Implement the ping method using webread instead of urlread

The webread function gives much higher ping results, but urlread is deprecated.

Author: Enric Sala

README.md

@@ -35,7 +35,7 @@ PASS = 'password';
 DATABASE = 'server_stats';
 influxdb = InfluxDB(HOST, USER, PASS, DATABASE);
 
-% Check if the InfluxDB server is running
+% Check the status of the InfluxDB instance
 [ok, ping] = influxdb.ping()
 
 % Show the databases in the server

influxdb-client/InfluxDB.m

@@ -28,13 +28,17 @@
             obj.WriteTimeout = timeout;
         end
 
-        % Test the connection with a ping
+        % Check the status of the InfluxDB instance
         function [ok, millis] = ping(obj)
-            timer = tic;
-            url = [obj.Host '/ping'];
-            [~, status] = urlread(url);
-            millis = toc(timer) * 1000;
-            ok = logical(status);
+            try
+                timer = tic;
+                webread([obj.Host '/ping']);
+                millis = toc(timer) * 1000;
+                ok = true;
+            catch
+                millis = Inf;
+                ok = false;
+            end
         end
 
         % Show databases