""" Ch10 配套代码 2 / 3 —— Cluster 客户端 API 演示 演示： 1. 用 redis.RedisCluster (redis-py 4.0+) 连接 Redis Cluster 2. 集群感知客户端的核心特性： - 自动 CRC16 计算 + slot 路由 - 自动处理 MOVED / ASK 重定向 - 节点拓扑自动感知（CLUSTER SLOTS） 3. 当无真实 Cluster 可用时，用纯 Python 模拟一个 6 节点（3 主 3 从）集群 使用： - 真集群： python 02_cluster_client.py --real --host 127.0.0.1 --port 7000 - 模拟器： python 02_cluster_client.py （默认） """ import argparse import random from typing import Dict, List, Optional, Tuple # 复用 01 里的 CRC16 + slot 计算 from importlib import import_module _crc = import_module("01_crc16_slot") if False else None # Python 不允许 01_ 开头的模块名 # 简单内联：避免动态导入受限于文件名 CRC16TAB = [ 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF, 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE, 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D, 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4, 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC, 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B, 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12, 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A, 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49, 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78, 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067, 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E, 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256, 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634, 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3, 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92, 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9, 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1, 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0, ] CLUSTER_SLOTS = 16384 def crc16(data: bytes) -> int: crc = 0x0000 for b in data: crc = ((crc << 8) & 0xFFFF) ^ CRC16TAB[((crc >> 8) ^ b) & 0xFF] return crc def extract_hashtag(key: str) -> Optional[str]: s = key.find("{") if s == -1: return None e = key.find("}", s + 1) if e == -1 or e == s + 1: return None return key[s + 1:e] def key_slot(key: str) -> int: tag = extract_hashtag(key) target = tag if tag is not None else key return crc16(target.encode("utf-8")) % CLUSTER_SLOTS def section(title: str) -> None: print("\n" + "=" * 64) print(title) print("=" * 64) # ────────────────────────────────────────────────────────────── # 模式 A：真实 RedisCluster # ────────────────────────────────────────────────────────────── def run_real_cluster(host: str, port: int) -> None: try: from redis.cluster import RedisCluster, ClusterNode except ImportError: print("❌ redis-py 未安装或版本过低（需要 4.0+）") print(" pip install 'redis>=4.0'") return try: rc = RedisCluster( startup_nodes=[ClusterNode(host, port)], decode_responses=True, require_full_coverage=False, ) section("Demo A1: 集群基本读写（自动路由）") for i in range(5): k, v = f"user:{1000 + i}", f"name-{i}" rc.set(k, v) slot = rc.keyslot(k) if hasattr(rc, "keyslot") else key_slot(k) print(f" SET {k:12} = {v:8} slot={slot:5} → 自动路由到正确 master") section("Demo A2: 集群拓扑") nodes = rc.get_nodes() for n in nodes: print(f" {n.host}:{n.port} role={n.server_type} name={n.name}") section("Demo A3: 跨槽 MGET 会失败，HashTag 拯救") try: rc.mget("user:1000", "user:1001", "user:1002") print(" （部分 redis-py 版本会自动拆分 mget，看不到原始 CROSSSLOT 错误）") except Exception as e: print(f" ❌ 跨槽 MGET 错：{e}") rc.mset({ "{user:9999}:profile": "p", "{user:9999}:cart": "c", "{user:9999}:orders": "o", }) result = rc.mget( "{user:9999}:profile", "{user:9999}:cart", "{user:9999}:orders", ) print(f" ✅ 带 HashTag 的 MGET：{result}") rc.delete( "{user:9999}:profile", "{user:9999}:cart", "{user:9999}:orders", *[f"user:{1000 + i}" for i in range(5)], ) except Exception as e: print(f"❌ 连接 Redis Cluster 失败: {e}") print(" 请确认提供的是「集群模式」节点（cluster-enabled yes）") # ────────────────────────────────────────────────────────────── # 模式 B：纯 Python 模拟一个 6 节点（3 主 3 从）集群 # ────────────────────────────────────────────────────────────── class FakeNode: """一个 master 或 slave 节点。