More refactoring for multi-shard commands

docs/src/content/docs/commands/COPY.md

@@ -12,7 +12,8 @@ COPY <source> <destination> [DB destination-db] [REPLACE]
 ```
 
 ## Parameters
-|Parameter | Description | Type | Required| 
+
+|Parameter | Description | Type | Required|
 |----------|-------------|------|:---------:|
 | source   |The key of the value you want to copy. This key must exist. | String | Yes|
 | destination | The key where the value will be copied to. This key must not exist unless the `REPLACE` option is specified. | String | Yes |
@@ -21,10 +22,11 @@ COPY <source> <destination> [DB destination-db] [REPLACE]
 
 
 ## Return Value
+
 | Condition | Return Value |
 |-----------| :-------------:|
 | key was copied successfully | `1` |
-| key was not copied | `0` | 
+| key was not copied | `0` |
 
 
 ## Behaviour
@@ -41,10 +43,10 @@ When the `COPY` command is executed, DiceDB will:
 
 The `COPY` command can raise the following errors:
 
-1. `Wrong type of value or key`:  
+1. `Wrong type of value or key`:
     - Error message `(error) WRONGTYPE Operation against a key holding the wrong kind of value`:  
     - This error occurs if the source key holds a value that is not compatible with the `COPY` operation.  
-2.  `Not existent key`:  
+2.  `Not existent key`:
     -  Error message: `(error) ERR no such key` 
     - This error occurs if the source key does not exist.  
     - This error occurs if the destination key already exists and the `REPLACE` option is not specified.
@@ -78,18 +80,19 @@ Copy the value from `key1` to `key2`, replacing `key2` if it already exists.
 ```
 
 ### Destination key already exist
+
 ```bash
 127.0.0.1:7379> COPY key1 key2
 (integer) 1
 127.0.0.1:7379> COPY key1 key2
 (integer) 0 
 
 ```
+
 ## Notes
 
 - The `COPY` command is available starting from DiceDB version 6.2.
 - The `COPY` command is atomic, meaning that the copy operation is performed as a single, indivisible operation.
 - The `COPY` command does not modify the source key; it only duplicates its value to the destination key.
 - The `DB destinationDB` is not yet supported with the current versions of DiceDB. It acts as a placeholder for now. It will still return `0`
 By understanding the `COPY` command and its parameters, you can effectively duplicate keys within your DiceDB databases, ensuring data consistency and reducing the need for manual data manipulation.
-

integration_tests/commands/async/copy_test.go → integration_tests/commands/resp/copy_test.go

@@ -1,4 +1,4 @@
-package async
+package resp
 
 import (
 	"testing"

integration_tests/commands/async/mget_test.go → integration_tests/commands/resp/mget_test.go

@@ -1,4 +1,4 @@
-package async
+package resp
 
 import (
 	"testing"

integration_tests/commands/async/mset_test.go → integration_tests/commands/resp/mset_test.go

@@ -1,4 +1,4 @@
-package async
+package resp
 
 import (
 	"testing"

internal/cmd/cmds.go

@@ -5,11 +5,36 @@ import (
 	"strings"
 
 	"github.com/dgryski/go-farm"
+	"github.com/dicedb/dice/internal/object"
 )
 
+// DiceDBCmd represents a command structure to be executed
+// within a DiceDB system. This struct emulates the way DiceDB commands
+// are structured, including the command itself, additional arguments,
+// and an optional object to store or manipulate.
 type DiceDBCmd struct {
-	Cmd  string
+	// Cmd represents the command to execute (e.g., "SET", "GET", "DEL").
+	// This is the main command keyword that specifies the action to perform
+	// in DiceDB. For example:
+	// - "SET": To store a value.
+	// - "GET": To retrieve a value.
+	// - "DEL": To delete a value.
+	// - "EXPIRE": To set a time-to-live for a key.
+	Cmd string
+
+	// Args holds any additional parameters required by the command.
+	// For example:
+	// - If Cmd is "SET", Args might contain ["key", "value"].
+	// - If Cmd is "EXPIRE", Args might contain ["key", "seconds"].
+	// This slice allows flexible support for commands with variable arguments.
 	Args []string
+
+	// Obj is a pointer to an ExtendedObj, representing an optional data structure
+	// associated with the command. This contains pointer to the underlying simple
+	// types such as int, string or even complex types
+	// like hashes, sets, or sorted sets, which are stored and manipulated as objects.
+	// WARN: This parameter should be used with caution
+	Obj *object.ExtendedObj
 }
 
