HBASE-18624 Added support for clearing BlockCache based on tablename

Signed-off-by: Chia-Ping Tsai <chia7712@gmail.com>

hbase-client/src/main/java/org/apache/hadoop/hbase/CacheEvictionStats.java

@@ -0,0 +1,54 @@
+/**
+ *
+ * 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;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+
+@InterfaceAudience.Public
+public final class CacheEvictionStats {
+
+  private final long evictedBlocks;
+  private final long maxCacheSize;
+
+  CacheEvictionStats(CacheEvictionStatsBuilder builder) {
+    this.evictedBlocks = builder.evictedBlocks;
+    this.maxCacheSize = builder.maxCacheSize;
+  }
+
+  public long getEvictedBlocks() {
+    return evictedBlocks;
+  }
+
+  public long getMaxCacheSize() {
+    return maxCacheSize;
+  }
+
+  @InterfaceAudience.Private
+  public static CacheEvictionStatsBuilder builder() {
+    return new CacheEvictionStatsBuilder();
+  }
+
+  @Override
+  public String toString() {
+    return "CacheEvictionStats{" +
+        "evictedBlocks=" + evictedBlocks +
+        ", maxCacheSize=" + maxCacheSize +
+        '}';
+  }
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/CacheEvictionStatsBuilder.java

@@ -0,0 +1,50 @@
+/**
+ *
+ * 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;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+
+@InterfaceAudience.Private
+public final class CacheEvictionStatsBuilder {
+  long evictedBlocks = 0;
+  long maxCacheSize = 0;
+
+  CacheEvictionStatsBuilder() {
+  }
+
+  public CacheEvictionStatsBuilder withEvictedBlocks(long evictedBlocks) {
+    this.evictedBlocks = evictedBlocks;
+    return this;
+  }
+
+  public CacheEvictionStatsBuilder withMaxCacheSize(long maxCacheSize) {
+    this.maxCacheSize = maxCacheSize;
+    return this;
+  }
+
+  public CacheEvictionStatsBuilder append(CacheEvictionStats stats) {
+    this.evictedBlocks += stats.getEvictedBlocks();
+    this.maxCacheSize += stats.getMaxCacheSize();
+    return this;
+  }
+
+  public CacheEvictionStats build() {
+    return new CacheEvictionStats(this);
+  }
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java

@@ -31,6 +31,7 @@ import java.util.regex.Pattern;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Abortable;
+import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.ClusterStatus;
 import org.apache.hadoop.hbase.ClusterStatus.Option;
 import org.apache.hadoop.hbase.HRegionInfo;
@@ -1047,6 +1048,18 @@ public interface Admin extends Abortable, Closeable {
    */
   boolean isBalancerEnabled() throws IOException;
 
+  /**
+   * Clear all the blocks corresponding to this table from BlockCache. For expert-admins.
+   * Calling this API will drop all the cached blocks specific to a table from BlockCache.
+   * This can significantly impact the query performance as the subsequent queries will
+   * have to retrieve the blocks from underlying filesystem.
+   *
+   * @param tableName table to clear block cache
+   * @return CacheEvictionStats related to the eviction
+   * @throws IOException if a remote or network exception occurs
+   */
+  CacheEvictionStats clearBlockCache(final TableName tableName) throws IOException;
+
   /**
    * Invoke region normalizer. Can NOT run for various reasons.  Check logs.
    *

hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java

@@ -46,6 +46,8 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Abortable;
+import org.apache.hadoop.hbase.CacheEvictionStats;
+import org.apache.hadoop.hbase.CacheEvictionStatsBuilder;
 import org.apache.hadoop.hbase.ClusterStatus;
 import org.apache.hadoop.hbase.ClusterStatus.Option;
 import org.apache.hadoop.hbase.CompoundConfiguration;
@@ -111,6 +113,7 @@ import org.apache.hadoop.hbase.shaded.protobuf.RequestConverter;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.AdminService;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CompactRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.FlushRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetRegionInfoRequest;
@@ -1475,6 +1478,51 @@ public class HBaseAdmin implements Admin {
     });
   }
 
