integration of "top" into metrics-core + unit tests

src/main/java/com/github/metricscore/hdr/top/TopMetricSet.java

@@ -0,0 +1,99 @@
+/*
+ *
+ *  Copyright 2016 Vladimir Bukhtoyarov
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
+
+package com.github.metricscore.hdr.top;
+
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Metric;
+import com.codahale.metrics.MetricSet;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+public class TopMetricSet implements MetricSet {
+
+    private final BigDecimal zero;
+    private final Map<String, Metric> gauges;
+
+    public TopMetricSet(String name, Top top, TimeUnit latencyUnit, int digitsAfterDecimalPoint) {
+        if (name == null) {
+            throw new IllegalArgumentException("name should not be null");
+        }
+        if (name.isEmpty()) {
+            throw new IllegalArgumentException("name should not be empty");
+        }
+        if (top == null) {
+            throw new IllegalArgumentException("top should not be null");
+        }
+        if (latencyUnit == null) {
+            throw new IllegalArgumentException("latencyUnit should not be null");
+        }
+        if (digitsAfterDecimalPoint < 0) {
+            throw new IllegalArgumentException("digitsAfterDecimalPoint should not be negative");
+        }
+
+        gauges = new HashMap<>();
+        gauges.put(name + ".latencyUnit", (Gauge<String>) latencyUnit::toString);
+
+        zero = BigDecimal.ZERO.setScale(digitsAfterDecimalPoint, RoundingMode.CEILING);
+
+        int size = top.getSize();
+        for (int i = 0; i < size; i++) {
+            String latencyName = name + "." + i + "." + "latency";
+            Gauge<BigDecimal> latencyGauge = createLatencyGauge(i, top, latencyUnit, digitsAfterDecimalPoint);
+            gauges.put(latencyName, latencyGauge);
+
+            String descriptionName = name + "." + i + "." + "description";
+            Gauge<String> descriptionGauge = createDescriptionGauge(i, top);
+            gauges.put(descriptionName, descriptionGauge);
+        }
+    }
+
+    @Override
+    public Map<String, Metric> getMetrics() {
+        return gauges;
+    }
+
+    private Gauge<BigDecimal> createLatencyGauge(int i, Top top, TimeUnit latencyUnit, int digitsAfterDecimalPoint) {
+        return () -> {
+            List<Position> positions = top.getPositionsInDescendingOrder();
+            if (positions.size() <= i) {
+                return zero;
+            }
+            double latencyNanos = positions.get(i).getLatencyInNanoseconds();
+            long scale = latencyUnit.toNanos(1);
+            double result = latencyNanos/scale;
+
+            return new BigDecimal(result).setScale(digitsAfterDecimalPoint, RoundingMode.CEILING);
+        };
+    }
+
+    private Gauge<String> createDescriptionGauge(int i, Top top) {
+        return () -> {
+            List<Position> positions = top.getPositionsInDescendingOrder();
+            if (positions.size() <= i) {
+                return "";
+            }
+            return positions.get(i).getQueryDescription();
+        };
+    }
+
+}