 type RedisCmds struct {

internal/errors/migrated_errors.go

@@ -71,3 +71,11 @@ var (
 		return fmt.Errorf("ERR wrong type of path value - expected %s but found %s", expectedType, actualType) // Signals an unexpected type received when an integer was expected.
 	}
 )
+
+type PreProcessError struct {
+	Result interface{}
+}
+
+func (e *PreProcessError) Error() string {
+	return fmt.Sprintf("%v", e.Result)
+}

internal/eval/commands.go

@@ -3,6 +3,7 @@ package eval
 import (
 	"strings"
 
+	"github.com/dicedb/dice/internal/cmd"
 	dstore "github.com/dicedb/dice/internal/store"
 )
 
@@ -29,6 +30,8 @@ type DiceCmdMeta struct {
 	// will utilize this function for evaluation, allowing for better handling of
 	// complex command execution scenarios and improved response consistency.
 	NewEval func([]string, *dstore.Store) *EvalResponse
+
+	StoreObjectEval func(*cmd.DiceDBCmd, *dstore.Store) *EvalResponse
 }
 
 type KeySpecs struct {
@@ -38,8 +41,11 @@ type KeySpecs struct {
 }
 
 var (
-	DiceCmds = map[string]DiceCmdMeta{}
+	PreProcessing = map[string]func([]string, *dstore.Store) *EvalResponse{}
+	DiceCmds      = map[string]DiceCmdMeta{}
+)
 
+var (
 	echoCmdMeta = DiceCmdMeta{
 		Name:  "ECHO",
 		Info:  `ECHO returns the string given as argument.`,
@@ -603,12 +609,24 @@ var (
 		Info: "PERSIST removes the expiration from a key",
 		Eval: evalPersist,
 	}
+
+	//TODO: supports only http protocol, needs to be removed once http is migrated to multishard
 	copyCmdMeta = DiceCmdMeta{
 		Name:  "COPY",
 		Info:  `COPY command copies the value stored at the source key to the destination key.`,
 		Eval:  evalCOPY,
 		Arity: -2,
 	}
+
+	//TODO: supports only http protocol, needs to be removed once http is migrated to multishard
+	objectCopyCmdMeta = DiceCmdMeta{
+		Name:            "OBJECTCOPY",
+		Info:            `COPY command copies the value stored at the source key to the destination key.`,
+		StoreObjectEval: evalCOPYObject,
+		IsMigrated:      true,
+		Arity:           -2,
+	}
+
 	decrCmdMeta = DiceCmdMeta{
 		Name: "DECR",
 		Info: `DECR decrements the value of the specified key in args by 1,
@@ -1299,6 +1317,9 @@ var (
 )
 
 func init() {
+	PreProcessing["COPY"] = evalGetObject
+	PreProcessing["RENAME"] = evalGET
+
 	DiceCmds["ABORT"] = abortCmdMeta
 	DiceCmds["APPEND"] = appendCmdMeta
 	DiceCmds["AUTH"] = authCmdMeta
@@ -1322,6 +1343,7 @@ func init() {
 	DiceCmds["COMMAND|DOCS"] = commandDocsCmdMeta
 	DiceCmds["COMMAND|GETKEYSANDFLAGS"] = commandGetKeysAndFlagsCmdMeta
 	DiceCmds["COPY"] = copyCmdMeta
+	DiceCmds["OBJECTCOPY"] = objectCopyCmdMeta
 	DiceCmds["DBSIZE"] = dbSizeCmdMeta
 	DiceCmds["DECR"] = decrCmdMeta
 	DiceCmds["DECRBY"] = decrByCmdMeta

internal/eval/eval.go

@@ -2157,7 +2157,7 @@ func evalCOPY(args []string, store *dstore.Store) []byte {
 
 	for i := 2; i < len(args); i++ {
 		arg := strings.ToUpper(args[i])
-		if arg == "REPLACE" {
+		if arg == dstore.Replace {
 			isReplace = true
 		}
 	}

internal/eval/execute.go

@@ -11,18 +11,50 @@ import (
 	dstore "github.com/dicedb/dice/internal/store"
 )
 
