1 files changed, 71 insertions, 0 deletions
diff --git a/go/src/lib/statusline/stopwatch.go b/go/src/lib/statusline/stopwatch.go
new file mode 100644
index 0000000..4e3bb5b
--- /dev/null
+++ b/go/src/lib/statusline/stopwatch.go
@@ -0,0 +1,71 @@
+package statusline
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+type stopWatch struct {
+	inner     StatusLine
+	precision time.Duration
+
+	start time.Time
+	line  string
+
+	once sync.Once
+
+	lines chan string
+	end1  chan bool
+	end2  chan struct{}
+}
+
+func StopWatch(sl StatusLine, precision time.Duration) StatusLine {
+	return &stopWatch{
+		inner:     sl,
+		precision: precision,
+		lines:     make(chan string),
+		end1:      make(chan bool),
+		end2:      make(chan struct{}),
+	}
+}
+
+func (sw *stopWatch) startWorker() {
+	go func() {
+		sw.start = time.Now()
+		ticker := time.NewTicker(sw.precision)
+		for {
+			select {
+			case <-ticker.C:
+				sw.tick()
+			case sw.line = <-sw.lines:
+				sw.tick()
+			case keep := <-sw.end1:
+				sw.tick()
+				sw.inner.End(keep)
+				ticker.Stop()
+				sw.end2 <- struct{}{}
+				close(sw.end2)
+				return
+			}
+		}
+	}()
+}
+
+func (sw *stopWatch) tick() {
+	d := time.Now().Sub(sw.start).Round(sw.precision)
+	sw.inner.Put(fmt.Sprintf("[ %v ] %s", d, sw.line))
+}
+
+func (sl *stopWatch) Put(line string) {
+	sl.once.Do(sl.startWorker)
+	sl.lines <- line
+}
+
+func (sl *stopWatch) End(keep bool) {
+	sl.once.Do(sl.startWorker)
+	sl.end1 <- keep
+	close(sl.lines)
+	close(sl.end1)
+	<-sl.end2
+}