/**
    * 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;
  
  import java.io.IOException;
  import java.util.Collection;
  import java.util.List;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.CompatibilitySingletonFactory;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HDFSBlocksDistribution;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.io.hfile.BlockCache;
  import org.apache.hadoop.hbase.io.hfile.CacheConfig;
  import org.apache.hadoop.hbase.io.hfile.CacheStats;
  import org.apache.hadoop.hbase.wal.BoundedRegionGroupingProvider;
  import org.apache.hadoop.hbase.wal.DefaultWALProvider;
  import org.apache.hadoop.hbase.mob.MobCacheConfig;
  import org.apache.hadoop.hbase.mob.MobFileCache;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.apache.hadoop.hdfs.DFSHedgedReadMetrics;
  import org.apache.hadoop.metrics2.MetricsExecutor;
  
  /**
   * Impl for exposing HRegionServer Information through Hadoop's metrics 2 system.
   */
  @InterfaceAudience.Private
  class MetricsRegionServerWrapperImpl
      implements MetricsRegionServerWrapper {
  
    private static final Log LOG = LogFactory.getLog(MetricsRegionServerWrapperImpl.class);
  
    private final HRegionServer regionServer;
  
    private BlockCache blockCache;
    private MobFileCache mobFileCache;
  
    private volatile long numStores = 0;
    private volatile long numWALFiles = 0;
    private volatile long walFileSize = 0;
    private volatile long numStoreFiles = 0;
    private volatile long memstoreSize = 0;
    private volatile long storeFileSize = 0;
    private volatile double requestsPerSecond = 0.0;
    private volatile long readRequestsCount = 0;
    private volatile long writeRequestsCount = 0;
    private volatile long checkAndMutateChecksFailed = 0;
    private volatile long checkAndMutateChecksPassed = 0;
    private volatile long storefileIndexSize = 0;
    private volatile long totalStaticIndexSize = 0;
    private volatile long totalStaticBloomSize = 0;
    private volatile long numMutationsWithoutWAL = 0;
    private volatile long dataInMemoryWithoutWAL = 0;
    private volatile double percentFileLocal = 0;
    private volatile double percentFileLocalSecondaryRegions = 0;
    private volatile long flushedCellsCount = 0;
    private volatile long compactedCellsCount = 0;
    private volatile long majorCompactedCellsCount = 0;
    private volatile long flushedCellsSize = 0;
    private volatile long compactedCellsSize = 0;
    private volatile long majorCompactedCellsSize = 0;
    private volatile long blockedRequestsCount = 0L;
    private volatile long mobCompactedIntoMobCellsCount = 0;
    private volatile long mobCompactedFromMobCellsCount = 0;
    private volatile long mobCompactedIntoMobCellsSize = 0;
    private volatile long mobCompactedFromMobCellsSize = 0;
    private volatile long mobFlushCount = 0;
    private volatile long mobFlushedCellsCount = 0;
    private volatile long mobFlushedCellsSize = 0;
    private volatile long mobScanCellsCount = 0;
    private volatile long mobScanCellsSize = 0;
    private volatile long mobFileCacheAccessCount = 0;
    private volatile long mobFileCacheMissCount = 0;
    private volatile double mobFileCacheHitRatio = 0;
    private volatile long mobFileCacheEvictedCount = 0;
   private volatile long mobFileCacheCount = 0;
 
   private CacheStats cacheStats;
   private ScheduledExecutorService executor;
   private Runnable runnable;
   private long period;
 
