SelectionPolicy.java

/*
 * Created by Andrey Cherkashin (acherkashin)
 * http://acherkashin.me
 * 
 * License
 * Copyright (c) 2015 Andrey Cherkashin
 * The project released under the MIT license: http://opensource.org/licenses/MIT
 */
package ragefist.core.distribution;

import com.juniform.JUniformObject;
import java.util.Random;
import javax.naming.directory.InvalidAttributesException;

/**
 *
 * @author acherkashin
 */
public abstract class SelectionPolicy
{
	// ---------------------------------------------------------------------- //
	// IMPLEMENTATIONS
	// ---------------------------------------------------------------------- //
	
	private static class SelectionPolicyRandom extends SelectionPolicy
	{
		private static final Random _rand = new Random();
		public SelectionPolicyRandom(JUniformObject configObject) throws InvalidAttributesException {
			// no attributes required
		}

		@Override
		public int select(int max) {
			return _rand.nextInt(max);
		}
	}
	
	// ---------------------------------------------------------------------- //
	// STATIC
	// ---------------------------------------------------------------------- //
	
	public static SelectionPolicy newInstance(JUniformObject configObject) throws InvalidAttributesException {
		if (configObject == null) {
			throw new InvalidAttributesException("EnvironmentSelectionPolicy is null");
		}
		
		String policyType = configObject.getProperty("Type").toStringDefault("");
		if (policyType == null) {
			throw new InvalidAttributesException("EnvironmentSelectionPolicy.Type is null");
		}
		switch(policyType) {
			default:
				throw new InvalidAttributesException("Unknown environment selection policy type: "+policyType);
				
			case "random":
				return new SelectionPolicyRandom(configObject);
		}
	}
	
	// ---------------------------------------------------------------------- //
	// PUBLIC
	// ---------------------------------------------------------------------- //
	
	/**
	 * Selects an Environment/Server
	 * @param max Maximum number of environments/servers
	 * @return Target id
	 */
	public abstract int select(int max);
}