add deadlock mutex package

write to deadlock stderr after closing gocui

more deadlock checking

2 files changed, 50 insertions, 0 deletions

diff --git a/pkg/utils/once_writer.go b/pkg/utils/once_writer.go
new file mode 100644
index 000000000..aecf20369
--- /dev/null
+++ b/pkg/utils/once_writer.go
@@ -0,0 +1,31 @@
+package utils
+
+import (
+	"io"
+	"sync"
+)
+
+// This wraps a writer and ensures that before we actually write anything we call a given function first
+
+type OnceWriter struct {
+	writer io.Writer
+	once   sync.Once
+	f      func()
+}
+
+var _ io.Writer = &OnceWriter{}
+
+func NewOnceWriter(writer io.Writer, f func()) *OnceWriter {
+	return &OnceWriter{
+		writer: writer,
+		f:      f,
+	}
+}
+
+func (self *OnceWriter) Write(p []byte) (n int, err error) {
+	self.once.Do(func() {
+		self.f()
+	})
+
+	return self.writer.Write(p)
+}
diff --git a/pkg/utils/once_writer_test.go b/pkg/utils/once_writer_test.go
new file mode 100644
index 000000000..47f64bb61
--- /dev/null
+++ b/pkg/utils/once_writer_test.go
@@ -0,0 +1,19 @@
+package utils
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestOnceWriter(t *testing.T) {
+	innerWriter := bytes.NewBuffer(nil)
+	counter := 0
+	onceWriter := NewOnceWriter(innerWriter, func() {
+		counter += 1
+	})
+	_, _ = onceWriter.Write([]byte("hello"))
+	_, _ = onceWriter.Write([]byte("hello"))
+	if counter != 1 {
+		t.Errorf("expected counter to be 1, got %d", counter)
+	}
+}