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/MDH/Integral.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

ONIXS_CMEMDH_LTWT_CLASS_DECL(NetFeed);
ONIXS_CMEMDH_EXPORTED_CLASS_DECL(NetFeedLink);
ONIXS_CMEMDH_EXPORTED_STRUCT_DECL(WatchService);

/// Designed to reflect various aspects
/// of feed engine processing flow.
class ONIXS_CMEMDH_LTWT 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 absence have been dispatched.
    bool eventsDispatched() const
    {
        return 0 != eventsDispatched_;
    }

    /// Indicates whether feed-related events like
    /// data reception or absence 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.
class ONIXS_CMEMDH_EXPORTED 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;

    /// A 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 retrieval 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;

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

private:
    NetFeedEngine(const NetFeedEngine&);

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

/// Carries out pending actions like
/// data retrieval 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_CMEMDH_NAMESPACE_END