feat: implement SPUBLISH command for Redis 7.0+ Sharded Pub/Sub

- Add SPUBLISH command in cmd_pubsub.cc
- Implement Server::SPublish() method for message distribution
- Add test cases in pubsubshard_test.go
- Support cluster mode with slot routing
- Add ok-loading flag for loading state execution

Author: xiaobiao

src/commands/cmd_pubsub.cc

@@ -252,6 +252,22 @@ class CommandPubSub : public Commander {
   std::string subcommand_;
 };
 
+class CommandSPublish : public Commander {
+ public:
+  Status Execute([[maybe_unused]] engine::Context &ctx, Server *srv, [[maybe_unused]] Connection *conn,
+                 std::string *output) override {
+    uint16_t slot = 0;
+    if (srv->GetConfig()->cluster_enabled) {
+      slot = GetSlotIdFromKey(args_[1]);
+    }
+
+    int receivers = srv->SPublish(args_[1], args_[2], slot);
+    *output = redis::Integer(receivers);
+
+    return Status::OK();
+  }
+};
+
 REDIS_REGISTER_COMMANDS(Pubsub, MakeCmdAttr<CommandPublish>("publish", 3, "read-only", NO_KEY),
                         MakeCmdAttr<CommandMPublish>("mpublish", -3, "read-only", NO_KEY),
                         MakeCmdAttr<CommandSubscribe>("subscribe", -2, "read-only no-multi no-script", NO_KEY),
@@ -260,6 +276,7 @@ REDIS_REGISTER_COMMANDS(Pubsub, MakeCmdAttr<CommandPublish>("publish", 3, "read-
                         MakeCmdAttr<CommandPUnSubscribe>("punsubscribe", -1, "read-only no-multi no-script", NO_KEY),
                         MakeCmdAttr<CommandSSubscribe>("ssubscribe", -2, "read-only no-multi no-script", NO_KEY),
                         MakeCmdAttr<CommandSUnSubscribe>("sunsubscribe", -1, "read-only no-multi no-script", NO_KEY),
+                        MakeCmdAttr<CommandSPublish>("spublish", 3, "read-only ok-loading", NO_KEY),
                         MakeCmdAttr<CommandPubSub>("pubsub", -2, "read-only no-script", NO_KEY), )
 
 }  // namespace redis

src/server/server.cc

@@ -619,6 +619,33 @@ void Server::ListSChannelSubscribeNum(const std::vector<std::string> &channels,
   }
 }
 
+int Server::SPublish(const std::string &channel, const std::string &msg, uint16_t slot) {
+  assert((config_->cluster_enabled && slot < HASH_SLOTS_SIZE) || slot == 0);
+
+  int cnt = 0;
+  std::lock_guard<std::mutex> guard(pubsub_shard_channels_mu_);
+
+  auto iter = pubsub_shard_channels_[slot].find(channel);
+  if (iter == pubsub_shard_channels_[slot].end()) {
+    return cnt;
+  }
+
+  std::string reply;
+  reply.append(redis::MultiLen(3));
+  reply.append(redis::BulkString("smessage"));
+  reply.append(redis::BulkString(channel));
+  reply.append(redis::BulkString(msg));
+
+  for (const auto &conn_ctx : iter->second) {
+    auto s = conn_ctx.owner->Reply(conn_ctx.fd, reply);
+    if (s.IsOK()) {
+      cnt++;
+    }
+  }
+
+  return cnt;
+}
+
 void Server::BlockOnKey(const std::string &key, redis::Connection *conn) {
   std::lock_guard<std::mutex> guard(blocking_keys_mu_);
 

src/server/server.h

@@ -227,6 +227,7 @@ class Server {
   size_t GetPubSubPatternSize() const { return pubsub_patterns_.size(); }
   void SSubscribeChannel(const std::string &channel, redis::Connection *conn, uint16_t slot);
   void SUnsubscribeChannel(const std::string &channel, redis::Connection *conn, uint16_t slot);
+  int SPublish(const std::string &channel, const std::string &msg, uint16_t slot);
   void GetSChannelsByPattern(const std::string &pattern, std::vector<std::string> *channels);
   void ListSChannelSubscribeNum(const std::vector<std::string> &channels,
                                 std::vector<ChannelSubscribeNum> *channel_subscribe_nums);

