Server.java

/*
 * JaamSim Discrete Event Simulation
 * Copyright (C) 2013 Ausenco Engineering Canada Inc.
 * Copyright (C) 2016 JaamSim Software 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 com.jaamsim.ProcessFlow;

import com.jaamsim.Graphics.DisplayEntity;
import com.jaamsim.Samples.SampleConstant;
import com.jaamsim.Samples.SampleInput;
import com.jaamsim.input.Keyword;
import com.jaamsim.units.TimeUnit;

/**
 * Server processes entities one by one from a queue.  When finished with an entity, it passes it to the next
 * LinkedComponent in the chain.
 */
public class Server extends LinkedService {

	@Keyword(description = "The service time required to process an entity.\n" +
			"A constant value, a distribution to be sampled, or a time series can be entered.",
	         exampleList = { "3.0 h", "NormalDistribution1", "'1[s] + 0.5*[TimeSeries1].PresentValue'" })
	private final SampleInput serviceTime;

	private DisplayEntity servedEntity;	// the DisplayEntity being server

	{
		serviceTime = new SampleInput("ServiceTime", "Key Inputs", new SampleConstant(TimeUnit.class, 0.0));
		serviceTime.setUnitType(TimeUnit.class);
		serviceTime.setEntity(this);
		serviceTime.setValidRange(0, Double.POSITIVE_INFINITY);
		this.addInput(serviceTime);
	}

	public Server() {}

	@Override
	public void earlyInit() {
		super.earlyInit();
		servedEntity = null;
	}

	@Override
	protected boolean startProcessing(double simTime) {

		// Determine the match value
		Integer m = this.getNextMatchValue(getSimTime());
		this.setMatchValue(m);

		// Stop if the queue is empty
		if (waitQueue.getValue().getMatchCount(m) == 0) {
			return false;
		}

		// Remove the first entity from the queue
		servedEntity = this.getNextEntityForMatch(m);
		this.moveToProcessPosition(servedEntity);
		return true;
	}

	@Override
	protected boolean processStep(double simTime) {

		// Send the entity to the next component in the chain
		this.sendToNextComponent(servedEntity);
		servedEntity = null;

		return true;
	}

	@Override
	protected double getStepDuration(double simTime) {
		return serviceTime.getValue().getNextSample(simTime);
	}

}