PathFinderRequestControl.java

/*******************************************************************************
 * Copyright 2014 See AUTHORS file.
 * 
 * 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.badlogic.gdx.ai.pfa;

import com.badlogic.gdx.ai.GdxAI;
import com.badlogic.gdx.ai.msg.MessageDispatcher;
import com.badlogic.gdx.ai.msg.MessageManager;
import com.badlogic.gdx.ai.msg.Telegraph;
import com.badlogic.gdx.utils.TimeUtils;

/** A {@code PathFinderRequestControl} manages execution and resume of any interruptible {@link PathFinderRequest}.
 * 
 * @param <N> Type of node
 * 
 * @author davebaol */
public class PathFinderRequestControl<N> {

	private static final String TAG = "PathFinderRequestControl";
	
	public static final boolean DEBUG = false;

	Telegraph server;
	PathFinder<N> pathFinder;
	long lastTime;
	long timeToRun;
	long timeTolerance;

	public PathFinderRequestControl () {
	}

	/** Executes the given pathfinding request resuming it if needed.
	 * @param request the pathfinding request
	 * @return {@code true} if this operation has completed; {@code false} if more time is needed to complete. */
	public boolean execute (PathFinderRequest<N> request) {

		request.executionFrames++;

		while (true) {
			if (DEBUG) GdxAI.getLogger().debug(TAG, "------");
			// Should perform search begin?
			if (request.status == PathFinderRequest.SEARCH_NEW) {
				long currentTime = TimeUtils.nanoTime();
				timeToRun -= currentTime - lastTime;
				if (timeToRun <= timeTolerance) return false;
				if (DEBUG) GdxAI.getLogger().debug(TAG, "search begin");
				if (!request.initializeSearch(timeToRun)) return false;
				request.changeStatus(PathFinderRequest.SEARCH_INITIALIZED);
				lastTime = currentTime;
			}

			// Should perform search path?
			if (request.status == PathFinderRequest.SEARCH_INITIALIZED) {
				long currentTime = TimeUtils.nanoTime();
				timeToRun -= currentTime - lastTime;
				if (timeToRun <= timeTolerance) return false;
				if (DEBUG) GdxAI.getLogger().debug(TAG, "search path");
				if (!request.search(pathFinder, timeToRun)) return false;
				request.changeStatus(PathFinderRequest.SEARCH_DONE);
				lastTime = currentTime;
			}

			// Should perform search end?
			if (request.status == PathFinderRequest.SEARCH_DONE) {
				long currentTime = TimeUtils.nanoTime();
				timeToRun -= currentTime - lastTime;
				if (timeToRun <= timeTolerance) return false;
				if (DEBUG) GdxAI.getLogger().debug(TAG, "search end");
				if (!request.finalizeSearch(timeToRun)) return false;
				request.changeStatus(PathFinderRequest.SEARCH_FINALIZED);

				// Search finished, send result to the client
				if (server != null) {
					MessageDispatcher dispatcher = request.dispatcher != null ? request.dispatcher : MessageManager.getInstance();
					dispatcher.dispatchMessage(server, request.client, request.responseMessageCode, request);
				}

				lastTime = currentTime;

				if (request.statusChanged && request.status == PathFinderRequest.SEARCH_NEW) {
					if (DEBUG) GdxAI.getLogger().debug(TAG, "search renew");
					continue;
				}
			}

			return true;
		}
	}
}