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public CacheEvictionStats clearBlockCache(final TableName tableName) throws IOException {
+    checkTableExists(tableName);
+    CacheEvictionStatsBuilder cacheEvictionStats = CacheEvictionStats.builder();
+    List<Pair<RegionInfo, ServerName>> pairs =
+      MetaTableAccessor.getTableRegionsAndLocations(connection, tableName);
+    for (Pair<RegionInfo, ServerName> pair: pairs) {
+      if (pair.getFirst().isOffline() || pair.getSecond() == null) {
+        continue;
+      }
+      try {
+        cacheEvictionStats = cacheEvictionStats.append(
+            clearBlockCache(pair.getSecond(), pair.getFirst()));
+      } catch (NotServingRegionException e) {
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Failed to clear block cache for " + pair.getFirst() + " on " +
+              pair.getSecond() + ": " + StringUtils.stringifyException(e));
+        }
+      }
+    }
+    return cacheEvictionStats.build();
+  }
+
+  private CacheEvictionStats clearBlockCache(final ServerName sn, final RegionInfo hri)
+      throws IOException {
+    HBaseRpcController controller = rpcControllerFactory.newController();
+    AdminService.BlockingInterface admin = this.connection.getAdmin(sn);
+    ClearRegionBlockCacheRequest request =
+      RequestConverter.buildClearRegionBlockCacheRequest(hri.getRegionName());
+    try {
+      return ProtobufUtil.toCacheEvictionStats(
+          admin.clearRegionBlockCache(controller, request).getStats());
+    } catch (ServiceException se) {
+      throw ProtobufUtil.getRemoteException(se);
+    }
+  }
+
+  /**
+   * Invoke region normalizer. Can NOT run for various reasons.  Check logs.
+   *
+   * @return True if region normalizer ran, false otherwise.
+   */
   @Override
   public boolean normalize() throws IOException {
     return executeCallable(new MasterCallable<Boolean>(getConnection(), getRpcControllerFactory()) {

hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java

@@ -30,6 +30,7 @@ import java.util.NavigableSet;
 import java.util.function.Function;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.CellScanner;

hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java

@@ -41,6 +41,7 @@ import java.util.stream.Collectors;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.ByteBufferCell;
+import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.CellScanner;
@@ -3385,4 +3386,18 @@ public final class ProtobufUtil {
         .filter(snap -> pattern != null ? pattern.matcher(snap.getName()).matches() : true)
         .collect(Collectors.toList());
   }
+
+  public static CacheEvictionStats toCacheEvictionStats(HBaseProtos.CacheEvictionStats cacheEvictionStats) {
+    return CacheEvictionStats.builder()
+        .withEvictedBlocks(cacheEvictionStats.getEvictedBlocks())
+        .withMaxCacheSize(cacheEvictionStats.getMaxCacheSize())
+        .build();
+  }
+
+  public static HBaseProtos.CacheEvictionStats toCacheEvictionStats(CacheEvictionStats cacheEvictionStats) {
+    return HBaseProtos.CacheEvictionStats.newBuilder()
+        .setEvictedBlocks(cacheEvictionStats.getEvictedBlocks())
+        .setMaxCacheSize(cacheEvictionStats.getMaxCacheSize())
+        .build();
+  }
 }

hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java

@@ -52,6 +52,7 @@ import org.apache.hadoop.hbase.client.replication.ReplicationSerDeHelper;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
 import org.apache.hadoop.hbase.filter.ByteArrayComparable;
 import org.apache.hadoop.hbase.replication.ReplicationPeerConfig;
+import org.apache.hadoop.hbase.shaded.com.google.common.collect.Lists;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.Pair;
@@ -60,6 +61,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hadoop.hbase.shaded.com.google.protobuf.UnsafeByteOperations;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CompactRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.FlushRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetOnlineRegionRequest;
@@ -1422,6 +1424,17 @@ public final class RequestConverter {
     return IsBalancerEnabledRequest.newBuilder().build();
   }
 
