/*
    * 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.coprocessor;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.NavigableSet;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CoprocessorEnvironment;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.client.Append;
  import org.apache.hadoop.hbase.client.Delete;
  import org.apache.hadoop.hbase.client.Durability;
  import org.apache.hadoop.hbase.client.Get;
  import org.apache.hadoop.hbase.client.Increment;
  import org.apache.hadoop.hbase.client.Mutation;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.filter.ByteArrayComparable;
  import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
  import org.apache.hadoop.hbase.io.FSDataInputStreamWrapper;
  import org.apache.hadoop.hbase.io.Reference;
  import org.apache.hadoop.hbase.io.hfile.CacheConfig;
  import org.apache.hadoop.hbase.regionserver.DeleteTracker;
  import org.apache.hadoop.hbase.regionserver.InternalScanner;
  import org.apache.hadoop.hbase.regionserver.KeyValueScanner;
  import org.apache.hadoop.hbase.regionserver.MiniBatchOperationInProgress;
  import org.apache.hadoop.hbase.regionserver.Region;
  import org.apache.hadoop.hbase.regionserver.Region.Operation;
  import org.apache.hadoop.hbase.regionserver.RegionScanner;
  import org.apache.hadoop.hbase.regionserver.ScanType;
  import org.apache.hadoop.hbase.regionserver.Store;
  import org.apache.hadoop.hbase.regionserver.StoreFile;
  import org.apache.hadoop.hbase.regionserver.StoreFile.Reader;
  import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
  import org.apache.hadoop.hbase.regionserver.wal.HLogKey;
  import org.apache.hadoop.hbase.wal.WALKey;
  import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
  import org.apache.hadoop.hbase.util.Pair;
  
  import com.google.common.collect.ImmutableList;
  
  /**
   * An abstract class that implements RegionObserver.
   * By extending it, you can create your own region observer without
   * overriding all abstract methods of RegionObserver.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
  @InterfaceStability.Evolving
  public abstract class BaseRegionObserver implements RegionObserver {
    @Override
    public void start(CoprocessorEnvironment e) throws IOException { }
  
    @Override
    public void stop(CoprocessorEnvironment e) throws IOException { }
  
    @Override
    public void preOpen(ObserverContext<RegionCoprocessorEnvironment> e) throws IOException { }
  
    @Override
    public void postOpen(ObserverContext<RegionCoprocessorEnvironment> e) { }
  
    @Override
    public void postLogReplay(ObserverContext<RegionCoprocessorEnvironment> e) { }
  
    @Override
    public void preClose(ObserverContext<RegionCoprocessorEnvironment> c, boolean abortRequested)
        throws IOException { }
  
    @Override
    public void postClose(ObserverContext<RegionCoprocessorEnvironment> e,
        boolean abortRequested) { }
  
    @Override
    public InternalScanner preFlushScannerOpen(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final KeyValueScanner memstoreScanner, final InternalScanner s)
       throws IOException {
     return s;
   }
 
   @Override
   public void preFlush(ObserverContext<RegionCoprocessorEnvironment> e) throws IOException {
   }
 
   @Override
   public void postFlush(ObserverContext<RegionCoprocessorEnvironment> e) throws IOException {
   }
 
   @Override
   public InternalScanner preFlush(ObserverContext<RegionCoprocessorEnvironment> e, Store store,
       InternalScanner scanner) throws IOException {
     return scanner;
   }
 
   @Override
   public void postFlush(ObserverContext<RegionCoprocessorEnvironment> e, Store store,
       StoreFile resultFile) throws IOException {
   }
 
   @Override
   public void preSplit(ObserverContext<RegionCoprocessorEnvironment> e) throws IOException {
   }
   
   @Override
   public void preSplit(ObserverContext<RegionCoprocessorEnvironment> c,
       byte[] splitRow) throws IOException {
   }
 
   @Override
   public void preSplitBeforePONR(ObserverContext<RegionCoprocessorEnvironment> ctx,
       byte[] splitKey, List<Mutation> metaEntries) throws IOException {
   }
   
