Adding the CompactionMetrics

The CompactionMetrics is used to report statistics about compaction. It
is based on calling the API that defined in compaction_manager.json

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

src/main/java/org/apache/cassandra/db/compaction/CompactionManager.java

@@ -19,11 +19,14 @@ package org.apache.cassandra.db.compaction;
 
 import java.lang.management.ManagementFactory;
 import java.util.*;
+
 import javax.management.MBeanServer;
 import javax.management.ObjectName;
 import javax.management.openmbean.TabularData;
 import javax.ws.rs.core.MultivaluedMap;
 
+import org.apache.cassandra.metrics.CompactionMetrics;
+
 import com.cloudius.urchin.api.APIClient;
 import com.sun.jersey.core.util.MultivaluedMapImpl;
 
@@ -46,6 +49,7 @@ public class CompactionManager implements CompactionManagerMBean {
             .getLogger(CompactionManager.class.getName());
     public static final CompactionManager instance;
     private APIClient c = new APIClient();
+    CompactionMetrics metrics = new CompactionMetrics();
 
     public void log(String str) {
         logger.info(str);

src/main/java/org/apache/cassandra/metrics/CompactionMetrics.java

@@ -0,0 +1,74 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Copyright 2015 Cloudius Systems
+ * 
+ * Modified by Cloudius Systems
+ */
+package org.apache.cassandra.metrics;
+
+import java.util.concurrent.TimeUnit;
+
+import com.cloudius.urchin.api.APIClient;
+import com.cloudius.urchin.metrics.APIMetrics;
+import com.cloudius.urchin.metrics.DefaultNameFactory;
+import com.cloudius.urchin.metrics.MetricNameFactory;
+import com.yammer.metrics.core.Counter;
+import com.yammer.metrics.core.Gauge;
+import com.yammer.metrics.core.Meter;
+
+/**
+ * Metrics for compaction.
+ */
+public class CompactionMetrics {
+    public static final MetricNameFactory factory = new DefaultNameFactory(
+            "Compaction");
+    private APIClient c = new APIClient();
+    /** Estimated number of compactions remaining to perform */
+    public final Gauge<Integer> pendingTasks;
+    /** Number of completed compactions since server [re]start */
+    public final Gauge<Long> completedTasks;
+    /** Total number of compactions since server [re]start */
+    public final Meter totalCompactionsCompleted;
+    /** Total number of bytes compacted since server [re]start */
+    public final Counter bytesCompacted;
+
+    public CompactionMetrics() {
+
+        pendingTasks = APIMetrics.newGauge(
+                factory.createMetricName("PendingTasks"), new Gauge<Integer>() {
+                    public Integer value() {
+                        return c.getIntValue("/compaction_manager/metrics/pending_tasks");
+                    }
+                });
+        completedTasks = APIMetrics.newGauge(
+                factory.createMetricName("CompletedTasks"), new Gauge<Long>() {
+                    public Long value() {
+                        return c.getLongValue("/compaction_manager/metrics/completed_tasks");
+                    }
+                });
+        totalCompactionsCompleted = APIMetrics.newMeter(
+                "/compaction_manager/metrics/total_compactions_completed",
+                factory.createMetricName("TotalCompactionsCompleted"),
+                "compaction completed", TimeUnit.SECONDS);
+        bytesCompacted = APIMetrics.newCounter(
+                "/compaction_manager/metrics/bytes_compacted",
+                factory.createMetricName("BytesCompacted"));
+    }
+}