1///////////////////////////////////////////////////////////////////////////
2//
3// Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
4// Digital Ltd. LLC
5//
6// All rights reserved.
7//
8// Redistribution and use in source and binary forms, with or without
9// modification, are permitted provided that the following conditions are
10// met:
11// *       Redistributions of source code must retain the above copyright
12// notice, this list of conditions and the following disclaimer.
13// *       Redistributions in binary form must reproduce the above
14// copyright notice, this list of conditions and the following disclaimer
15// in the documentation and/or other materials provided with the
16// distribution.
17// *       Neither the name of Industrial Light & Magic nor the names of
18// its contributors may be used to endorse or promote products derived
19// from this software without specific prior written permission.
20//
21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32//
33///////////////////////////////////////////////////////////////////////////
34
35#ifndef INCLUDED_ILM_THREAD_H
36#define INCLUDED_ILM_THREAD_H
37
38//-----------------------------------------------------------------------------
39//
40//	class Thread
41//
42//	Class Thread is a portable interface to a system-dependent thread
43//	primitive.  In order to make a thread actually do something useful,
44//	you must derive a subclass from class Thread and implement the
45//	run() function.  If the operating system supports threading then
46//	the run() function will be executed int a new thread.
47//
48//	The actual creation of the thread is done by the start() routine
49//	which then calls the run() function.  In general the start()
50//	routine should be called from the constructor of the derived class.
51//
52//	The base-class thread destructor will join/destroy the thread.
53//
54//	IMPORTANT: Due to the mechanisms that encapsulate the low-level
55//	threading primitives in a C++ class there is a race condition
56//	with code resembling the following:
57//
58//	    {
59//		WorkerThread myThread;
60//	    } // myThread goes out of scope, is destroyed
61//	      // and the thread is joined
62//
63//	The race is between the parent thread joining the child thread
64//	in the destructor of myThread, and the run() function in the
65//	child thread.  If the destructor gets executed first then run()
66//	will be called with an invalid "this" pointer.
67//
68//	This issue can be fixed by using a Semaphore to keep track of
69//	whether the run() function has already been called.  You can
70//	include a Semaphore member variable within your derived class
71//	which you post() on in the run() function, and wait() on in the
72//	destructor before the thread is joined.  Alternatively you could
73//	do something like this:
74//
75//	    Semaphore runStarted;
76//
77//	    void WorkerThread::run ()
78//	    {
79//		runStarted.post()
80//		// do some work
81//		...
82//	    }
83//
84//	    {
85//		WorkerThread myThread;
86//		runStarted.wait ();    // ensure that we have started
87//				       // the run function
88//	    } // myThread goes out of scope, is destroyed
89//	      // and the thread is joined
90//
91//-----------------------------------------------------------------------------
92
93#include "IlmBaseConfig.h"
94
95#if defined _WIN32 || defined _WIN64
96    #ifdef NOMINMAX
97        #undef NOMINMAX
98    #endif
99    #define NOMINMAX
100    #include <windows.h>
101    #include <process.h>
102#elif HAVE_PTHREAD
103    #include <pthread.h>
104#endif
105
106#if defined(OPENEXR_DLL) && !defined(ZENO_STATIC)
107    #ifdef ILMTHREAD_EXPORTS
108    #define ILMTHREAD_EXPORT __declspec(dllexport)
109    #else
110    #define ILMTHREAD_EXPORT __declspec(dllimport)
111    #endif
112#else
113    #define ILMTHREAD_EXPORT
114#endif
115
116namespace IlmThread {
117
118//
119// Query function to determine if the current platform supports
120// threads AND this library was compiled with threading enabled.
121//
122
123ILMTHREAD_EXPORT bool supportsThreads ();
124
125
126class ILMTHREAD_EXPORT Thread
127{
128  public:
129
130    Thread ();
131    virtual ~Thread ();
132
133    void		start ();
134    virtual void	run () = 0;
135
136  private:
137
138    #if defined _WIN32 || defined _WIN64
139    HANDLE _thread;
140    #elif HAVE_PTHREAD
141    pthread_t _thread;
142    #endif
143
144    void operator = (const Thread& t);	// not implemented
145    Thread (const Thread& t);		// not implemented
146};
147
148
149} // namespace IlmThread
150
151#endif
152