source: trunk/synergy/lib/mt/CThread.h@ 3848

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2002 Chris Schoeneman
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#ifndef CTHREAD_H
#define CTHREAD_H

#include "IArchMultithread.h"

class IJob;

//! Thread handle
/*!
Creating a CThread creates a new context of execution (i.e. thread) that
runs simulatenously with the calling thread.  A CThread is only a handle
to a thread;  deleting a CThread does not cancel or destroy the thread it
refers to and multiple CThread objects can refer to the same thread.

Threads can terminate themselves but cannot be forced to terminate by
other threads.  However, other threads can signal a thread to terminate
itself by cancelling it.  And a thread can wait (block) on another thread
to terminate.

Most functions that can block for an arbitrary time are cancellation
points.  A cancellation point is a function that can be interrupted by
a request to cancel the thread.  Cancellation points are noted in the
documentation.
*/
// note -- do not derive from this class
class CThread {
public:
        //! Run \c adoptedJob in a new thread
        /*!
        Create and start a new thread executing the \c adoptedJob.  The
        new thread takes ownership of \c adoptedJob and will delete it.
        */
        CThread(IJob* adoptedJob);

        //! Duplicate a thread handle
        /*!
        Make a new thread object that refers to an existing thread.
        This does \b not start a new thread.
        */
        CThread(const CThread&);

        //! Release a thread handle
        /*!
        Release a thread handle.  This does not terminate the thread.  A thread
        will keep running until the job completes or calls exit() or allows
        itself to be cancelled.
        */
        ~CThread();

        //! @name manipulators
        //@{

        //! Assign thread handle
        /*!
        Assign a thread handle.  This has no effect on the threads, it simply
        makes this thread object refer to another thread.  It does \b not
        start a new thread.
        */
        CThread&                        operator=(const CThread&);

        //! Terminate the calling thread
        /*!
        Terminate the calling thread.  This function does not return but
        the stack is unwound and automatic objects are destroyed, as if
        exit() threw an exception (which is, in fact, what it does).  The
        argument is saved as the result returned by getResult().  If you
        have \c catch(...) blocks then you should add the following before
        each to avoid catching the exit:
        \code
        catch(CThreadExit&) { throw; }
        \endcode
        or add the \c RETHROW_XTHREAD macro to the \c catch(...) block.
        */
        static void                     exit(void*);

        //! Cancel thread
        /*!
        Cancel the thread.  cancel() never waits for the thread to
        terminate;  it just posts the cancel and returns.  A thread will
        terminate when it enters a cancellation point with cancellation
        enabled.  If cancellation is disabled then the cancel is
        remembered but not acted on until the first call to a
        cancellation point after cancellation is enabled.
        
        A cancellation point is a function that can act on cancellation.
        A cancellation point does not return if there's a cancel pending.
        Instead, it unwinds the stack and destroys automatic objects, as
        if cancel() threw an exception (which is, in fact, what it does).
        Threads must take care to unlock and clean up any resources they
        may have, especially mutexes.  They can \c catch(XThreadCancel) to
        do that then rethrow the exception or they can let it happen
        automatically by doing clean up in the d'tors of automatic
        objects (like CLock).  Clients are strongly encouraged to do the latter.
        During cancellation, further cancel() calls are ignored (i.e.
        a thread cannot be interrupted by a cancel during cancellation).
        
        Clients that \c catch(XThreadCancel) must always rethrow the
        exception.  Clients that \c catch(...) must either rethrow the
        exception or include a \c catch(XThreadCancel) handler that
        rethrows.  The \c RETHROW_XTHREAD macro may be useful for that.
        */
        void                            cancel();

        //! Change thread priority
        /*!
        Change the priority of the thread.  Normal priority is 0, 1 is
        the next lower, etc.  -1 is the next higher, etc. but boosting
        the priority may not be permitted and will be silenty ignored.
        */
        void                            setPriority(int n);

        //! Force pollSocket() to return
        /*!
        Forces a currently blocked pollSocket() in the thread to return
        immediately.
        */
        void                            unblockPollSocket();

        //@}
        //! @name accessors
        //@{

        //! Get current thread's handle
        /*!
        Return a CThread object representing the calling thread.
        */
        static CThread          getCurrentThread();

        //! Test for cancellation
        /*!
        testCancel() does nothing but is a cancellation point.  Call
        this to make a function itself a cancellation point.  If the
        thread was cancelled and cancellation is enabled this will
        cause the thread to unwind the stack and terminate.

        (cancellation point)
        */
        static void                     testCancel();

        //! Wait for thread to terminate
        /*!
        Waits for the thread to terminate (by exit() or cancel() or
        by returning from the thread job) for up to \c timeout seconds,
        returning true if the thread terminated and false otherwise.
        This returns immediately with false if called by a thread on
        itself and immediately with true if the thread has already
        terminated.  This will wait forever if \c timeout < 0.0.

        (cancellation point)
        */
        bool                            wait(double timeout = -1.0) const;

        //! Get the exit result
        /*!
        Returns the exit result.  This does an implicit wait().  It returns
        NULL immediately if called by a thread on itself or on a thread that
        was cancelled.

        (cancellation point)
        */
        void*                           getResult() const;

        //! Get the thread id
        /*!
        Returns an integer id for this thread.  This id must not be used to
        check if two CThread objects refer to the same thread.  Use
        operator==() for that.
        */
        IArchMultithread::ThreadID
                                                getID() const;

        //! Compare thread handles
        /*!
        Returns true if two CThread objects refer to the same thread.
        */
        bool                            operator==(const CThread&) const;

        //! Compare thread handles
        /*!
        Returns true if two CThread objects do not refer to the same thread.
        */
        bool                            operator!=(const CThread&) const;

        //@}

private:
        CThread(CArchThread);

        static void*            threadFunc(void*);

private:
        CArchThread                     m_thread;
};

#endif