-func ExecuteCommand(c *cmd.DiceDBCmd, client *comm.Client, store *dstore.Store, httpOp, websocketOp bool) *EvalResponse {
-	diceCmd, ok := DiceCmds[c.Cmd]
+type Eval struct {
+	cmd                   *cmd.DiceDBCmd
+	client                *comm.Client
+	store                 *dstore.Store
+	isHTTPOperation       bool
+	isWebSocketOperation  bool
+	isPreprocessOperation bool
+}
+
+func NewEval(c *cmd.DiceDBCmd, client *comm.Client, store *dstore.Store, httpOp, websocketOp, preProcessing bool) *Eval {
+	return &Eval{
+		cmd:                   c,
+		client:                client,
+		store:                 store,
+		isHTTPOperation:       httpOp,
+		isWebSocketOperation:  websocketOp,
+		isPreprocessOperation: preProcessing,
+	}
+}
+
+func (e *Eval) PreProcessCommand() *EvalResponse {
+	if f, ok := PreProcessing[e.cmd.Cmd]; ok {
+		return f(e.cmd.Args, e.store)
+	}
+	return &EvalResponse{Result: nil, Error: diceerrors.ErrInternalServer}
+}
+
+func (e *Eval) ExecuteCommand() *EvalResponse {
+	diceCmd, ok := DiceCmds[e.cmd.Cmd]
 	if !ok {
-		return &EvalResponse{Result: diceerrors.NewErrWithFormattedMessage("unknown command '%s', with args beginning with: %s", c.Cmd, strings.Join(c.Args, " ")), Error: nil}
+		return &EvalResponse{Result: diceerrors.NewErrWithFormattedMessage("unknown command '%s', with args beginning with: %s", e.cmd.Cmd, strings.Join(e.cmd.Args, " ")), Error: nil}
 	}
 
 	// Temporary logic till we move all commands to new eval logic.
 	// MigratedDiceCmds map contains refactored eval commands
 	// For any command we will first check in the existing map
 	// if command is NA then we will check in the new map
+
 	if diceCmd.IsMigrated {
-		return diceCmd.NewEval(c.Args, store)
+		if e.cmd.Obj != nil {
+			return diceCmd.StoreObjectEval(e.cmd, e.store)
+		}
+
+		return diceCmd.NewEval(e.cmd.Args, e.store)
 	}
 
 	// The following commands could be handled at the shard level, however, we can randomly let any shard handle them
@@ -31,14 +63,14 @@ func ExecuteCommand(c *cmd.DiceDBCmd, client *comm.Client, store *dstore.Store,
 	// Old implementation kept as it is, but we will be moving
 	// to the new implementation soon for all commands
 	case "SUBSCRIBE", "Q.WATCH":
-		return &EvalResponse{Result: EvalQWATCH(c.Args, httpOp, websocketOp, client, store), Error: nil}
+		return &EvalResponse{Result: EvalQWATCH(e.cmd.Args, e.isHTTPOperation, e.isWebSocketOperation, e.client, e.store), Error: nil}
 	case "UNSUBSCRIBE", "Q.UNWATCH":
-		return &EvalResponse{Result: EvalQUNWATCH(c.Args, httpOp, client), Error: nil}
+		return &EvalResponse{Result: EvalQUNWATCH(e.cmd.Args, e.isHTTPOperation, e.client), Error: nil}
 	case auth.Cmd:
-		return &EvalResponse{Result: EvalAUTH(c.Args, client), Error: nil}
+		return &EvalResponse{Result: EvalAUTH(e.cmd.Args, e.client), Error: nil}
 	case "ABORT":
 		return &EvalResponse{Result: clientio.RespOK, Error: nil}
 	default:
-		return &EvalResponse{Result: diceCmd.Eval(c.Args, store), Error: nil}
+		return &EvalResponse{Result: diceCmd.Eval(e.cmd.Args, e.store), Error: nil}
 	}
 }