   /**
    * Can be null if not on hdfs.
    */
   private DFSHedgedReadMetrics dfsHedgedReadMetrics;
 
   public MetricsRegionServerWrapperImpl(final HRegionServer regionServer) {
     this.regionServer = regionServer;
     initBlockCache();
     initMobFileCache();
 
     this.period =
         regionServer.conf.getLong(HConstants.REGIONSERVER_METRICS_PERIOD,
           HConstants.DEFAULT_REGIONSERVER_METRICS_PERIOD);
 
     this.executor = CompatibilitySingletonFactory.getInstance(MetricsExecutor.class).getExecutor();
     this.runnable = new RegionServerMetricsWrapperRunnable();
     this.executor.scheduleWithFixedDelay(this.runnable, this.period, this.period,
       TimeUnit.MILLISECONDS);
 
     try {
       this.dfsHedgedReadMetrics = FSUtils.getDFSHedgedReadMetrics(regionServer.getConfiguration());
     } catch (IOException e) {
       LOG.warn("Failed to get hedged metrics", e);
     }
     if (LOG.isInfoEnabled()) {
       LOG.info("Computing regionserver metrics every " + this.period + " milliseconds");
     }
   }
 
   /**
    * It's possible that due to threading the block cache could not be initialized
    * yet (testing multiple region servers in one jvm).  So we need to try and initialize
    * the blockCache and cacheStats reference multiple times until we succeed.
    */
   private synchronized  void initBlockCache() {
     CacheConfig cacheConfig = this.regionServer.cacheConfig;
     if (cacheConfig != null && this.blockCache == null) {
       this.blockCache = cacheConfig.getBlockCache();
     }
 
     if (this.blockCache != null && this.cacheStats == null) {
       this.cacheStats = blockCache.getStats();
     }
   }
 
   /**
    * Initializes the mob file cache.
    */
   private synchronized void initMobFileCache() {
     MobCacheConfig mobCacheConfig = this.regionServer.mobCacheConfig;
     if (mobCacheConfig != null && this.mobFileCache == null) {
       this.mobFileCache = mobCacheConfig.getMobFileCache();
     }
   }
 
   @Override
   public String getClusterId() {
     return regionServer.getClusterId();
   }
 
   @Override
   public long getStartCode() {
     return regionServer.getStartcode();
   }
 
   @Override
   public String getZookeeperQuorum() {
     ZooKeeperWatcher zk = regionServer.getZooKeeper();
     if (zk == null) {
       return "";
     }
     return zk.getQuorum();
   }
 
   @Override
   public String getCoprocessors() {
     String[] coprocessors = regionServer.getRegionServerCoprocessors();
     if (coprocessors == null || coprocessors.length == 0) {
       return "";
     }
     return StringUtils.join(coprocessors, ", ");
   }
 
   @Override
   public String getServerName() {
     ServerName serverName = regionServer.getServerName();
     if (serverName == null) {
       return "";
     }
     return serverName.getServerName();
   }
 
   @Override
   public long getNumOnlineRegions() {
     Collection<Region> onlineRegionsLocalContext = regionServer.getOnlineRegionsLocalContext();
     if (onlineRegionsLocalContext == null) {
       return 0;
     }
     return onlineRegionsLocalContext.size();
   }
 
   @Override
   public long getTotalRequestCount() {
     return regionServer.rpcServices.requestCount.get();
   }
 
   @Override
   public int getSplitQueueSize() {
     if (this.regionServer.compactSplitThread == null) {
       return 0;
     }
     return this.regionServer.compactSplitThread.getSplitQueueSize();
   }
 
   @Override
   public int getCompactionQueueSize() {
     //The thread could be zero.  if so assume there is no queue.
     if (this.regionServer.compactSplitThread == null) {
       return 0;
     }
     return this.regionServer.compactSplitThread.getCompactionQueueSize();
   }
 
   @Override
   public int getSmallCompactionQueueSize() {
     //The thread could be zero.  if so assume there is no queue.
     if (this.regionServer.compactSplitThread == null) {
       return 0;
     }
     return this.regionServer.compactSplitThread.getSmallCompactionQueueSize();
   }
 
   @Override
   public int getLargeCompactionQueueSize() {
     //The thread could be zero.  if so assume there is no queue.
     if (this.regionServer.compactSplitThread == null) {
       return 0;
     }
     return this.regionServer.compactSplitThread.getLargeCompactionQueueSize();
   }
 
   @Override
   public int getFlushQueueSize() {
     //If there is no flusher there should be no queue.
     if (this.regionServer.cacheFlusher == null) {
       return 0;
     }
     return this.regionServer.cacheFlusher.getFlushQueueSize();
   }
 