src/test/java/com/github/metricscore/hdr/top/TopMetricSetTest.java

@@ -0,0 +1,125 @@
+/*
+ *
+ *  Copyright 2016 Vladimir Bukhtoyarov
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
+
+package com.github.metricscore.hdr.top;
+
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Metric;
+import org.junit.Test;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.time.Duration;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import static com.github.metricscore.hdr.top.TestData.first;
+import static com.github.metricscore.hdr.top.TestData.second;
+import static com.github.metricscore.hdr.top.TestData.third;
+import static com.github.metricscore.hdr.top.impl.TopTestUtil.update;
+import static org.junit.Assert.*;
+
+public class TopMetricSetTest {
+
+    private Top top = Top.builder(3).withSnapshotCachingDuration(Duration.ZERO).build();
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldDisallowNullName() {
+        new TopMetricSet(null, top, TimeUnit.MILLISECONDS, 3);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldDisallowEmptyName() {
+        new TopMetricSet("", top, TimeUnit.MILLISECONDS, 3);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldDisallowNullTop() {
+        new TopMetricSet("my-top", null, TimeUnit.MILLISECONDS, 3);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldDisallowNullLatencyUnit() {
+        new TopMetricSet("my-top", top, null, 3);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldDisallowNegativeDigitsAfterDecimalPoint() {
+        new TopMetricSet("my-top", top, TimeUnit.MILLISECONDS, -1);
+    }
+
+    @Test
+    public void shouldAddLatencyUnitGauge() {
+        for (TimeUnit timeUnit: TimeUnit.values()) {
+            TopMetricSet metricSet = new TopMetricSet("my-top", top, timeUnit, 3);
+            Map<String, Metric> metrics = metricSet.getMetrics();
+            Gauge<String> timeUnitGauge = (Gauge<String>) metrics.get("my-top.latencyUnit");
+            assertNotNull(timeUnitGauge);
+            assertEquals(timeUnit.toString(), timeUnitGauge.getValue());
+        }
+    }
+
+    @Test
+    public void testDescriptionGauges() {
+        TopMetricSet metricSet = new TopMetricSet("my-top", top, TimeUnit.MILLISECONDS, 3);
+        checkDescriptions(metricSet, "my-top", "", "", "");
+
+        update(top, first);
+        checkDescriptions(metricSet, "my-top", first.getQueryDescription(), "", "");
+
+        update(top, second);
+        checkDescriptions(metricSet, "my-top", second.getQueryDescription(), first.getQueryDescription(), "");
+
+        update(top, third);
+        checkDescriptions(metricSet, "my-top", third.getQueryDescription(), second.getQueryDescription(), first.getQueryDescription());
+    }
+
+    @Test
+    public void testValueGauges() {
+        TopMetricSet metricSet = new TopMetricSet("my-top", top, TimeUnit.MILLISECONDS, 3);
+        checkValues(metricSet, "my-top", 3, 0.0d, 0.0d, 0.0d);
+
+        top.update(0, 13_345_456, TimeUnit.NANOSECONDS, () -> "SELECT * FROM USERS");
+        checkValues(metricSet, "my-top", 3, 13.345d, 0.0d, 0.0d);
+
+
+        top.update(0, 11_666_957, TimeUnit.NANOSECONDS, () -> "SELECT * FROM USERS");
+        checkValues(metricSet, "my-top", 3, 13.345d, 11.666d, 0.0d);
+
+        top.update(0, 2_004_123, TimeUnit.NANOSECONDS, () -> "SELECT * FROM DUAL");
+        checkValues(metricSet, "my-top", 3, 13.345d, 11.666d, 2.004d);
+    }
+
+    private void checkDescriptions(TopMetricSet metricSet, String name, String... requiredDescriptions) {
+        for (int i = 0; i < requiredDescriptions.length; i++) {
+            String requiredDescription = requiredDescriptions[i];
+            Gauge<String> gauge = (Gauge<String>) metricSet.getMetrics().get(name + "." + i + ".description");
+            String description = gauge.getValue();
+            assertEquals(requiredDescription, description);
+        }
+    }
+
+    private void checkValues(TopMetricSet metricSet, String name, int digitsAfterDecimalPoint, double... requiredLatencies) {
+        for (int i = 0; i < requiredLatencies.length; i++) {
+            BigDecimal requiredLatency = new BigDecimal(requiredLatencies[i]).setScale(digitsAfterDecimalPoint, RoundingMode.CEILING);
+            Gauge<BigDecimal> gauge = (Gauge<BigDecimal>) metricSet.getMetrics().get(name + "." + i + ".latency");
+            BigDecimal latency = gauge.getValue();
+            assertEquals(requiredLatency, latency);
+        }
+    }
+
+}