   @Override
   public void preSplitAfterPONR(
       ObserverContext<RegionCoprocessorEnvironment> ctx) throws IOException {
   }
   
   @Override
   public void preRollBackSplit(ObserverContext<RegionCoprocessorEnvironment> ctx)
       throws IOException {
   }
   
   @Override
   public void postRollBackSplit(
       ObserverContext<RegionCoprocessorEnvironment> ctx) throws IOException {
   }
   
   @Override
   public void postCompleteSplit(
       ObserverContext<RegionCoprocessorEnvironment> ctx) throws IOException {
   }
 
   @Override
   public void postSplit(ObserverContext<RegionCoprocessorEnvironment> e, Region l, Region r)
       throws IOException {
   }
 
   @Override
   public void preCompactSelection(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final List<StoreFile> candidates) throws IOException { }
 
   @Override
   public void preCompactSelection(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final List<StoreFile> candidates, final CompactionRequest request)
       throws IOException {
     preCompactSelection(c, store, candidates);
   }
 
   @Override
   public void postCompactSelection(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final ImmutableList<StoreFile> selected) { }
 
   @Override
   public void postCompactSelection(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final ImmutableList<StoreFile> selected, CompactionRequest request) {
     postCompactSelection(c, store, selected);
   }
 
   @Override
   public InternalScanner preCompact(ObserverContext<RegionCoprocessorEnvironment> e,
       final Store store, final InternalScanner scanner, final ScanType scanType)
       throws IOException {
     return scanner;
   }
 
   @Override
   public InternalScanner preCompact(ObserverContext<RegionCoprocessorEnvironment> e,
       final Store store, final InternalScanner scanner, final ScanType scanType,
       CompactionRequest request) throws IOException {
     return preCompact(e, store, scanner, scanType);
   }
 
   @Override
   public InternalScanner preCompactScannerOpen(
       final ObserverContext<RegionCoprocessorEnvironment> c, final Store store,
       List<? extends KeyValueScanner> scanners, final ScanType scanType, final long earliestPutTs,
       final InternalScanner s) throws IOException {
     return s;
   }
 
   @Override
   public InternalScanner preCompactScannerOpen(
       final ObserverContext<RegionCoprocessorEnvironment> c, final Store store,
       List<? extends KeyValueScanner> scanners, final ScanType scanType, final long earliestPutTs,
       final InternalScanner s, CompactionRequest request) throws IOException {
     return preCompactScannerOpen(c, store, scanners, scanType, earliestPutTs, s);
   }
 
   @Override
   public void postCompact(ObserverContext<RegionCoprocessorEnvironment> e, final Store store,
       final StoreFile resultFile) throws IOException {
   }
 
 @Override
   public void postCompact(ObserverContext<RegionCoprocessorEnvironment> e, final Store store,
       final StoreFile resultFile, CompactionRequest request) throws IOException {
     postCompact(e, store, resultFile);
   }
 
   @Override
   public void preGetClosestRowBefore(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final Result result)
     throws IOException {
   }
 
   @Override
   public void postGetClosestRowBefore(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final Result result)
       throws IOException {
   }
 
   @Override
   public void preGetOp(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Get get, final List<Cell> results) throws IOException {
   }
 
   @Override
   public void postGetOp(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Get get, final List<Cell> results) throws IOException {
   }
 
   @Override
   public boolean preExists(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Get get, final boolean exists) throws IOException {
     return exists;
   }
 
   @Override
   public boolean postExists(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Get get, boolean exists) throws IOException {
     return exists;
   }
 
   @Override
   public void prePut(final ObserverContext<RegionCoprocessorEnvironment> e, 
       final Put put, final WALEdit edit, final Durability durability) throws IOException {
   }
 
   @Override
   public void postPut(final ObserverContext<RegionCoprocessorEnvironment> e, 
       final Put put, final WALEdit edit, final Durability durability) throws IOException {
   }
 
