net.spy.memcached.HashAlgorithmRegistry Maven / Gradle / Ivy
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/**
* Copyright (C) 2009-2011 Couchbase, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALING
* IN THE SOFTWARE.
*/
package net.spy.memcached;
import java.util.HashMap;
import java.util.Map;
/**
* Registry of known hashing algorithms for locating a server for a key. Useful
* when configuring from files using algorithm names.
*
*
* Please, make sure you register your algorithm with {
* {@link #registerHashAlgorithm(String, HashAlgorithm)} before referring to it
* by name
*/
public final class HashAlgorithmRegistry {
private HashAlgorithmRegistry() {
// Empty
}
/**
* Internal registry storage.
*/
private static final Map REGISTRY =
new HashMap();
// initializing with the default algorithms implementation
static {
for (DefaultHashAlgorithm alg : DefaultHashAlgorithm.values()) {
registerHashAlgorithm(alg.name().replace("_HASH", "").toLowerCase(),
alg);
}
}
/**
* Registers provided {@link HashAlgorithm} instance with the given name. Name
* is not case sensitive. Any registered algorithm with the same name will be
* substituted
*
* @param name name of the algorithm
* @param alg algorithm instance to register
*/
public static synchronized void registerHashAlgorithm(String name,
HashAlgorithm alg) {
validateName(name);
validateAlgorithm(alg);
REGISTRY.put(name.toLowerCase(), alg);
}
/**
* Tries to find selected hash algorithm using name provided.
*
*
* Note, that lookup is being performed using name's lower-case value
*
* @param name the algorithm name to be used for lookup
* @return a {@link HashAlgorithm} instance or null
if there's no
* algorithm with the specified name
*/
public static synchronized HashAlgorithm lookupHashAlgorithm(String name) {
validateName(name);
return REGISTRY.get(name.toLowerCase());
}
/**
* Validates name of the algorithm. A non-empty name should be provided An
* {@link IllegalArgumentException} is being thrown in case of incorrect name
*
* @param name a name to validate
*/
private static void validateName(String name) {
if (name == null || "".equals(name)) {
throw new IllegalArgumentException("HashAlgorithm name should be"
+ "provided in order to perform the lookup: either NULL or "
+ "empty string has been provided");
}
}
/**
* Validates algorithm instance. A non-null
instance should be
* provided. An {@link IllegalArgumentException} is being thrown in case of
* null
instance
*
* @param alg a {@link HashAlgorithm} instance to validate
*/
private static void validateAlgorithm(HashAlgorithm alg) {
if (alg == null) {
throw new IllegalArgumentException("HashAlgorithm instance should be "
+ "provided in order to register a new algorithm");
}
}
}