FeedEngineListener.h

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/*
 * Copyright (c) Onix Solutions Limited. All rights reserved.
 *
 * This software owned by Onix Solutions Limited 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 "Export.h"

namespace OnixS { namespace ICE { namespace iMpact { namespace MarketData {

/// Identifies reasons feed engine threads becomes idle.
struct FeedEngineThreadIdleReasons
{
    /// \copydoc FeedEngineThreadIdleReasons
    enum Enum
    {
        /// Thread waited for incoming data using corresponding
        /// I/O operations (like 'select') and exited waiting with
        /// no data availability signs.
        DataWaitTimeout,

        /// Thread entered idle state due to absence of any data and
        /// while other threads are waiting for new incoming data.
        Redundant
    };
};

/// Reason feed engine threads becomes idle.
typedef FeedEngineThreadIdleReasons::Enum FeedEngineThreadIdleReason;

/// forward declarations
class FeedEngine;

/// Listener for thread-related events.
///
/// Members of this classes are invoked to reflect
/// various life-time events of threads spawned and
/// used by the feed engine while processing market data.
class ONIXS_ICEMDH_EXPORT FeedEngineListener
{
public:
    /// Member invoked by feed engine when
    /// a new processing thread is spawned.
    ///
    /// \note Invocation is done within newly started thread.
    ///
    /// \param engine An instance of the feed angine.
    virtual void onFeedEngineThreadBegin(const FeedEngine& engine);

    /// Member is invoked by feed engine when processing
    /// thread is about to end.
    ///
    /// \note Invocation is done within the thread that is
    /// about to end.
    ///
    /// \param engine An instance of the feed angine.
    virtual void onFeedEngineThreadEnd(const FeedEngine& engine);

    /// Is called when feed engine's thread is idle.
    ///
    /// Thread becomes idle when either no data is received within
    /// time interval defined by FeedEngineSettings::dataWaitTime
    /// parameter or no pending data is available for processing.
    /// In the first case, callback is invoked with 'DataWaitTimeout'
    /// reason. In the second case, thread is considered as redundant
    /// and thus callback is invoked with 'Redundant' reason.
    /// After callback invocation threads may sleep in kernel to reduce
    /// load onto CPU and racing between feed engine working threads.
    ///
    /// \param engine An instance of the feed angine.
    /// \param reason Reason feed engine threads becomes idle.
    /// \param timeout Defines amount of time feed engine suggest
    /// for thread to sleep in kernel after invoking given member.
    virtual void onFeedEngineThreadIdle(
        const FeedEngine& engine,
        FeedEngineThreadIdleReason reason,
        unsigned int& timeout
    );

protected:
    virtual ~FeedEngineListener() {}
};

inline void FeedEngineListener::onFeedEngineThreadBegin(const FeedEngine&) {}

inline void FeedEngineListener::onFeedEngineThreadEnd(const FeedEngine&) {}

inline void FeedEngineListener::onFeedEngineThreadIdle(const FeedEngine&, FeedEngineThreadIdleReason, unsigned int&) {}

}}}} // namespace OnixS::ICE::iMpact::MarketData