我正在使用spymemcached。我设置了几个项目。然后我运行一个php脚本,但是我无法使用php memcached获取所有这些项目。PHP-Memcached 只能部分检索这些项目。
我无法更改 php 的哈希算法或分发策略。在我们的系统中,我们使用默认哈希(根据 php.net 文档,这是 jenkin 一次一个的哈希(。并且分配策略是php-memcached的模数。我读过 spymemcached 使用一致的哈希。有什么方法可以在 spymemcached 中使用模哈希。
换句话说,如何使 spymemcached 的集合操作或任何其他存储操作与 php-memcached 的 get 操作兼容?
如果 spymemcached 无法做到这一点,Java 中是否有任何其他 memcached 客户端允许我这样做?
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爪哇代码:
public static void main(String [] args) {
List<InetSocketAddress> addrs = new ArrayList<>();
addrs.add(new InetSocketAddress("10.90.12.87", 11211));
addrs.add(new InetSocketAddress("10.90.12.87", 11311));
try {
MemcachedClient memcache = new MemcachedClient(addrs);
memcache.add("foo", 0, "bar");
memcache.add("sample", 0, "key");
memcache.add("try", 0, "another");
memcache.add("ax-spadg-list", 0, "3045,6645");
} catch (IOException ex) {
Logger.getLogger(CategoryDataOperator.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("Done");
}
PHP代码:
<?php
$mem = new Memcached();
$mem->addServer('10.90.12.87', 11211);
$mem->addServer('10.90.12.87', 11311);
var_dump $mem->get('foo');
var_dump($mem->get('try'));
var_dump($mem->get('sample'));
var_dump($mem->get('ax-spadg-list'));
问题在于哈希,默认的 php-memcached 哈希是
(詹金斯一次一个(项目键哈希算法
而 spymemcached 哈希的列表是:
-
NATIVE_HASH
:只是Native hash (String.hashCode()).
与默认的php-memcachedMemcached::HASH_DEFAULT
不匹配 -
CRC_HASH
=>Memcached::HASH_CRC
-
FNV1_64_HASH
=>Memcached::HASH_FNV1_64
-
FNV1A_64_HASH
=>Memcached::HASH_FNV1A_64
-
FNV1_32_HASH
=>Memcached::HASH_FNV1_32
-
FNV1A_32_HASH
=>Memcached::HASH_FNV1A_32
-
KETAMA_HASH
=> "ketama 使用的基于 MD5 的哈希算法"。所以也许Memcached::HASH_MD5
但无论如何都不Memcached::HASH_DEFAULT
因此,如果您无法更改 PHP 客户端配置或扩展 spymemcached 库,则两个库之间没有直接匹配。
解决方案 1:如果您查看历史记录(您可以有一个 php 客户端哈希修改的示例(。
解决方案 2:否则,您可以创建一个 JenkinHash 类(我复制了 Xmemcached 代码:https://code.google.com/p/xmemcached/source/browse/trunk/src/main/java/net/rubyeye/xmemcached/HashAlgorithm.java?r=801#176 [但请考虑 Xmemcached 许可证并将作者/许可证保留在源代码中](
import net.spy.memcached.HashAlgorithm;
import java.io.UnsupportedEncodingException;
public class JenkinsHash implements HashAlgorithm {
@Override
public long hash(String k) {
try {
int hash = 0;
for (byte bt : k.getBytes("utf-8")) {
hash += (bt & 0xFF);
hash += (hash << 10);
hash ^= (hash >>> 6);
}
hash += (hash << 3);
hash ^= (hash >>> 11);
hash += (hash << 15);
return hash;
} catch (UnsupportedEncodingException e) {
throw new IllegalStateException("Hash function error", e);
}
}
}
然后:
import net.spy.memcached.*;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Main {
public static void main(String[] args) throws IOException {
List<InetSocketAddress> addrs = new ArrayList<InetSocketAddress>();
addrs.add(new InetSocketAddress("127.0.0.1", 11211));
addrs.add(new InetSocketAddress("172.28.29.22", 11211));
try {
ConnectionFactory connectionFactory = new ConnectionFactoryBuilder()
.setProtocol(ConnectionFactoryBuilder.Protocol.TEXT)
.setHashAlg(new JenkinsHash())
.setLocatorType(ConnectionFactoryBuilder.Locator.ARRAY_MOD).build();
MemcachedClient memcache = new MemcachedClient(connectionFactory, addrs);
memcache.add("foo", 0, "bar2");
memcache.add("sample", 0, "key");
memcache.add("try", 0, "another");
memcache.add("ax-spadg-list", 0, "3045,6645");
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("Done");
}
}
使用 php 脚本:
<?php
$memcached = new Memcached();
$memcached->addserver('127.0.0.1', 11211);
$memcached->addserver('172.28.29.22', 11211);
var_dump($memcached->get('foo'));
var_dump($memcached->get('try'));
var_dump($memcached->get('sample'));
var_dump($memcached->get('ax-spadg-list'));
测试:
