1 files changed, 84 insertions, 0 deletions
diff --git a/predicate-search/src/main/java/com/yahoo/search/predicate/benchmarks/ResultMetrics.java b/predicate-search/src/main/java/com/yahoo/search/predicate/benchmarks/ResultMetrics.java
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+++ b/predicate-search/src/main/java/com/yahoo/search/predicate/benchmarks/ResultMetrics.java
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+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.predicate.benchmarks;
+
+import java.util.Map;
+
+/**
+ * Various metrics stored during query execution
+ *
+ * @author bjorncs
+ */
+public class ResultMetrics {
+    private static final int MAX_LATENCY = 100; // ms
+    private static final int RESOLUTION = 25; // sample points per ms
+    private static final int SLOTS = MAX_LATENCY * RESOLUTION;
+
+    private long totalQueries = 0;
+    private long totalHits = 0;
+    private double maxLatency = Double.MIN_VALUE;
+    private double minLatency = Double.MAX_VALUE;
+    private final long[] latencyHistogram = new long[SLOTS];
+
+    public void registerResult(long hits, double latencyMilliseconds) {
+        if (latencyMilliseconds > maxLatency) {
+            maxLatency = latencyMilliseconds;
+        }
+        if (latencyMilliseconds < minLatency) {
+            minLatency = latencyMilliseconds;
+        }
+        totalHits += hits;
+        ++totalQueries;
+        int latencySlot = (int) Math.round(latencyMilliseconds * RESOLUTION);
+        // Note: extreme latency values are ignored in the histogram for simplicity
+        if (latencySlot < SLOTS) {
+            ++latencyHistogram[latencySlot];
+        }
+    }
+
+    public void combine(ResultMetrics other) {
+        totalQueries += other.totalQueries;
+        minLatency = Math.min(minLatency, other.minLatency);
+        maxLatency = Math.max(maxLatency, other.maxLatency);
+        totalHits += other.totalHits;
+        for (int i = 0; i < SLOTS; i++) {
+            latencyHistogram[i] += other.latencyHistogram[i];
+        }
+    }
+
+    public void writeMetrics(Map<String, Object> metricMap, long timeSearch) {
+        double qps = timeSearch == 0 ? 0 : (1000d * totalQueries / timeSearch);
+        metricMap.put("QPS", qps);
+        metricMap.put("Time search", timeSearch);
+        metricMap.put("Total hits", totalHits);
+        metricMap.put("Total queries", totalQueries);
+        metricMap.put("Max latency", latencyToString(maxLatency));
+        metricMap.put("Min latency", latencyToString(minLatency));
+        metricMap.put("99.9 percentile", latencyToString(percentile(0.999)));
+        metricMap.put("99 percentile", latencyToString(percentile(0.99)));
+        metricMap.put("90 percentile", latencyToString(percentile(0.90)));
+        metricMap.put("75 percentile", latencyToString(percentile(0.75)));
+        metricMap.put("50 percentile", latencyToString(percentile(0.50)));
+    }
+
+    private double percentile(double percentile) {
+        int targetCount = (int) Math.round(totalQueries * percentile);
+        int currentCount = 0;
+        int index = 0;
+        while (currentCount < targetCount && index < SLOTS) {
+            currentCount += latencyHistogram[index];
+            ++index;
+        }
+        if (index == SLOTS) {
+            return maxLatency;
+        }
+        return toLatency(currentCount == targetCount ? index + 1 : index);
+    }
+
+    private static String latencyToString(double averageLatency) {
+        return String.format("%.2fms", averageLatency);
+    }
+
+    private static double toLatency(int index) {
+        return (index + 0.5) / (double) RESOLUTION;
+    }
+}