Merge pull request 'df-lockedsettings-patch' (#18) from df/webif:df-lockedsettings-patch into master

Reviewed-on: #18

webif/lib/settings.class

@@ -54,6 +54,28 @@ class settings {
 	rtschedule	0
 }
 
+proc {settings _safer_query} { queryText args } {
+	global settingsdb
+
+	# allow 4 tries from 0.5s delay, doubling, to get access
+	for {set lockCnt 4; set delay 0.5} {true} {sleep $delay; set delay $(2*$delay)} {
+		try {
+			return [$settingsdb query $queryText {*}$args]
+		} on error {msg opts} {
+			if {[string first "database is locked" $msg] >= 0} {
+				if {[incr lockCnt -1] > 0} {
+					continue
+				} else {
+					# raise error from caller
+					set msg "Persistently unable to access Settings: database locked"
+					incr opts(-level)
+				}
+			}
+			return {*}$opts $msg
+		}
+	}
+}
+
 settings method hostname {{name ""}} {
 	if {$name == ""} {
 		# Get
@@ -104,11 +126,10 @@ settings method smtp_server {{server ""}} {
 }
 
 settings method _nval_setting {name {val -1}} {
-	global settingsdb
 
 	if {$val == -1} {
 		# Get
-		set res [$settingsdb query "
+		set res [settings _safer_query "
 			select nval from settings
 			where name = '$name'
 		"]
@@ -118,7 +139,7 @@ settings method _nval_setting {name {val -1}} {
 		return 0
 	} else {
 		# Set
-		$settingsdb query "
+		settings _safer_query "
 			replace into settings(name,nval)
 			values('$name', $val)
 		"
@@ -127,11 +148,10 @@ settings method _nval_setting {name {val -1}} {
 }
 
 settings method _tval_setting {name {val -1} {def 0}} {
-	global settingsdb
 
 	if {$val eq "-1"} {
 		# Get
-		set res [$settingsdb query "
+		set res [settings _safer_query "
 			select tval from settings
 			where name = '$name'
 		"]
@@ -141,7 +161,7 @@ settings method _tval_setting {name {val -1} {def 0}} {
 		return $def
 	} else {
 		# Set
-		$settingsdb query "
+		settings _safer_query "
 			replace into settings(name,tval)
 			values('$name', '%s')
 		" $val