+  /**
+   * Creates a protocol buffer ClearRegionBlockCacheRequest
+   *
+   * @return a ClearRegionBlockCacheRequest
+   */
+  public static ClearRegionBlockCacheRequest buildClearRegionBlockCacheRequest(final byte[]
+                                                                                 regionName) {
+    RegionSpecifier region = buildRegionSpecifier(RegionSpecifierType.REGION_NAME, regionName);
+    return ClearRegionBlockCacheRequest.newBuilder().addAllRegion(Lists.newArrayList(region)).build();
+  }
+
   /**
    * Creates a protocol buffer GetClusterStatusRequest
    *

hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ResponseConverter.java

@@ -33,6 +33,7 @@ import org.apache.hadoop.hbase.client.RegionInfo;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.client.SingleResponse;
 import org.apache.hadoop.hbase.ipc.ServerRpcController;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 
@@ -435,4 +436,14 @@ public final class ResponseConverter {
 
     return metricMap;
   }
+
+  /**
+   * Creates a protocol buffer ClearRegionBlockCacheResponse
+   *
+   * @return a ClearRegionBlockCacheResponse
+   */
+  public static AdminProtos.ClearRegionBlockCacheResponse buildClearRegionBlockCacheResponse(final HBaseProtos.CacheEvictionStats
+                                                                                   cacheEvictionStats) {
+    return AdminProtos.ClearRegionBlockCacheResponse.newBuilder().setStats(cacheEvictionStats).build();
+  }
 }

hbase-protocol-shaded/src/main/protobuf/Admin.proto

@@ -248,6 +248,14 @@ message ClearCompactionQueuesRequest {
 message ClearCompactionQueuesResponse {
 }
 
+message ClearRegionBlockCacheRequest {
+  repeated RegionSpecifier region = 1;
+}
+
+message ClearRegionBlockCacheResponse {
+  required CacheEvictionStats stats = 1;
+}
+
 message ExecuteProceduresRequest {
   repeated OpenRegionRequest open_region = 1;
   repeated CloseRegionRequest close_region = 2;
@@ -310,6 +318,9 @@ service AdminService {
   rpc ClearCompactionQueues(ClearCompactionQueuesRequest)
     returns(ClearCompactionQueuesResponse);
 
+  rpc ClearRegionBlockCache(ClearRegionBlockCacheRequest)
+    returns(ClearRegionBlockCacheResponse);
+
   /** Fetches the RegionServer's view of space quotas */
   rpc GetSpaceQuotaSnapshots(GetSpaceQuotaSnapshotsRequest)
     returns(GetSpaceQuotaSnapshotsResponse);

hbase-protocol-shaded/src/main/protobuf/HBase.proto

@@ -241,3 +241,9 @@ message RegionServerInfo {
   optional int32 infoPort = 1;
   optional VersionInfo version_info = 2;
 }
+
+message CacheEvictionStats {
+  optional int64 evicted_blocks = 1;
+  optional int64 bytes_evicted = 2;
+  optional int64 max_cache_size = 3;
+}

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

@@ -59,6 +59,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.Abortable;
+import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.ChoreService;
 import org.apache.hadoop.hbase.ClockOutOfSyncException;
 import org.apache.hadoop.hbase.CoordinatedStateManager;
@@ -99,6 +100,7 @@ import org.apache.hadoop.hbase.executor.ExecutorService;
 import org.apache.hadoop.hbase.executor.ExecutorType;
 import org.apache.hadoop.hbase.fs.HFileSystem;
 import org.apache.hadoop.hbase.http.InfoServer;
+import org.apache.hadoop.hbase.io.hfile.BlockCache;
 import org.apache.hadoop.hbase.io.hfile.CacheConfig;
 import org.apache.hadoop.hbase.io.hfile.HFile;
 import org.apache.hadoop.hbase.io.util.MemorySizeUtil;
@@ -3269,7 +3271,7 @@ public class HRegionServer extends HasThread implements
   }
 
