selectThreadImpl.h

Go to the documentation of this file.

/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file selectThreadImpl.h
 * @author drose
 * @date 2002-08-09
 */

#ifndef SELECTTHREADIMPL_H
#define SELECTTHREADIMPL_H

#include "dtoolbase.h"

/*
 * This file decides which of the core implementations of the various
 * threading and locking implementations we should use, based on platform
 * andor available libraries.  This file, along with mutexImpl.h and the
 * various Mutex implementation classes, are defined in dtool so that some
 * form of critical-section protection will be available to view low-level
 * classes like TypeRegistry.  Most of the rest of the threading and
 * synchronization classes are defined in pandasrcexpress.
 */

// This keyword should be used to mark any variable which is possibly volatile
// because multiple threads might contend on it, unprotected by a mutex.  It
// will be defined out in the non-threaded case.  Other uses for volatile (dma
// buffers, for instance) should use the regular volatile keyword.
#define TVOLATILE volatile

#if !defined(HAVE_THREADS) || defined(CPPPARSER)

// With threading disabled, use the do-nothing implementation.
#define THREAD_DUMMY_IMPL 1

// And the TVOLATILE keyword means nothing in the absence of threads.
#undef TVOLATILE
#define TVOLATILE

#elif defined(SIMPLE_THREADS)
// Use the simulated threading library.
#define THREAD_SIMPLE_IMPL 1
#undef TVOLATILE
#define TVOLATILE

#elif defined(WIN32_VC)

// In Windows, use the native threading library.
#define THREAD_WIN32_IMPL 1

#elif defined(HAVE_POSIX_THREADS)

// Posix threads are nice.
#define THREAD_POSIX_IMPL 1

#else

// This is a configuration error.  For some reason, HAVE_THREADS is defined
// but we don't have any way to implement it.
#error No thread implementation defined for platform.

#endif

// Let's also factor out some of the other configuration variables.
#if defined(DO_PIPELINING) && defined(HAVE_THREADS)
#define THREADED_PIPELINE 1
#else
#undef THREADED_PIPELINE
#endif

#endif