org.apache.hudi.org.apache.hadoop.hbase.master.procedure.FairQueue Maven / Gradle / Ivy
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* 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.hadoop.hbase.master.procedure;
import org.apache.hadoop.hbase.util.AvlUtil.AvlIterableList;
import org.apache.yetus.audience.InterfaceAudience;
@InterfaceAudience.Private
public class FairQueue> {
private Queue queueHead = null;
private int size = 0;
public boolean hasRunnables() {
return size > 0;
}
public void add(Queue queue) {
// For normal priority queue, just append it to the tail
if (queueHead == null || queue.getPriority() == 1) {
queueHead = AvlIterableList.append(queueHead, queue);
size++;
return;
}
// Find the one which priority is less than us
// For now only TableQueue and ServerQueue has priority. For TableQueue there are only a small
// number of tables which have higher priority, and for ServerQueue there is only one server
// which could carry meta which leads to a higher priority, so this will not be an expensive
// operation.
Queue base = queueHead;
do {
if (base.getPriority() < queue.getPriority()) {
queueHead = AvlIterableList.prepend(queueHead, base, queue);
size++;
return;
}
base = AvlIterableList.readNext(base);
} while (base != queueHead);
// no one is lower than us, append to the tail
queueHead = AvlIterableList.append(queueHead, queue);
size++;
}
public void remove(Queue queue) {
queueHead = AvlIterableList.remove(queueHead, queue);
size--;
}
public Queue poll() {
if (queueHead == null) {
return null;
}
Queue q = queueHead;
do {
if (q.isAvailable()) {
if (q.getPriority() == 1) {
// for the normal priority queue, remove it and append it to the tail
queueHead = AvlIterableList.remove(queueHead, q);
queueHead = AvlIterableList.append(queueHead, q);
}
return q;
}
q = AvlIterableList.readNext(q);
} while (q != queueHead);
return null;
}
}