使用php memcached無法獲取使用spymemcached設置的項目

Question

我正在使用spymemcached。 我設置了幾個項目。 然后我運行一個PHP腳本，然而我無法使用php memcached獲取所有這些項目。 PHP-Memcached只能部分檢索這些項目。

我無法改變php的哈希算法或分發策略。 在我們的系統中，我們使用默認散列（根據php.net文檔，這是jenkin的一次一個）。 並且分發策略是php-memcached的模數。 我已經讀過spymemcached使用一致性散列。 有什么方法可以在spymemcached中使用模數散列。

換句話說，如何使spymemcached的set操作或任何其他存儲操作與php-memcached的get操作兼容？

如果spymemcached無法做到這一點，java中是否有任何其他memcached客戶端允許我這樣做？

幫助不僅會被欣賞，也會得到賞金。

Java代碼：

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代碼：

<?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'));

Answer 1

問題是關於Hash，默認的php-memcached哈希是

（Jenkins one-at-a-time）項密鑰散列算法

而spymemcached哈希列表是：

• NATIVE_HASH ：簡單的Native hash (String.hashCode()). 與默認的php-memcached Memcached::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使用的基於MD5的哈希算法。” 也許Memcached::HASH_MD5但無論如何不是Memcached::HASH_DEFAULT

因此，如果您無法更改PHP客戶端配置或擴展spymemcached lib，則兩個庫之間不會直接匹配。

解決方案1：如果您查看歷史記錄 （您可以使用php客戶端哈希修改示例）。

解決方案2：否則你可以創建一個JenkinHash類（我復制過Xmemcached代碼： https ： //code.google.com/p/xmemcached/source/browse/trunk/src/main/java/net/rubyeye/xmemcached/ HashAlgorithm.java?r=801#176 [但考慮到Xmemcached許可證並將作者/許可證保留在源代碼中]）

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腳本：

<?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'));

測試：

$ 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"

解決方案3：使用https://code.google.com/p/xmemcached/和ONE_AT_A_TIME哈希算法

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");
    }
}

Answer 2

spymemcached支持的哈希算法在這里： https ： //github.com/couchbase/spymemcached/blob/master/src/main/java/net/spy/memcached/DefaultHashAlgorithm.java

您應該能夠通過使用ConnectionFactory來創建MemcachedClient來更改哈希算法。 做這樣的事情：

ConnectionFactoryBuilder builder = new ConnectionFactoryBuilder();
builder.setHashAlgorithm(HashAlgorithm.CRC_HASH);
ConnectionFactory factory = builder.build();
MemcachedClient client = new MemcachedClient(Arrays.asList(new InetSocketAddr("localhost", 11211)), factory);

Answer 3

回復：Kakawait（以及Shades88）

解決方案＃2不正確，因為xmemcached沒有正確移植使用unsigned的Jenkins哈希的原始C代碼。 修復此問題還將解決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()));
        }
    }
}

測試數據文件用於將Java代碼與C代碼進行比較。 構建C代碼然后散列一堆隨機單詞並將它們映射到一個文件中，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

...添加任意多個