   /**
-   * Protected utility method for safely obtaining an HRegion handle.
+   * Protected Utility method for safely obtaining an HRegion handle.
    *
    * @param regionName
    *          Name of online {@link HRegion} to return
@@ -3613,6 +3615,22 @@ public class HRegionServer extends HasThread implements
     configurationManager.notifyAllObservers(conf);
   }
 
+  public CacheEvictionStats clearRegionBlockCache(Region region) {
+    BlockCache blockCache = this.getCacheConfig().getBlockCache();
+    long evictedBlocks = 0;
+
+    for(Store store : region.getStores()) {
+      for(StoreFile hFile : store.getStorefiles()) {
+        evictedBlocks += blockCache.evictBlocksByHfileName(hFile.getPath().getName());
+      }
+    }
+
+    return CacheEvictionStats.builder()
+        .withEvictedBlocks(evictedBlocks)
+        .withMaxCacheSize(blockCache.getMaxSize())
+        .build();
+  }
+
   @Override
   public double getCompactionPressure() {
     double max = 0;

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

@@ -49,6 +49,8 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.ByteBufferCell;
+import org.apache.hadoop.hbase.CacheEvictionStats;
+import org.apache.hadoop.hbase.CacheEvictionStatsBuilder;
 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.CellScannable;
 import org.apache.hadoop.hbase.CellScanner;
@@ -130,6 +132,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.shaded.com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.hbase.shaded.com.google.common.cache.Cache;
 import org.apache.hadoop.hbase.shaded.com.google.common.cache.CacheBuilder;
+import org.apache.hadoop.hbase.shaded.com.google.common.collect.Lists;
 import org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString;
 import org.apache.hadoop.hbase.shaded.com.google.protobuf.Message;
 import org.apache.hadoop.hbase.shaded.com.google.protobuf.RpcController;
@@ -142,6 +145,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.ResponseConverter;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.AdminService;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CloseRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CompactRegionRequest;
@@ -1361,19 +1366,24 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
   @VisibleForTesting
   public HRegion getRegion(
       final RegionSpecifier regionSpecifier) throws IOException {
-    ByteString value = regionSpecifier.getValue();
-    RegionSpecifierType type = regionSpecifier.getType();
-    switch (type) {
-      case REGION_NAME:
-        byte[] regionName = value.toByteArray();
-        String encodedRegionName = RegionInfo.encodeRegionName(regionName);
-        return regionServer.getRegionByEncodedName(regionName, encodedRegionName);
-      case ENCODED_REGION_NAME:
-        return regionServer.getRegionByEncodedName(value.toStringUtf8());
-      default:
-        throw new DoNotRetryIOException(
-          "Unsupported region specifier type: " + type);
+    return regionServer.getRegion(regionSpecifier.getValue().toByteArray());
+  }
+
+  /**
+   * Find the List of HRegions based on a list of region specifiers
+   *
+   * @param regionSpecifiers the list of region specifiers
+   * @return the corresponding list of regions
+   * @throws IOException if any of the specifiers is not null,
+   *    but failed to find the region
+   */
+  private List<HRegion> getRegions(
+      final List<RegionSpecifier> regionSpecifiers) throws IOException {
+    List<HRegion> regions = Lists.newArrayListWithCapacity(regionSpecifiers.size());
+    for (RegionSpecifier regionSpecifier: regionSpecifiers) {
+      regions.add(regionServer.getRegion(regionSpecifier.getValue().toByteArray()));
     }
+    return regions;
   }
 
