add couple examples

examples/emplace.cc

@@ -0,0 +1,124 @@
+#include <map>
+#include <unordered_map>
+#include <string>
+#include <iostream>
+#include <chrono>
+#include <vector>
+#include <parallel_hashmap/phmap.h>
+
+#include <sstream>
+
+namespace patch
+{
+    template <typename T> std::string to_string(const T& n)
+    {
+        std::ostringstream stm;
+        stm << n;
+        return stm.str();
+    }
+}
+
+template <typename T>
+using milliseconds = std::chrono::duration<T, std::milli>;
+
+class custom_type
+{
+    std::string one = "one";
+    std::string two = "two";
+    std::uint32_t three = 3;
+    std::uint64_t four = 4;
+    std::uint64_t five = 5;
+public:
+    custom_type() = default;
+    // Make object movable and non-copyable
+    custom_type(custom_type &&) = default;
+    custom_type& operator=(custom_type &&) = default;
+    // should be automatically deleted per http://www.slideshare.net/ripplelabs/howard-hinnant-accu2014
+    //custom_type(custom_type const&) = delete;
+    //custom_type& operator=(custom_type const&) = delete;
+};
+
+void test(std::size_t iterations, std::size_t container_size)
+{
+    std::clog << "bench: iterations: " << iterations <<  " / container_size: "  << container_size << "\n";
+    {
+        std::size_t count = 0;
+        auto t1 = std::chrono::high_resolution_clock::now();
+        for (std::size_t i=0; i<iterations; ++i)
+        {
+            std::unordered_map<std::string,custom_type> m;
+            m.reserve(container_size);
+            for (std::size_t j=0; j<container_size; ++j)
+                m.emplace(patch::to_string(j),custom_type());
+            count += m.size();
+        }
+        auto t2 = std::chrono::high_resolution_clock::now();
+        auto elapsed = milliseconds<double>(t2 - t1).count();
+        if (count != iterations*container_size)
+            std::clog << "  invalid count: " << count << "\n";
+        std::clog << "  std::unordered_map:     " << std::fixed << int(elapsed) << " ms\n";
+    }
+
+    {
+        std::size_t count = 0;
+        auto t1 = std::chrono::high_resolution_clock::now();
+        for (std::size_t i=0; i<iterations; ++i)
+        {
+            std::map<std::string,custom_type> m;
+            for (std::size_t j=0; j<container_size; ++j)
+                m.emplace(patch::to_string(j),custom_type());
+            count += m.size();
+        }
+        auto t2 = std::chrono::high_resolution_clock::now();
+        auto elapsed = milliseconds<double>(t2 - t1).count();
+        if (count != iterations*container_size)
+            std::clog << "  invalid count: " << count << "\n";
+        std::clog << "  std::map:               " << std::fixed << int(elapsed) << " ms\n";
+    }
+
+    {
+        std::size_t count = 0;
+        auto t1 = std::chrono::high_resolution_clock::now();
+        for (std::size_t i=0; i<iterations; ++i)
+        {
+            std::vector<std::pair<std::string,custom_type>> m;
+            m.reserve(container_size);
+            for (std::size_t j=0; j<container_size; ++j)
+                m.emplace_back(patch::to_string(j),custom_type());
+            count += m.size();
+        }
+        auto t2 = std::chrono::high_resolution_clock::now();
+        auto elapsed = milliseconds<double>(t2 - t1).count();
+        if (count != iterations*container_size)
+            std::clog << "  invalid count: " << count << "\n";
+        std::clog << "  std::vector<std::pair>: " << std::fixed << int(elapsed) << " ms\n";
+    }
+
+    {
+        std::size_t count = 0;
+        auto t1 = std::chrono::high_resolution_clock::now();
+        for (std::size_t i=0; i<iterations; ++i)
+        {
+            phmap::flat_hash_map<std::string,custom_type> m;
+            m.reserve(container_size);
+            for (std::size_t j=0; j<container_size; ++j)
+                m.emplace(patch::to_string(j),custom_type());
+            count += m.size();
+        }
+        auto t2 = std::chrono::high_resolution_clock::now();
+        auto elapsed = milliseconds<double>(t2 - t1).count();
+        if (count != iterations*container_size)
+            std::clog << "  invalid count: " << count << "\n";
+        std::clog << "  phmap::flat_hash_map:   " << std::fixed << int(elapsed) << " ms\n";
+    }
+
+}
+
+int main()
+{
+    std::size_t iterations = 100000;
+
+    test(iterations,1);
+    test(iterations,10);
+    test(iterations,50);
+}