chore: optimize single-record blocking write

api/writeAPIBlocking.go

@@ -51,7 +51,8 @@ import (
 //	}
 type WriteAPIBlocking interface {
 	// WriteRecord writes line protocol record(s) into bucket.
-	// WriteRecord writes without implicit batching. Batch is created from given number of records
+	// WriteRecord writes without implicit batching. Batch is created from given number of records.
+	// Individual arguments can also be batches (multiple records separated by newline).
 	// Non-blocking alternative is available in the WriteAPI interface
 	WriteRecord(ctx context.Context, line ...string) error
 	// WritePoint data point into bucket.
@@ -80,18 +81,25 @@ func (w *writeAPIBlocking) write(ctx context.Context, line string) error {
 }
 
 func (w *writeAPIBlocking) WriteRecord(ctx context.Context, line ...string) error {
-	if len(line) > 0 {
-		var sb strings.Builder
-		for _, line := range line {
-			b := []byte(line)
-			b = append(b, 0xa)
-			if _, err := sb.Write(b); err != nil {
-				return err
-			}
+	if len(line) == 0 {
+		return nil
+	}
+	if len(line) == 1 {
+		ln := line[0]
+		if ln[len(ln)-1] != '\n' {
+			ln += "\n"
 		}
-		return w.write(ctx, sb.String())
+		return w.write(ctx, ln)
 	}
-	return nil
+	var sb strings.Builder
+	for _, line := range line {
+		b := []byte(line)
+		b = append(b, 0xa)
+		if _, err := sb.Write(b); err != nil {
+			return err
+		}
+	}
+	return w.write(ctx, sb.String())
 }
 
 func (w *writeAPIBlocking) WritePoint(ctx context.Context, point ...*write.Point) error {

api/writeAPIBlocking_test.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"net"
 	"net/http"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -57,6 +58,20 @@ func TestWriteRecord(t *testing.T) {
 	require.Equal(t, "invalid: data", err.Error())
 }
 
+func TestWriteRecordBatch(t *testing.T) {
+	service := test.NewTestService(t, "http://localhost:8888")
+	writeAPI := NewWriteAPIBlocking("my-org", "my-bucket", service, write.DefaultOptions().SetBatchSize(5))
+	lines := test.GenRecords(10)
+	batch := strings.Join(lines, "\n")
+	err := writeAPI.WriteRecord(context.Background(), batch)
+	require.Nil(t, err)
+	require.Len(t, service.Lines(), 10)
+	for i, l := range lines {
+		assert.Equal(t, l, service.Lines()[i])
+	}
+	service.Close()
+}
+
 func TestWriteParallel(t *testing.T) {
 	service := test.NewTestService(t, "http://localhost:8888")
 	writeAPI := NewWriteAPIBlocking("my-org", "my-bucket", service, write.DefaultOptions().SetBatchSize(5))