master 维护 (slot 范围) 内的 KV""" def __init__(self, name: str, port: int, role: str): self.name = name # "A", "B", "C", "A1"... self.port = port # 7000~7005 self.role = role # "master" | "slave" self.alive = True self.master_of: Optional["FakeNode"] = None # slave→master self.slaves: List["FakeNode"] = [] self.slot_range: Optional[Tuple[int, int]] = None self.kv: Dict[str, str] = {} def __repr__(self) -> str: sr = f"{self.slot_range[0]}~{self.slot_range[1]}" if self.slot_range else "-" return f"<{self.name}/{self.port}/{self.role}/slot={sr}/alive={self.alive}>" class FakeCluster: """6 节点 3 主 3 从模拟集群（一切只在内存里）""" def __init__(self) -> None: self.nodes: List[FakeNode] = [] # 3 master for i, name in enumerate(["A", "B", "C"]): self.nodes.append(FakeNode(name, 7000 + i, "master")) # 3 slave，分别挂到 A/B/C for i, (name, master_idx) in enumerate(zip(["A1", "B1", "C1"], [0, 1, 2])): sl = FakeNode(name, 7003 + i, "slave") sl.master_of = self.nodes[master_idx] self.nodes[master_idx].slaves.append(sl) self.nodes.append(sl) # 槽位均分 masters = [n for n in self.nodes if n.role == "master"] ranges = self._distribute_slots(len(masters)) for m, r in zip(masters, ranges): m.slot_range = r @staticmethod def _distribute_slots(n: int) -> List[Tuple[int, int]]: base = CLUSTER_SLOTS // n extra = CLUSTER_SLOTS % n out, cursor = [], 0 for i in range(n): size = base + (1 if i < extra else 0) out.append((cursor, cursor + size - 1)) cursor += size return out def find_master(self, slot: int) -> Optional[FakeNode]: for n in self.nodes: if n.role == "master" and n.alive and n.slot_range: if n.slot_range[0] <= slot <= n.slot_range[1]: return n return None def get(self, key: str) -> Tuple[Optional[str], FakeNode]: slot = key_slot(key) node = self.find_master(slot) if node is None: raise RuntimeError(f"slot {slot} 无可用 master！") return node.kv.get(key), node def set(self, key: str, val: str) -> FakeNode: slot = key_slot(key) node = self.find_master(slot) if node is None: raise RuntimeError(f"slot {slot} 无可用 master！") node.kv[key] = val return node def fail_node(self, name: str) -> None: """模拟节点宕机 + 故障转移""" for n in self.nodes: if n.name == name: n.alive = False if n.role == "master" and n.slaves: # 选第一个还活着的 slave 接管 for sl in n.slaves: if sl.alive: print(f" 💥 {name} 宕机，从节点 {sl.name} 当选新 master") sl.role = "master" sl.slot_range = n.slot_range sl.master_of = None n.slot_range = None return print(f" 💥 {name} 宕机，但无可用 slave 接管 → slot 不可用！") def topology(self) -> str: out = [] for n in self.nodes: sr = f"slot {n.slot_range[0]:5}~{n.slot_range[1]:5}" if n.slot_range else " " * 19 mark = "✓" if n.alive else "✗" mast = f" → master={n.master_of.name}" if n.master_of else "" out.append(f" [{mark}] {n.name:3} :{n.port} {n.role:6} {sr}{mast}") return "\n".join(out) def run_simulator() -> None: cl = FakeCluster() section("Demo B1: 集群拓扑（6 节点 3 主 3 从）") print(cl.topology()) section("Demo B2: 集群读写 —— 客户端自动算 slot 找节点") keys = ["user:1001", "order:8888", "product:42", "session:abc", "cart:7", "stock:gpu"] for k in keys: node = cl.set(k, f"val-of-{k}") slot = key_slot(k) print(f" SET {k:13} → slot={slot:5} → 路由到 {node.name}({node.port})") section("Demo B3: 模拟 master B 宕机 + 故障转移") print(" 宕机前 B 上的数据：", {k: v for k, v in cl.nodes[1].kv.items()}) cl.fail_node("B") print(cl.topology()) print("\n 下次写 slot 5461~10922 的 key 自动路由到新 master（原 B1）：") n = cl.set("order:8888", "rewritten") print(f" SET order:8888 → 路由到 {n.name}({n.port})") print(" ⚠️ 但是宕机前的数据丢了 —— 因为模拟器没实现复制；真实 Cluster 中 slave 是异步复制 master 的") section("Demo B4: HashTag 强制同节点 演示") keys2 = ["{user:1001}:profile", "{user:1001}:cart", "{user:1001}:orders"] nodes_set = set() for k in keys2: n = cl.set(k, "x") nodes_set.add(n.name) print(f" SET {k:30} → 落到 {n.name}({n.port})") print(f"\n ✅ 三个 key 全部落到同一节点：{nodes_set} —— 可以原子地 MGET / MULTI / EVAL") def main() -> None: parser = argparse.ArgumentParser(description="Ch10 Cluster 客户端演示") parser.add_argument("--real", action="store_true", help="连接真实 Redis Cluster") parser.add_argument("--host", default="127.0.0.1") parser.add_argument("--port", type=int, default=7000) args = parser.parse_args() if args.real: print(f">>> 模式：连接真实 Cluster {args.host}:{args.port}") run_real_cluster(args.host, args.port) else: print(">>> 模式：纯 Python 模拟器（无需真实 Redis Cluster）") run_simulator() if __name__ == "__main__": main()