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///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2005-2012, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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///////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_ILM_THREAD_H
#define INCLUDED_ILM_THREAD_H
//-----------------------------------------------------------------------------
//
// class Thread
//
// Class Thread is a portable interface to a system-dependent thread
// primitive. In order to make a thread actually do something useful,
// you must derive a subclass from class Thread and implement the
// run() function. If the operating system supports threading then
// the run() function will be executed int a new thread.
//
// The actual creation of the thread is done by the start() routine
// which then calls the run() function. In general the start()
// routine should be called from the constructor of the derived class.
//
// The base-class thread destructor will join/destroy the thread.
//
// IMPORTANT: Due to the mechanisms that encapsulate the low-level
// threading primitives in a C++ class there is a race condition
// with code resembling the following:
//
// {
// WorkerThread myThread;
// } // myThread goes out of scope, is destroyed
// // and the thread is joined
//
// The race is between the parent thread joining the child thread
// in the destructor of myThread, and the run() function in the
// child thread. If the destructor gets executed first then run()
// will be called with an invalid "this" pointer.
//
// This issue can be fixed by using a Semaphore to keep track of
// whether the run() function has already been called. You can
// include a Semaphore member variable within your derived class
// which you post() on in the run() function, and wait() on in the
// destructor before the thread is joined. Alternatively you could
// do something like this:
//
// Semaphore runStarted;
//
// void WorkerThread::run ()
// {
// runStarted.post()
// // do some work
// ...
// }
//
// {
// WorkerThread myThread;
// runStarted.wait (); // ensure that we have started
// // the run function
// } // myThread goes out of scope, is destroyed
// // and the thread is joined
//
//-----------------------------------------------------------------------------
#include "IlmBaseConfig.h"
#include "IlmThreadExport.h"
#include "IlmThreadNamespace.h"
#if defined _WIN32 || defined _WIN64
#ifdef NOMINMAX
#undef NOMINMAX
#endif
#define NOMINMAX
#include <windows.h>
#include <process.h>
#elif HAVE_PTHREAD
#include <pthread.h>
#endif
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
//
// Query function to determine if the current platform supports
// threads AND this library was compiled with threading enabled.
//
ILMTHREAD_EXPORT bool supportsThreads ();
class ILMTHREAD_EXPORT Thread
{
public:
Thread ();
virtual ~Thread ();
void start ();
virtual void run () = 0;
private:
#if defined _WIN32 || defined _WIN64
HANDLE _thread;
#elif HAVE_PTHREAD
pthread_t _thread;
#endif
void operator = (const Thread& t); // not implemented
Thread (const Thread& t); // not implemented
};
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
#endif // INCLUDED_ILM_THREAD_H
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