   @Override
   public long getBlockCacheCount() {
     if (this.blockCache == null) {
       return 0;
     }
     return this.blockCache.getBlockCount();
   }
 
   @Override
   public long getBlockCacheSize() {
     if (this.blockCache == null) {
       return 0;
     }
     return this.blockCache.getCurrentSize();
   }
 
   @Override
   public long getBlockCacheFreeSize() {
     if (this.blockCache == null) {
       return 0;
     }
     return this.blockCache.getFreeSize();
   }
 
   @Override
   public long getBlockCacheHitCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getHitCount();
   }
 
   @Override
   public long getBlockCachePrimaryHitCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getPrimaryHitCount();
   }
 
   @Override
   public long getBlockCacheMissCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getMissCount();
   }
 
   @Override
   public long getBlockCachePrimaryMissCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getPrimaryMissCount();
   }
 
   @Override
   public long getBlockCacheEvictedCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getEvictedCount();
   }
 
   @Override
   public long getBlockCachePrimaryEvictedCount() {
     if (this.cacheStats == null) {
       return 0;
     }
     return this.cacheStats.getPrimaryEvictedCount();
   }
 
   @Override
   public double getBlockCacheHitPercent() {
     if (this.cacheStats == null) {
       return 0;
     }
     double ratio = this.cacheStats.getHitRatio();
     if (Double.isNaN(ratio)) {
       ratio = 0;
     }
     return (ratio * 100);
   }
 
   @Override
   public int getBlockHitPercent() {
     if (this.cacheStats == null) {
       return 0;
     }
     return (int) (this.cacheStats.getHitRatio() * 100);
   }
 
   @Override
   public double getBlockCacheHitCachingPercent() {
     if (this.cacheStats == null) {
       return 0;
     }
 
     double ratio = this.cacheStats.getHitCachingRatio();
 
     if (Double.isNaN(ratio)) {
       ratio = 0;
     }
     return (ratio * 100);
   }
 
   @Override
   public long getBlockCacheFailedInsertions() {
     return this.cacheStats.getFailedInserts();
   }
 
   @Override public void forceRecompute() {
     this.runnable.run();
   }
 
   @Override
   public long getNumStores() {
     return numStores;
   }
   
   @Override
   public long getNumWALFiles() {
     return numWALFiles;
   }
 
   @Override
   public long getWALFileSize() {
     return walFileSize;
   }
   
   @Override
   public long getNumStoreFiles() {
     return numStoreFiles;
   }
 
   @Override
   public long getMemstoreSize() {
     return memstoreSize;
   }
 
   @Override
   public long getStoreFileSize() {
     return storeFileSize;
   }
 
   @Override public double getRequestsPerSecond() {
     return requestsPerSecond;
   }
 
   @Override
   public long getReadRequestsCount() {
     return readRequestsCount;
   }
 
   @Override
   public long getWriteRequestsCount() {
     return writeRequestsCount;
   }
 
   @Override
   public long getCheckAndMutateChecksFailed() {
     return checkAndMutateChecksFailed;
   }
 
   @Override
   public long getCheckAndMutateChecksPassed() {
     return checkAndMutateChecksPassed;
   }
 
   @Override
   public long getStoreFileIndexSize() {
     return storefileIndexSize;
   }
 
   @Override
   public long getTotalStaticIndexSize() {
     return totalStaticIndexSize;
   }
 
   @Override
   public long getTotalStaticBloomSize() {
     return totalStaticBloomSize;
   }
 
   @Override
   public long getNumMutationsWithoutWAL() {
     return numMutationsWithoutWAL;
   }
 
   @Override
   public long getDataInMemoryWithoutWAL() {
     return dataInMemoryWithoutWAL;
   }
 
   @Override
   public double getPercentFileLocal() {
     return percentFileLocal;
   }
 
   @Override
   public double getPercentFileLocalSecondaryRegions() {
     return percentFileLocalSecondaryRegions;
   }
 
