HBASE-15412 Add average region size metric (Alicia Ying Shu)

Conflicts:
	hbase-hadoop2-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerSourceImpl.java
	hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperImpl.java
	hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperStub.java

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerSource.java

@@ -422,4 +422,7 @@ public interface MetricsRegionServerSource extends BaseSource {
   String RPC_MUTATE_REQUEST_COUNT = "rpcMutateRequestCount";
   String RPC_MUTATE_REQUEST_COUNT_DESC =
       "Number of rpc mutation requests this region server has answered.";
+  String AVERAGE_REGION_SIZE = "averageRegionSize";
+  String AVERAGE_REGION_SIZE_DESC = 
+      "Average region size over the region server including memstore and storefile sizes.";
 }

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapper.java

@@ -322,4 +322,9 @@ public interface MetricsRegionServerWrapper {
    * Get the number of rpc mutate requests to this region server.
    */
   long getRpcMutateRequestsCount();
+
+  /**
+   * Get the average region size to this region server.
+   */
+  long getAverageRegionSize();
 }

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerSourceImpl.java

@@ -328,6 +328,7 @@ public class MetricsRegionServerSourceImpl
               rsWrap.getNumReferenceFiles())
           .addGauge(Interns.info(RS_START_TIME_NAME, RS_START_TIME_DESC),
               rsWrap.getStartCode())
+          .addGauge(Interns.info(AVERAGE_REGION_SIZE, AVERAGE_REGION_SIZE_DESC), rsWrap.getAverageRegionSize())
           .addCounter(Interns.info(TOTAL_REQUEST_COUNT, TOTAL_REQUEST_COUNT_DESC),
               rsWrap.getTotalRequestCount())
           .addCounter(Interns.info(READ_REQUEST_COUNT, READ_REQUEST_COUNT_DESC),
@@ -412,7 +413,6 @@ public class MetricsRegionServerSourceImpl
               rsWrap.getCompactedCellsSize())
           .addCounter(Interns.info(MAJOR_COMPACTED_CELLS_SIZE, MAJOR_COMPACTED_CELLS_SIZE_DESC),
               rsWrap.getMajorCompactedCellsSize())
-
           .addCounter(Interns.info(BLOCKED_REQUESTS_COUNT, BLOCKED_REQUESTS_COUNT_DESC),
             rsWrap.getBlockedRequestsCount())
 

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperImpl.java

@@ -81,6 +81,7 @@ class MetricsRegionServerWrapperImpl
   private volatile long compactedCellsSize = 0;
   private volatile long majorCompactedCellsSize = 0;
   private volatile long blockedRequestsCount = 0L;
+  private volatile long averageRegionSize = 0L;
 
   private CacheStats cacheStats;
   private ScheduledExecutorService executor;
@@ -538,6 +539,7 @@ class MetricsRegionServerWrapperImpl
         long tempMajorCompactedCellsSize = 0;
         long tempBlockedRequestsCount = 0L;
 
+        int regionCount = 0;
         for (Region r : regionServer.getOnlineRegionsLocalContext()) {
           tempNumMutationsWithoutWAL += r.getNumMutationsWithoutWAL();
           tempDataInMemoryWithoutWAL += r.getDataInMemoryWithoutWAL();
@@ -582,6 +584,7 @@ class MetricsRegionServerWrapperImpl
           if (r.getRegionInfo().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
             hdfsBlocksDistributionSecondaryRegions.add(distro);
           }
+          regionCount++;
         }
 
         float localityIndex =
@@ -627,6 +630,9 @@ class MetricsRegionServerWrapperImpl
         memstoreSize = tempMemstoreSize;
         storeFileSize = tempStoreFileSize;
         maxStoreFileAge = tempMaxStoreFileAge;
+        if (regionCount > 0) {
+          averageRegionSize = (memstoreSize + storeFileSize) / regionCount;
+        }
         if (tempMinStoreFileAge != Long.MAX_VALUE) {
           minStoreFileAge = tempMinStoreFileAge;
         }
@@ -664,4 +670,10 @@ class MetricsRegionServerWrapperImpl
   public long getBlockedRequestsCount() {
     return blockedRequestsCount;
   }
+
+  @Override
+  public long getAverageRegionSize() {
+    return averageRegionSize;
+  }
+
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperStub.java

@@ -314,4 +314,9 @@ public class MetricsRegionServerWrapperStub implements MetricsRegionServerWrappe
   public int getSplitQueueSize() {
     return 0;
   }
+
+  @Override
+  public long getAverageRegionSize() {
+    return 10000000;
+  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestRegionServerMetrics.java

@@ -625,4 +625,25 @@ public class TestRegionServerMetrics {
 
     table.close();
   }
+
+  @Test
+  public void testAverageRegionSize() throws Exception {
+    TableName tableName = TableName.valueOf("testAverageRegionSize");
+    byte[] cf = Bytes.toBytes("d");
+    byte[] row = Bytes.toBytes("rk");
+    byte[] qualifier = Bytes.toBytes("qual");
+    byte[] val = Bytes.toBytes("Value");
+
+    //Force a hfile.
+    Table t = TEST_UTIL.createTable(tableName, cf);
+    Put p = new Put(row);
+    p.addColumn(cf, qualifier, val);
+    t.put(p);
+    TEST_UTIL.getHBaseAdmin().flush(tableName);
+
+    metricsRegionServer.getRegionServerWrapper().forceRecompute();
+    assertTrue(metricsHelper.getGaugeDouble("averageRegionSize", serverSource) > 0.0);
+
+    t.close();
+  }
 }