Pr/core threadpool (#401)

Move GlobeBrowsing thread pool to OpenSpace core

src/CMakeLists.txt

@@ -159,6 +159,7 @@ set(OPENSPACE_SOURCE
     ${OPENSPACE_BASE_DIR}/src/util/histogram.cpp
     ${OPENSPACE_BASE_DIR}/src/util/task.cpp
     ${OPENSPACE_BASE_DIR}/src/util/taskloader.cpp
+    ${OPENSPACE_BASE_DIR}/src/util/threadpool.cpp
     ${OPENSPACE_BASE_DIR}/src/util/time.cpp
     ${OPENSPACE_BASE_DIR}/src/util/timeline.cpp
     ${OPENSPACE_BASE_DIR}/src/util/timemanager.cpp
@@ -296,6 +297,10 @@ set(OPENSPACE_HEADER
     ${OPENSPACE_BASE_DIR}/include/openspace/util/blockplaneintersectiongeometry.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/boxgeometry.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/camera.h
+    ${OPENSPACE_BASE_DIR}/include/openspace/util/concurrentjobmanager.h
+    ${OPENSPACE_BASE_DIR}/include/openspace/util/concurrentjobmanager.inl
+    ${OPENSPACE_BASE_DIR}/include/openspace/util/concurrentqueue.h
+    ${OPENSPACE_BASE_DIR}/include/openspace/util/concurrentqueue.inl
     ${OPENSPACE_BASE_DIR}/include/openspace/util/factorymanager.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/factorymanager.inl
     ${OPENSPACE_BASE_DIR}/include/openspace/util/keys.h
@@ -318,6 +323,7 @@ set(OPENSPACE_HEADER
     ${OPENSPACE_BASE_DIR}/include/openspace/util/timerange.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/updatestructures.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/transformationmanager.h
+    ${OPENSPACE_BASE_DIR}/include/openspace/util/threadpool.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/histogram.h
     ${OPENSPACE_BASE_DIR}/include/openspace/util/gpudata.h
 )

src/util/threadpool.cpp

@@ -0,0 +1,106 @@
+/*****************************************************************************************
+ *                                                                                       *
+ * OpenSpace                                                                             *
+ *                                                                                       *
+ * Copyright (c) 2014-2017                                                               *
+ *                                                                                       *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
+ * software and associated documentation files (the "Software"), to deal in the Software *
+ * without restriction, including without limitation the rights to use, copy, modify,    *
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
+ * permit persons to whom the Software is furnished to do so, subject to the following   *
+ * conditions:                                                                           *
+ *                                                                                       *
+ * The above copyright notice and this permission notice shall be included in all copies *
+ * or substantial portions of the Software.                                              *
+ *                                                                                       *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
+ * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
+ * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
+ ****************************************************************************************/
+
+#include <openspace/util/threadpool.h>
+
+namespace openspace {
+
+Worker::Worker(ThreadPool& pool) : pool(pool) {}
+
+void Worker::operator()() {
+    std::function<void()> task;
+    while (true) {
+        // acquire lock
+        {
+            std::unique_lock<std::mutex> lock(pool.queue_mutex);
+
+            // look for a work item
+            while (!pool.stop && pool.tasks.empty()) {
+                // if there are none wait for notification
+                pool.condition.wait(lock);
+            }
+
+            if (pool.stop) { // exit if the pool is stopped
+                return;
+            }
+
+            // get the task from the queue
+            task = pool.tasks.front();
+            pool.tasks.pop_front();
+
+        }// release lock
+
+        // execute the task
+        task();
+    }
+}
+
+ThreadPool::ThreadPool(size_t numThreads)
+    : stop(false)
+{
+    for (size_t i = 0; i < numThreads; ++i) {
+        workers.push_back(std::thread(Worker(*this)));
+    }
+}
+
+ThreadPool::ThreadPool(const ThreadPool& toCopy)
+    : ThreadPool(toCopy.workers.size())
+{ }
+
+// the destructor joins all threads
+ThreadPool::~ThreadPool() {
+    // stop all threads
+    {
+        std::unique_lock<std::mutex> lock(queue_mutex);
+        stop = true;
+    }
+    condition.notify_all();
+
+    // join them
+    for (size_t i = 0; i < workers.size(); ++i) {
+        workers[i].join();
+    }
+}
+
+// add new work item to the pool
+void ThreadPool::enqueue(std::function<void()> f) {
+    { // acquire lock
+        std::unique_lock<std::mutex> lock(queue_mutex);
+
+        // add the task
+        tasks.push_back(f);
+    } // release lock
+
+        // wake up one thread
+    condition.notify_one();
+}
+
+void ThreadPool::clearTasks() {
+    { // acquire lock
+        std::unique_lock<std::mutex> lock(queue_mutex);
+        tasks.clear();
+    } // release lock
+}
+
+} // namespace openspace