   @Override
   public void preDelete(final ObserverContext<RegionCoprocessorEnvironment> e, final Delete delete,
       final WALEdit edit, final Durability durability) throws IOException {
   }
 
   @Override
   public void prePrepareTimeStampForDeleteVersion(
       final ObserverContext<RegionCoprocessorEnvironment> e, final Mutation delete,
       final Cell cell, final byte[] byteNow, final Get get) throws IOException {
   }
 
   @Override
   public void postDelete(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Delete delete, final WALEdit edit, final Durability durability)
       throws IOException {
   }
   
   @Override
   public void preBatchMutate(final ObserverContext<RegionCoprocessorEnvironment> c,
       final MiniBatchOperationInProgress<Mutation> miniBatchOp) throws IOException {
   }
 
   @Override
   public void postBatchMutate(final ObserverContext<RegionCoprocessorEnvironment> c,
       final MiniBatchOperationInProgress<Mutation> miniBatchOp) throws IOException {
   }
 
   @Override
   public void postBatchMutateIndispensably(final ObserverContext<RegionCoprocessorEnvironment> ctx,
       MiniBatchOperationInProgress<Mutation> miniBatchOp, final boolean success) throws IOException {
   }
 
   @Override
   public boolean preCheckAndPut(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final CompareOp compareOp, final ByteArrayComparable comparator,
       final Put put, final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public boolean preCheckAndPutAfterRowLock(
       final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte[] row, final byte[] family, final byte[] qualifier, final CompareOp compareOp,
       final ByteArrayComparable comparator, final Put put,
       final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public boolean postCheckAndPut(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final CompareOp compareOp, final ByteArrayComparable comparator,
       final Put put, final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public boolean preCheckAndDelete(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final CompareOp compareOp, final ByteArrayComparable comparator,
       final Delete delete, final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public boolean preCheckAndDeleteAfterRowLock(
       final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte[] row, final byte[] family, final byte[] qualifier, final CompareOp compareOp,
       final ByteArrayComparable comparator, final Delete delete,
       final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public boolean postCheckAndDelete(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final CompareOp compareOp, final ByteArrayComparable comparator,
       final Delete delete, final boolean result) throws IOException {
     return result;
   }
 
   @Override
   public Result preAppend(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Append append) throws IOException {
     return null;
   }
 
   @Override
   public Result preAppendAfterRowLock(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Append append) throws IOException {
     return null;
   }
 
   @Override
   public Result postAppend(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Append append, final Result result) throws IOException {
     return result;
   }
 
   @Override
   public long preIncrementColumnValue(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final long amount, final boolean writeToWAL) throws IOException {
     return amount;
   }
 
   @Override
   public long postIncrementColumnValue(final ObserverContext<RegionCoprocessorEnvironment> e,
       final byte [] row, final byte [] family, final byte [] qualifier,
       final long amount, final boolean writeToWAL, long result)
       throws IOException {
     return result;
   }
 
   @Override
   public Result preIncrement(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Increment increment) throws IOException {
     return null;
   }
 
   @Override
   public Result preIncrementAfterRowLock(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Increment increment) throws IOException {
     return null;
   }
 
   @Override
   public Result postIncrement(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Increment increment, final Result result) throws IOException {
     return result;
   }
 
   @Override
   public RegionScanner preScannerOpen(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Scan scan, final RegionScanner s) throws IOException {
     return s;
   }
 
   @Override
   public KeyValueScanner preStoreScannerOpen(final ObserverContext<RegionCoprocessorEnvironment> c,
       final Store store, final Scan scan, final NavigableSet<byte[]> targetCols,
       final KeyValueScanner s) throws IOException {
     return s;
   }
 
   @Override
   public RegionScanner postScannerOpen(final ObserverContext<RegionCoprocessorEnvironment> e,
       final Scan scan, final RegionScanner s) throws IOException {
     return s;
   }
 
