Github user chtyim commented on a diff in the pull request:
https://github.com/apache/incubator-tephra/pull/37#discussion_r102343334
--- Diff:
tephra-core/src/main/java/org/apache/tephra/manager/InvalidTxList.java ---
@@ -0,0 +1,127 @@
+/*
+ * 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.tephra.manager;
+
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+import it.unimi.dsi.fastutil.longs.LongCollection;
+import it.unimi.dsi.fastutil.longs.LongList;
+import org.apache.tephra.TransactionManager;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import javax.annotation.concurrent.NotThreadSafe;
+
+/**
+ * This is an internal class used by the {@link TransactionManager} to
store invalid transaction ids.
+ * This class uses both a list and an array to keep track of the invalid
ids. The list is the primary
+ * data structure for storing the invalid ids. The array is populated
lazily on changes to the list.
+ * The array is used to avoid creating a new array every time method
{@link #toSortedArray()} is invoked.
+ *
+ * This class is not thread safe and relies on external synchronization.
TransactionManager always
+ * accesses an instance of this class after synchronization.
+ */
+@NotThreadSafe
+public class InvalidTxList {
+ private static final long[] NO_INVALID_TX = { };
+
+ private final LongList invalid = new LongArrayList();
+ private long[] invalidArray = NO_INVALID_TX;
+
+ private boolean dirty = false; // used to track changes to the invalid
list
+
+ public int size() {
+ return invalid.size();
+ }
+
+ public boolean isEmpty() {
+ return invalid.isEmpty();
+ }
+
+ public boolean add(long id) {
+ boolean changed = invalid.add(id);
+ dirty = dirty || changed;
+ return changed;
+ }
+
+ public boolean addAll(Collection<? extends Long> ids) {
+ boolean changed = invalid.addAll(ids);
+ dirty = dirty || changed;
+ return changed;
+ }
+
+ public boolean addAll(LongCollection ids) {
--- End diff --
Should use `LongList` instead of `LongCollection` as the `LongArrayList`
only optimize if it is a `LongList`.
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