From c3d5a06082dfe75bcf4ac065a72d6a3b71b35c02 Mon Sep 17 00:00:00 2001
From: Paul Ferrand <paul@ferrand.cc>
Date: Sun, 12 Jan 2020 11:00:43 +0100
Subject: [PATCH] Print statistic on destruction

---
 src/sfizz/Logger.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/src/sfizz/Logger.cpp b/src/sfizz/Logger.cpp
index 5214bc5a..451b84f9 100644
--- a/src/sfizz/Logger.cpp
+++ b/src/sfizz/Logger.cpp
@@ -1,9 +1,71 @@
 #include "Logger.h"
+#include "absl/algorithm/container.h"
+#include "ghc/fs_std.hpp"
+#include <iostream>
+#include <cmath>
+
 using namespace std::chrono_literals;
+
+template<class T>
+void printStatistics(std::vector<T>& data)
+{
+    absl::c_sort(data);
+    const auto maxToTake = std::min(data.size(), size_t(10));
+    std::vector<T> maxValues;
+    auto it = data.rbegin();
+    for (size_t i = 0; i < maxToTake; ++i)
+        maxValues.push_back(*it++);
+
+    const auto sum = absl::c_accumulate(data, 0.0);
+    const auto size = static_cast<T>(data.size());
+    const auto mean = sum / size;
+    std::vector<T> squares;
+    absl::c_transform(data, std::back_inserter(squares), [mean](T x) { return x * x; });
+    const auto sumOfSquares = absl::c_accumulate(squares, 0.0);
+    const auto variance = sumOfSquares / (size - 1.0) - (mean * mean) / size / (size - 1.0);
+    std::cout << "Mean: " << mean << '\n';
+    std::cout << "Variance: " << variance << '\n';
+    std::cout << "(Biased) deviation: " << std::sqrt(variance) << '\n';
+    std::cout << "Maximum values:";
+    for (auto& value: maxValues)
+        std::cout << value << ' ';
+    std::cout << '\n';
+}
+
 sfz::Logger::~Logger()
 {
     keepRunning.clear();
     loggingThread.join();
+
+    if (!loadTimes.empty()) {
+        std::vector<double> loadTimesStats;
+        std::vector<double> normLoadTimesStats;
+        absl::c_transform(loadTimes, std::back_inserter(loadTimesStats), [](auto x) { return x.value.count(); });
+        absl::c_transform(loadTimes, std::back_inserter(normLoadTimesStats), [](auto x) {
+            if (x.fileSize == 0)
+                return x.value.count();
+
+            return x.value.count() / static_cast<double>(x.fileSize);
+        });
+        std::cout << "\nFile load times" << '\n';
+        printStatistics(loadTimesStats);
+        std::cout << "\nNormalized file load times (per sample)" << '\n';
+        printStatistics(normLoadTimesStats);
+    }
+
+    if (!waitTimes.empty()) {
+        std::vector<double> waitTimesStats;
+        absl::c_transform(waitTimes, std::back_inserter(waitTimesStats), [](auto x) { return x.count(); });
+        std::cout << "\nWaiting times" << '\n';
+        printStatistics(waitTimesStats);
+    }
+
+    if (!callbackTimes.empty()) {
+        std::vector<double> callbackTimesStats;
+        absl::c_transform(callbackTimes, std::back_inserter(callbackTimesStats), [](auto x) { return x.count(); });
+        std::cout << "\nCallback times" << '\n';
+        printStatistics(callbackTimesStats);
+    }
 }