✨ logs Add support for reading line by line in FIFO reader

changes/20250530105438.feature

@@ -0,0 +1 @@
+:sparkles: `logs` Add support for reading line by line in FIFO reader

utils/logs/fifo_logger.go

@@ -2,12 +2,19 @@ package logs
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
+	"iter"
 	"log"
 	"sync"
+	"time"
+
+	"github.com/ARM-software/golang-utils/utils/parallelisation"
 )
 
+var _ Loggers = &FIFOLoggers{}
+
 type FIFOWriter struct {
 	io.WriteCloser
 	mu   sync.RWMutex
@@ -39,6 +46,68 @@ func (w *FIFOWriter) Read() string {
 	return string(bytes)
 }
 
+func (w *FIFOWriter) ReadLines(ctx context.Context) iter.Seq[string] {
+	return func(yield func(string) bool) {
+		var partial []byte
+		for {
+			if err := parallelisation.DetermineContextError(ctx); err != nil {
+				return
+			}
+
+			buf := func() []byte {
+				w.mu.Lock()
+				defer w.mu.Unlock()
+				defer w.Logs.Reset()
+				tmp := w.Logs.Bytes()
+				buf := make([]byte, len(tmp))
+				copy(buf, tmp)
+				return buf
+			}()
+
+			if len(buf) == 0 {
+				if err := parallelisation.DetermineContextError(ctx); err != nil {
+					if len(partial) > 0 {
+						yield(string(partial))
+					}
+					return
+				}
+
+				parallelisation.SleepWithContext(ctx, 50*time.Millisecond)
+				continue
+			}
+
+			if len(partial) > 0 {
+				buf = append(partial, buf...)
+				partial = nil
+			}
+
+			for {
+				idx := bytes.IndexByte(buf, '\n')
+				if idx < 0 {
+					break
+				}
+				line := buf[:idx]
+
+				if len(line) > 0 && line[len(line)-1] == '\r' {
+					line = line[:len(line)-1]
+				}
+				buf = buf[idx+1:]
+				if len(line) == 0 {
+					continue
+				}
+
+				if !yield(string(line)) {
+					return
+				}
+			}
+
+			if len(buf) > 0 {
+				partial = buf
+			}
+		}
+	}
+}
+
 type FIFOLoggers struct {
 	GenericLoggers
 	LogWriter FIFOWriter
@@ -52,6 +121,10 @@ func (l *FIFOLoggers) Read() string {
 	return l.LogWriter.Read()
 }
 
+func (l *FIFOLoggers) ReadLines(ctx context.Context) iter.Seq[string] {
+	return l.LogWriter.ReadLines(ctx)
+}
+
 // Close closes the logger
 func (l *FIFOLoggers) Close() (err error) {
 	err = l.LogWriter.Close()

utils/logs/fifo_logger_test.go

@@ -1,13 +1,17 @@
 package logs
 
 import (
+	"context"
+	"regexp"
 	"strings"
 	"testing"
+	"time"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func TestFIFOLogger(t *testing.T) {
+func TestFIFOLoggerRead(t *testing.T) {
 	loggers, err := NewFIFOLogger("Test")
 	require.NoError(t, err)
 	testLog(t, loggers)
@@ -27,7 +31,7 @@ func TestFIFOLogger(t *testing.T) {
 	require.Empty(t, contents)
 }
 
-func TestPlainFIFOLogger(t *testing.T) {
+func TestPlainFIFOLoggerRead(t *testing.T) {
 	loggers, err := NewPlainFIFOLogger()
 	require.NoError(t, err)
 	testLog(t, loggers)
@@ -46,3 +50,55 @@ func TestPlainFIFOLogger(t *testing.T) {
 	contents = loggers.Read()
 	require.Empty(t, contents)
 }
+
+func TestFIFOLoggerReadlines(t *testing.T) {
+	loggers, err := NewFIFOLogger("Test")
+	require.NoError(t, err)
+	testLog(t, loggers)
+	loggers.LogError("Test err\n")
+	loggers.Log("Test1")
+	count := 0
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	var b strings.Builder
+	for line := range loggers.ReadLines(ctx) {
+		_, err := b.WriteString(line + "\n")
+		require.NoError(t, err)
+		count++
+	}
+
+	assert.Regexp(t, regexp.MustCompile(`\[Test\] Error: .* .* Test err\n\[Test\] Output: .* .* Test1\n`), b.String())
+	assert.Equal(t, 2, count)
+}
+
+func TestPlainFIFOLoggerReadlines(t *testing.T) {
+	loggers, err := NewPlainFIFOLogger()
+	require.NoError(t, err)
+	testLog(t, loggers)
+
+	go func() {
+		time.Sleep(500 * time.Millisecond)
+		loggers.LogError("Test err")
+		loggers.Log("")
+		time.Sleep(100 * time.Millisecond)
+		loggers.Log("Test1")
+		loggers.Log("\n\n\n")
+		time.Sleep(200 * time.Millisecond)
+		loggers.Log("Test2")
+	}()
+
+	count := 0
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	var b strings.Builder
+	for line := range loggers.ReadLines(ctx) {
+		_, err := b.WriteString(line + "\n")
+		require.NoError(t, err)
+		count++
+	}
+
+	assert.Equal(t, "Test err\nTest1\nTest2\n", b.String())
+	assert.Equal(t, 3, count)
+}