Added a retry clause when doing battery check in adb.go

Some devices may not boot up fast enough when battery check
is done as it currently is in adb.go. Therefore,
getBatteryLevel() is modified to take in a parameter to determine
the number of times to retry before giving up.

1 files changed, 15 insertions, 5 deletions

diff --git a/vm/adb/adb.go b/vm/adb/adb.go
index 49a29d418..4d5bacb6d 100644
--- a/vm/adb/adb.go
+++ b/vm/adb/adb.go
@@ -259,7 +259,7 @@ func (inst *instance) checkBatteryLevel() error {
 		minLevel      = 20
 		requiredLevel = 30
 	)
-	val, err := inst.getBatteryLevel()
+	val, err := inst.getBatteryLevel(3)
 	if err != nil {
 		return err
 	}
@@ -272,7 +272,7 @@ func (inst *instance) checkBatteryLevel() error {
 		if !vm.SleepInterruptible(time.Minute) {
 			return nil
 		}
-		val, err = inst.getBatteryLevel()
+		val, err = inst.getBatteryLevel(0)
 		if err != nil {
 			return err
 		}
@@ -283,10 +283,20 @@ func (inst *instance) checkBatteryLevel() error {
 	return nil
 }
 
-func (inst *instance) getBatteryLevel() (int, error) {
+func (inst *instance) getBatteryLevel(numRetry int) (int, error) {
 	out, err := inst.adb("shell", "dumpsys battery | grep level:")
-	if err != nil {
-		return 0, err
+
+	// allow for retrying for devices that does not boot up so fast
+	for ; numRetry >= 0 && err != nil; numRetry-- {
+		if numRetry > 0 {
+			// sleep for 5 seconds before retrying
+			time.Sleep(5 * time.Second)
+			out, err = inst.adb("shell", "dumpsys battery | grep level:")
+		} else {
+			if err != nil {
+				return 0, err
+			}
+		}
 	}
 	val := 0
 	for _, c := range out {