Add transformStatistics and printStatistics

Author: Henry Qin

src/Stats.cc

@@ -66,20 +66,48 @@ computeStatistics(uint64_t* rawdata, size_t count) {
     return stats;
 }
 
+Statistics
+transformStatistics(Statistics stats, uint64_t (*function)(uint64_t)) {
+    Statistics result;
+    result.count = stats.count;
+    result.average = function(stats.average);
+    result.stddev = function(stats.stddev);
+    result.min = function(stats.min);
+    result.median = function(stats.median);
+    result.P10 = function(stats.P10);
+    result.P20 = function(stats.P20);
+    result.P30 = function(stats.P30);
+    result.P40 = function(stats.P40);
+    result.P50 = function(stats.P50);
+    result.P60 = function(stats.P60);
+    result.P70 = function(stats.P70);
+    result.P80 = function(stats.P80);
+    result.P90 = function(stats.P90);
+    result.P99 = function(stats.P99);
+    result.P999 = function(stats.P999);
+    result.P9999 = function(stats.P9999);
+    result.max = function(stats.max);
+	return result;
+}
+
+void
+printStatistics(Statistics stats, const char* label) {
+	static bool headerPrinted = false;
+	if (!headerPrinted) {
+		puts("Benchmark,Count,Avg,Stddev,Median,Min,99%,"
+				"99.9%,99.99%,Max");
+		headerPrinted = true;
+	}
+	printf("%s,%lu,%lu,%lu,%lu,%lu,%lu,%lu,%lu,%lu\n", label, stats.count, stats.average,
+			stats.stddev, stats.median, stats.min, stats.P99, stats.P999, stats.P9999,
+			stats.max);
+}
+
 void
 printStatistics(const char* label, uint64_t* rawdata, size_t count,
                 const char* datadir) {
-    static bool headerPrinted = false;
-    if (!headerPrinted) {
-        puts(
-            "Benchmark,Count,Avg,Median,Min,99%,"
-            "99.9%,99.99%,Max");
-        headerPrinted = true;
-    }
     Statistics stats = computeStatistics(rawdata, count);
-    printf("%s,%zu,%lu,%lu,%lu,%lu,%lu,%lu,%lu\n", label, count, stats.average,
-           stats.median, stats.min, stats.P99, stats.P999, stats.P9999,
-           stats.max);
+	printStatistics(stats, label);
 
     // Dump the data out
     if (datadir != NULL) {

src/StatsMinimal.h

@@ -17,6 +17,7 @@
 
 #include <stdint.h>
 #include <stddef.h>
+#include <stdbool.h>
 
 /**
  * This file exists to make the computeStatistics function available from C
@@ -44,4 +45,18 @@ struct Statistics {
 };
 
 struct Statistics computeStatistics(uint64_t* rawdata, size_t count);
+
+
+/**
+ * Apply a transformation function on all statistics, usually to change the
+ * units. It is assumed that the units on all statistics are initially
+ * identical.
+ */
+struct Statistics transformStatistics(struct Statistics stats, uint64_t (*function)(uint64_t));
+
+/**
+ * Print out all the statistics in CSV format.
+ */
+void printStatistics(struct Statistics stats, const char* label);
+
 #endif // PERFUTILS_STATS_MINIMAL_H

src/StatsTest.cc

@@ -23,6 +23,12 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
+/**
+ * Simple test function for transforming statistics.
+ */
+uint64_t half(uint64_t n) {
+	return n / 2;
+}
 
 TEST(StatsTest, allStats) {
     const int numElements = 100;
@@ -37,3 +43,31 @@ TEST(StatsTest, allStats) {
     EXPECT_EQ(49, stats.average);
     EXPECT_EQ(28, stats.stddev);
 }
+
+TEST(StatsTest, transformStatistics) {
+    const int numElements = 100;
+    uint64_t input[numElements];
+    for (uint64_t i = 0; i < numElements; i++)
+        input[i] = i;
+    Statistics stats = computeStatistics(input, numElements);
+	Statistics halfStats =  transformStatistics(stats, half);
+
+	EXPECT_EQ(stats.count, halfStats.count);
+    EXPECT_EQ(half(stats.average), halfStats.average);
+    EXPECT_EQ(half(stats.stddev), halfStats.stddev);
+    EXPECT_EQ(half(stats.min), halfStats.min);
+    EXPECT_EQ(half(stats.median), halfStats.median);
+    EXPECT_EQ(half(stats.P10), halfStats.P10);
+    EXPECT_EQ(half(stats.P20), halfStats.P20);
+    EXPECT_EQ(half(stats.P30), halfStats.P30);
+    EXPECT_EQ(half(stats.P40), halfStats.P40);
+    EXPECT_EQ(half(stats.P50), halfStats.P50);
+    EXPECT_EQ(half(stats.P60), halfStats.P60);
+    EXPECT_EQ(half(stats.P70), halfStats.P70);
+    EXPECT_EQ(half(stats.P80), halfStats.P80);
+    EXPECT_EQ(half(stats.P90), halfStats.P90);
+    EXPECT_EQ(half(stats.P99), halfStats.P99);
+    EXPECT_EQ(half(stats.P999), halfStats.P999);
+    EXPECT_EQ(half(stats.P9999), halfStats.P9999);
+    EXPECT_EQ(half(stats.max), halfStats.max);
+}