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* https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
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package com.pdd.pop.ext.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 com.pdd.pop.ext.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 boolean USE_CUSTOM_CHM8;
private final static Class LTQclass;
static {
String className = null;
boolean useCustomCHM8 = false;
Class c;
try {
final JdkVersion jdkVersion = JdkVersion.getJdkVersion();
final JdkVersion jdk18Version = JdkVersion.parseVersion("1.8.0");
useCustomCHM8 = jdkVersion.isUnsafeSupported() &&
jdk18Version.compareTo(jdkVersion) > 0;
final JdkVersion jdk17Version = JdkVersion.parseVersion("1.7.0");
className = (jdk17Version.compareTo(jdkVersion) <= 0)
? "java.util.concurrent.LinkedTransferQueue"
: "com.pdd.pop.ext.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;
USE_CUSTOM_CHM8 = useCustomCHM8;
}
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 USE_CUSTOM_CHM8 ?
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 USE_CUSTOM_CHM8 ?
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 USE_CUSTOM_CHM8 ?
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 USE_CUSTOM_CHM8 ?
new ConcurrentHashMapV8(initialCapacity, loadFactor, concurrencyLevel) :
new ConcurrentHashMap(initialCapacity, loadFactor, concurrencyLevel);
}
}