$ echo "flush_all" | nc 172.28.29.22 11211 && echo "flush_all" | nc 127.0.0.1 11211
OK
OK
$ php mem.php
bool(false)
bool(false)
bool(false)
bool(false)
RUN JAVA
$ php mem.php
string(4) "bar2"
string(7) "another"
string(3) "key"
string(9) "3045,6645"
解决方案 3:将 https://code.google.com/p/xmemcached/与ONE_AT_A_TIME
哈希算法结合使用
import net.rubyeye.xmemcached.HashAlgorithm;
import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.MemcachedClientBuilder;
import net.rubyeye.xmemcached.XMemcachedClientBuilder;
import net.rubyeye.xmemcached.exception.MemcachedException;
import net.rubyeye.xmemcached.impl.ArrayMemcachedSessionLocator;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeoutException;
public class Main {
public static void main(String[] args) throws IOException, InterruptedException, MemcachedException, TimeoutException {
List<InetSocketAddress> addrs = new ArrayList<InetSocketAddress>();
addrs.add(new InetSocketAddress("127.0.0.1", 11211));
addrs.add(new InetSocketAddress("172.28.29.22", 11211));
MemcachedClientBuilder builder = new XMemcachedClientBuilder(addrs);
builder.setSessionLocator(new ArrayMemcachedSessionLocator(HashAlgorithm.ONE_AT_A_TIME));
MemcachedClient memcachedClient = builder.build();
memcachedClient.set("foo", 0, "bar2");
memcachedClient.set("sample", 0, "key");
memcachedClient.set("try", 0, "another");
memcachedClient.set("ax-spadg-list", 0, "3045,6645");
memcachedClient.shutdown();
System.out.println("Done");
}
}
spymemcached 支持的哈希算法如下: https://github.com/couchbase/spymemcached/blob/master/src/main/java/net/spy/memcached/DefaultHashAlgorithm.java
您应该能够通过使用 ConnectionFactory 来创建 MemcachedClient 来更改哈希算法。做这样的事情:
ConnectionFactoryBuilder builder = new ConnectionFactoryBuilder();
builder.setHashAlgorithm(HashAlgorithm.CRC_HASH);
ConnectionFactory factory = builder.build();
MemcachedClient client = new MemcachedClient(Arrays.asList(new InetSocketAddr("localhost", 11211)), factory);
Re: Kakawait(以及 Shades88(
解决方案 #2 不正确,因为 xmemcached 没有正确移植 Jenkins 哈希的原始 C 代码,该代码使用无符号。 修复此问题还将解决Shades88看到的ArrayIndexOutOfBoundsException。
public class JenkinsHash implements HashAlgorithm {
@Override
public long hash(String k) {
try {
int hash = 0;
for (byte bt : k.getBytes("utf-8")) {
hash += (bt & 0xFF);
hash += (hash << 10);
hash ^= (hash >>> 6);
}
hash += (hash << 3);
hash ^= (hash >>> 11);
hash += (hash << 15);
// the hash variable in the original C code is a uint32.
// convert the java signed int to an "unsigned",
// represented via a long:
return hash & 0xFFFFFFFFl;
} catch (UnsupportedEncodingException e) {
throw new IllegalStateException("Hash function error", e);
}
}
}
// Unit test
public class JenkinsHashTest {
@Test
public void testHash() throws Exception {
JenkinsHash j = new JenkinsHash();
Properties p = new Properties();
// This file contains k/v mappings,
// with values generated by the reference C code
p.load(new FileReader("src/test/resources/jenkinsHashTest.dat"));
for (Entry<Object, Object> entry : p.entrySet()) {
long result = j.hash((String)entry.getKey());
// Print out hash mismatches
if (result != Long.parseLong((String)entry.getValue())) {
System.out.println("Key: " + (String)entry.getKey());
System.out.println("Expected Hash Value: " + Long.parseLong((String)entry.getValue()));
System.out.println("Actual Hash Value: " + result);
}
assertEquals(result, Long.parseLong((String)entry.getValue()));
}
}
}
测试数据文件用于将 Java 代码与 C 代码进行比较。 构建 C 代码,然后对一堆随机单词进行哈希处理并将它们映射到一个文件中,如下所示:
jenkinsHashTest.dat:
sausage=2834523395
blubber=1103975961
pencil=3318404908
cloud=670342857
moon=2385442906
water=3403519606
computer=2375101981
school=1513618861
network=2981967937
hammer=1218821080
。添加任意数量