Re: [PR] EB-PPS Sampling sketch (datasketches-java)

["leerho (via GitHub)" <gi...@apache.org>]

leerho commented on code in PR #499:
URL: https://github.com/apache/datasketches-java/pull/499#discussion_r1474896587


##########
src/main/java/org/apache/datasketches/sampling/EbppsItemsSample.java:
##########
@@ -0,0 +1,301 @@
+/*
+ * 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.datasketches.sampling;
+
+import static org.apache.datasketches.common.Util.LS;
+
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
+
+// this is a supporting class used to hold the raw data sample
+class EbppsItemsSample<T> {
+
+  private double c_;            // Current sample size, including fractional part
+  private T partialItem_;       // a sample item corresponding to a partial weight
+  private ArrayList<T> data_;   // full sample items
+  
+  private Random rand_;         // ThreadLocalRandom.current() in general
+
+  // basic constructor
+  EbppsItemsSample(final int reservedSize) {
+    c_ = 0.0;
+    data_ = new ArrayList<>(reservedSize);
+    rand_ = ThreadLocalRandom.current();
+  }
+
+  // copy constructor used during merge
+  EbppsItemsSample(final EbppsItemsSample<T> other) {
+    c_ = other.c_;
+    partialItem_ = other.partialItem_;
+    data_ = new ArrayList<>(other.data_);
+    rand_ = other.rand_;
+  }
+
+  // constructor used for deserialization and testing
+  // does NOT copy the incoming ArrayList since this is an internal
+  // class's package-private constructor, not something directly
+  // taking user data
+  EbppsItemsSample(ArrayList<T> data, T partialItem, final double c) {
+    c_ = c;
+    partialItem_ = partialItem;
+    data_ = data;
+    rand_ = ThreadLocalRandom.current();
+  }
+
+  // Used in lieu of a constructor to populate a temporary sample
+  // with data before immediately merging it. This approach
+  // avoids excessive object allocation calls.
+  // rand_ is not set since it is not expected to be used from
+  // this object
+  void replaceContent(final T item, final double theta) {
+    c_ = theta;
+    if (theta == 1.0) {
+      if (data_ != null && data_.size() == 1) {
+        data_.set(0, item);
+      } else {
+        data_ = new ArrayList<T>(1);
+        data_.add(item);  
+      }
+      partialItem_ = null;
+    } else {
+      data_ = null;
+      partialItem_ = item;
+    }
+  }
+
+  public void reset() {

Review Comment:
   You should be using Checkstyle. many of your public methods do not have javadocs, -or- they  don't need to be public.  Use the SketchesCheckstyle.xml in the /tools/ directory.



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