   @Override
   public boolean preScannerNext(final ObserverContext<RegionCoprocessorEnvironment> e,
       final InternalScanner s, final List<Result> results,
       final int limit, final boolean hasMore) throws IOException {
     return hasMore;
   }
 
   @Override
   public boolean postScannerNext(final ObserverContext<RegionCoprocessorEnvironment> e,
       final InternalScanner s, final List<Result> results, final int limit,
       final boolean hasMore) throws IOException {
     return hasMore;
   }
 
   @Override
   public boolean postScannerFilterRow(final ObserverContext<RegionCoprocessorEnvironment> e,
       final InternalScanner s, final byte[] currentRow, final int offset, final short length,
       final boolean hasMore) throws IOException {
     return hasMore;
   }
 
   @Override
   public void preScannerClose(final ObserverContext<RegionCoprocessorEnvironment> e,
       final InternalScanner s) throws IOException {
   }
 
   @Override
   public void postScannerClose(final ObserverContext<RegionCoprocessorEnvironment> e,
       final InternalScanner s) throws IOException {
   }
 
   /**
    * Implementers should override this version of the method and leave the deprecated one as-is.
    */
   @Override
   public void preWALRestore(ObserverContext<? extends RegionCoprocessorEnvironment> env,
       HRegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {
   }
 
   @Override
   public void preWALRestore(ObserverContext<RegionCoprocessorEnvironment> env, HRegionInfo info,
       HLogKey logKey, WALEdit logEdit) throws IOException {
     preWALRestore(env, info, (WALKey)logKey, logEdit);
   }
 
   /**
    * Implementers should override this version of the method and leave the deprecated one as-is.
    */
   @Override
   public void postWALRestore(ObserverContext<? extends RegionCoprocessorEnvironment> env,
       HRegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {
   }
 
   @Override
   public void postWALRestore(ObserverContext<RegionCoprocessorEnvironment> env,
       HRegionInfo info, HLogKey logKey, WALEdit logEdit) throws IOException {
     postWALRestore(env, info, (WALKey)logKey, logEdit);
   }
 
   @Override
   public void preBulkLoadHFile(final ObserverContext<RegionCoprocessorEnvironment> ctx,
     List<Pair<byte[], String>> familyPaths) throws IOException {
   }
 
   @Override
   public boolean postBulkLoadHFile(ObserverContext<RegionCoprocessorEnvironment> ctx,
     List<Pair<byte[], String>> familyPaths, boolean hasLoaded) throws IOException {
     return hasLoaded;
   }
 
   @Override
   public Reader preStoreFileReaderOpen(ObserverContext<RegionCoprocessorEnvironment> ctx,
       FileSystem fs, Path p, FSDataInputStreamWrapper in, long size, CacheConfig cacheConf,
       Reference r, Reader reader) throws IOException {
     return reader;
   }
 
   @Override
   public Reader postStoreFileReaderOpen(ObserverContext<RegionCoprocessorEnvironment> ctx,
       FileSystem fs, Path p, FSDataInputStreamWrapper in, long size, CacheConfig cacheConf,
       Reference r, Reader reader) throws IOException {
     return reader;
   }
 
   @Override
   public Cell postMutationBeforeWAL(ObserverContext<RegionCoprocessorEnvironment> ctx,
       MutationType opType, Mutation mutation, Cell oldCell, Cell newCell) throws IOException {
     return newCell;
   }
 
   @Override
   public void postStartRegionOperation(final ObserverContext<RegionCoprocessorEnvironment> ctx,
       Operation op) throws IOException {
   }
 
   @Override
   public void postCloseRegionOperation(final ObserverContext<RegionCoprocessorEnvironment> ctx,
       Operation op) throws IOException {
   }
 
   @Override
   public DeleteTracker postInstantiateDeleteTracker(
       final ObserverContext<RegionCoprocessorEnvironment> ctx, DeleteTracker delTracker)
       throws IOException {
     return delTracker;
   }
 }