   @VisibleForTesting
@@ -3442,15 +3452,33 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
        ExecuteProceduresRequest request) throws ServiceException {
     ExecuteProceduresResponse.Builder builder = ExecuteProceduresResponse.newBuilder();
     if (request.getOpenRegionCount() > 0) {
-      for (OpenRegionRequest req: request.getOpenRegionList()) {
+      for (OpenRegionRequest req : request.getOpenRegionList()) {
         builder.addOpenRegion(openRegion(controller, req));
       }
-     }
-     if (request.getCloseRegionCount() > 0) {
-       for (CloseRegionRequest req: request.getCloseRegionList()) {
-         builder.addCloseRegion(closeRegion(controller, req));
-       }
-     }
-     return builder.build();
+    }
+    if (request.getCloseRegionCount() > 0) {
+      for (CloseRegionRequest req : request.getCloseRegionList()) {
+        builder.addCloseRegion(closeRegion(controller, req));
+      }
+    }
+    return builder.build();
+  }
+
+  @Override
+  public ClearRegionBlockCacheResponse clearRegionBlockCache(RpcController controller,
+                                                             ClearRegionBlockCacheRequest request)
+    throws ServiceException {
+    CacheEvictionStatsBuilder stats = CacheEvictionStats.builder();
+    try {
+      List<HRegion> regions = getRegions(request.getRegionList());
+      for (HRegion region : regions) {
+        stats = stats.append(this.regionServer.clearRegionBlockCache(region));
+      }
+    } catch (Exception e) {
+      throw new ServiceException(e);
+    }
+    return ClearRegionBlockCacheResponse.newBuilder()
+        .setStats(ProtobufUtil.toCacheEvictionStats(stats.build()))
+        .build();
   }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/master/MockRegionServer.java

@@ -74,6 +74,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearCompactionQueuesResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ClearRegionBlockCacheResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CloseRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.CompactRegionRequest;
@@ -590,6 +592,13 @@ ClientProtos.ClientService.BlockingInterface, RegionServerServices {
     return null;
   }
 
+  @Override
+  public ClearRegionBlockCacheResponse clearRegionBlockCache(RpcController controller,
+                                                             ClearRegionBlockCacheRequest request)
+    throws ServiceException {
+    return null;
+  }
+
   @Override
   public HeapMemoryManager getHeapMemoryManager() {
     return null;

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

@@ -0,0 +1,125 @@
+/**
+ *
+ * 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 org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.MiniHBaseCluster;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.io.hfile.BlockCache;
+import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.io.IOException;
+import java.util.ArrayList;
+
+import static org.junit.Assert.assertEquals;
+
+@Category(MediumTests.class)
+@RunWith(Parameterized.class)
+public class TestClearRegionBlockCache {
+  private static final TableName TABLE_NAME = TableName.valueOf("testClearRegionBlockCache");
+  private static final byte[] FAMILY = Bytes.toBytes("family");
+  private static final byte[][] SPLIT_KEY = new byte[][] { Bytes.toBytes("5") };
+  private static final int NUM_MASTERS = 1;
+  private static final int NUM_RS = 2;
+
+  private final HBaseTestingUtility HTU = new HBaseTestingUtility();
+
+  private Configuration CONF = HTU.getConfiguration();
+  private Table table;
+  private HRegionServer rs1, rs2;
+  private MiniHBaseCluster cluster;
+
+  @Parameterized.Parameter public String cacheType;
+
+  @Parameterized.Parameters(name = "{index}: {0}")
+  public static Object[] data() {
+    return new Object[] { "lru", "bucket" };
+  }
+
+  @Before
+  public void setup() throws Exception {
+    if (cacheType.equals("bucket")) {
+      CONF.set(HConstants.BUCKET_CACHE_IOENGINE_KEY, "offheap");
+      CONF.setInt(HConstants.BUCKET_CACHE_SIZE_KEY, 30);
+    }
+
+    cluster = HTU.startMiniCluster(NUM_MASTERS, NUM_RS);
+    rs1 = cluster.getRegionServer(0);
+    rs2 = cluster.getRegionServer(1);
+
+    // Create table
+    table = HTU.createTable(TABLE_NAME, FAMILY, SPLIT_KEY);
+  }
+
+  @After
+  public void teardown() throws Exception {
+    HTU.shutdownMiniCluster();
+  }
+
+  @Test
+  public void testClearBlockCache() throws Exception {
+    HTU.loadNumericRows(table, FAMILY, 1, 10);
+    HTU.flush(TABLE_NAME);
+
+    BlockCache blockCache1 = rs1.getCacheConfig().getBlockCache();
+    BlockCache blockCache2 = rs2.getCacheConfig().getBlockCache();
+
+    long initialBlockCount1 = blockCache1.getBlockCount();
+    long initialBlockCount2 = blockCache2.getBlockCount();
+
+    // scan will cause blocks to be added in BlockCache
+    scanAllRegionsForRS(rs1);
+    assertEquals(blockCache1.getBlockCount() - initialBlockCount1,
+                 HTU.getNumHFilesForRS(rs1, TABLE_NAME, FAMILY));
+    clearRegionBlockCache(rs1);
+
+    scanAllRegionsForRS(rs2);
+    assertEquals(blockCache2.getBlockCount() - initialBlockCount2,
+                 HTU.getNumHFilesForRS(rs2, TABLE_NAME, FAMILY));
+    clearRegionBlockCache(rs2);
+
+    assertEquals(initialBlockCount1, blockCache1.getBlockCount());
+    assertEquals(initialBlockCount2, blockCache2.getBlockCount());
+  }
+
+  private void scanAllRegionsForRS(HRegionServer rs) throws IOException {
+    for (Region region : rs.getRegions(TABLE_NAME)) {
+      RegionScanner scanner = region.getScanner(new Scan());
+      while (scanner.next(new ArrayList<Cell>()));
+    }
+  }
+
+  private void clearRegionBlockCache(HRegionServer rs) {
+    for (Region region : rs.getRegions(TABLE_NAME)) {
+      rs.clearRegionBlockCache(region);
+    }
+  }
+}