tests/gocase/unit/pubsub/pubsubshard_test.go

@@ -162,3 +162,85 @@ func TestPubSubShard(t *testing.T) {
 		}
 	})
 }
+
+func TestSPublish(t *testing.T) {
+	ctx := context.Background()
+
+	srv := util.StartServer(t, map[string]string{})
+	defer srv.Close()
+	rdb := srv.NewClient()
+	defer func() { require.NoError(t, rdb.Close()) }()
+
+	t.Run("SPUBLISH to no subscribers", func(t *testing.T) {
+		// Should return 0 when no subscribers
+		n, err := rdb.Do(ctx, "SPUBLISH", "mychannel", "hello").Int()
+		require.NoError(t, err)
+		require.EqualValues(t, 0, n)
+	})
+
+	t.Run("SPUBLISH to one subscriber", func(t *testing.T) {
+		pubsub := rdb.SSubscribe(ctx, "mychannel")
+		defer pubsub.Close()
+
+		// Receive the subscription message
+		receiveType(t, pubsub, &redis.Subscription{})
+		require.EqualValues(t, 1, receiveType(t, pubsub, &redis.Subscription{}).Count)
+
+		// Publish message
+		n, err := rdb.Do(ctx, "SPUBLISH", "mychannel", "hello world").Int()
+		require.NoError(t, err)
+		require.EqualValues(t, 1, n)
+
+		// Receive the message
+		msg := receiveType(t, pubsub, &redis.Message{})
+		require.EqualValues(t, "mychannel", msg.Channel)
+		require.EqualValues(t, "hello world", msg.Payload)
+	})
+
+	t.Run("SPUBLISH to multiple subscribers", func(t *testing.T) {
+		channel := "testchannel{tag}"
+
+		pubsub1 := rdb.SSubscribe(ctx, channel)
+		defer pubsub1.Close()
+		receiveType(t, pubsub1, &redis.Subscription{})
+
+		pubsub2 := rdb.SSubscribe(ctx, channel)
+		defer pubsub2.Close()
+		receiveType(t, pubsub2, &redis.Subscription{})
+
+		// Publish message
+		n, err := rdb.Do(ctx, "SPUBLISH", channel, "message from spublish").Int()
+		require.NoError(t, err)
+		require.EqualValues(t, 2, n)
+
+		// Both subscribers should receive the message
+		msg1 := receiveType(t, pubsub1, &redis.Message{})
+		require.EqualValues(t, "message from spublish", msg1.Payload)
+
+		msg2 := receiveType(t, pubsub2, &redis.Message{})
+		require.EqualValues(t, "message from spublish", msg2.Payload)
+	})
+
+	t.Run("SPUBLISH with cluster enabled", func(t *testing.T) {
+		csrv := util.StartServer(t, map[string]string{"cluster-enabled": "yes"})
+		defer csrv.Close()
+		crdb := csrv.NewClient()
+		defer func() { require.NoError(t, crdb.Close()) }()
+
+		nodeID := "test_node_id_12345678901234567890123456789012"
+		require.NoError(t, crdb.Do(ctx, "clusterx", "SETNODEID", nodeID).Err())
+		clusterNodes := fmt.Sprintf("%s %s %d master - 0-16383", nodeID, csrv.Host(), csrv.Port())
+		require.NoError(t, crdb.Do(ctx, "clusterx", "SETNODES", clusterNodes, "1").Err())
+
+		pubsub := crdb.SSubscribe(ctx, "mychannel{tag}")
+		defer pubsub.Close()
+		receiveType(t, pubsub, &redis.Subscription{})
+
+		n, err := crdb.Do(ctx, "SPUBLISH", "mychannel{tag}", "cluster message").Int()
+		require.NoError(t, err)
+		require.EqualValues(t, 1, n)
+
+		msg := receiveType(t, pubsub, &redis.Message{})
+		require.EqualValues(t, "cluster message", msg.Payload)
+	})
+}