1 /* 2 * Copyright (C) 2011 University of Szeged 3 * Copyright (C) 2011 Gabor Loki <loki (at) webkit.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY 16 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF SZEGED OR 19 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 22 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 23 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #ifndef ParallelJobs_h 29 #define ParallelJobs_h 30 31 #include "platform/Task.h" 32 #include "public/platform/Platform.h" 33 #include "public/platform/WebThread.h" 34 #include "wtf/Assertions.h" 35 #include "wtf/Noncopyable.h" 36 #include "wtf/OwnPtr.h" 37 #include "wtf/Vector.h" 38 39 // Usage: 40 // 41 // // Initialize parallel jobs 42 // ParallelJobs<TypeOfParameter> parallelJobs(&worker, requestedNumberOfJobs); 43 // 44 // // Fill the parameter array 45 // for(i = 0; i < parallelJobs.numberOfJobs(); ++i) { 46 // TypeOfParameter& params = parallelJobs.parameter(i); 47 // params.attr1 = localVars ... 48 // ... 49 // } 50 // 51 // // Execute parallel jobs 52 // parallelJobs.execute(); 53 // 54 55 namespace WebCore { 56 57 template<typename Type> 58 class ParallelJobs { 59 WTF_MAKE_NONCOPYABLE(ParallelJobs); 60 WTF_MAKE_FAST_ALLOCATED; 61 public: 62 typedef void (*WorkerFunction)(Type*); 63 64 ParallelJobs(WorkerFunction func, size_t requestedJobNumber) 65 : m_func(func) 66 { 67 size_t numberOfJobs = std::max(static_cast<size_t>(2), std::min(requestedJobNumber, blink::Platform::current()->numberOfProcessors())); 68 m_parameters.grow(numberOfJobs); 69 // The main thread can execute one job, so only create requestJobNumber - 1 threads. 70 for (size_t i = 0; i < numberOfJobs - 1; ++i) { 71 OwnPtr<blink::WebThread> thread = adoptPtr(blink::Platform::current()->createThread("Unfortunate parallel worker")); 72 m_threads.append(thread.release()); 73 } 74 } 75 76 size_t numberOfJobs() 77 { 78 return m_parameters.size(); 79 } 80 81 Type& parameter(size_t i) 82 { 83 return m_parameters[i]; 84 } 85 86 void execute() 87 { 88 for (size_t i = 0; i < numberOfJobs() - 1; ++i) 89 m_threads[i]->postTask(new Task(WTF::bind(m_func, ¶meter(i)))); 90 m_func(¶meter(numberOfJobs() - 1)); 91 m_threads.clear(); 92 } 93 94 private: 95 WorkerFunction m_func; 96 Vector<OwnPtr<blink::WebThread> > m_threads; 97 Vector<Type> m_parameters; 98 }; 99 100 } // namespace WebCore 101 102 #endif // ParallelJobs_h 103