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/*! @file
 *  Pool of threads.
 */
#ifndef THREAD_POOL_H
#define THREAD_POOL_H

#include "../Utils/runnable.h"
#include "../Utils/threadlib.h"

/*!
 * Runnable object that exits the current thread.
 */
class EXIT_THREAD_OBJ : public RUNNABLE_OBJ
{
public:
    void Run() {ExitCurrentThread();}
};

/*!
 * Pool of threads that can be used to execute runnable objects.
 * External access to this singleton must be serialized. It is guaranteed
 * if the thread pool is managed by a single (main) thread of the process.
 */
class THREAD_POOL
{
public:

    // Constructor
    THREAD_POOL() : m_numThreads(0) {}

    // Destructor
    ~THREAD_POOL() {TerminateAll();}

    // Create specified number of new threads in the pool.
    // @return number of threads created successfully
    unsigned long Create(unsigned long numThreads);

    // Start running the specified object in the specified thread.
    // The function is non-blocking - it does not wait for the completion
    // of the RUNNABLE_OBJ::Run() function.
    // @return TRUE - success, FALSE - failure
    bool Start(unsigned long tid, RUNNABLE_OBJ * runObj); 

    // Block the current thread until a runnable object, assigned to the specified thread,
    // completes its function,
    // @return runnable object assigned to the thread or NULL.
    RUNNABLE_OBJ * Wait(unsigned long tid); 

    unsigned long NumThreads() const {return m_numThreads;}

    // Terminate all threads in the pool.
    void TerminateAll();

private:
    unsigned long m_numThreads;

    struct TLS_ELEMENT
    {
        THREAD_HANDLE m_handle;
        RUNNABLE_OBJ * volatile m_runObj;
        volatile bool m_semaphore;

        // Initialize TLS element
        void Init() {m_handle = 0; m_runObj = 0; m_semaphore = false;}

        // Semaphore manipulation functions
        void SwitchSemaphore(bool semaphoreState);
        void WaitSemaphore(bool semaphoreState) const;
        bool CheckSemaphore() const;

    }m_tls[MAXTHREADS];

    //Disable copy constructor and assignment operator
    THREAD_POOL(const THREAD_POOL &);
    THREAD_POOL & operator = (const THREAD_POOL &);

    // Main routine of threads in the pool
    static void * ThreadRoutine(void * tlsArg);
};

#endif //THREAD_POOL_H

/* ===================================================================== */
/* eof */
/* ===================================================================== */
