PthreadLib.h

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//=============================================================================
//  Pthread class
//-----------------------------------------------------------------------------
//  POSIX Pthread class library
//  Copyright (C) 1997-1999  The University of Texas
//
//  This library is free software; you can redistribute it and/or modify it
//  under the terms of the GNU Library General Public License as published
//  by the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This library 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
//  Library General Public License for more details.
//
//  The GNU Public License is available in the file LICENSE, or you
//  can write to the Free Software Foundation, Inc., 59 Temple Place -
//  Suite 330, Boston, MA 02111-1307, USA, or you can find it on the
//  World Wide Web at http://www.fsf.org.
//=============================================================================

#ifndef Pthread_h
#define Pthread_h
#pragma once

#ifdef EXTERNAL_TEMPLATES
#     pragma interface
#endif
#include <cpn/common.h>
#include <cpn/threading/PthreadDefs.h>
#ifdef _POSIX_THREADS

#include <cpn/threading/PthreadBase.h>
#include <cpn/threading/PthreadMutex.h>
#include <cpn/threading/PthreadCondition.h>

//=============================================================================
//  WARNING: subclassing class Pthread can lead to race conditions.
//  It is recommended that you instead use PthreadFunctional.
//-----------------------------------------------------------------------------
//  This Pthread class was written in the style of the Java Thread class.
//  Unfortunately, C++ has some behaviors that can cause problems when you
//  use inheritance with a thread class. Some simple rules can mitigate:
//  1) NEVER call Start() in the constructor of a derived class. There are
//      no virtual methods inside of C++ constructors, and Pthread::EntryPoint()
//      must be virtual. This can lead to attempted execution before the
//      vtables are initialized.
//  2) ALWAYS call Join() before doing anything else in the destructor of EVERY
//      class that is an inheritance descendent of the Pthread class. Because of
//      the calling order of destructors, your destructor could be executing at
//      the same time as your spawned thread. This could lead to your thread
//      operating on descructed data and deallocated memory.
//=============================================================================

class Pthread : public PthreadBase {
  public:
    Pthread(void);
    Pthread(const PthreadAttr& attr);
    virtual ~Pthread(void);

    void Start(void);

    int Running(void) {
        PthreadMutexProtected p(mutex);
        return state == running;
    }

    int Done(void) {
        PthreadMutexProtected p(mutex);
        return state == done || state == joined;
    }

    void *Join(void);

  protected:
    virtual void* EntryPoint(void) = 0;
//  virtual void  Cleanup(void)     { }

  private:
    PthreadMutex    mutex;
    PthreadCondition cond;
    void *returnResult;
    bool inJoin;

    enum PthreadState { uninitialized = 0, created, started, running, done, joined, canceled };
    PthreadState    state;

    static void*    PthreadEntryPoint(void* arg);
    static void     PthreadCleanup(void* arg);
};


#endif
#endif