HBASE-3900 Expose progress of a major compaction in UI and/or in shell

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1162296 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/hadoop/hbase/regionserver/compactions/CompactionProgress.java

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+/**
+ * Copyright 2011 The Apache Software Foundation
+ *
+ * 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.
+ */
+
+package org.apache.hadoop.hbase.regionserver.compactions;
+
+/**
+ * This class holds information relevant for tracking the progress of a
+ * compaction.
+ *
+ * <p>The metrics tracked allow one to calculate the percent completion of the
+ * compaction based on the number of Key/Value pairs already compacted vs.
+ * total amount scheduled to be compacted.
+ *
+ */
+public class CompactionProgress {
+
+  /** the total compacting key values in currently running compaction */
+  public long totalCompactingKVs;
+  /** the completed count of key values in currently running compaction */
+  public long currentCompactedKVs = 0;
+
+  /** Constructor
+   * @param totalCompactingKVs the total Key/Value pairs to be compacted
+   */
+  public CompactionProgress(long totalCompactingKVs) {
+    this.totalCompactingKVs = totalCompactingKVs;
+  }
+
+  /** getter for calculated percent complete
+   * @return float
+   */
+  public float getProgressPct() {
+    return currentCompactedKVs / totalCompactingKVs;
+  }
+
+}