termstatus: don't buffer stdout

There's not much use in doing so as nearly every write call was paired
with a flush call. Thus, just use an unbuffered writer.

internal/ui/termstatus/status.go

@@ -1,7 +1,6 @@
 package termstatus
 
 import (
-	"bufio"
 	"context"
 	"fmt"
 	"io"
@@ -19,7 +18,7 @@ import (
 // updated. When the output is redirected to a file, the status lines are not
 // printed.
 type Terminal struct {
-	wr              *bufio.Writer
+	wr              io.Writer
 	fd              uintptr
 	errWriter       io.Writer
 	msg             chan message
@@ -57,7 +56,7 @@ type fder interface {
 // are printed even if the terminal supports it.
 func New(wr io.Writer, errWriter io.Writer, disableStatus bool) *Terminal {
 	t := &Terminal{
-		wr:        bufio.NewWriter(wr),
+		wr:        wr,
 		errWriter: errWriter,
 		msg:       make(chan message),
 		status:    make(chan status),
@@ -118,13 +117,6 @@ func (t *Terminal) run(ctx context.Context) {
 			var dst io.Writer
 			if msg.err {
 				dst = t.errWriter
-
-				// assume t.wr and t.errWriter are different, so we need to
-				// flush clearing the current line
-				err := t.wr.Flush()
-				if err != nil {
-					fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-				}
 			} else {
 				dst = t.wr
 			}
@@ -135,11 +127,6 @@ func (t *Terminal) run(ctx context.Context) {
 			}
 
 			t.writeStatus(status)
-
-			if err := t.wr.Flush(); err != nil {
-				fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-			}
-
 		case stat := <-t.status:
 			status = append(status[:0], stat.lines...)
 
@@ -169,26 +156,15 @@ func (t *Terminal) writeStatus(status []string) {
 	for _, line := range status {
 		t.clearCurrentLine(t.wr, t.fd)
 
-		_, err := t.wr.WriteString(line)
+		_, err := t.wr.Write([]byte(line))
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
 		}
-
-		// flush is needed so that the current line is updated
-		err = t.wr.Flush()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-		}
 	}
 
 	if len(status) > 0 {
 		t.moveCursorUp(t.wr, t.fd, len(status)-1)
 	}
-
-	err := t.wr.Flush()
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-	}
 }
 
 // runWithoutStatus listens on the channels and just prints out the messages,
@@ -199,28 +175,18 @@ func (t *Terminal) runWithoutStatus(ctx context.Context) {
 		case <-ctx.Done():
 			return
 		case msg := <-t.msg:
-			var flush func() error
 
 			var dst io.Writer
 			if msg.err {
 				dst = t.errWriter
 			} else {
 				dst = t.wr
-				flush = t.wr.Flush
 			}
 
 			if _, err := io.WriteString(dst, msg.line); err != nil {
 				_, _ = fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
 			}
 
-			if flush == nil {
-				continue
-			}
-
-			if err := flush(); err != nil {
-				_, _ = fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-			}
-
 		case stat := <-t.status:
 			for _, line := range stat.lines {
 				// Ensure that each message ends with exactly one newline.
@@ -228,9 +194,6 @@ func (t *Terminal) runWithoutStatus(ctx context.Context) {
 					_, _ = fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
 				}
 			}
-			if err := t.wr.Flush(); err != nil {
-				_, _ = fmt.Fprintf(os.Stderr, "flush failed: %v\n", err)
-			}
 		}
 	}
 }