    bool isValid() const { return server_node_id.isUnicast(); }
};
 
template <typename DataType>
class UAVCAN_EXPORT ServiceCallResult : Noncopyable
{
public:
    typedef ReceivedDataStructure<typename DataType::Response> ResponseFieldType;
 
    enum Status { Success, ErrorTimeout };
 
private:
    const Status status_;               
    ServiceCallID call_id_;             
    ResponseFieldType& response_;       
 
public:
    ServiceCallResult(Status arg_status, ServiceCallID arg_call_id, ResponseFieldType& arg_response)
        : status_(arg_status)
        , call_id_(arg_call_id)
        , response_(arg_response)
    {
        UAVCAN_ASSERT(call_id_.isValid());
        UAVCAN_ASSERT((status_ == Success) || (status_ == ErrorTimeout));
    }
 
    bool isSuccessful() const { return status_ == Success; }
 
    Status getStatus() const { return status_; }
 
    ServiceCallID getCallID() const { return call_id_; }
 
    const ResponseFieldType& getResponse() const { return response_; }
    ResponseFieldType& getResponse() { return response_; }
};
 
template <typename Stream, typename DataType>
static Stream& operator<<(Stream& s, const ServiceCallResult<DataType>& scr)
{
    s << "# Service call result [" << DataType::getDataTypeFullName() << "] "
      << (scr.isSuccessful() ? "OK" : "FAILURE")
      << " server_node_id=" << int(scr.getCallID().server_node_id.get())
      << " tid=" << int(scr.getCallID().transfer_id.get()) << "\n";
    if (scr.isSuccessful())
    {
        s << scr.getResponse();
    }
    else
    {
        s << "# (no data)";
    }
    return s;
}
 
class ServiceClientBase : protected ITransferAcceptanceFilter
                        , protected DeadlineHandler
{
    const DataTypeDescriptor* data_type_descriptor_;  
 
protected:
    class CallState : DeadlineHandler
    {
        ServiceClientBase& owner_;
        const ServiceCallID id_;
        bool timed_out_;
 
        virtual void handleDeadline(MonotonicTime);
 
    public:
        CallState(INode& node, ServiceClientBase& owner, ServiceCallID call_id)
            : DeadlineHandler(node.getScheduler())
            , owner_(owner)
            , id_(call_id)
            , timed_out_(false)
        {
            UAVCAN_ASSERT(id_.isValid());
            DeadlineHandler::startWithDelay(owner_.request_timeout_);
        }
 
        ServiceCallID getCallID() const { return id_; }
 
        bool hasTimedOut() const { return timed_out_; }
 
        static bool hasTimedOutPredicate(const CallState& cs) { return cs.hasTimedOut(); }
 
        bool operator==(const CallState& rhs) const
        {
            return (&owner_ == &rhs.owner_) && (id_ == rhs.id_);
        }
    };
 
    struct CallStateMatchingPredicate
    {
        const ServiceCallID id;
        CallStateMatchingPredicate(ServiceCallID reference) : id(reference) { }
        bool operator()(const CallState& state) const { return (state.getCallID() == id) && !state.hasTimedOut(); }
    };
 
    struct ServerSearchPredicate
    {
        const NodeID server_node_id;
        ServerSearchPredicate(NodeID nid) : server_node_id(nid) { }
        bool operator()(const CallState& state) const { return state.getCallID().server_node_id == server_node_id; }
    };
 
    MonotonicDuration request_timeout_;
 
    ServiceClientBase(INode& node)
        : DeadlineHandler(node.getScheduler())
        , data_type_descriptor_(UAVCAN_NULLPTR)
        , request_timeout_(getDefaultRequestTimeout())
    { }
 
    virtual ~ServiceClientBase() { }
 
    int prepareToCall(INode& node, const char* dtname, NodeID server_node_id, ServiceCallID& out_call_id);
 
public:
    static MonotonicDuration getDefaultRequestTimeout() { return MonotonicDuration::fromMSec(1000); }
    static MonotonicDuration getMinRequestTimeout() { return MonotonicDuration::fromMSec(10); }
    static MonotonicDuration getMaxRequestTimeout() { return MonotonicDuration::fromMSec(60000); }
};
 
template <typename DataType_,
#if UAVCAN_CPP_VERSION >= UAVCAN_CPP11
          typename Callback_ = std::function<void (const ServiceCallResult<DataType_>&)>
#else
          typename Callback_ = void (*)(const ServiceCallResult<DataType_>&)
#endif
          >
class UAVCAN_EXPORT ServiceClient
    : public GenericSubscriber<DataType_,
                               typename DataType_::Response, TransferListenerWithFilter>
    , public ServiceClientBase
{
public:
    typedef DataType_ DataType;
    typedef typename DataType::Request RequestType;
    typedef typename DataType::Response ResponseType;
    typedef ServiceCallResult<DataType> ServiceCallResultType;
    typedef Callback_ Callback;
 
private:
    typedef ServiceClient<DataType, Callback> SelfType;
    typedef GenericPublisher<DataType, RequestType> PublisherType;
    typedef GenericSubscriber<DataType, ResponseType, TransferListenerWithFilter> SubscriberType;
 
    typedef Multiset<CallState> CallRegistry;
 
    struct TimeoutCallbackCaller
    {
        ServiceClient& owner;
 
