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 115 116 namespace IlmThread { 117 118 // 119 // Query function to determine if the current platform supports 120 // threads AND this library was compiled with threading enabled. 121 // 122 123 ILMTHREAD_EXPORT bool supportsThreads (); 124 125 126 class 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