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

@@ -399,6 +399,12 @@ public class TestReplicator extends TestReplicationBase {
       throws ServiceException {
         return null;
       }
+
+      @Override
+      public ClearRegionBlockCacheResponse clearRegionBlockCache(RpcController controller,
+                                                               ClearRegionBlockCacheRequest request) throws ServiceException {
+        return delegate.clearRegionBlockCache(controller, request);
+      }
     }
 
     public class FailureInjectingReplicatorForTest extends ReplicatorForTest {

hbase-shell/src/main/ruby/hbase/admin.rb

@@ -196,6 +196,12 @@ module Hbase
       @admin.isBalancerEnabled
     end
 
+    #----------------------------------------------------------------------------------------------
+    # Requests clear block cache for table
+    def clear_block_cache(table_name)
+      @admin.clearBlockCache(org.apache.hadoop.hbase.TableName.valueOf(table_name)).toString
+    end
+
     #----------------------------------------------------------------------------------------------
     # Requests region normalization for all configured tables in the cluster
     # Returns true if normalizer ran successfully

hbase-shell/src/main/ruby/shell.rb

@@ -360,6 +360,7 @@ Shell.load_command_group(
     clear_compaction_queues
     list_deadservers
     clear_deadservers
+    clear_block_cache
   ],
   # TODO: remove older hlog_roll command
   aliases: {

hbase-shell/src/main/ruby/shell/commands/clear_block_cache.rb

@@ -0,0 +1,39 @@
+#
+# 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.
+#
+
+module Shell
+  module Commands
+    class ClearBlockCache < Command
+      def help
+        <<-EOF
+Clear all the blocks corresponding to this table from BlockCache. For expert-admins.
+Calling this API will drop all the cached blocks specific to a table from BlockCache.
+This can significantly impact the query performance as the subsequent queries will
+have to retrieve the blocks from underlying filesystem.
+For example:
+
+  hbase> clear_block_cache 'TABLENAME'
+EOF
+      end
+
+      def command(table_name)
+        formatter.row([admin.clear_block_cache(table_name)])
+      end
+    end
+  end
+end