// 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
// 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.cloud.utils.concurrency;

import org.apache.log4j.Logger;

public class SynchronizationEvent {
    protected final static Logger s_logger = Logger.getLogger(SynchronizationEvent.class);
	
	private boolean signalled;
	
	public SynchronizationEvent() {
		signalled = false;
	}
	
	public SynchronizationEvent(boolean signalled) {
		this.signalled = signalled;
	}
	
	public void setEvent() {
		synchronized(this) {
			signalled = true;
			notifyAll();
		}
	}
	
	public void resetEvent() {
		synchronized(this) {
			signalled = false;
		}		
	}
	
	public boolean waitEvent() throws InterruptedException {
		synchronized(this) {
			if(signalled)
				return true;
			
			while(true) {
				try {
					wait();
					assert(signalled);
					return signalled;
				} catch (InterruptedException e) {
					s_logger.debug("unexpected awaken signal in wait()");
					throw e;
				}
			}
		}
	}
	
	public boolean waitEvent(long timeOutMiliseconds) throws InterruptedException {
		synchronized(this) {
			if(signalled)
				return true;
			
			try {
				wait(timeOutMiliseconds);
				return signalled;
			} catch (InterruptedException e) {
				// TODO, we don't honor time out semantics when the waiting thread is interrupted
				s_logger.debug("unexpected awaken signal in wait(...)");
				throw e;
			}
		}
	}
	
	public boolean isSignalled() {
		synchronized(this) {
			return signalled;
		}
	}
}
