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    • at.chrl.cbutils.memoizer.MemoizeCallback Maven / Gradle / Ivy

    /**
 * This file is part of ChRL Util Collection.
 * 
 * ChRL Util Collection is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version.
 * 
 * ChRL Util Collection is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * ChRL Util Collection. If not, see .
 */
package at.chrl.cbutils.memoizer;

import java.util.Map;
import java.util.Objects;
import java.util.function.Supplier;

import at.chrl.callbacks.Callback;
import at.chrl.callbacks.CallbackResult;
import at.chrl.callbacks.util.GlobalCallbackHelper;

/**
 * 
 * @author Vinzynth 08.11.2014 - 16:51:03
 *
 */
@SuppressWarnings({ "rawtypes", "unchecked", "deprecation" })
public class MemoizeCallback implements Callback {

	private static final Object STATIC;

	static {
		GlobalCallbackHelper.addCallback(SingletonHolder.instance);
		STATIC = new Object();
	}

	private final Map>> cache;
	private final Supplier mapSupplier;
	private final Supplier weakMapSupplier;

	private long hits;
	private long misses;

	private MemoizeCallback(final Supplier mapSupplier, final Supplier weakMapSupplier) {
		this.cache = mapSupplier.get();
		this.mapSupplier = mapSupplier;
		this.weakMapSupplier = weakMapSupplier;
		this.hits = 0;
		this.misses = 0;
	}

	private static String getCallingMethod() {
		String string = new Throwable().getStackTrace()[3].toString();
		string = string.substring(string.lastIndexOf('$') + 1, string.lastIndexOf('('));
		return string;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see at.chrl.callbacks.Callback#beforeCall(java.lang.Object,
	 *      java.lang.Object[])
	 */
	@Override
	public CallbackResult beforeCall(Object obj, Object[] args) {
		String callingMethod = getCallingMethod();
		if (!cache.containsKey(callingMethod))
			cache.putIfAbsent(callingMethod, mapSupplier.get());

		Map> cache2 = cache.get(callingMethod);
		if (!cache2.containsKey(obj))
			if (Objects.nonNull(obj))
				cache2.putIfAbsent(obj, weakMapSupplier.get());
			else
				cache2.putIfAbsent(STATIC, mapSupplier.get());

		int hash = 0;
		for (Object object : args)
			hash = hash * 31 + object.hashCode();

		Object object = null;
		if (Objects.nonNull(obj))
			object = cache2.get(obj).get(hash);
		else
			object = cache2.get(STATIC).get(hash);

		if (Objects.nonNull(object)) {
			++hits;
			return CallbackResult.newFullBlocker(object);
		}
		++misses;
		return CallbackResult.newContinue();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @param obj
	 * @param args
	 * @param methodResult
	 * @return
	 */
	public CallbackResult afterCall(Object obj, Object[] args, Object methodResult) {
		String callingMethod = getCallingMethod();

		int hash = 0;
		for (Object object : args)
			hash = hash * 31 + object.hashCode();

		if (Objects.nonNull(obj))
			cache.get(callingMethod).get(obj).put(hash, methodResult);
		else
			cache.get(callingMethod).get(STATIC).put(hash, methodResult);

		return CallbackResult.newContinue();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return "Memoize Cache | Hits: " + hits + " | Misses: " + misses + " | Hit Ratio: " + ((float) hits / (hits + misses)) + " | " + super.toString();
	}

	public static String printString() {
		return SingletonHolder.instance.toString();
	}

	private static final class SingletonHolder {
		private static final MemoizeCallback instance = new MemoizeCallback(CollectionSupplier.rawSupplier(CollectionSupplier.getMapSupplier()), CollectionSupplier.rawSupplier(CollectionSupplier.getWeakMapSupplier()));
	}
}
    
    
    
    

    




    
    
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