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Amazon ElastiCache Cluster Client is an enhanced Java library to connect to ElastiCache clusters. This client library has been built upon Spymemcached and is released under the Amazon Software License.
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/**
* Copyright (C) 2009-2015 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.net.InetSocketAddress;
import java.util.HashMap;
import java.util.Map;
/**
* Known key formats used in Ketama for assigning nodes around the ring
*/
public class KetamaNodeKeyFormatter {
public enum Format {
/**
* SPYMEMCACHED uses the format traditionally used by spymemcached to map
* nodes to names. The format is HOSTNAME/IP:PORT-ITERATION
*
*
* This default implementation uses the socket-address of the MemcachedNode
* and concatenates it with a hyphen directly against the repetition number
* for example a key for a particular server's first repetition may look like:
*
*
*
* myhost/10.0.2.1-0
*
*
*
* for the second repetition
*
*
*
* myhost/10.0.2.1-1
*
*
*
* for a server where reverse lookups are failing the returned keys may look
* like
*
*
*
* /10.0.2.1-0
and /10.0.2.1-1
*
*/
SPYMEMCACHED,
/**
* LIBMEMCACHED uses the format traditionally used by libmemcached to map
* nodes to names. The format is HOSTNAME:[PORT]-ITERATION the PORT is not
* part of the node identifier if it is the default memecached port (11211)
*/
LIBMEMCACHED
}
private final Format format;
public Format getFormat() {
return format;
}
// Carrried over from the DefaultKetamaNodeLocatorConfiguration:
// Internal lookup map to try to carry forward the optimisation that was
// previously in KetamaNodeLocator
private Map nodeKeys = new HashMap();
public KetamaNodeKeyFormatter() {
this(Format.SPYMEMCACHED);
}
public KetamaNodeKeyFormatter(Format format) {
this.format = format;
}
/**
* Returns a uniquely identifying key, suitable for hashing by the
* KetamaNodeLocator algorithm.
*
* @param node The MemcachedNode to use to form the unique identifier
* @param repetition The repetition number for the particular node in question
* (0 is the first repetition)
* @return The key that represents the specific repetition of the node
*/
public String getKeyForNode(MemcachedNode node, int repetition) {
// Carrried over from the DefaultKetamaNodeLocatorConfiguration:
// Internal Using the internal map retrieve the socket addresses
// for given nodes.
// I'm aware that this code is inherently thread-unsafe as
// I'm using a HashMap implementation of the map, but the worst
// case ( I believe) is we're slightly in-efficient when
// a node has never been seen before concurrently on two different
// threads, so it the socketaddress will be requested multiple times!
// all other cases should be as fast as possible.
String nodeKey = nodeKeys.get(node);
if (nodeKey == null) {
switch(this.format) {
case LIBMEMCACHED:
InetSocketAddress address = (InetSocketAddress)node.getSocketAddress();
nodeKey = address.getHostName();
if (address.getPort() != 11211) {
nodeKey += ":" + address.getPort();
}
break;
case SPYMEMCACHED:
nodeKey = String.valueOf(node.getSocketAddress());
if (nodeKey.startsWith("/")) {
nodeKey = nodeKey.substring(1);
}
break;
default:
assert false;
}
nodeKeys.put(node, nodeKey);
}
return nodeKey + "-" + repetition;
}
}
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