   @Override
   public long getUpdatesBlockedTime() {
     if (this.regionServer.cacheFlusher == null) {
       return 0;
     }
     return this.regionServer.cacheFlusher.getUpdatesBlockedMsHighWater().get();
   }
 
   @Override
   public long getFlushedCellsCount() {
     return flushedCellsCount;
   }
 
   @Override
   public long getCompactedCellsCount() {
     return compactedCellsCount;
   }
 
   @Override
   public long getMajorCompactedCellsCount() {
     return majorCompactedCellsCount;
   }
 
   @Override
   public long getFlushedCellsSize() {
     return flushedCellsSize;
   }
 
   @Override
   public long getCompactedCellsSize() {
     return compactedCellsSize;
   }
 
   @Override
   public long getMajorCompactedCellsSize() {
     return majorCompactedCellsSize;
   }
 
   @Override
   public long getMobCompactedFromMobCellsCount() {
     return mobCompactedFromMobCellsCount;
   }
 
   @Override
   public long getMobCompactedIntoMobCellsCount() {
     return mobCompactedIntoMobCellsCount;
   }
 
   @Override
   public long getMobCompactedFromMobCellsSize() {
     return mobCompactedFromMobCellsSize;
   }
 
   @Override
   public long getMobCompactedIntoMobCellsSize() {
     return mobCompactedIntoMobCellsSize;
   }
 
   @Override
   public long getMobFlushCount() {
     return mobFlushCount;
   }
 
   @Override
   public long getMobFlushedCellsCount() {
     return mobFlushedCellsCount;
   }
 
   @Override
   public long getMobFlushedCellsSize() {
     return mobFlushedCellsSize;
   }
 
   @Override
   public long getMobScanCellsCount() {
     return mobScanCellsCount;
   }
 
   @Override
   public long getMobScanCellsSize() {
     return mobScanCellsSize;
   }
 
   @Override
   public long getMobFileCacheAccessCount() {
     return mobFileCacheAccessCount;
   }
 
   @Override
   public long getMobFileCacheMissCount() {
     return mobFileCacheMissCount;
   }
 
   @Override
   public long getMobFileCacheCount() {
     return mobFileCacheCount;
   }
 
   @Override
   public long getMobFileCacheEvictedCount() {
     return mobFileCacheEvictedCount;
   }
 
   @Override
   public int getMobFileCacheHitPercent() {
     return (int) (mobFileCacheHitRatio * 100);
   }
 
   /**
    * This is the runnable that will be executed on the executor every PERIOD number of seconds
    * It will take metrics/numbers from all of the regions and use them to compute point in
    * time metrics.
    */
   public class RegionServerMetricsWrapperRunnable implements Runnable {
 
     private long lastRan = 0;
     private long lastRequestCount = 0;
 
     @Override
     synchronized public void run() {
       try {
         initBlockCache();
         initMobFileCache();
         cacheStats = blockCache.getStats();
 
         HDFSBlocksDistribution hdfsBlocksDistribution = new HDFSBlocksDistribution();
         HDFSBlocksDistribution hdfsBlocksDistributionSecondaryRegions =
             new HDFSBlocksDistribution();
 
         long tempNumStores = 0;
         long tempNumStoreFiles = 0;
         long tempMemstoreSize = 0;
         long tempStoreFileSize = 0;
         long tempReadRequestsCount = 0;
         long tempWriteRequestsCount = 0;
         long tempCheckAndMutateChecksFailed = 0;
         long tempCheckAndMutateChecksPassed = 0;
         long tempStorefileIndexSize = 0;
         long tempTotalStaticIndexSize = 0;
         long tempTotalStaticBloomSize = 0;
         long tempNumMutationsWithoutWAL = 0;
         long tempDataInMemoryWithoutWAL = 0;
         double tempPercentFileLocal = 0;
         double tempPercentFileLocalSecondaryRegions = 0;
         long tempFlushedCellsCount = 0;
         long tempCompactedCellsCount = 0;
         long tempMajorCompactedCellsCount = 0;
         long tempFlushedCellsSize = 0;
         long tempCompactedCellsSize = 0;
         long tempMajorCompactedCellsSize = 0;
         long tempBlockedRequestsCount = 0L;
         long tempMobCompactedIntoMobCellsCount = 0;
 	long tempMobCompactedFromMobCellsCount = 0;
 	long tempMobCompactedIntoMobCellsSize = 0;
 	long tempMobCompactedFromMobCellsSize = 0;
 	long tempMobFlushCount = 0;
 	long tempMobFlushedCellsCount = 0;
 	long tempMobFlushedCellsSize = 0;
 	long tempMobScanCellsCount = 0;
 	long tempMobScanCellsSize = 0;
 
