DiceDB#654: feat: Implement HSETNX command (DiceDB#715)

integration_tests/commands/async/hsetnx_test.go

@@ -0,0 +1,38 @@
+package async
+
+import (
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestHSETNX(t *testing.T) {
+	conn := getLocalConnection()
+	defer conn.Close()
+
+	testCases := []TestCase{
+		{
+			commands: []string{"HSETNX key_nx_t1 field value", "HSET key_nx_t1 field value_new"},
+			expected: []interface{}{ONE, ZERO},
+		},
+		{
+			commands: []string{"HSETNX key_nx_t2 field1 value1"},
+			expected: []interface{}{ONE},
+		},
+		{
+			commands: []string{"HSETNX key_nx_t3 field value", "HSETNX key_nx_t3 field new_value", "HSETNX key_nx_t3"},
+			expected: []interface{}{ONE, ZERO, "ERR wrong number of arguments for 'hsetnx' command"},
+		},
+		{
+			commands: []string{"SET key_nx_t4 v", "HSETNX key_nx_t4 f v"},
+			expected: []interface{}{"OK", "WRONGTYPE Operation against a key holding the wrong kind of value"},
+		},
+	}
+
+	for _, tc := range testCases {
+		for i, cmd := range tc.commands {
+			result := FireCommand(conn, cmd)
+			assert.DeepEqual(t, tc.expected[i], result)
+		}
+	}
+}

internal/eval/commands.go

@@ -599,6 +599,15 @@ var (
 		Arity:    -4,
 		KeySpecs: KeySpecs{BeginIndex: 1},
 	}
+	hsetnxCmdMeta = DiceCmdMeta{
+		Name: "HSETNX",
+		Info: `Sets field in the hash stored at key to value, only if field does not yet exist. 
+		If key does not exist, a new key holding a hash is created. If field already exists, 
+		this operation has no effect.`,
+		Eval:     evalHSETNX,
+		Arity:    4,
+		KeySpecs: KeySpecs{BeginIndex: 1},
+	}
 	hgetCmdMeta = DiceCmdMeta{
 		Name:     "HGET",
 		Info:     `Returns the value associated with field in the hash stored at key.`,
@@ -958,6 +967,7 @@ func init() {
 	DiceCmds["GETEX"] = getexCmdMeta
 	DiceCmds["PTTL"] = pttlCmdMeta
 	DiceCmds["HSET"] = hsetCmdMeta
+	DiceCmds["HSETNX"] = hsetnxCmdMeta
 	DiceCmds["OBJECT"] = objectCmdMeta
 	DiceCmds["TOUCH"] = touchCmdMeta
 	DiceCmds["LPUSH"] = lpushCmdMeta

internal/eval/eval.go

@@ -2903,6 +2903,26 @@ func evalHSET(args []string, store *dstore.Store) []byte {
 	return clientio.Encode(numKeys, false)
 }
 
+func evalHSETNX(args []string, store *dstore.Store) []byte {
+	if len(args) != 3 {
+		return diceerrors.NewErrArity("HSETNX")
+	}
+
+	key := args[0]
+	hmKey := args[1]
+
+	val, errWithMessage := getValueFromHashMap(key, hmKey, store)
+	if errWithMessage != nil {
+		return errWithMessage
+	}
+	if !bytes.Equal(val, clientio.RespNIL) { // hmKey is already present in hash map
+		return clientio.RespZero
+	}
+
+	evalHSET(args, store)
+	return clientio.RespOne
+}
+
 func evalHGETALL(args []string, store *dstore.Store) []byte {
 	if len(args) != 1 {
 		return diceerrors.NewErrArity("HGETALL")

internal/eval/eval_test.go

@@ -9,7 +9,7 @@ import (
 	"strings"
 	"testing"
 	"time"
-
+  
 	"github.com/bytedance/sonic"
 	"github.com/dicedb/dice/internal/server/utils"
 	"github.com/ohler55/ojg/jp"
@@ -87,6 +87,7 @@ func TestEval(t *testing.T) {
 	testEvalCOMMAND(t, store)
 	testEvalJSONOBJKEYS(t, store)
 	testEvalGETRANGE(t, store)
+	testEvalHSETNX(t, store)
 	testEvalPING(t, store)
 	testEvalSETEX(t, store)
 	testEvalFLUSHDB(t, store)
@@ -3486,6 +3487,68 @@ func BenchmarkEvalGETRANGE(b *testing.B) {
 	}
 }
 
+func BenchmarkEvalHSETNX(b *testing.B) {
+	store := dstore.NewStore(nil)
+	for i := 0; i < b.N; i++ {
+		evalHSETNX([]string{"KEY", fmt.Sprintf("FIELD_%d", i/2), fmt.Sprintf("VALUE_%d", i)}, store)
+	}
+}
+
+func testEvalHSETNX(t *testing.T, store *dstore.Store) {
+	tests := map[string]evalTestCase{
+		"no args passed": {
+			setup:  func() {},
+			input:  nil,
+			output: []byte("-ERR wrong number of arguments for 'hsetnx' command\r\n"),
+		},
+		"only key passed": {
+			setup:  func() {},
+			input:  []string{"key"},
+			output: []byte("-ERR wrong number of arguments for 'hsetnx' command\r\n"),
+		},
+		"only key and field_name passed": {
+			setup:  func() {},
+			input:  []string{"KEY", "field_name"},
+			output: []byte("-ERR wrong number of arguments for 'hsetnx' command\r\n"),
+		},
+		"more than one field and value passed": {
+			setup: func() {},
+			input: []string{"KEY", "field1", "value1", "field2", "value2"},
+			output: []byte("-ERR wrong number of arguments for 'hsetnx' command\r\n"),
+		},
+		"key, field and value passed": {
+			setup:  func() {},
+			input:  []string{"KEY1", "field_name", "value"},
+			output: clientio.Encode(int64(1), false),
+		},
+		"new set of key, field and value added": {
+			setup:  func() {},
+			input:  []string{"KEY2", "field_name_new", "value_new_new"},
+			output: clientio.Encode(int64(1), false),
+		},
+		"apply with duplicate key, field and value names": {
+			setup: func() {
+				key := "KEY_MOCK"
+				field := "mock_field_name"
+				newMap := make(HashMap)
+				newMap[field] = "mock_field_value"
+
+				obj := &object.Obj{
+					TypeEncoding:   object.ObjTypeHashMap | object.ObjEncodingHashMap,
+					Value:          newMap,
+					LastAccessedAt: uint32(time.Now().Unix()),
+				}
+
+				store.Put(key, obj)
+			},
+			input:  []string{"KEY_MOCK", "mock_field_name", "mock_field_value_2"},
+			output: clientio.Encode(int64(0), false),
+		},
+	}
+
+	runEvalTests(t, tests, evalHSETNX, store)
+}
+
 func TestMSETConsistency(t *testing.T) {
 	store := dstore.NewStore(nil)
 	evalMSET([]string{"KEY", "VAL", "KEY2", "VAL2"}, store)