From 2fb700aaabda57103776297c6cac913d33f95136 Mon Sep 17 00:00:00 2001
From: Adam Bozanich <adam.boz@gmail.com>
Date: Tue, 25 Apr 2017 16:45:51 -0700
Subject: [PATCH] ui: drain events

---
 ui/processor.go | 10 +++++++---
 ui/tuiwriter.go | 41 ++++++++++++++++++++++++++++++++---------
 2 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/ui/processor.go b/ui/processor.go
index 952fc7d..94a4c46 100644
--- a/ui/processor.go
+++ b/ui/processor.go
@@ -34,6 +34,10 @@ const (
 	ceventResult    ceventId = "action-result"
 )
 
+const (
+	pBufSiz = 15
+)
+
 type cevent struct {
 	id          ceventId
 	containerId string
@@ -66,8 +70,8 @@ func newProcessor(w writer) *processor {
 		pools:      make(map[string]*pool),
 		containers: make(map[string]*container),
 
-		poolch:      make(chan pevent),
-		containerch: make(chan cevent),
+		poolch:      make(chan pevent, pBufSiz),
+		containerch: make(chan cevent, pBufSiz),
 		donech:      make(chan bool),
 	}
 
@@ -78,7 +82,7 @@ func newProcessor(w writer) *processor {
 }
 
 func (p *processor) stop() {
-	close(p.donech)
+	defer close(p.donech)
 	p.writer.stop()
 }
 
diff --git a/ui/tuiwriter.go b/ui/tuiwriter.go
index 3b2e242..54192ab 100644
--- a/ui/tuiwriter.go
+++ b/ui/tuiwriter.go
@@ -13,6 +13,8 @@ import (
 const (
 	tuiMaxPeriod = time.Second / 2
 	tuiMinPeriod = time.Second / 15
+
+	tuiCHBufsiz = 15
 )
 
 type crec struct {
@@ -39,8 +41,12 @@ type tuiWriter struct {
 	// closed when user quits.
 	shutdownch chan bool
 
+	// closed when completely shut down
 	donech chan bool
 
+	// signal closing down
+	drainch chan bool
+
 	app    *views.Application
 	window *tuiWindow
 }
@@ -55,14 +61,16 @@ func newTUIWriter(shutdownch chan bool) (writer, error) {
 		pupdate: make(map[string]tuiTR),
 		pdelete: make(map[string]tuiTR),
 
-		pch: make(chan pool),
-		cch: make(chan container),
-		dch: make(chan container),
+		pch: make(chan pool, tuiCHBufsiz),
+		cch: make(chan container, tuiCHBufsiz),
+		dch: make(chan container, tuiCHBufsiz),
 
 		drawch: make(chan bool),
 
 		shutdownch: shutdownch,
-		donech:     make(chan bool),
+
+		donech:  make(chan bool),
+		drainch: make(chan bool),
 
 		app:    app,
 		window: window,
@@ -117,18 +125,32 @@ func (w *tuiWriter) deleteContainer(c container) {
 }
 
 func (w *tuiWriter) stop() {
-	w.throttle.Stop()
-	close(w.donech)
+	w.drainch <- true
+	<-w.donech
 }
 
 func (w *tuiWriter) run() {
+	defer close(w.donech)
 	defer w.app.Quit()
+	defer w.throttle.Stop()
+
+	shuttingdown := 0
+
 	for {
 		select {
-		case <-w.donech:
-			return
+		case <-w.drainch:
+			shuttingdown++
 		case <-w.drawch:
-			w.draw()
+			switch {
+			case shuttingdown > 2:
+				return
+			case shuttingdown > 0:
+				w.throttle.Trigger()
+				shuttingdown++
+				fallthrough
+			case shuttingdown == 0:
+				w.draw()
+			}
 		case p := <-w.pch:
 			w.handlePool(p)
 			w.throttle.Trigger()
@@ -139,6 +161,7 @@ func (w *tuiWriter) run() {
 			w.handleDeleteContainer(c)
 			w.throttle.Trigger()
 		case <-time.After(tuiMaxPeriod):
+			w.throttle.Trigger()
 		}
 	}
 }