APIMeter update the included value on each click

This change update the internal value on each time click, after this
change the rate calculation will be done on the proxy at the price of
continuesly query the server. It is yet to be determine if this is a
problem, if so, it is possible to do and store those calculation on the
server and just pull them on demend.

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>

src/main/java/com/yammer/metrics/core/APIMeter.java

@@ -21,9 +21,25 @@ public class APIMeter extends Meter {
         url = _url;
     }
 
-    @Override
-    public long count() {
+    public long get_value() {
         return c.getLongValue(url);
     }
 
+    // Meter doesn't have a set value method.
+    // to mimic it, we clear the old value and set it to a new one.
+    // This is safe because the only this method would be used
+    // to update the values
+    public long set(long new_value) {
+        long res = super.count();
+        mark(-res);
+        mark(new_value);
+        return res;
+    }
+
+    @Override
+    void tick() {
+        set(get_value());
+        super.tick();
+    }
+
 }