Add retry_quiet() function to retry quietly for an event to occur

(cherry picked from commit 31264a7e00)

bin/tests/system/conf.sh.common

@@ -338,9 +338,9 @@ nextpartpeek() {
 	nextpartread $1 2> /dev/null
 }
 
-# retry: keep running a command until it succeeds, up to $1 times, with
-# one-second intervals
-retry() {
+# _retry: keep running a command until it succeeds, up to $1 times, with
+# one-second intervals, optionally printing a message upon every attempt
+_retry() {
 	__retries="${1}"
 	shift
 
@@ -350,7 +350,9 @@ retry() {
 		fi
 		__retries=$((__retries-1))
 		if [ "${__retries}" -gt 0 ]; then
-			echo_i "retrying"
+			if [ "${__retry_quiet}" -ne 1 ]; then
+				echo_i "retrying"
+			fi
 			sleep 1
 		else
 			return 1
@@ -358,6 +360,18 @@ retry() {
 	done
 }
 
+# retry: call _retry() in verbose mode
+retry() {
+	__retry_quiet=0
+	_retry "$@"
+}
+
+# retry_quiet: call _retry() in silent mode
+retry_quiet() {
+	__retry_quiet=1
+	_retry "$@"
+}
+
 rndc_reload() {
     echo_i "`$RNDC -c ../common/rndc.conf -s $2 -p ${CONTROLPORT} reload $3 2>&1 | sed 's/^/'$1' /'`"
     # reloading single zone is synchronous, if we're reloading whole server