From fbcfddc006f709a4be34cbc3744eebc614672554 Mon Sep 17 00:00:00 2001
From: Christopher Young <cyoung@gmail.com>
Date: Mon, 19 Oct 2015 08:17:02 -0400
Subject: [PATCH] Isolate CPU temperature monitor to its own goroutine.

Addresses #63.
---
 main/gen_gdl90.go | 39 ++++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/main/gen_gdl90.go b/main/gen_gdl90.go
index fd666f8b..f495398d 100644
--- a/main/gen_gdl90.go
+++ b/main/gen_gdl90.go
@@ -431,6 +431,31 @@ func updateMessageStats() {
 
 }
 
+/*
+	cpuTempMonitor() reads the RPi board temperature every second and updates it in globalStatus.
+	This is broken out into its own function (run as its own goroutine) because the RPi temperature
+	 monitor code is buggy, and often times reading this file hangs quite some time.
+*/
+func cpuTempMonitor() {
+	timer := time.NewTicker(1 * time.Second)
+	for {
+		<-timer.C
+
+		// Update CPUTemp.
+		globalStatus.CPUTemp = float32(-99.0) // Default value - in case code below hangs.
+
+		temp, err := ioutil.ReadFile("/sys/class/thermal/thermal_zone0/temp")
+		tempStr := strings.Trim(string(temp), "\n")
+		if err == nil {
+			tInt, err := strconv.Atoi(tempStr)
+			if err == nil {
+				globalStatus.CPUTemp = float32(tInt) / float32(1000.0)
+			}
+		}		
+
+	}
+}
+
 func updateStatus() {
 	if isGPSValid() {
 		globalStatus.GPS_satellites_locked = mySituation.Satellites
@@ -438,17 +463,6 @@ func updateStatus() {
 
 	// Update Uptime value
 	globalStatus.Uptime = time.Since(timeStarted).Nanoseconds() / 1000000
-
-	// Update CPUTemp.
-	temp, err := ioutil.ReadFile("/sys/class/thermal/thermal_zone0/temp")
-	tempStr := strings.Trim(string(temp), "\n")
-	globalStatus.CPUTemp = float32(-99.0)
-	if err == nil {
-		tInt, err := strconv.Atoi(tempStr)
-		if err == nil {
-			globalStatus.CPUTemp = float32(tInt) / float32(1000.0)
-		}
-	}
 }
 
 func replayLog(msg string, msgclass int) {
@@ -883,6 +897,9 @@ func main() {
 	// Start printing stats periodically to the logfiles.
 	go printStats()
 
+	// Monitor RPi CPU temp.
+	go cpuTempMonitor()
+
 	reader := bufio.NewReader(os.Stdin)
 
 	for {