capture go build / go mod tidy output to outputcapture (#2540)

Author: sawka

.golangci.yml

@@ -3,8 +3,7 @@ version: 2
 linters:
     disable:
         - unused
-        - unusedfunc
-        - unusedparams
+
 issues:
     exclude-rules:
         - linters:

pkg/util/utilfn/streamtolines.go

@@ -83,3 +83,32 @@ func StreamToLinesChan(input io.Reader) chan LineOutput {
 	}()
 	return ch
 }
+
+// LineWriter is an io.Writer that processes data line-by-line via a callback.
+// Lines do not include the trailing newline. Lines longer than maxLineLength are dropped.
+type LineWriter struct {
+	lineBuf lineBuf
+	lineFn  func([]byte)
+}
+
+// NewLineWriter creates a new LineWriter with the given callback function.
+func NewLineWriter(lineFn func([]byte)) *LineWriter {
+	return &LineWriter{
+		lineFn: lineFn,
+	}
+}
+
+// Write implements io.Writer, processing the data and calling the callback for each complete line.
+func (lw *LineWriter) Write(p []byte) (n int, err error) {
+	streamToLines_processBuf(&lw.lineBuf, p, lw.lineFn)
+	return len(p), nil
+}
+
+// Flush outputs any remaining buffered data as a final line.
+// Should be called when the input stream is complete (e.g., at EOF).
+func (lw *LineWriter) Flush() {
+	if len(lw.lineBuf.buf) > 0 && !lw.lineBuf.inLongLine {
+		lw.lineFn(lw.lineBuf.buf)
+		lw.lineBuf.buf = nil
+	}
+}

tsunami/build/build.go

@@ -30,18 +30,42 @@ const MinSupportedGoMinorVersion = 22
 const TsunamiUIImportPath = "github.com/wavetermdev/waveterm/tsunami/ui"
 
 type OutputCapture struct {
-	lock  sync.Mutex
-	lines []string
+	lock       sync.Mutex
+	lines      []string
+	lineWriter *util.LineWriter
 }
 
 func MakeOutputCapture() *OutputCapture {
-	return &OutputCapture{
+	oc := &OutputCapture{
 		lines: make([]string, 0),
 	}
+	oc.lineWriter = util.NewLineWriter(func(line []byte) {
+		// synchronized via the Write/Flush functions
+		oc.lines = append(oc.lines, string(line))
+	})
+	return oc
 }
 
-func (oc *OutputCapture) Printf(format string, args ...interface{}) {
+func (oc *OutputCapture) Write(p []byte) (n int, err error) {
 	if oc == nil {
+		return os.Stdout.Write(p)
+	}
+	oc.lock.Lock()
+	defer oc.lock.Unlock()
+	return oc.lineWriter.Write(p)
+}
+
+func (oc *OutputCapture) Flush() {
+	if oc == nil || oc.lineWriter == nil {
+		return
+	}
+	oc.lock.Lock()
+	defer oc.lock.Unlock()
+	oc.lineWriter.Flush()
+}
+
+func (oc *OutputCapture) Printf(format string, args ...interface{}) {
+	if oc == nil || oc.lineWriter == nil {
 		log.Printf(format, args...)
 		return
 	}
@@ -319,15 +343,16 @@ func createGoMod(tempDir, appName, goVersion string, opts BuildOpts, verbose boo
 	tidyCmd := exec.Command("go", "mod", "tidy")
 	tidyCmd.Dir = tempDir
 
-	if verbose {
+	if oc != nil || verbose {
 		oc.Printf("Running go mod tidy")
-		tidyCmd.Stdout = os.Stdout
-		tidyCmd.Stderr = os.Stderr
+		tidyCmd.Stdout = oc
+		tidyCmd.Stderr = oc
 	}
 
 	if err := tidyCmd.Run(); err != nil {
 		return fmt.Errorf("failed to run go mod tidy: %w", err)
 	}
+	oc.Flush()
 
 	if verbose {
 		oc.Printf("Successfully ran go mod tidy")
@@ -651,15 +676,16 @@ func runGoBuild(tempDir string, opts BuildOpts) error {
 	buildCmd := exec.Command("go", args...)
 	buildCmd.Dir = tempDir
 
