From 7c161f22cc25772627e98f0bb317e443795620e9 Mon Sep 17 00:00:00 2001
From: Jim Yang <Zhuoran.Yang@apulis.com>
Date: Tue, 13 Jul 2021 17:22:12 +0800
Subject: [PATCH] initial commit

---
 .gitignore      |  4 ++++
 FunctionTimer.h | 61 +++++++++++++++++++++++++++++++++++++++++++++++++
 Makefile        |  7 ++++++
 main.cpp        | 28 +++++++++++++++++++++++
 4 files changed, 100 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 FunctionTimer.h
 create mode 100644 Makefile
 create mode 100644 main.cpp

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9932039
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.idea
+cmake*
+CMakeLists.txt
+main
diff --git a/FunctionTimer.h b/FunctionTimer.h
new file mode 100644
index 0000000..3f3f192
--- /dev/null
+++ b/FunctionTimer.h
@@ -0,0 +1,61 @@
+#ifndef FUNCTIONTIMER_H
+#define FUNCTIONTIMER_H
+
+#include <iostream>
+#include <limits>
+#include <sys/time.h>
+
+class FunctionStats {
+private:
+    int64_t longest_time = 0;   // the longest function running time
+    int64_t shortest_time = std::numeric_limits<int>::max();    // the shortest function running time
+    int64_t total_time = 0;
+    int64_t count = 0;          // number of times the function being called
+    std::string time_unit;
+
+public:
+    FunctionStats(std::string time_unit_): time_unit(time_unit_){}
+
+    void update_time(int running_time) {
+        ++count;
+        total_time += running_time;
+        
+        if (running_time > longest_time) longest_time = running_time;
+        if (running_time < shortest_time) shortest_time = running_time;
+    }
+
+    void print_stats() const{
+        std::cout << "=========================================================" << std::endl;
+        std::cout << "this function has run " << count << " times" << std::endl;
+        std::cout << "average function running time: " << (int64_t)(total_time / count) << time_unit << std::endl;
+        std::cout << "longest function running time: " << longest_time << time_unit << std::endl;
+        std::cout << "shortest function running time: " << shortest_time << time_unit << std::endl;
+        std::cout << "=========================================================" << std::endl;
+    }
+};
+
+// time the function for running once, default unit is millisecond
+class FunctionTimer {
+private:
+    timeval start;
+    timeval end;
+
+public:
+    void start_timer () {
+        gettimeofday(&start, NULL);
+    }
+
+    void calculate_time() {
+        gettimeofday(&end, NULL);
+    }
+
+    int64_t get_elapsed_time_in_milliseconds() const {
+        return (end.tv_usec - start.tv_usec) / 1000;
+    }
+
+    int64_t get_elapsed_time_in_microseconds() const {
+        return end.tv_usec - start.tv_usec;
+    }
+}; 
+
+#endif
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5f67694
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,7 @@
+CC=g++
+
+main: main.cpp
+	${CC} -o $@ $^ 
+
+clean:
+	rm -f main
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..738af26
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,28 @@
+#include <iostream>
+#include "FunctionTimer.h"
+
+using namespace std;
+
+FunctionStats STAT("u");
+
+void func() {
+    int x = 0;
+    for (int i = 0; i < 1000000; ++i) {
+        x += 1;
+    }
+}
+
+int main() {
+    FunctionTimer timer(1000000);
+    cout << "Program starts" << endl;
+
+    for (int i = 0; i < 10; ++i) {
+        timer.start_timer();
+        func();
+        timer.calculate_time();
+        STAT.update_time(timer.get_elapsed_time());
+    }
+    STAT.print_stats();
+
+    return 0;
+}