From 39960ccef14230d7d72eac8efd993cc5d3dae390 Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Fri, 27 Jan 2017 22:14:12 +0100
Subject: [PATCH] Add simple benachmark for string builder

---
 tests/stringbuilder-bench.cpp | 65 +++++++++++++++++++++++++++++++++++
 tests/stringbuilder-bench.md  | 51 +++++++++++++++++++++++++++
 2 files changed, 116 insertions(+)
 create mode 100644 tests/stringbuilder-bench.cpp
 create mode 100644 tests/stringbuilder-bench.md

diff --git a/tests/stringbuilder-bench.cpp b/tests/stringbuilder-bench.cpp
new file mode 100644
index 0000000..3a1115c
--- /dev/null
+++ b/tests/stringbuilder-bench.cpp
@@ -0,0 +1,65 @@
+#include "../conversion/stringbuilder.h"
+#include "../conversion/stringconversion.h"
+#include "../chrono/datetime.h"
+
+#include <vector>
+#include <iostream>
+#include <sstream>
+
+using namespace std;
+using namespace ConversionUtilities;
+using namespace ChronoUtilities;
+
+int main()
+{
+    cout << "Benchmarking string builder vs. stringstream" << endl;
+
+    constexpr unsigned int iterations = 500000;
+    constexpr unsigned int iterations2 = 50;
+
+    vector<string> v1, v2;
+    v1.reserve(iterations);
+    v2.reserve(iterations);
+
+    DateTime t1 = DateTime::now();
+    for(unsigned int r = 0; r < iterations2; ++r) {
+        for(unsigned int i = 0; i < iterations; ++i) {
+            stringstream ss;
+            v1.emplace_back("left. " + numberToString(i + 1) + "; right: " + numberToString(i + 2) + "; top: " + numberToString(i + 3) + "; bottom: " + numberToString(i + 4) + ';');
+        }
+        v1.clear();
+    }
+    DateTime t2 = DateTime::now();
+    cout << "plus operator: " << (t2 - t1).toString(TimeSpanOutputFormat::Normal, true) << endl;
+
+    t1 = DateTime::now();
+    for(unsigned int r = 0; r < iterations2; ++r) {
+        for(unsigned int i = 0; i < iterations; ++i) {
+            stringstream ss;
+            ss << "left: " << (i + 1) << "; right: " << (i + 2) << "; top: " << (i + 3) << "; bottom: " << (i + 4) << ';';
+            v1.emplace_back(ss.str());
+        }
+        v1.clear();
+    }
+    t2 = DateTime::now();
+    const TimeSpan diff1 = t2 - t1;
+    cout << "stringstream: " << diff1.toString(TimeSpanOutputFormat::Normal, true) << endl;
+
+    t1 = DateTime::now();
+    for(unsigned int r = 0; r < iterations2; ++r) {
+        for(unsigned int i = 0; i < iterations; ++i) {
+            v2.emplace_back("left. " % numberToString(i + 1) % "; right: " % numberToString(i + 2) % "; top: " % numberToString(i + 3) % "; bottom: " % numberToString(i + 4) + ';');
+        }
+        v2.clear();
+    }
+    t2 = DateTime::now();
+    const TimeSpan diff2 = t2 - t1;
+    cout << "string builder: " << diff2.toString(TimeSpanOutputFormat::Normal, true) << endl;
+
+    v1.swap(v2);
+
+    cout << "diff (stringstream minus string builder): " << (diff1 - diff2).toString(TimeSpanOutputFormat::Normal, true) << endl;
+    cout << "factor (stringstream / string builder): " << (static_cast<double>(diff1.totalTicks()) / diff2.totalTicks()) << endl;
+
+    return 0;
+}
diff --git a/tests/stringbuilder-bench.md b/tests/stringbuilder-bench.md
new file mode 100644
index 0000000..641f2d1
--- /dev/null
+++ b/tests/stringbuilder-bench.md
@@ -0,0 +1,51 @@
+# Simple/stupid benchmarking
+
+Compares the string builder and numberToString() function as provided by c++utilities
+with std::stringstream (without reserving stringstream buffer).
+
+The string builder is actually just a fancy syntax for std::string::reserve()
+making its use more convenient.
+
+## Compile and run
+
+eg.
+```
+g++ -O3 stringbuilder-bench.cpp -o stringbuilder-bench-O3 -Wl,-rpath /lib/path -L /lib/path -lc++utilities
+./stringbuilder-bench-O3
+```
+
+## Results on my machine
+
+Results with -03:
+
+```
+plus operator: 00:00:17
+stringstream: 00:00:16
+string builder: 00:00:07
+diff (stringstream minus string builder): 00:00:09
+factor (stringstream / string builder): 2.28571
+```
+
+However, with -O0 4 times *slower*:
+
+```
+plus operator: 00:00:29
+stringstream: 00:00:16
+string builder: 00:01:04
+diff (stringstream minus string builder): - 00:35:22
+factor (stringstream / string builder): 0.25
+```
+
+Still 1.45 times faster than stringstream with -O2:
+
+```
+plus operator: 00:00:21
+stringstream: 00:00:16
+string builder: 00:00:11
+diff (stringstream minus string builder): 00:00:05
+factor (stringstream / string builder): 1.45455
+```
+
+So this basic tests show that string builder is up to 2 times faster when using full optimization
+and still 1.4 times faster when using -O2 (default under Arch Linux). However, this templating
+stuff completely relies on optimization (as expected). Results with clang++ where similar.