From 0f9b9d873bf08485208220a4ed63cb546ffe77ae Mon Sep 17 00:00:00 2001
From: Yurii Soldak <ysoldak@gmail.com>
Date: Wed, 20 Oct 2021 00:08:20 +0200
Subject: [PATCH] wifinina: avoid busy wait

---
 wifinina/tcp.go      | 13 ++++++-------
 wifinina/timer.go    | 28 ----------------------------
 wifinina/wifinina.go | 19 +++++++++++--------
 3 files changed, 17 insertions(+), 43 deletions(-)
 delete mode 100644 wifinina/timer.go

diff --git a/wifinina/tcp.go b/wifinina/tcp.go
index 1f09ee0..fb747e4 100644
--- a/wifinina/tcp.go
+++ b/wifinina/tcp.go
@@ -87,7 +87,8 @@ func (drv *Driver) connectSocket(addr, portStr string, mode uint8) error {
 	}
 
 	// FIXME: this 4 second timeout is simply mimicking the Arduino driver
-	for t := newTimer(4 * time.Second); !t.Expired(); {
+	start := time.Now()
+	for time.Since(start) < 4*time.Second {
 		connected, err := drv.IsConnected()
 		if err != nil {
 			return err
@@ -95,7 +96,7 @@ func (drv *Driver) connectSocket(addr, portStr string, mode uint8) error {
 		if connected {
 			return nil
 		}
-		wait(1 * time.Millisecond)
+		time.Sleep(1 * time.Millisecond)
 	}
 
 	return ErrConnectionTimeout
@@ -272,15 +273,13 @@ func (drv *Driver) stop() error {
 		return nil
 	}
 	drv.dev.StopClient(drv.sock)
-	for t := newTimer(5 * time.Second); !t.Expired(); {
+	start := time.Now()
+	for time.Since(start) < 5*time.Second {
 		st, _ := drv.status()
 		if st == TCPStateClosed {
 			break
 		}
-		// FIXME: without the time.Sleep below this blocks until TCPStateClosed,
-		// however with it got goroutine stack overflows; not sure if this is still
-		// an issue so should investigate further
-		//time.Sleep(1 * time.Millisecond)
+		time.Sleep(1 * time.Millisecond)
 	}
 	drv.sock = NoSocketAvail
 	return nil
diff --git a/wifinina/timer.go b/wifinina/timer.go
deleted file mode 100644
index ca58e82..0000000
--- a/wifinina/timer.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package wifinina
-
-import "time"
-
-func wait(duration time.Duration) {
-	newTimer(duration).WaitUntilExpired()
-}
-
-type timer struct {
-	start    int64
-	interval int64
-}
-
-func newTimer(interval time.Duration) timer {
-	return timer{
-		start:    time.Now().UnixNano(),
-		interval: int64(interval),
-	}
-}
-
-func (t timer) Expired() bool {
-	return time.Now().UnixNano() > (t.start + t.interval)
-}
-
-func (t timer) WaitUntilExpired() {
-	for !t.Expired() {
-	}
-}
diff --git a/wifinina/wifinina.go b/wifinina/wifinina.go
index 290f1b0..6875629 100644
--- a/wifinina/wifinina.go
+++ b/wifinina/wifinina.go
@@ -379,7 +379,7 @@ func (d *Device) CheckDataSent(sock uint8) (bool, error) {
 		if sent > 0 {
 			return true, nil
 		}
-		wait(100 * time.Microsecond)
+		time.Sleep(100 * time.Microsecond)
 	}
 	return false, lastErr
 }
@@ -1023,8 +1023,7 @@ func (d *Device) checkStartCmd() (bool, error) {
 }
 
 func (d *Device) waitForChipSelect() (err error) {
-	err = d.waitForChipReady()
-	if err == nil {
+	if err = d.waitForChipReady(); err == nil {
 		err = d.spiChipSelect()
 	}
 	return
@@ -1034,12 +1033,14 @@ func (d *Device) waitForChipReady() error {
 	if _debug {
 		println("waitForChipReady()\r")
 	}
-	for t := newTimer(10 * time.Second); !(d.ACK.Get() == false); {
-		if t.Expired() {
-			return ErrTimeoutChipReady
+	start := time.Now()
+	for time.Since(start) < 10*time.Second {
+		if !d.ACK.Get() {
+			return nil
 		}
+		time.Sleep(1 * time.Millisecond)
 	}
-	return nil
+	return ErrTimeoutChipReady
 }
 
 func (d *Device) spiChipSelect() error {
@@ -1047,10 +1048,12 @@ func (d *Device) spiChipSelect() error {
 		println("spiChipSelect()\r")
 	}
 	d.CS.Low()
-	for t := newTimer(5 * time.Millisecond); !t.Expired(); {
+	start := time.Now()
+	for time.Since(start) < 5*time.Millisecond {
 		if d.ACK.Get() {
 			return nil
 		}
+		time.Sleep(100 * time.Microsecond)
 	}
 	return ErrTimeoutChipSelect
 }