Adding the APISettableMeter

Sometimes it is required that a meter will not handle its own data, like
the APIMeter does.

This patch break the added functionality of APIMeter into two classes,
APISettableMeter is a Meter with a set value method and APIMeter adds
the functionality that reads from the API.

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

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

@@ -10,7 +10,7 @@ import java.util.concurrent.TimeUnit;
 
 import com.cloudius.urchin.api.APIClient;
 
-public class APIMeter extends Meter {
+public class APIMeter extends APISettableMeter {
     String url;
     private APIClient c = new APIClient();
 
@@ -25,19 +25,8 @@ public class APIMeter extends Meter {
         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() {
+    public void tick() {
         set(get_value());
         super.tick();
     }

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

@@ -0,0 +1,49 @@
+package com.yammer.metrics.core;
+
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+/*
+ * Copyright 2015 ScyllaDB
+ *
+ */
+/*
+ * This file is part of Scylla.
+ *
+ * Scylla is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Scylla is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+public class APISettableMeter extends Meter {
+
+    public APISettableMeter(ScheduledExecutorService tickThread,
+            String eventType, TimeUnit rateUnit, Clock clock) {
+        super(tickThread, eventType, rateUnit, clock);
+    }
+
+    // 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
+    public void tick() {
+        super.tick();
+    }
+}