| /** |
| * 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.hadoop.hbase.procedure2; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.concurrent.TimeUnit; |
| import org.apache.yetus.audience.InterfaceAudience; |
| |
| /** |
| * Keep track of the runnable procedures |
| */ |
| @InterfaceAudience.Private |
| public interface ProcedureScheduler { |
| /** |
| * Start the scheduler |
| */ |
| void start(); |
| |
| /** |
| * Stop the scheduler |
| */ |
| void stop(); |
| |
| /** |
| * In case the class is blocking on poll() waiting for items to be added, |
| * this method should awake poll() and poll() should return. |
| */ |
| void signalAll(); |
| |
| /** |
| * Inserts the specified element at the front of this queue. |
| * @param proc the Procedure to add |
| */ |
| void addFront(Procedure proc); |
| |
| /** |
| * Inserts the specified element at the front of this queue. |
| * @param proc the Procedure to add |
| * @param notify whether need to notify worker |
| */ |
| void addFront(Procedure proc, boolean notify); |
| |
| /** |
| * Inserts all elements in the iterator at the front of this queue. |
| */ |
| void addFront(Iterator<Procedure> procedureIterator); |
| |
| /** |
| * Inserts the specified element at the end of this queue. |
| * @param proc the Procedure to add |
| */ |
| void addBack(Procedure proc); |
| |
| /** |
| * Inserts the specified element at the end of this queue. |
| * @param proc the Procedure to add |
| * @param notify whether need to notify worker |
| */ |
| void addBack(Procedure proc, boolean notify); |
| |
| /** |
| * The procedure can't run at the moment. |
| * add it back to the queue, giving priority to someone else. |
| * @param proc the Procedure to add back to the list |
| */ |
| void yield(Procedure proc); |
| |
| /** |
| * The procedure in execution completed. |
| * This can be implemented to perform cleanups. |
| * @param proc the Procedure that completed the execution. |
| */ |
| void completionCleanup(Procedure proc); |
| |
| /** |
| * @return true if there are procedures available to process, otherwise false. |
| */ |
| boolean hasRunnables(); |
| |
| /** |
| * Fetch one Procedure from the queue |
| * @return the Procedure to execute, or null if nothing present. |
| */ |
| Procedure poll(); |
| |
| /** |
| * Fetch one Procedure from the queue |
| * @param timeout how long to wait before giving up, in units of unit |
| * @param unit a TimeUnit determining how to interpret the timeout parameter |
| * @return the Procedure to execute, or null if nothing present. |
| */ |
| Procedure poll(long timeout, TimeUnit unit); |
| |
| /** |
| * List lock queues. |
| * @return the locks |
| */ |
| List<LockedResource> getLocks(); |
| |
| /** |
| * @return {@link LockedResource} for resource of specified type & name. null if resource is not |
| * locked. |
| */ |
| LockedResource getLockResource(LockedResourceType resourceType, String resourceName); |
| |
| /** |
| * Returns the number of elements in this queue. |
| * @return the number of elements in this queue. |
| */ |
| int size(); |
| |
| /** |
| * Clear current state of scheduler such that it is equivalent to newly created scheduler. |
| * Used for testing failure and recovery. To emulate server crash/restart, |
| * {@link ProcedureExecutor} resets its own state and calls clear() on scheduler. |
| */ |
| void clear(); |
| } |