-	if opts.Verbose {
+	if oc != nil || opts.Verbose {
 		oc.Printf("Running: %s", strings.Join(buildCmd.Args, " "))
-		buildCmd.Stdout = os.Stdout
-		buildCmd.Stderr = os.Stderr
+		buildCmd.Stdout = oc
+		buildCmd.Stderr = oc
 	}
 
 	if err := buildCmd.Run(); err != nil {
 		return fmt.Errorf("failed to build application: %w", err)
 	}
+	oc.Flush()
 
 	if opts.Verbose {
 		if opts.OutputFile != "" {

tsunami/util/streamtolines.go

@@ -0,0 +1,114 @@
+// Copyright 2025, Command Line Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+package util
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"time"
+)
+
+type LineOutput struct {
+	Line  string
+	Error error
+}
+
+type lineBuf struct {
+	buf        []byte
+	inLongLine bool
+}
+
+const maxLineLength = 128 * 1024
+
+func ReadLineWithTimeout(ch chan LineOutput, timeout time.Duration) (string, error) {
+	select {
+	case output := <-ch:
+		if output.Error != nil {
+			return "", output.Error
+		}
+		return output.Line, nil
+	case <-time.After(timeout):
+		return "", context.DeadlineExceeded
+	}
+}
+
+func streamToLines_processBuf(lineBuf *lineBuf, readBuf []byte, lineFn func([]byte)) {
+	for len(readBuf) > 0 {
+		nlIdx := bytes.IndexByte(readBuf, '\n')
+		if nlIdx == -1 {
+			if lineBuf.inLongLine || len(lineBuf.buf)+len(readBuf) > maxLineLength {
+				lineBuf.buf = nil
+				lineBuf.inLongLine = true
+				return
+			}
+			lineBuf.buf = append(lineBuf.buf, readBuf...)
+			return
+		}
+		if !lineBuf.inLongLine && len(lineBuf.buf)+nlIdx <= maxLineLength {
+			line := append(lineBuf.buf, readBuf[:nlIdx]...)
+			lineFn(line)
+		}
+		lineBuf.buf = nil
+		lineBuf.inLongLine = false
+		readBuf = readBuf[nlIdx+1:]
+	}
+}
+
+func StreamToLines(input io.Reader, lineFn func([]byte)) error {
+	var lineBuf lineBuf
+	readBuf := make([]byte, 64*1024)
+	for {
+		n, err := input.Read(readBuf)
+		streamToLines_processBuf(&lineBuf, readBuf[:n], lineFn)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+// starts a goroutine to drive the channel
+// line output does not include the trailing newline
+func StreamToLinesChan(input io.Reader) chan LineOutput {
+	ch := make(chan LineOutput)
+	go func() {
+		defer close(ch)
+		err := StreamToLines(input, func(line []byte) {
+			ch <- LineOutput{Line: string(line)}
+		})
+		if err != nil && err != io.EOF {
+			ch <- LineOutput{Error: err}
+		}
+	}()
+	return ch
+}
+
+// LineWriter is an io.Writer that processes data line-by-line via a callback.
+// Lines do not include the trailing newline. Lines longer than maxLineLength are dropped.
+type LineWriter struct {
+	lineBuf lineBuf
+	lineFn  func([]byte)
+}
+
+// NewLineWriter creates a new LineWriter with the given callback function.
+func NewLineWriter(lineFn func([]byte)) *LineWriter {
+	return &LineWriter{
+		lineFn: lineFn,
+	}
+}
+
+// Write implements io.Writer, processing the data and calling the callback for each complete line.
+func (lw *LineWriter) Write(p []byte) (n int, err error) {
+	streamToLines_processBuf(&lw.lineBuf, p, lw.lineFn)
+	return len(p), nil
+}
+
+// Flush outputs any remaining buffered data as a final line.
+// Should be called when the input stream is complete (e.g., at EOF).
+func (lw *LineWriter) Flush() {
+	if len(lw.lineBuf.buf) > 0 && !lw.lineBuf.inLongLine {
+		lw.lineFn(lw.lineBuf.buf)
+		lw.lineBuf.buf = nil
+	}
+}