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cs440-acg/ext/tbb/examples/task/tree_sum/SimpleParallelSumTree.cpp

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+/*
+    Copyright (c) 2005-2020 Intel Corporation
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+#include "common.h"
+#include "tbb/task.h"
+
+class SimpleSumTask: public tbb::task {
+    Value* const sum;
+    TreeNode* root;
+public:
+    SimpleSumTask( TreeNode* root_, Value* sum_ ) : root(root_), sum(sum_) {}
+    task* execute() /*override*/ {
+        if( root->node_count<1000 ) {
+            *sum = SerialSumTree(root);
+        } else {
+            Value x, y;
+            int count = 1; 
+            tbb::task_list list;
+            if( root->left ) {
+                ++count;
+                list.push_back( *new( allocate_child() ) SimpleSumTask(root->left,&x) );
+            }
+            if( root->right ) {
+                ++count;
+                list.push_back( *new( allocate_child() ) SimpleSumTask(root->right,&y) );
+            }
+            // Argument to set_ref_count is one more than size of the list,
+            // because spawn_and_wait_for_all expects an augmented ref_count.
+            set_ref_count(count);
+            spawn_and_wait_for_all(list);
+            *sum = root->value;
+            if( root->left ) *sum += x;
+            if( root->right ) *sum += y;
+        }
+        return NULL;
+    }
+};
+
+Value SimpleParallelSumTree( TreeNode* root ) {
+    Value sum;
+    SimpleSumTask& a = *new(tbb::task::allocate_root()) SimpleSumTask(root,&sum);
+    tbb::task::spawn_root_and_wait(a);
+    return sum;
+}
+