com.hazelcast.spi.impl.operationexecutor.impl.OperationQueue Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2020, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.spi.impl.operationexecutor.impl;
/**
* The OperationQueue is the queue used to schedule operations/tasks on an
* OperationThread.
*
* Implementations must support Multiple-Producer Multiple-Consumers scenario
* as multiple {@link GenericOperationThread} share a single queue.
*
* The ScheduledQueue also support priority tasks; so if a task with a priority
* comes in, than that one is taken before any other normal operation is taken.
*
* The ordering between normal tasks will always be FIFO. And the same goes for
* the ordering between priority tasks, but there is no ordering guarantee between
* priority and normal tasks.
*/
public interface OperationQueue {
/**
* Adds an task to this queue.
*
* This method is thread safe.
*
* @param task the item to add
* @param priority if the task has priority or not
* @throws java.lang.NullPointerException if task is null
*/
void add(Object task, boolean priority);
/**
* Takes an item from this queue. If no item is available, the call blocks.
*
* This method should always be called by the same thread.
*
* @param priorityOnly true if only priority items should be taken. This is
* useful for priority generic threads since they
* should only take priority items.
* @return the taken item.
* @throws InterruptedException if the thread is interrupted while waiting.
*/
Object take(boolean priorityOnly) throws InterruptedException;
/**
* returns the number of normal operations pending.
*
* This method is thread safe.
*
* This method returns a best effort value and should only be used for
* monitoring purposes.
*
* @return the number of normal pending operations.
*/
int normalSize();
/**
* returns the number of priority operations pending.
*
* This method is thread safe.
*
* This method returns a best effort value and should only be used for
* monitoring purposes.
*
* @return the number of priority pending operations.
*/
int prioritySize();
/**
* Returns the total number of pending operations.
*
* This method is thread safe.
*
* This method returns a best effort value and should only be used for
* monitoring purposes.
*
* @return the total number of pending operations.
*/
int size();
}