        TimeoutCallbackCaller(ServiceClient& arg_owner) : owner(arg_owner) { }
 
        void operator()(const CallState& state)
        {
            if (state.hasTimedOut())
            {
                UAVCAN_TRACE("ServiceClient::TimeoutCallbackCaller", "Timeout from nid=%d, tid=%d, dtname=%s",
                             int(state.getCallID().server_node_id.get()), int(state.getCallID().transfer_id.get()),
                             DataType::getDataTypeFullName());
 
                typename SubscriberType::ReceivedDataStructureSpec rx_struct; // Default-initialized
 
                ServiceCallResultType result(ServiceCallResultType::ErrorTimeout, state.getCallID(),
                                             rx_struct);    // Mutable!
 
                owner.invokeCallback(result);
            }
        }
    };
 
    CallRegistry call_registry_;
 
    PublisherType publisher_;
    Callback callback_;
 
    virtual bool shouldAcceptFrame(const RxFrame& frame) const; // Called from the transfer listener
 
    void invokeCallback(ServiceCallResultType& result);
 
    virtual void handleReceivedDataStruct(ReceivedDataStructure<ResponseType>& response);
 
    virtual void handleDeadline(MonotonicTime);
 
    int addCallState(ServiceCallID call_id);
 
public:
    explicit ServiceClient(INode& node, const Callback& callback = Callback())
        : SubscriberType(node)
        , ServiceClientBase(node)
        , call_registry_(node.getAllocator())
        , publisher_(node, getDefaultRequestTimeout())
        , callback_(callback)
    {
        setPriority(TransferPriority::MiddleLower);
        setRequestTimeout(getDefaultRequestTimeout());
#if UAVCAN_DEBUG
        UAVCAN_ASSERT(getRequestTimeout() == getDefaultRequestTimeout());  // Making sure default values are OK
#endif
    }
 
    virtual ~ServiceClient() { cancelAllCalls(); }
 
    int init()
    {
        return publisher_.init();
    }
 
    int init(TransferPriority priority)
    {
        return publisher_.init(priority);
    }
 
    int call(NodeID server_node_id, const RequestType& request);
 
    int call(NodeID server_node_id, const RequestType& request, ServiceCallID& out_call_id);
 
    void cancelCall(ServiceCallID call_id);
 
    void cancelAllCalls();
 
    bool hasPendingCallToServer(NodeID server_node_id) const;
 
    ServiceCallID getCallIDByIndex(unsigned index) const;
 
    const Callback& getCallback() const { return callback_; }
    void setCallback(const Callback& cb) { callback_ = cb; }
 
    unsigned getNumPendingCalls() const { return call_registry_.getSize(); }
 
    bool hasPendingCalls() const { return !call_registry_.isEmpty(); }
 
    uint32_t getResponseFailureCount() const { return SubscriberType::getFailureCount(); }
 
    MonotonicDuration getRequestTimeout() const { return request_timeout_; }
    void setRequestTimeout(MonotonicDuration timeout)
    {
        timeout = max(timeout, getMinRequestTimeout());
        timeout = min(timeout, getMaxRequestTimeout());
 
        publisher_.setTxTimeout(timeout);
        request_timeout_ = max(timeout, publisher_.getTxTimeout());  // No less than TX timeout
    }
 
    TransferPriority getPriority() const { return publisher_.getPriority(); }
    void setPriority(const TransferPriority prio) { publisher_.setPriority(prio); }
};
 
// ----------------------------------------------------------------------------
 
template <typename DataType_, typename Callback_>
void ServiceClient<DataType_, Callback_>::invokeCallback(ServiceCallResultType& result)
{
    if (coerceOrFallback<bool>(callback_, true))
    {
        callback_(result);
    }
    else
    {
        handleFatalError("Srv client clbk");
    }
}
 
template <typename DataType_, typename Callback_>
bool ServiceClient<DataType_, Callback_>::shouldAcceptFrame(const RxFrame& frame) const
{
    UAVCAN_ASSERT(frame.getTransferType() == TransferTypeServiceResponse); // Other types filtered out by dispatcher
 
    return UAVCAN_NULLPTR != call_registry_.find(CallStateMatchingPredicate(ServiceCallID(frame.getSrcNodeID(),
                                                                                          frame.getTransferID())));
 
}
 
template <typename DataType_, typename Callback_>
void ServiceClient<DataType_, Callback_>::handleReceivedDataStruct(ReceivedDataStructure<ResponseType>& response)
{
    UAVCAN_ASSERT(response.getTransferType() == TransferTypeServiceResponse);
 
