Feat: add support of READONLY and READWRITE

src/cluster/cluster.cc

@@ -802,7 +802,8 @@ Status Cluster::CanExecByMySelf(const redis::CommandAttributes *attributes, cons
   }
 
   if (myself_ && myself_->role == kClusterSlave && !(attributes->flags & redis::kCmdWrite) &&
-      nodes_.find(myself_->master_id) != nodes_.end() && nodes_[myself_->master_id] == slots_nodes_[slot]) {
+      nodes_.find(myself_->master_id) != nodes_.end() && nodes_[myself_->master_id] == slots_nodes_[slot] &&
+      conn->IsFlagEnabled(redis::Connection::KReadOnly)) {
     return Status::OK();  // My master is serving this slot
   }
 

src/commands/cmd_cluster.cc

@@ -23,6 +23,7 @@
 #include "cluster/sync_migrate_context.h"
 #include "commander.h"
 #include "error_constants.h"
+#include "status.h"
 
 namespace redis {
 
@@ -292,8 +293,27 @@ static uint64_t GenerateClusterFlag(const std::vector<std::string> &args) {
   return 0;
 }
 
+class CommandReadOnly : public Commander {
+ public:
+  Status Execute(Server *srv, Connection *conn, std::string *output) override {
+    *output = redis::SimpleString("OK");
+    conn->EnableFlag(redis::Connection::KReadOnly);
+    return Status::OK();
+  }
+};
+
+class CommandReadWrite : public Commander {
+ public:
+  Status Execute(Server *srv, Connection *conn, std::string *output) override {
+    *output = redis::SimpleString("OK");
+    conn->DisableFlag(redis::Connection::KReadOnly);
+    return Status::OK();
+  }
+};
+
 REDIS_REGISTER_COMMANDS(MakeCmdAttr<CommandCluster>("cluster", -2, "cluster no-script", 0, 0, 0, GenerateClusterFlag),
-                        MakeCmdAttr<CommandClusterX>("clusterx", -2, "cluster no-script", 0, 0, 0,
-                                                     GenerateClusterFlag), )
+                        MakeCmdAttr<CommandClusterX>("clusterx", -2, "cluster no-script", 0, 0, 0, GenerateClusterFlag),
+                        MakeCmdAttr<CommandReadOnly>("readonly", 1, "cluster no-multi", 0, 0, 0),
+                        MakeCmdAttr<CommandReadWrite>("readwrite", 1, "cluster no-multi", 0, 0, 0), )
 
 }  // namespace redis

src/server/redis_connection.h

@@ -45,6 +45,7 @@ class Connection : public EvbufCallbackBase<Connection> {
     kCloseAfterReply = 1 << 6,
     kCloseAsync = 1 << 7,
     kMultiExec = 1 << 8,
+    KReadOnly = 1 << 9,
   };
 
   explicit Connection(bufferevent *bev, Worker *owner);

tests/gocase/integration/cluster/cluster_test.go

@@ -334,6 +334,11 @@ func TestClusterMultiple(t *testing.T) {
 		require.ErrorContains(t, rdb[3].Set(ctx, util.SlotTable[16383], 16383, 0).Err(), "MOVED")
 		// request a read-only command to node3 that serve slot 16383, that's ok
 		util.WaitForOffsetSync(t, rdb[2], rdb[3])
+		//the default option is READWRITE, which will redirect both read and write to master
+		require.ErrorContains(t, rdb[3].Get(ctx, util.SlotTable[16383]).Err(), "MOVED")
+
+		require.NoError(t, rdb[3].Do(ctx, "READONLY").Err())
+
 		require.Equal(t, "16383", rdb[3].Get(ctx, util.SlotTable[16383]).Val())
 	})
 
@@ -369,4 +374,18 @@ func TestClusterMultiple(t *testing.T) {
 		require.ErrorContains(t, rdb[1].Do(ctx, "EXEC").Err(), "EXECABORT")
 		require.Equal(t, "no-multi", rdb[1].Get(ctx, util.SlotTable[0]).Val())
 	})
+
+	t.Run("requests on cluster are ok when enable readonly", func(t *testing.T) {
+
+		require.NoError(t, rdb[3].Do(ctx, "READONLY").Err())
+		require.NoError(t, rdb[2].Set(ctx, util.SlotTable[8192], 8192, 0).Err())
+		util.WaitForOffsetSync(t, rdb[2], rdb[3])
+		// request node3 that serves slot 8192, that's ok
+		require.Equal(t, "8192", rdb[3].Get(ctx, util.SlotTable[8192]).Val())
+
+		require.NoError(t, rdb[3].Do(ctx, "READWRITE").Err())
+
+		// when enable READWRITE, request node3 that serves slot 8192, that's not ok
+		util.ErrorRegexp(t, rdb[3].Get(ctx, util.SlotTable[8192]).Err(), fmt.Sprintf("MOVED 8192.*%d.*", srv[2].Port()))
+	})
 }