         for (Region r : regionServer.getOnlineRegionsLocalContext()) {
           tempNumMutationsWithoutWAL += r.getNumMutationsWithoutWAL();
           tempDataInMemoryWithoutWAL += r.getDataInMemoryWithoutWAL();
           tempReadRequestsCount += r.getReadRequestsCount();
           tempWriteRequestsCount += r.getWriteRequestsCount();
           tempCheckAndMutateChecksFailed += r.getCheckAndMutateChecksFailed();
           tempCheckAndMutateChecksPassed += r.getCheckAndMutateChecksPassed();
           tempBlockedRequestsCount += r.getBlockedRequestsCount();
           List<Store> storeList = r.getStores();
           tempNumStores += storeList.size();
           for (Store store : storeList) {
             tempNumStoreFiles += store.getStorefilesCount();
             tempMemstoreSize += store.getMemStoreSize();
             tempStoreFileSize += store.getStorefilesSize();
             tempStorefileIndexSize += store.getStorefilesIndexSize();
             tempTotalStaticBloomSize += store.getTotalStaticBloomSize();
             tempTotalStaticIndexSize += store.getTotalStaticIndexSize();
             tempFlushedCellsCount += store.getFlushedCellsCount();
             tempCompactedCellsCount += store.getCompactedCellsCount();
             tempMajorCompactedCellsCount += store.getMajorCompactedCellsCount();
             tempFlushedCellsSize += store.getFlushedCellsSize();
             tempCompactedCellsSize += store.getCompactedCellsSize();
             tempMajorCompactedCellsSize += store.getMajorCompactedCellsSize();
             if (store instanceof HMobStore) {
               HMobStore mobStore = (HMobStore) store;
               tempMobCompactedIntoMobCellsCount += mobStore.getMobCompactedIntoMobCellsCount();
               tempMobCompactedFromMobCellsCount += mobStore.getMobCompactedFromMobCellsCount();
               tempMobCompactedIntoMobCellsSize += mobStore.getMobCompactedIntoMobCellsSize();
               tempMobCompactedFromMobCellsSize += mobStore.getMobCompactedFromMobCellsSize();
               tempMobFlushCount += mobStore.getMobFlushCount();
               tempMobFlushedCellsCount += mobStore.getMobFlushedCellsCount();
               tempMobFlushedCellsSize += mobStore.getMobFlushedCellsSize();
               tempMobScanCellsCount += mobStore.getMobScanCellsCount();
               tempMobScanCellsSize += mobStore.getMobScanCellsSize();
             }
           }
 
           HDFSBlocksDistribution distro = r.getHDFSBlocksDistribution();
           hdfsBlocksDistribution.add(distro);
           if (r.getRegionInfo().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
             hdfsBlocksDistributionSecondaryRegions.add(distro);
           }
         }
 
         float localityIndex =
             hdfsBlocksDistribution
                 .getBlockLocalityIndex(regionServer.getServerName().getHostname());
         tempPercentFileLocal = Double.isNaN(tempBlockedRequestsCount) ? 0 : (localityIndex * 100);
 
         float localityIndexSecondaryRegions =
             hdfsBlocksDistributionSecondaryRegions.getBlockLocalityIndex(regionServer
                 .getServerName().getHostname());
         tempPercentFileLocalSecondaryRegions = Double
             .isNaN(localityIndexSecondaryRegions) ? 0 : (localityIndexSecondaryRegions * 100);
 
         // Compute the number of requests per second
         long currentTime = EnvironmentEdgeManager.currentTime();
 
