[GitHub] peng-yongsheng commented on a change in pull request #2239: Support Top sql

[GitBox <gi...@apache.org>]

peng-yongsheng commented on a change in pull request #2239: Support Top sql
URL: https://github.com/apache/incubator-skywalking/pull/2239#discussion_r255948249
 
 

 ##########
 File path: oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/data/LimitedSizeDataCollection.java
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 @@ -0,0 +1,115 @@
+/*
+ * 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.skywalking.oap.server.core.analysis.data;
+
+import java.util.*;
+import org.apache.skywalking.oap.server.core.storage.ComparableStorageData;
+
+public class LimitedSizeDataCollection<STORAGE_DATA extends ComparableStorageData> implements SWCollection<STORAGE_DATA> {
+
+    private final HashMap<STORAGE_DATA, LinkedList<STORAGE_DATA>> data;
+    private final int limitedSize;
+    private volatile boolean writing;
+    private volatile boolean reading;
+
+    LimitedSizeDataCollection(int limitedSize) {
+        this.data = new HashMap<>();
+        this.writing = false;
+        this.reading = false;
+        this.limitedSize = limitedSize;
+    }
+
+    public void finishWriting() {
+        writing = false;
+    }
+
+    @Override public void writing() {
+        writing = true;
+    }
+
+    @Override public boolean isWriting() {
+        return writing;
+    }
+
+    @Override public void finishReading() {
+        reading = false;
+    }
+
+    @Override public void reading() {
+        reading = true;
+    }
+
+    @Override public boolean isReading() {
+        return reading;
+    }
+
+    @Override public int size() {
+        return data.size();
+    }
+
+    @Override public void clear() {
+        data.clear();
+    }
+
+    @Override public boolean containsKey(STORAGE_DATA key) {
+        throw new UnsupportedOperationException("Limited size data collection doesn't support containsKey operation.");
+    }
+
+    @Override public STORAGE_DATA get(STORAGE_DATA key) {
+        throw new UnsupportedOperationException("Limited size data collection doesn't support get operation.");
+    }
+
+    @Override public void put(STORAGE_DATA value) {
+        LinkedList<STORAGE_DATA> storageDataList = this.data.get(value);
+        if (storageDataList == null) {
+            storageDataList = new LinkedList<>();
+            data.put(value, storageDataList);
+        }
+
+        if (storageDataList.size() < limitedSize) {
+            storageDataList.add(value);
+            return;
+        }
+
+        for (int i = 0; i < storageDataList.size(); i++) {
+            STORAGE_DATA storageData = storageDataList.get(i);
+            if (value.compareTo(storageData) <= 0) {
+                if (i == 0) {
+                    // input value is less than the smallest in top N list, ignore
+                } else {
+                    // Remove the smallest in top N list
+                    // add the current value into the right position
+                    storageDataList.removeFirst();
+                    storageDataList.add(i, value);
 
 Review comment:
   add(I-1, value);
   
   Init: 1,3,5,7,9
   limit size: 5
   income: 4
   result: 3,5,4,7,9
   

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