org.quartz.core.ThreadPool Maven / Gradle / Ivy
/*
* Copyright 2001-2009 Terracotta, Inc.
*
* 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 org.quartz.core;
import org.quartz.exceptions.SchedulerConfigException;
/**
*
* The interface to be implemented by classes that want to provide a thread pool for the {@link org.quartz.QuartzScheduler}'s use.
*
*
* ThreadPool implementation instances should ideally be made for the sole use of Quartz. Most importantly, when the method
* blockForAvailableThreads() returns a value of 1 or greater, there must still be at least one available thread in the pool when the
* method runInThread(Runnable) is called a few moments (or many moments) later. If this assumption does not hold true, it may result in
* extra JobStore queries and updates, and if clustering features are being used, it may result in greater imballance of load.
*
*
* @see org.quartz.QuartzScheduler
* @author James House
*/
public interface ThreadPool {
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interface.
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
/**
*
* Execute the given {@link java.lang.Runnable} in the next available Thread.
*
*
* The implementation of this interface should not throw exceptions unless there is a serious problem (i.e. a serious misconfiguration). If there
* are no immediately available threads false should be returned.
*
*
* @return true, if the runnable was assigned to run on a Thread.
*/
boolean runInThread(Runnable runnable);
/**
*
* Determines the number of threads that are currently available in in the pool. Useful for determining the number of times
* runInThread(Runnable) can be called before returning false.
*
*
* The implementation of this method should block until there is at least one available thread.
*
*
* @return the number of currently available threads
*/
int blockForAvailableThreads();
/**
*
* Must be called before the ThreadPool is used, in order to give the it a chance to initialize.
*
*
* Typically called by the SchedulerFactory.
*
*/
void initialize() throws SchedulerConfigException;
/**
*
* Called by the QuartzScheduler to inform the ThreadPool that it should free up all of it's resources because the scheduler is
* shutting down.
*
*/
void shutdown(boolean waitForJobsToComplete);
/**
*
* Get the current number of threads in the ThreadPool.
*
*/
int getPoolSize();
}