Redis Cluster：键存在哪里，多键怎样一起操作

import java.nio.charset.StandardCharsets;
import java.util.*;

public class Main {
  static byte[] input(String key) {
    byte[] b = key.getBytes(StandardCharsets.UTF_8);
    int left = -1;
    for (int i=0; i<b.length; i++) if (b[i]=='{') { left=i; break; }
    if (left >= 0) {
      for (int i=left+1; i<b.length; i++) if (b[i]=='}') {
        return i == left+1 ? b : Arrays.copyOfRange(b,left+1,i); // 空标签不继续寻找
      }
    }
    return b;
  }
  static int crc(byte[] bytes) {
    int value = 0;
    for (byte b : bytes) {
      value ^= (b & 0xff) << 8; // byte 有符号，先还原为无符号八位数
      for (int bit=0; bit<8; bit++)
        value = ((value & 0x8000) != 0 ? (value << 1) ^ 0x1021 : value << 1) & 0xffff;
    }
    return value; // 每步掩码保持十六位余数
  }
  static int slot(String key) { return crc(input(key)) & 0x3fff; }
  static Map<Integer,List<String>> group(List<String> keys) {
    Map<Integer,List<String>> result = new TreeMap<>();
    for (String key : keys) result.computeIfAbsent(slot(key), s -> new ArrayList<>()).add(key);
    return result; // 只是独立槽批次，不能据此执行跨槽原子操作
  }
  static int requireSameSlot(List<String> keys) {
    if (keys.isEmpty()) throw new IllegalArgumentException("empty keys");
    int expected = slot(keys.get(0));
    for (String key : keys) if (slot(key) != expected) throw new IllegalArgumentException("CROSSSLOT");
    return expected;
  }
  static void check(boolean ok) { if (!ok) throw new AssertionError(); }
  static String selected(String key) { return new String(input(key), StandardCharsets.UTF_8); }
  public static void main(String[] args) {
    check(crc("123456789".getBytes(StandardCharsets.US_ASCII)) == 0x31c3);
    check(slot("") == 0);
    check(requireSameSlot(List.of("a{123456789}","b{123456789}")) == 12739);
    check(selected("foo{}{bar}").equals("foo{}{bar}"));
    check(selected("foo{{bar}}zap").equals("{bar"));
    check(selected("foo{bar}{zap}").equals("bar"));
    check(selected("foo{bar").equals("foo{bar"));
    check(selected("stock:{优惠券7}").equals("优惠券7"));
    check(group(List.of("a{123456789}","b{123456789}","")).size()==2);
    boolean rejected=false;
    try { requireSameSlot(List.of("a{123456789}","")); }
    catch (IllegalArgumentException expected) { rejected=true; }
    check(rejected);
    System.out.println("10 cluster slot checks passed");
  }
}