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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2011-2013 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */
package org.glassfish.grizzly.utils;

import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Level;
import org.glassfish.grizzly.Grizzly;

/*
 * Utility class, which tries to pickup the best collection implementation depending
 * on running environment.
 * 
 * @author gustav trede
 */
public class DataStructures {
    private final static Class LTQclass;

    static {
        String className = null;
        
        Class c;
        try {
            JdkVersion jdkVersion = JdkVersion.getJdkVersion();
            JdkVersion minimumVersion = JdkVersion.parseVersion("1.7.0");
            
            className = (minimumVersion.compareTo(jdkVersion) <= 0)
                    ? "java.util.concurrent.LinkedTransferQueue"
                    : "org.glassfish.grizzly.utils.LinkedTransferQueue";
            
            c = getAndVerify(className);
            Grizzly.logger(DataStructures.class).log(Level.FINE, "USING LTQ class:{0}", c);
        } catch (Throwable t) {
            Grizzly.logger(DataStructures.class).log(Level.FINE,
                    "failed loading datastructure class:" + className +
                    " fallback to embedded one", t);
            
            c = LinkedBlockingQueue.class; // fallback to LinkedBlockingQueue
        }
        
        LTQclass = c;
    }

    private static Class getAndVerify(String cname) throws Throwable {
        return DataStructures.class.getClassLoader().loadClass(cname).newInstance().getClass();
    }

    @SuppressWarnings("unchecked")
    public static  BlockingQueue getLTQInstance() {
        try {
            return (BlockingQueue) LTQclass.newInstance();
        } catch (Exception ea) {
            throw new RuntimeException(ea);
        }
    }

    @SuppressWarnings("unchecked")
    public static  BlockingQueue getLTQInstance(Class t) {
        try {
            return (BlockingQueue) LTQclass.newInstance();
        } catch (Exception ea) {
            throw new RuntimeException(ea);
        }
    }
    
    /**
     * Creates a new, empty map with a default initial capacity (16),
     * load factor (0.75) and concurrencyLevel (16).
     * 
     * @since 2.3.5
     */
    public static  ConcurrentMap getConcurrentMap() {
        return JdkVersion.getJdkVersion().isUnsafeSupported() ?
                new ConcurrentHashMapV8() :
                new ConcurrentHashMap();
    }
    
    /**
     * Creates a new map with the same mappings as the given map.
     *
     * @param m the map
     * 
     * @since 2.3.5
     */
    public static  ConcurrentMap getConcurrentMap(
            final Map map) {
        return JdkVersion.getJdkVersion().isUnsafeSupported() ?
                new ConcurrentHashMapV8(map) :
                new ConcurrentHashMap(map);
    }
    
    /**
     * Creates a new, empty map with an initial table size
     * accommodating the specified number of elements without the need
     * to dynamically resize.
     *
     * @param initialCapacity The implementation performs internal
     * sizing to accommodate this many elements.
     * @throws IllegalArgumentException if the initial capacity of
     * elements is negative
     * 
     * @since 2.3.5
     */
    public static  ConcurrentMap getConcurrentMap(
            final int initialCapacity) {
        return JdkVersion.getJdkVersion().isUnsafeSupported() ?
                new ConcurrentHashMapV8(initialCapacity) :
                new ConcurrentHashMap(initialCapacity);
    }
    
    /**
     * Creates a new, empty map with an initial table size based on
     * the given number of elements ({@code initialCapacity}), table
     * density ({@code loadFactor}), and number of concurrently
     * updating threads ({@code concurrencyLevel}).
     *
     * @param initialCapacity the initial capacity. The implementation
     * performs internal sizing to accommodate this many elements,
     * given the specified load factor.
     * @param loadFactor the load factor (table density) for
     * establishing the initial table size
     * @param concurrencyLevel the estimated number of concurrently
     * updating threads. The implementation may use this value as
     * a sizing hint.
     * @throws IllegalArgumentException if the initial capacity is
     * negative or the load factor or concurrencyLevel are
     * nonpositive
     * 
     * @since 2.3.5
     */
    public static  ConcurrentMap getConcurrentMap(
            final int initialCapacity, final float loadFactor,
            final int concurrencyLevel) {
        return JdkVersion.getJdkVersion().isUnsafeSupported() ?
                new ConcurrentHashMapV8(initialCapacity, loadFactor, concurrencyLevel) :
                new ConcurrentHashMap(initialCapacity, loadFactor, concurrencyLevel);
    }
}