thread.h

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      const PString & threadName = PString::Empty() ///< The name of the thread (for Debug/Trace)
    );

    /** Destroy the thread, this simply calls the #Terminate()# function
       with all its restrictions and penalties. See that function for more
       information.

       Note that the correct way for a thread to terminate is to return from
       the #Main()# function.
     */
    ~PThread();
  //@}

  /**@name Overrides from PObject */
  //@{
    /**Standard stream print function.
       The PObject class has a << operator defined that calls this function
       polymorphically.
      */
    void PrintOn(
      ostream & strm    ///< Stream to output text representation
    ) const;
  //@}

  /**@name Control functions */
  //@{
    /** Restart a terminated thread using the same stack priority etc that
       was current when the thread terminated.
       
       If the thread is still running then this function is ignored.
     */
    virtual void Restart();

    /** Terminate the thread. It is highly recommended that this is not used
       except in abnormal abort situations as not all clean up of resources
       allocated to the thread will be executed. This is especially true in
       C++ as the destructors of objects that are automatic variables are not
       called causing at the very least the possiblity of memory leaks.

       Note that the correct way for a thread to terminate is to return from
       the #Main()# function or self terminate by calling
       #Terminate()# within the context of the thread which can then
       assure that all resources are cleaned up.
     */
    virtual void Terminate();

    /** Determine if the thread has been terminated or ran to completion.

       @return
       TRUE if the thread has been terminated.
     */
    virtual BOOL IsTerminated() const;

    /** Block and wait for the thread to terminate.

       @return
       FALSE if the thread has not terminated and the timeout has expired.
     */
    void WaitForTermination() const;
    BOOL WaitForTermination(
      const PTimeInterval & maxWait  ///< Maximum time to wait for termination.
    ) const;

    /** Suspend or resume the thread.
    
       If #susp# is TRUE this increments an internal count of
       suspensions that must be matched by an equal number of calls to
       #Resume()# or #Suspend(FALSE)# before the
       thread actually executes again.

       If #susp# is FALSE then this decrements the internal count of
       suspensions. If the count is <= 0 then the thread will run. Note that
       the thread will not be suspended until an equal number of
       #Suspend(TRUE)# calls are made.
     */
    virtual void Suspend(
      BOOL susp = TRUE    ///< Flag to suspend or resume a thread.
    );

    /** Resume thread execution, this is identical to
       #Suspend(FALSE)#.

      The Resume() method may be called from within the constructor of a
      PThread descendant.  However, the Resume() should be in the
      constructor of the most descendant class. So, if you have a
      class B (which is descended of PThread), and a class C (which is
      descended of B), placing the call to Resume in the constructor of B is
      unwise.

      If you do place a call to Resume in the constructor, it
      should be at the end of the constructor, after all the other
      initialisation in the constructor.

      The reason the call to Resume() should be at the end of the
      construction process is simple - you want the thread to start
      when all the variables in the class have been correctly
      initialised.
     */
    virtual void Resume();

    /** Determine if the thread is currently suspended. This checks the
       suspension count and if greater than zero returns TRUE for a suspended
       thread.

       @return
       TRUE if thread is suspended.
     */
    virtual BOOL IsSuspended() const;

    /// Suspend the current thread for the specified amount of time.
    static void Sleep(
      const PTimeInterval & delay   ///< Time interval to sleep for.
    );

    /** Set the priority of the thread relative to other threads in the current
       process.
     */
    virtual void SetPriority(
      Priority priorityLevel    ///< New priority for thread.
    );

    /** Get the current priority of the thread in the current process.

       @return
       current thread priority.
     */
    virtual Priority GetPriority() const;

    /** Set the flag indicating thread object is to be automatically deleted
        when the thread ends.
     */
    virtual void SetAutoDelete(
      AutoDeleteFlag deletion = AutoDeleteThread  ///< New auto delete setting.
    );

    /** Reet the flag indicating thread object is to be automatically deleted
        when the thread ends.
     */
    void SetNoAutoDelete() { SetAutoDelete(NoAutoDeleteThread); }

    /** Get the name of the thread. Thread names are a optional debugging aid.

       @return
       current thread name.
     */
    virtual PString GetThreadName() const;

    /** Change the name of the thread. Thread names are a optional debugging aid.

       @return
       current thread name.
     */
    virtual void SetThreadName(
      const PString & name        ///< New name for the thread.
    );
  //@}

  /**@name Miscellaneous */
  //@{
    /** Get operating system specific thread identifier for this thread.
      * Note that the return value from these functions is only valid
      * if called by the owning thread. Calling this function for another
      * thread that may be terminating is a very bad idea.
      */
    virtual PThreadIdentifier GetThreadId() const;
    static PThreadIdentifier GetCurrentThreadId();

    /** User override function for the main execution routine of the thread. A
       descendent class must provide the code that will be executed in the
       thread within this function.
       
       Note that the correct way for a thread to terminate is to return from
       this function.
     */
    virtual void Main() = 0;

    /** Get the currently running thread object instance. It is possible, even
       likely, that the smae code may be executed in the context of differenct
       threads. Under some circumstances it may be necessary to know what the
       current codes thread is and this static function provides that
       information.

       @return
       pointer to current thread.
     */
    static PThread * Current();

    /** Yield to another thread without blocking.
        This duplicates the implicit thread yield that may occur on some
        I/O operations or system calls.

        This may not be implemented on all platforms.
     */
    static void Yield();

    /**Create a simple thread executing the specified notifier.
       This creates a simple PThread class that automatically executes the
       function defined by the PNotifier in the context of a new thread.
      */
    static PThread * Create(
      const PNotifier & notifier,     ///< Function to execute in thread.
      INT parameter = 0,              ///< Parameter value to pass to notifier.
      AutoDeleteFlag deletion = AutoDeleteThread,
        ///< Automatically delete PThread instance on termination of thread.
      Priority priorityLevel = NormalPriority,  ///< Initial priority of thread.
      const PString & threadName = PString::Empty(), ///< The name of the thread (for Debug/Trace)
      PINDEX stackSize = 10000         ///< Stack size on some platforms
    );
  //@}

  protected:
    void InitialiseProcessThread();
    /* Initialialise the primordial thread, the one in the PProcess. This is
       required due to the bootstrap logic of processes and threads.
     */

  private:
    PThread();
    // Create a new thread instance as part of a PProcess class.

    friend class PProcess;
    // So a PProcess can get at PThread() constructor but nothing else.

    PThread(const PThread &) { }
    // Empty constructor to prevent copying of thread instances.

    PThread & operator=(const PThread &) { return *this; }
    // Empty assignment operator to prevent copying of thread instances.

    BOOL autoDelete;
    // Automatically delete the thread on completion.

    // Give the thread a name for debugging purposes.
    PString threadName;

  private:
    unsigned traceBlockIndentLevel;
    friend class PTrace::Block;


// Include platform dependent part of class
#ifdef _WIN32
#include "msos/ptlib/thread.h"
#else
#include "unix/ptlib/thread.h"
#endif
};

#endif // _PTHREAD

// End Of File ///////////////////////////////////////////////////////////////