omnithread.h

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// -*- Mode: C++; -*-
//				Package : omnithread
// omnithread.h			Created : 7/94 tjr
//
//    Copyright (C) 1994,1995,1996, 1997 Olivetti & Oracle Research Laboratory
//
//    This file is part of the omnithread library
//
//    The omnithread 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.
//
//    You should have received a copy of the GNU Library General Public
//    License along with this library; if not, write to the Free
//    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  
//    02111-1307, USA
//

//
// Interface to OMNI thread abstraction.
//
// This file declares classes for threads and synchronisation objects
// (mutexes, condition variables and counting semaphores).
//
// Wherever a seemingly arbitrary choice has had to be made as to the interface
// provided, the intention here has been to be as POSIX-like as possible.  This
// is why there is no semaphore timed wait, for example.
//

#ifndef __omnithread_h_
#define __omnithread_h_

#ifndef NULL
#define NULL 0
#endif

class omni_mutex;
class omni_condition;
class omni_semaphore;
class omni_thread;

//
// OMNI_THREAD_EXPOSE can be defined as public or protected to expose the
// implementation class - this may be useful for debugging.  Hopefully this
// won't change the underlying structure which the compiler generates so that
// this can work without recompiling the library.
//

#ifndef OMNI_THREAD_EXPOSE
#define OMNI_THREAD_EXPOSE private
#endif

//
// Include implementation-specific header file.
//
// This must define 4 CPP macros of the form OMNI_x_IMPLEMENTATION for mutex,
// condition variable, semaphore and thread.  Each should define any
// implementation-specific members of the corresponding classes.
//


//
// For now, we assume they've always got a Posix Threads implementation.
// If not, it'll take some configure hacking to sort it out, along with
// the relevant libraries to link with, etc.
//

#if !defined(OMNITHREAD_POSIX) && !defined(OMNITHREAD_NT) && defined HAVE_CONFIG_H
#include <config.h>
#endif

#if defined(OMNITHREAD_POSIX)
#include <ot_posix.h>

#elif defined(OMNITHREAD_NT)
#include <ot_nt.h>

#ifdef _MSC_VER

// Using MSVC++ to compile. If compiling library as a DLL,
// define _OMNITHREAD_DLL. If compiling as a statuc library, define
// _WINSTATIC
// If compiling an application that is to be statically linked to omnithread,
// define _WINSTATIC (if the application is  to be dynamically linked, 
// there is no need to define any of these macros).

#if defined (_OMNITHREAD_DLL) && defined(_WINSTATIC)
#error "Both _OMNITHREAD_DLL and _WINSTATIC are defined."
#elif defined(_OMNITHREAD_DLL)
#define _OMNITHREAD_NTDLL_ __declspec(dllexport)
#elif !defined(_WINSTATIC)
#define _OMNITHREAD_NTDLL_ __declspec(dllimport)
#elif defined(_WINSTATIC)
#define _OMNITHREAD_NTDLL_
#endif
 // _OMNITHREAD_DLL && _WINSTATIC

#else

// Not using MSVC++ to compile
#define _OMNITHREAD_NTDLL_

#endif
 // _MSC_VER
 
#elif defined(__vxWorks__)
#include <ot_VxThread.h>

#elif defined(__sunos__)
#if __OSVERSION__ != 5
// XXX Workaround for SUN C++ compiler (seen on 4.2) Template.DB code
//     regeneration bug. See omniORB2/CORBA_sysdep.h for details.
#if !defined(__SUNPRO_CC) || __OSVERSION__ != '5'
#error "Only SunOS 5.x or later is supported."
#endif
#endif
#ifdef UseSolarisThreads
#include <ot_solaris.h>
#else
#include <ot_posix.h>
#endif

#elif defined(__rtems__)
#include <ot_posix.h>
#include <sched.h>

#elif defined(__macos__)
#include <ot_posix.h>
#include <sched.h>

#else
#error "No implementation header file"
#endif


#if !defined(__WIN32__)
#define _OMNITHREAD_NTDLL_
#endif

#if (!defined(OMNI_MUTEX_IMPLEMENTATION)        || \
     !defined(OMNI_MUTEX_LOCK_IMPLEMENTATION)   || \
     !defined(OMNI_MUTEX_UNLOCK_IMPLEMENTATION) || \
     !defined(OMNI_CONDITION_IMPLEMENTATION)    || \
     !defined(OMNI_SEMAPHORE_IMPLEMENTATION)    || \
     !defined(OMNI_THREAD_IMPLEMENTATION))
#error "Implementation header file incomplete"
#endif


