refactor(learn): 并行执行时使用一个线程池

Signed-off-by: YdrMaster <[email protected]>

exercises/19_runtime_datatype/main.cpp

@@ -34,12 +34,12 @@ int main(int argc, char **argv) {
     xf.f = 5.f;
     auto yf = sigmoid_dyn(xf);
     ASSERT(yf.type == DataType::Float, "type mismatch");
-    ASSERT(yf.f == 1 / (1 + exp(-5.f)), "sigmoid float");
+    ASSERT(yf.f == 1 / (1 + std::exp(-5.f)), "sigmoid float");
 
     TaggedUnion xd{DataType::Double};
     xd.d = 5.0;
     auto yd = sigmoid_dyn(xd);
     ASSERT(yd.type == DataType::Double, "type mismatch");
-    ASSERT(yd.d == 1 / (1 + exp(-5.0)), "sigmoid double");
+    ASSERT(yd.d == 1 / (1 + std::exp(-5.0)), "sigmoid double");
     return 0;
 }

learn/summary.cpp

@@ -1,4 +1,5 @@
 #include "test.h"
+#include <atomic>
 #include <chrono>
 #include <cstring>
 #include <iomanip>
@@ -24,14 +25,29 @@ int main(int argc, char **argv) {
         return EXIT_SUCCESS;
     }
     if (argc == 2 && std::strcmp(argv[1], "--simple") == 0) {
-        Log log{Null{}};
+        auto concurrency = std::thread::hardware_concurrency();
+        if (concurrency == 0) {
+            concurrency = 1;
+        }
+
+        std::atomic_int k{0};
         std::vector<std::thread> threads;
-        for (auto i = 0; i <= MAX_EXERCISE; ++i) {
-            threads.emplace_back([&log, i]() { log << i; });
+        threads.reserve(concurrency);
+
+        Log log{Null{}};
+        for (auto i = 0u; i <= concurrency; ++i) {
+            threads.emplace_back([&log, &k] {
+                int i = k.fetch_add(1);
+                while (i <= MAX_EXERCISE) {
+                    log << i;
+                    i = k.fetch_add(1);
+                }
+            });
         }
-        for (auto i = 0; i <= MAX_EXERCISE; ++i) {
-            threads[i].join();
+        for (auto &thread : threads) {
+            thread.join();
         }
+
         std::cout << std::accumulate(log.result.begin(), log.result.end(), 0, std::plus{}) << '/' << MAX_EXERCISE + 1 << std::endl;
         return EXIT_SUCCESS;
     }