    ServiceCallID call_id(response.getSrcNodeID(), response.getTransferID());
    cancelCall(call_id);
    ServiceCallResultType result(ServiceCallResultType::Success, call_id, response);    // Mutable!
    invokeCallback(result);
}
 
 
template <typename DataType_, typename Callback_>
void ServiceClient<DataType_, Callback_>::handleDeadline(MonotonicTime)
{
    UAVCAN_TRACE("ServiceClient", "Shared deadline event received");
    /*
     * Invoking callbacks for timed out call state objects.
     */
    TimeoutCallbackCaller callback_caller(*this);
    call_registry_.template forEach<TimeoutCallbackCaller&>(callback_caller);
    /*
     * Removing timed out objects.
     * This operation cannot be merged with the previous one because that will not work with recursive calls.
     */
    call_registry_.removeAllWhere(&CallState::hasTimedOutPredicate);
    /*
     * Subscriber does not need to be registered if we don't have any pending calls.
     * Removing it makes processing of incoming frames a bit faster.
     */
    if (call_registry_.isEmpty())
    {
        SubscriberType::stop();
    }
}
 
template <typename DataType_, typename Callback_>
int ServiceClient<DataType_, Callback_>::addCallState(ServiceCallID call_id)
{
    if (call_registry_.isEmpty())
    {
        const int subscriber_res = SubscriberType::startAsServiceResponseListener();
        if (subscriber_res < 0)
        {
            UAVCAN_TRACE("ServiceClient", "Failed to start the subscriber, error: %i", subscriber_res);
            return subscriber_res;
        }
    }
 
    if (UAVCAN_NULLPTR == call_registry_.template emplace<INode&, ServiceClientBase&,
                                                          ServiceCallID>(SubscriberType::getNode(), *this, call_id))
    {
        SubscriberType::stop();
        return -ErrMemory;
    }
 
    return 0;
}
 
template <typename DataType_, typename Callback_>
int ServiceClient<DataType_, Callback_>::call(NodeID server_node_id, const RequestType& request)
{
   ServiceCallID dummy;
   return call(server_node_id, request, dummy);
}
 
template <typename DataType_, typename Callback_>
int ServiceClient<DataType_, Callback_>::call(NodeID server_node_id, const RequestType& request,
                                              ServiceCallID& out_call_id)
{
    if (!coerceOrFallback<bool>(callback_, true))
    {
        UAVCAN_TRACE("ServiceClient", "Invalid callback");
        return -ErrInvalidConfiguration;
    }
 
    /*
     * Common procedures that don't depend on the struct data type
     */
    const int prep_res =
        prepareToCall(SubscriberType::getNode(), DataType::getDataTypeFullName(), server_node_id, out_call_id);
    if (prep_res < 0)
    {
        UAVCAN_TRACE("ServiceClient", "Failed to prepare the call, error: %i", prep_res);
        return prep_res;
    }
 
    /*
     * Initializing the call state - this will start the subscriber ad-hoc
     */
    const int call_state_res = addCallState(out_call_id);
    if (call_state_res < 0)
    {
        UAVCAN_TRACE("ServiceClient", "Failed to add call state, error: %i", call_state_res);
        return call_state_res;
    }
 
    /*
     * Configuring the listener so it will accept only the matching responses
     * TODO move to init(), but this requires to somewhat refactor GenericSubscriber<> (remove TransferForwarder)
     */
    TransferListenerWithFilter* const tl = SubscriberType::getTransferListener();
    if (tl == UAVCAN_NULLPTR)
    {
        UAVCAN_ASSERT(0);  // Must have been created
        cancelCall(out_call_id);
        return -ErrLogic;
    }
    tl->installAcceptanceFilter(this);
 
    /*
     * Publishing the request
     */
    const int publisher_res = publisher_.publish(request, TransferTypeServiceRequest, server_node_id,
                                                 out_call_id.transfer_id);
    if (publisher_res < 0)
    {
        cancelCall(out_call_id);
        return publisher_res;
    }
 
    UAVCAN_ASSERT(server_node_id == out_call_id.server_node_id);
    return publisher_res;
}
 
template <typename DataType_, typename Callback_>
void ServiceClient<DataType_, Callback_>::cancelCall(ServiceCallID call_id)
{
    call_registry_.removeFirstWhere(CallStateMatchingPredicate(call_id));
    if (call_registry_.isEmpty())
    {
        SubscriberType::stop();
    }
}
 
template <typename DataType_, typename Callback_>
void ServiceClient<DataType_, Callback_>::cancelAllCalls()
{
    call_registry_.clear();
    SubscriberType::stop();
}
 
template <typename DataType_, typename Callback_>
bool ServiceClient<DataType_, Callback_>::hasPendingCallToServer(NodeID server_node_id) const
{
    return UAVCAN_NULLPTR != call_registry_.find(ServerSearchPredicate(server_node_id));
}
 
template <typename DataType_, typename Callback_>
ServiceCallID ServiceClient<DataType_, Callback_>::getCallIDByIndex(unsigned index) const
{
    const CallState* const id = call_registry_.getByIndex(index);
    return (id == UAVCAN_NULLPTR) ? ServiceCallID() : id->getCallID();
}
 
}
 
#endif // UAVCAN_NODE_SERVICE_CLIENT_HPP_INCLUDED