Add BITFIELD_RO Command (#2820)

Co-authored-by: Chayim <chayim@users.noreply.github.com>

bitmap_commands.go

@@ -1,6 +1,8 @@
 package redis
 
-import "context"
+import (
+	"context"
+)
 
 type BitMapCmdable interface {
 	GetBit(ctx context.Context, key string, offset int64) *IntCmd
@@ -127,3 +129,21 @@ func (c cmdable) BitField(ctx context.Context, key string, values ...interface{}
 	_ = c(ctx, cmd)
 	return cmd
 }
+
+// BitFieldRO - Read-only variant of the BITFIELD command.
+// It is like the original BITFIELD but only accepts GET subcommand and can safely be used in read-only replicas.
+// - BitFieldRO(ctx, key, "<Encoding0>", "<Offset0>", "<Encoding1>","<Offset1>")
+func (c cmdable) BitFieldRO(ctx context.Context, key string, values ...interface{}) *IntSliceCmd {
+	args := make([]interface{}, 2, 2+len(values))
+	args[0] = "BITFIELD_RO"
+	args[1] = key
+	if len(values)%2 != 0 {
+		panic("BitFieldRO: invalid number of arguments, must be even")
+	}
+	for i := 0; i < len(values); i += 2 {
+		args = append(args, "GET", values[i], values[i+1])
+	}
+	cmd := NewIntSliceCmd(ctx, args...)
+	_ = c(ctx, cmd)
+	return cmd
+}

commands_test.go

@@ -1279,6 +1279,20 @@ var _ = Describe("Commands", func() {
 			Expect(nn).To(Equal([]int64{0, 4}))
 		})
 
+		It("should BitFieldRO", func() {
+			nn, err := client.BitField(ctx, "mykey", "SET", "u8", 8, 255).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(nn).To(Equal([]int64{0}))
+
+			nn, err = client.BitFieldRO(ctx, "mykey", "u8", 0).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(nn).To(Equal([]int64{0}))
+
+			nn, err = client.BitFieldRO(ctx, "mykey", "u8", 0, "u4", 8, "u4", 12, "u4", 13).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(nn).To(Equal([]int64{0, 15, 15, 14}))
+		})
+
 		It("should Decr", func() {
 			set := client.Set(ctx, "key", "10", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())