org.apache.flume.util.RoundRobinOrderSelector Maven / Gradle / Ivy
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* 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.flume.util;
import java.util.Iterator;
import java.util.List;
/**
* An implementation of OrderSelector which returns objects in round robin order.
* Also supports backoff.
*/
public class RoundRobinOrderSelector extends OrderSelector {
private int nextHead = 0;
public RoundRobinOrderSelector(boolean shouldBackOff) {
super(shouldBackOff);
}
@Override
public Iterator createIterator() {
List activeIndices = getIndexList();
int size = activeIndices.size();
// possible that the size has shrunk so gotta adjust nextHead for that
if (nextHead >= size) {
nextHead = 0;
}
int begin = nextHead++;
if (nextHead == activeIndices.size()) {
nextHead = 0;
}
int[] indexOrder = new int[size];
for (int i = 0; i < size; i++) {
indexOrder[i] = activeIndices.get((begin + i) % size);
}
return new SpecificOrderIterator(indexOrder, getObjects());
}
}
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