         // assume that it took PERIOD seconds to start the executor.
         // this is a guess but it's a pretty good one.
         if (lastRan == 0) {
           lastRan = currentTime - period;
         }
 
         // If we've time traveled keep the last requests per second.
         if ((currentTime - lastRan) > 0) {
           long currentRequestCount = getTotalRequestCount();
           requestsPerSecond =
               (currentRequestCount - lastRequestCount) / ((currentTime - lastRan) / 1000.0);
           lastRequestCount = currentRequestCount;
         }
         lastRan = currentTime;
 
         numWALFiles =
             DefaultWALProvider.getNumLogFiles(regionServer.walFactory)
                 + BoundedRegionGroupingProvider.getNumLogFiles(regionServer.walFactory);
         walFileSize =
             DefaultWALProvider.getLogFileSize(regionServer.walFactory)
                 + BoundedRegionGroupingProvider.getLogFileSize(regionServer.walFactory);
         // Copy over computed values so that no thread sees half computed values.
         numStores = tempNumStores;
         numStoreFiles = tempNumStoreFiles;
         memstoreSize = tempMemstoreSize;
         storeFileSize = tempStoreFileSize;
         readRequestsCount = tempReadRequestsCount;
         writeRequestsCount = tempWriteRequestsCount;
         checkAndMutateChecksFailed = tempCheckAndMutateChecksFailed;
         checkAndMutateChecksPassed = tempCheckAndMutateChecksPassed;
         storefileIndexSize = tempStorefileIndexSize;
         totalStaticIndexSize = tempTotalStaticIndexSize;
         totalStaticBloomSize = tempTotalStaticBloomSize;
         numMutationsWithoutWAL = tempNumMutationsWithoutWAL;
         dataInMemoryWithoutWAL = tempDataInMemoryWithoutWAL;
         percentFileLocal = tempPercentFileLocal;
         percentFileLocalSecondaryRegions = tempPercentFileLocalSecondaryRegions;
         flushedCellsCount = tempFlushedCellsCount;
         compactedCellsCount = tempCompactedCellsCount;
         majorCompactedCellsCount = tempMajorCompactedCellsCount;
         flushedCellsSize = tempFlushedCellsSize;
         compactedCellsSize = tempCompactedCellsSize;
         majorCompactedCellsSize = tempMajorCompactedCellsSize;
         blockedRequestsCount = tempBlockedRequestsCount;
         mobCompactedIntoMobCellsCount = tempMobCompactedIntoMobCellsCount;
         mobCompactedFromMobCellsCount = tempMobCompactedFromMobCellsCount;
         mobCompactedIntoMobCellsSize = tempMobCompactedIntoMobCellsSize;
         mobCompactedFromMobCellsSize = tempMobCompactedFromMobCellsSize;
         mobFlushCount = tempMobFlushCount;
         mobFlushedCellsCount = tempMobFlushedCellsCount;
         mobFlushedCellsSize = tempMobFlushedCellsSize;
         mobScanCellsCount = tempMobScanCellsCount;
         mobScanCellsSize = tempMobScanCellsSize;
         mobFileCacheAccessCount = mobFileCache.getAccessCount();
         mobFileCacheMissCount = mobFileCache.getMissCount();
         mobFileCacheHitRatio = mobFileCache.getHitRatio();
         mobFileCacheEvictedCount = mobFileCache.getEvictedFileCount();
         mobFileCacheCount = mobFileCache.getCacheSize();
       } catch (Throwable e) {
         LOG.warn("Caught exception! Will suppress and retry.", e);
       }
     }
   }
 
   @Override
   public long getBlockedRequestsCount() {
     return blockedRequestsCount;
   }
 
   @Override
   public long getHedgedReadOps() {
     return this.dfsHedgedReadMetrics == null? 0: this.dfsHedgedReadMetrics.getHedgedReadOps();
   }
 
   @Override
   public long getHedgedReadWins() {
     return this.dfsHedgedReadMetrics == null? 0: this.dfsHedgedReadMetrics.getHedgedReadWins();
   }
 }