FeedEngineThreadPool.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
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// 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 <vector>

#include <OnixS/CME/MDH/String.h>
#include <OnixS/CME/MDH/Integral.h>
#include <OnixS/CME/MDH/TinySet.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

ONIXS_CMEMDH_EXPORTED_CLASS_DECL(FeedEngineThreadPool);

/// Listener for thread-related events.
///
/// Members of this classes are invoked to reflect
/// various life-time events of threads spawned and
/// used by feed engines while processing market data.
struct ONIXS_CMEMDH_EXPORTED FeedEngineThreadPoolListener
{
    /// Invoked by the thread before entering the processing loop.
    ///
    /// @note This callback allows the subscriber to perform thread-specific tuning (e.g., setting thread affinity or priority).
    virtual void onFeedEngineThreadBegin(const FeedEngineThreadPool&) {}

    /// Invoked by the thread when it is about to end.
    ///
    /// @note This callback allows the subscriber to perform thread-specific cleanup.
    virtual void onFeedEngineThreadEnd(const FeedEngineThreadPool&) {}

    /// Invoked when the thread is idle.
    ///
    /// @return `true` if the thread should sleep for some time to reduce the CPU load, and `false` - to resume processing without delay.
    virtual bool onFeedEngineThreadIdle(const FeedEngineThreadPool&)
    {
        return false;
    }

    /// Invoked when the thread experiences an issue while processing its tasks.
    /// Once invoked, the thread continues performing its tasks.
    virtual void onFeedEngineThreadIssue(const FeedEngineThreadPool&, const Char*){}
};

/// Zero-based index of CPU.
typedef Int32 CpuIndex;

/// Alias for collection of CPU indices.
typedef TinySet<CpuIndex> CpuIndices;

/// Represents a set of CPU indices.
class ONIXS_CMEMDH_LTWT ThreadAffinity
{
public:
    /// Initializes the empty set.
    ThreadAffinity() {}

    /// Initializes as a copy of the other set.
    ThreadAffinity(const ThreadAffinity& other)
        : indices_(other.indices_)
    {
    }

    /// Utilizes internal resources.
    ~ThreadAffinity() {}

    /// Indicates whether affinity is defined.
    operator bool() const
    {
        return indices_.empty();
    }

    /// Read-only access to the indices.
    const CpuIndices& cpus() const
    {
        return indices_;
    }

    /// Collection of the CPU indices.
    CpuIndices& cpus()
    {
        return indices_;
    }

private:
    CpuIndices indices_;
};

/// Serializes thread affinity into a string.
ONIXS_CMEMDH_EXPORTED
void toStr(std::string&, const ThreadAffinity&);

/// Serializes thread affinity into a string.
inline std::string toStr(const ThreadAffinity& affinity)
{
    std::string str;

    toStr(str, affinity);

    return str;
}

//

/// The collection of parameters affecting behavior
/// of a thread pool. The given class serves as a base for
/// defining and manipulating thread pool related parameters.
class ONIXS_CMEMDH_LTWT ThreadPoolSettings
{
public:
    /// Assigns the default values for the given
    /// instance of the thread pool settings.
    ThreadPoolSettings()
        : affinity_()
        , size_(1)
    {
    }

    /// Cleans everything up.
    ~ThreadPoolSettings() {}

    /// Defines set of CPUs allowed for each working
    /// thread to be executed on while running tasks.
    ///
    /// @note By default set is empty thus allowing threads
    /// to be executed on any CPU available in the system.
    const ThreadAffinity& affinity() const
    {
        return affinity_;
    }

    /// Defines set of CPUs allowed for each working
    /// thread to be executed on while running tasks.
    ///
    /// @note By default set is empty thus allowing threads
    /// to be executed on any CPU available in the system.
    ThreadAffinity& affinity()
    {
        return affinity_;
    }

    /// Number of working threads in the pool.
    ///
    /// @note Default value is '1'.
    UInt32 size() const
    {
        return size_;
    }

    /// Defines the number of working threads in the pool.
    ThreadPoolSettings& size(UInt32 value)
    {
        size_ = value;
        return *this;
    }

private:
    ThreadAffinity affinity_;
    UInt32 size_;
};

/// Serializes thread pool settings into a string.
ONIXS_CMEMDH_EXPORTED
void toStr(std::string&, const ThreadPoolSettings&);

/// Serializes thread pool settings into a string.
inline std::string toStr(const ThreadPoolSettings& settings)
{
    std::string str;

    toStr(str, settings);

    return str;
}

/// The collection of parameters affecting behavior
/// of a Feed Engine thread pool.
class ONIXS_CMEMDH_LTWT FeedEngineThreadSettings
{
public:
    /// Assigns the default values for the given
    /// instance of the thread pool settings.
    FeedEngineThreadSettings()
        : loopBeforeIdle_(1)
    {
    }

    /// Settings related to the thread pool.
    ThreadPoolSettings& pool()
    {
        return pool_;
    }

    /// Settings related to the thread pool.
    const ThreadPoolSettings& pool() const
    {
        return pool_;
    }

    /// Defines amount of cycles a working thread keeps
    /// cycling before entering the idle state if no useful
    /// activity can be done.
    ///
    /// Value is measured in number of processing cycles.
    ///
    /// @note Default value is '1'.
    ///
    /// @warning The given parameter may direct influence
    /// onto CPU load.
    UInt32 loopBeforeIdle() const
    {
        return loopBeforeIdle_;
    }

    /// Updates amount of cycles a working thread keeps
    /// cycling before entering the idle state if no useful
    /// activity can be done.
    ///
    /// @see loopBeforeIdle.
    void loopBeforeIdle(UInt32 value)
    {
        loopBeforeIdle_ = value;
    }

private:
    ThreadPoolSettings pool_;
    UInt32 loopBeforeIdle_;
};

/// Serializes settings defining behavior
/// of feed engine threads into a string.
ONIXS_CMEMDH_EXPORTED
void toStr(std::string&, const FeedEngineThreadSettings&);

/// Serializes settings defining behavior
/// of feed engine threads into a string.
inline std::string toStr(const FeedEngineThreadSettings& settings)
{
    std::string str;

    toStr(str, settings);

    return str;
}

ONIXS_CMEMDH_EXPORTED_CLASS_DECL(NetFeedEngine);

/// A pool of threads executing feed engine tasks.
class ONIXS_CMEMDH_EXPORTED FeedEngineThreadPool
{
public:
    /// Initializes working threads and spawns
    /// feed engine process() routine invocation.
    FeedEngineThreadPool(NetFeedEngine&, const FeedEngineThreadSettings&, FeedEngineThreadPoolListener* = ONIXS_CMEMDH_NULLPTR);

    /// Stops all tasks and destructs the working threads.
    ~FeedEngineThreadPool();

private:
    class Workhorse;
    Workhorse* workhorse_;
};


/// Current thread related tasks.
class ONIXS_CMEMDH_EXPORTED ThisThread
{
public:
    /// Sets the processor affinity mask for the current thread.
    static void affinity(const ThreadAffinity&);
    static void affinity(CpuIndex);
};

ONIXS_CMEMDH_NAMESPACE_END