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Subject [GitHub] [cassandra] jasonstack commented on a change in pull request #446: CASSANDRA-15564 Refactor repair coordinator to centralize stage change logic and improved the public facing errors
Date Tue, 10 Mar 2020 06:37:39 GMT
jasonstack commented on a change in pull request #446: CASSANDRA-15564 Refactor repair coordinator
to centralize stage change logic and improved the public facing errors
URL: https://github.com/apache/cassandra/pull/446#discussion_r390117908
 
 

 ##########
 File path: test/distributed/org/apache/cassandra/distributed/api/QueryResult.java
 ##########
 @@ -0,0 +1,139 @@
+/*
+ * 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.cassandra.distributed.api;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.function.Predicate;
+
+/**
+ * A table of data representing a complete query result.
+ *
+ * A <code>QueryResult</code> is different from {@link java.sql.ResultSet} in
several key ways:
+ *
+ * <ul>
+ *     <li>represents a complete result rather than a cursor</li>
+ *     <li>returns a {@link Row} to access the current row of data</li>
+ *     <li>relies on object pooling; {@link #hasNext()} may return the same object
just with different data, accessing a
+ *     {@link Row} from a previous {@link #hasNext()} call has undefined behavior.</li>
+ *     <li>includes {@link #filter(Predicate)}, this will do client side filtering
since Apache Cassandra is more
+ *     restrictive on server side filtering</li>
+ * </ul>
+ *
+ * <h2>Unsafe patterns</h2>
+ *
+ * Below are a few unsafe patterns which may lead to unexpected results
+ *
+ * <code>{@code
+ * while (rs.hasNext()) {
+ *   list.add(rs.next());
 
 Review comment:
   just curious, is there any benefit of reusing the same `Row` object?

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