Added MurmureHash as sharding algo.

src/main/java/redis/clients/util/Hashing.java

@@ -0,0 +1,79 @@
+package redis.clients.util;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public abstract class Hashing {
+    public static final Hashing MURMURE_HASH = new Hashing() {
+	public long hash(String key) {
+	    // 'm' and 'r' are mixing constants generated offline.
+	    // They're not really 'magic', they just happen to work well.
+	    byte[] data = key.getBytes();
+	    int seed = 0x1234ABCD;
+	    int m = 0x5bd1e995;
+	    int r = 24;
+
+	    // Initialize the hash to a 'random' value
+	    int len = data.length;
+	    int h = seed ^ len;
+
+	    int i = 0;
+	    while (len >= 4) {
+		int k = data[i + 0] & 0xFF;
+		k |= (data[i + 1] & 0xFF) << 8;
+		k |= (data[i + 2] & 0xFF) << 16;
+		k |= (data[i + 3] & 0xFF) << 24;
+
+		k *= m;
+		k ^= k >>> r;
+		k *= m;
+
+		h *= m;
+		h ^= k;
+
+		i += 4;
+		len -= 4;
+	    }
+
+	    switch (len) {
+	    case 3:
+		h ^= (data[i + 2] & 0xFF) << 16;
+	    case 2:
+		h ^= (data[i + 1] & 0xFF) << 8;
+	    case 1:
+		h ^= (data[i + 0] & 0xFF);
+		h *= m;
+	    }
+
+	    h ^= h >>> 13;
+	    h *= m;
+	    h ^= h >>> 15;
+
+	    return h;
+	}
+    };
+    public static final Hashing MD5 = new Hashing() {
+	private MessageDigest md5 = null; // avoid recurring construction
+
+	public long hash(String key) {
+	    if (md5 == null) {
+		try {
+		    md5 = MessageDigest.getInstance("MD5");
+		} catch (NoSuchAlgorithmException e) {
+		    throw new IllegalStateException(
+			    "++++ no md5 algorythm found");
+		}
+	    }
+
+	    md5.reset();
+	    md5.update(key.getBytes());
+	    byte[] bKey = md5.digest();
+	    long res = ((long) (bKey[3] & 0xFF) << 24)
+		    | ((long) (bKey[2] & 0xFF) << 16)
+		    | ((long) (bKey[1] & 0xFF) << 8) | (long) (bKey[0] & 0xFF);
+	    return res;
+	}
+    };
+
+    public abstract long hash(String key);
+}