degist-concurrency-bugfix

dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/aggregate/DubboAbstractTDigest.java

@@ -0,0 +1,86 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.dubbo.metrics.aggregate;
+
+import com.tdunning.math.stats.Centroid;
+import com.tdunning.math.stats.TDigest;
+
+public abstract class DubboAbstractTDigest extends TDigest {
+    boolean recordAllData = false;
+
+    /**
+     * Same as {@link #weightedAverageSorted(double, double, double, double)} but flips
+     * the order of the variables if <code>x2</code> is greater than
+     * <code>x1</code>.
+     */
+    static double weightedAverage(double x1, double w1, double x2, double w2) {
+        if (x1 <= x2) {
+            return weightedAverageSorted(x1, w1, x2, w2);
+        } else {
+            return weightedAverageSorted(x2, w2, x1, w1);
+        }
+    }
+
+    /**
+     * Compute the weighted average between <code>x1</code> with a weight of
+     * <code>w1</code> and <code>x2</code> with a weight of <code>w2</code>.
+     * This expects <code>x1</code> to be less than or equal to <code>x2</code>
+     * and is guaranteed to return a number in <code>[x1, x2]</code>. An
+     * explicit check is required since this isn't guaranteed with floating-point
+     * numbers.
+     */
+    private static double weightedAverageSorted(double x1, double w1, double x2, double w2) {
+        assert x1 <= x2;
+        final double x = (x1 * w1 + x2 * w2) / (w1 + w2);
+        return Math.max(x1, Math.min(x, x2));
+    }
+
+    abstract void add(double x, int w, Centroid base);
+
+    /**
+     * Sets up so that all centroids will record all data assigned to them.  For testing only, really.
+     */
+    @Override
+    public TDigest recordAllData() {
+        recordAllData = true;
+        return this;
+    }
+
+    @Override
+    public boolean isRecording() {
+        return recordAllData;
+    }
+
+    /**
+     * Adds a sample to a histogram.
+     *
+     * @param x The value to add.
+     */
+    @Override
+    public void add(double x) {
+        add(x, 1);
+    }
+
+    @Override
+    public void add(TDigest other) {
+        for (Centroid centroid : other.centroids()) {
+            add(centroid.mean(), centroid.count(), centroid);
+        }
+    }
+
+}