refactor(frontend); try ping backend for 2 minutes

fixes #1665

lib/Ravada/WebSocket.pm

@@ -267,7 +267,7 @@ sub _list_recent_requests($rvd, $seconds) {
 }
 
 sub _ping_backend($rvd, $args) {
-    my @reqs = _list_recent_requests($rvd, 20);
+    my @reqs = _list_recent_requests($rvd, 120);
 
     my $requested = scalar( grep { $_->{status} eq 'requested' } @reqs );
 

public/js/admin.js

@@ -311,7 +311,12 @@ ravadaApp.directive("solShowMachine", swMach)
           ws.onmessage = function(event) {
             var data = JSON.parse(event.data);
             $scope.$apply(function () {
-                        $scope.pingbe_fail = !data;
+                        var time1 = new Date() / 1000;
+                        if(time1 - time0 > 120 ) {
+                            $scope.pingbe_fail = !data;
+                        } else {
+                            $scope.pingbe_fail = false;
+                        }
             });
           }
       };
@@ -436,6 +441,8 @@ ravadaApp.directive("solShowMachine", swMach)
     $scope.new_name_duplicated=false;
     $scope.show_clones = { '0': false };
     $scope.show_machine = { '0': false };
+    $scope.pingbe_fail = false;
+    var time0 = new Date() / 1000;
   };
 
     function usersPageC($scope, $http, $interval, request) {

script/rvd_back

@@ -223,6 +223,7 @@ sub do_start {
 
     my $ravada = Ravada->new( %CONFIG );
     _do_start_logging();
+    $ravada->_clean_requests('ping_backend');
 
     #    Ravada::Request->enforce_limits();
     #Ravada::Request->refresh_vms();