//
// This exception is thrown in the event of a fatal error.
//

class _OMNITHREAD_NTDLL_ omni_thread_fatal {
public:
    int error;
    omni_thread_fatal(int e = 0) : error(e) {}
};


//
// This exception is thrown when an operation is invoked with invalid
// arguments.
//

class _OMNITHREAD_NTDLL_ omni_thread_invalid {};


///////////////////////////////////////////////////////////////////////////
//
// Mutex
//
///////////////////////////////////////////////////////////////////////////

class _OMNITHREAD_NTDLL_ omni_mutex {

public:
    omni_mutex(void);
    ~omni_mutex(void);

    inline void lock(void)    { OMNI_MUTEX_LOCK_IMPLEMENTATION   }
    inline void unlock(void)  { OMNI_MUTEX_UNLOCK_IMPLEMENTATION }
    inline void acquire(void) { lock(); }
    inline void release(void) { unlock(); }
	// the names lock and unlock are preferred over acquire and release
	// since we are attempting to be as POSIX-like as possible.

    friend class omni_condition;

private:
    // dummy copy constructor and operator= to prevent copying
    omni_mutex(const omni_mutex&);
    omni_mutex& operator=(const omni_mutex&);

OMNI_THREAD_EXPOSE:
    OMNI_MUTEX_IMPLEMENTATION
};

//
// As an alternative to:
// {
//   mutex.lock();
//   .....
//   mutex.unlock();
// }
//
// you can use a single instance of the omni_mutex_lock class:
//
// {
//   omni_mutex_lock l(mutex);
//   ....
// }
//
// This has the advantage that mutex.unlock() will be called automatically
// when an exception is thrown.
//

class _OMNITHREAD_NTDLL_ omni_mutex_lock {
    omni_mutex& mutex;
public:
    omni_mutex_lock(omni_mutex& m) : mutex(m) { mutex.lock(); }
    ~omni_mutex_lock(void) { mutex.unlock(); }
private:
    // dummy copy constructor and operator= to prevent copying
    omni_mutex_lock(const omni_mutex_lock&);
    omni_mutex_lock& operator=(const omni_mutex_lock&);
};


///////////////////////////////////////////////////////////////////////////
//
// Condition variable
//
///////////////////////////////////////////////////////////////////////////

class _OMNITHREAD_NTDLL_ omni_condition {

    omni_mutex* mutex;

public:
    omni_condition(omni_mutex* m);
	// constructor must be given a pointer to an existing mutex. The
	// condition variable is then linked to the mutex, so that there is an
	// implicit unlock and lock around wait() and timed_wait().

    ~omni_condition(void);

    void wait(void);
	// wait for the condition variable to be signalled.  The mutex is
	// implicitly released before waiting and locked again after waking up.
	// If wait() is called by multiple threads, a signal may wake up more
	// than one thread.  See POSIX threads documentation for details.

    int timedwait(unsigned long secs, unsigned long nanosecs = 0);
	// timedwait() is given an absolute time to wait until.  To wait for a
	// relative time from now, use omni_thread::get_time. See POSIX threads
	// documentation for why absolute times are better than relative.
	// Returns 1 (true) if successfully signalled, 0 (false) if time
	// expired.

    void signal(void);
	// if one or more threads have called wait(), signal wakes up at least
	// one of them, possibly more.  See POSIX threads documentation for
	// details.

    void broadcast(void);
	// broadcast is like signal but wakes all threads which have called
	// wait().

private:
    // dummy copy constructor and operator= to prevent copying
    omni_condition(const omni_condition&);
    omni_condition& operator=(const omni_condition&);

OMNI_THREAD_EXPOSE:
    OMNI_CONDITION_IMPLEMENTATION
};


///////////////////////////////////////////////////////////////////////////
//
// Counting semaphore
//
///////////////////////////////////////////////////////////////////////////

class _OMNITHREAD_NTDLL_ omni_semaphore {

public:
    omni_semaphore(unsigned int initial = 1);
    ~omni_semaphore(void);

    void wait(void);
	// if semaphore value is > 0 then decrement it and carry on. If it's
	// already 0 then block.

    int trywait(void);
	// if semaphore value is > 0 then decrement it and return 1 (true).
	// If it's already 0 then return 0 (false).

    void post(void);
	// if any threads are blocked in wait(), wake one of them up. Otherwise
	// increment the value of the semaphore.