mwan3: remove pgrep usage

pgrep is pretty slow as it needs to read all /proc/*/cmdline
or /proc/*/status, and it's called twice per wan.
Add STARTED and PID files to speedup mwan3_get_mwan3track_status().

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

net/mwan3/files/lib/mwan3/common.sh

@@ -94,28 +94,40 @@ readfile() {
 
 mwan3_get_mwan3track_status()
 {
-	local track_ips pid
+	local interface=$1
+	local track_ips pid cmdline started
 	mwan3_list_track_ips()
 	{
 		track_ips="$1 $track_ips"
 	}
-	config_list_foreach "$1" track_ip mwan3_list_track_ips
+	config_list_foreach "$interface" track_ip mwan3_list_track_ips
 
-	if [ -n "$track_ips" ]; then
-		pid="$(pgrep -f "mwan3track $1$")"
-		if [ -n "$pid" ]; then
-			if [ "$(cat /proc/"$(pgrep -P $pid)"/cmdline)" = "sleep${MAX_SLEEP}" ]; then
-				tracking="paused"
-			else
-				tracking="active"
-			fi
-		else
-			tracking="down"
-		fi
-	else
-		tracking="disabled"
+	if [ -z "$track_ips" ]; then
+		echo "disabled"
+		return
 	fi
-	echo "$tracking"
+	readfile pid $MWAN3TRACK_STATUS_DIR/$interface/PID 2>/dev/null
+	if [ -z "$pid" ]; then
+		echo "down"
+		return
+	fi
+	readfile cmdline /proc/$pid/cmdline 2>/dev/null
+	if [ $cmdline != "/bin/sh/usr/sbin/mwan3track${interface}" ]; then
+		echo "down"
+		return
+	fi
+	readfile started $MWAN3TRACK_STATUS_DIR/$interface/STARTED
+	case "$started" in
+		0)
+			echo "paused"
+			;;
+		1)
+			echo "active"
+			;;
+		*)
+			echo "down"
+			;;
+	esac
 }
 
 mwan3_init()

net/mwan3/files/usr/sbin/mwan3track

@@ -36,7 +36,7 @@ if_up() {
 	LOG info "Detect ifup event on interface ${INTERFACE} (${DEVICE})"
 	IFDOWN_EVENT=0
 	IFUP_EVENT=1
-	STARTED=1
+	started
 	stop_subprocs
 }
 
@@ -164,7 +164,7 @@ connecting() {
 disabled() {
 	STATUS='disabled'
 	echo "disabled" > $MWAN3TRACK_STATUS_DIR/$INTERFACE/STATUS
-	STARTED=0
+	stopped
 }
 
 firstconnect() {
@@ -187,7 +187,7 @@ firstconnect() {
 
 	LOG debug "firstconnect: called on $INTERFACE/$true_iface ($DEVICE). Status is $STATUS. SRC_IP is $SRC_IP"
 
-	STARTED=1
+	started
 	if [ "$STATUS" = "offline" ]; then
 		disconnected 1
 	else
@@ -195,6 +195,16 @@ firstconnect() {
 	fi
 }
 
+stopped() {
+	STARTED=0
+	echo 0 > $MWAN3TRACK_STATUS_DIR/$INTERFACE/STARTED
+}
+
+started() {
+	STARTED=1
+	echo 1 > $MWAN3TRACK_STATUS_DIR/$INTERFACE/STARTED
+}
+
 update_status() {
 	local track_ip=$1
 
@@ -214,13 +224,13 @@ main() {
 
 	INTERFACE=$1
 	STATUS=""
-	STARTED=0
+	mkdir -p $MWAN3TRACK_STATUS_DIR/$INTERFACE
+	echo $$ > $MWAN3TRACK_STATUS_DIR/$INTERFACE/PID
+	stopped
 	TRACK_OUTPUT=$MWAN3TRACK_STATUS_DIR/$INTERFACE/TRACK_OUTPUT
 
 	mwan3_init
 
-	mkdir -p $MWAN3TRACK_STATUS_DIR/$INTERFACE
-
 	trap clean_up TERM
 	trap if_down USR1
 	trap if_up USR2