FeedEngine.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
// This software owned by Onix Solutions Limited [OnixS] and is 
// protected by copyright law and international copyright treaties.
//
// Access to and use of the software is governed by the terms of the applicable 
// OnixS Software Services Agreement (the Agreement) and Customer end user license 
// agreements granting a non-assignable, non-transferable and non-exclusive license 
// to use the software for it's own data processing purposes under the terms defined 
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or 
// reproduction of any part of this source code or associated reference material 
// to any other location for further reproduction or redistribution, and any 
// amendments to this copyright notice, are expressly prohibited.
//
// Any reproduction or redistribution for sale or hiring of the Software not in 
// accordance with the terms of the Agreement is a violation of copyright law.
//

#pragma once

#include <string>

#include <OnixS/CME/ConflatedUDP/Integral.h>

ONIXS_CONFLATEDUDP_NAMESPACE_BEGIN

ONIXS_CONFLATEDUDP_LTWT_CLASS_DECL(NetFeed);
ONIXS_CONFLATEDUDP_EXPORTED_CLASS_DECL(NetFeedLink);
ONIXS_CONFLATEDUDP_EXPORTED_STRUCT_DECL(WatchService);

/// Designed to reflect various aspects 
/// of feed engine processing flow. 
ONIXS_CONFLATEDUDP_LTWT_CLASS 
NetFeedEngineProcessResult
{
public:
    /// Aliases integral type whose bits 
    /// are used to indicate flag presence. 
    typedef UInt32 Flags;

    /// Initializes zero-state instance. 
    NetFeedEngineProcessResult()
      : eventsDispatched_(0)
      , ioWaited_(0)
      , reserved_(0)
    {
    }

    /// Indicates whether feed-related events like 
    /// data reception or absense have been dispatched.
    bool 
    eventsDispatched() const
    {
        return 
            0 != 
            eventsDispatched_;
    }

    /// Indicates whether feed-related events like 
    /// data reception or absense have been dispatched.
    void 
    eventsDispatched(bool state)
    {
        eventsDispatched_ = 
            state 
            ? 1 
            : 0;
    }

    /// Indicates whether processing had to sleep 
    /// in kernel while checking data availability.
    bool 
    ioWaited() const
    {
        return 
            0 != 
            ioWaited_;
    }

    /// Indicates whether processing had to sleep 
    /// in kernel while checking data availability.
    void
    ioWaited(
        bool state)
    {
        ioWaited_ = 
            state 
            ? 1 
            : 0;
    }

    /// Reserved (unused) flags.
    Flags 
    reserved() const
    {
        return reserved_;
    }

    /// Reserved (unused) flags.
    void 
    reserved(
        Flags flags)
    {
        reserved_ = flags;
    }

private:
    Flags eventsDispatched_ : 1;
    Flags ioWaited_ : 1;
    Flags reserved_ : 30;
};

/// Abstraction for the Feed Engine machinery. 
/// 
/// The given abstract class exposes the interface 
/// through which instances of the Handler class 
/// manipulate feeds. 
ONIXS_CONFLATEDUDP_EXPORTED_CLASS NetFeedEngine
{
    NetFeedEngine(
        const NetFeedEngine&);

    NetFeedEngine& 
    operator =(
        const NetFeedEngine&);

protected:
    /// Construction through the descendants. 
    NetFeedEngine()
    {
    }

public:
    /// Finalizes the instance. 
    virtual ~NetFeedEngine()
    {
    }

    /// Provides information about the actual 
    /// implementation of the feed engine. 
    virtual 
    void 
    info(
        std::string&) = 0;

    /// Constructs a link for the given feed. 
    /// 
    /// Caller is responsible for releasing the returned 
    /// instance using the NetFeedLink::release() member. 
    virtual 
    NetFeedLink& 
    allocate(
        const NetFeed&) = 0;

    /// Watch service used by the Feed Engine 
    /// to assign timestamps for received packets 
    /// and to track heartbeats. 
    virtual
    WatchService& 
    watch() = 0;

    /// Carries out pending actions like 
    /// data retrival and event dispatching. 
    /// 
    /// The particular implementation of the feed 
    /// engine concept may have own specific on returned 
    /// value. Thus, see the documentation for the particular 
    /// feed engine on the behavior and returned value. 
    virtual 
    NetFeedEngineProcessResult
    process() = 0;
};

/// Carries out pending actions like 
/// data retrival and event dispatching. 
///
/// The returned value indicates whether any 
/// events have been handled by the engine. 
inline 
bool 
process(
    NetFeedEngine& engine)
{
    return 
        engine.
            process().
                eventsDispatched();
}

ONIXS_CONFLATEDUDP_NAMESPACE_END