finish hw06

main.cpp

@@ -5,35 +5,52 @@
 #include <numeric>
 #include <algorithm>
 #include "ticktock.h"
-
+#include <mutex>
+#include <tbb/parallel_for.h>
+#include <tbb/parallel_reduce.h>
+#include <tbb/parallel_scan.h>
 // TODO: 并行化所有这些 for 循环
 
 template <class T, class Func>
 std::vector<T> fill(std::vector<T> &arr, Func const &func) {
     TICK(fill);
-    for (size_t i = 0; i < arr.size(); i++) {
-        arr[i] = func(i);
-    }
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, arr.size()), 
+    [&func, &arr](const tbb::blocked_range<size_t>& r) {
+        for (auto i = r.begin(); i != r.end(); i++)
+        {
+            arr[i] = func(i);
+        }
+    });
     TOCK(fill);
     return arr;
 }
 
 template <class T>
 void saxpy(T a, std::vector<T> &x, std::vector<T> const &y) {
     TICK(saxpy);
-    for (size_t i = 0; i < x.size(); i++) {
-       x[i] = a * x[i] + y[i];
-    }
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, x.size()), 
+    [a, &x, &y](const tbb::blocked_range<size_t>& r) {
+        for (auto i = r.begin(); i != r.end(); i++)
+        {
+            x[i] = a * x[i] + y[i];
+        }
+    });
     TOCK(saxpy);
 }
 
 template <class T>
 T sqrtdot(std::vector<T> const &x, std::vector<T> const &y) {
     TICK(sqrtdot);
     T ret = 0;
-    for (size_t i = 0; i < std::min(x.size(), y.size()); i++) {
-        ret += x[i] * y[i];
-    }
+    ret = tbb::parallel_reduce(tbb::blocked_range<size_t>(0, std::min(x.size(), y.size())),
+    T{},
+    [&x, &y](const tbb::blocked_range<size_t>& r, T local_val) {
+        for (size_t i = r.begin(); i != r.end(); i++)
+        {
+            local_val += x[i] * y[i];
+        }
+        return local_val;
+    }, std::plus<T>{});
     ret = std::sqrt(ret);
     TOCK(sqrtdot);
     return ret;
@@ -42,11 +59,15 @@ T sqrtdot(std::vector<T> const &x, std::vector<T> const &y) {
 template <class T>
 T minvalue(std::vector<T> const &x) {
     TICK(minvalue);
-    T ret = x[0];
-    for (size_t i = 1; i < x.size(); i++) {
-        if (x[i] < ret)
-            ret = x[i];
-    }
+    T ret = tbb::parallel_reduce(tbb::blocked_range<size_t>(1, x.size()),
+    x[0],
+    [&x](const tbb::blocked_range<size_t>& r, T local_val) {
+        for (size_t i = r.begin(); i != r.end(); ++i) 
+            if (x[i] < local_val)
+                local_val = x[i];
+        return local_val;
+    }, 
+    [](T x, T y) { return std::min(x, y);});
     TOCK(minvalue);
     return ret;
 }
@@ -55,14 +76,24 @@ template <class T>
 std::vector<T> magicfilter(std::vector<T> const &x, std::vector<T> const &y) {
     TICK(magicfilter);
     std::vector<T> res;
-    for (size_t i = 0; i < std::min(x.size(), y.size()); i++) {
-        if (x[i] > y[i]) {
-            res.push_back(x[i]);
-        } else if (y[i] > x[i] && y[i] > 0.5f) {
-            res.push_back(y[i]);
-            res.push_back(x[i] * y[i]);
-        }
-    }
+    size_t MIN_LEN = std::min(x.size(), y.size());
+    res.reserve( MIN_LEN * 2 / 3);
+    std::mutex mut;
+
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, MIN_LEN),
+    [&res, &mut, &x, &y](const tbb::blocked_range<size_t>& r) {
+        std::vector<T> local_vec;
+        local_vec.reserve(r.size());
+        for (auto i = r.begin(); i != r.end(); i++)
+            if (x[i] > y[i]) {
+                local_vec.push_back(x[i]);
+            } else if (y[i] > x[i] && y[i] > 0.5f) {
+                local_vec.push_back(y[i]);
+                local_vec.push_back(x[i] * y[i]);
+            }
+        std::lock_guard lck(mut);
+        std::copy(local_vec.begin(), local_vec.end(), std::back_inserter(res));
+    });
     TOCK(magicfilter);
     return res;
 }
@@ -71,10 +102,17 @@ template <class T>
 T scanner(std::vector<T> &x) {
     TICK(scanner);
     T ret = 0;
-    for (size_t i = 0; i < x.size(); i++) {
-        ret += x[i];
-        x[i] = ret;
-    }
+    ret = tbb::parallel_scan(tbb::blocked_range<size_t>(0, x.size()),
+    T{},
+    [&x](const tbb::blocked_range<size_t>& r, T local_res, bool is_final) {
+        for (size_t i = r.begin(); i != r.end(); i++)
+        {
+            local_res += x[i];
+            if (is_final)
+                x[i] = local_res;    
+        }
+        return local_res;
+    }, std::plus<T>{});
     TOCK(scanner);
     return ret;
 }