/*
    * 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.Map;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellComparator;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HDFSBlocksDistribution;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.client.Append;
  import org.apache.hadoop.hbase.client.Delete;
  import org.apache.hadoop.hbase.client.Get;
  import org.apache.hadoop.hbase.client.Increment;
  import org.apache.hadoop.hbase.client.IsolationLevel;
  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.RowMutations;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.conf.ConfigurationObserver;
  import org.apache.hadoop.hbase.exceptions.FailedSanityCheckException;
  import org.apache.hadoop.hbase.filter.ByteArrayComparable;
  import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetRegionInfoResponse.CompactionState;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.CoprocessorServiceCall;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.wal.WALSplitter.MutationReplay;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.protobuf.Message;
  import com.google.protobuf.RpcController;
  import com.google.protobuf.Service;
  
  /**
   * Regions store data for a certain region of a table.  It stores all columns
   * for each row. A given table consists of one or more Regions.
   *
   * <p>An Region is defined by its table and its key extent.
   *
   * <p>Locking at the Region level serves only one purpose: preventing the
   * region from being closed (and consequently split) while other operations
   * are ongoing. Each row level operation obtains both a row lock and a region
   * read lock for the duration of the operation. While a scanner is being
   * constructed, getScanner holds a read lock. If the scanner is successfully
   * constructed, it holds a read lock until it is closed. A close takes out a
   * write lock and consequently will block for ongoing operations and will block
   * new operations from starting while the close is in progress.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
  @InterfaceStability.Evolving
  public interface Region extends ConfigurationObserver {
  
    ///////////////////////////////////////////////////////////////////////////
    // Region state
  
    /** @return region information for this region */
    HRegionInfo getRegionInfo();
  
    /** @return table descriptor for this region */
    HTableDescriptor getTableDesc();
  
    /** @return true if region is available (not closed and not closing) */
    boolean isAvailable();
  
    /** @return true if region is closed */
    boolean isClosed();
  
    /** @return True if closing process has started */
    boolean isClosing();
  
    /** @return True if region is in recovering state */
    boolean isRecovering();
  
    /** @return True if region is read only */
    boolean isReadOnly();
  
   /**
    * Return the list of Stores managed by this region
    * <p>Use with caution.  Exposed for use of fixup utilities.
    * @return a list of the Stores managed by this region
    */
   List<Store> getStores();
 
   /**
    * Return the Store for the given family
    * <p>Use with caution.  Exposed for use of fixup utilities.
    * @return the Store for the given family
    */
   Store getStore(byte[] family);
 
   /** @return list of store file names for the given families */
   List<String> getStoreFileList(byte [][] columns);
 
   /**
    * Check the region's underlying store files, open the files that have not
    * been opened yet, and remove the store file readers for store files no
    * longer available.
    * @throws IOException
    */
   boolean refreshStoreFiles() throws IOException;
 
   /** @return the latest sequence number that was read from storage when this region was opened */
   long getOpenSeqNum();
 
   /** @return the max sequence id of flushed data on this region; no edit in memory will have
    * a sequence id that is less that what is returned here.
    */
   long getMaxFlushedSeqId();
 
   /** @return the oldest flushed sequence id for the given family; can be beyond
    * {@link #getMaxFlushedSeqId()} in case where we've flushed a subset of a regions column
    * families
    * @deprecated Since version 1.2.0. Exposes too much about our internals; shutting it down.
    * Do not use.
    */
   @VisibleForTesting
   @Deprecated
   public long getOldestSeqIdOfStore(byte[] familyName);
 
   /**
    * This can be used to determine the last time all files of this region were major compacted.
    * @param majorCompactioOnly Only consider HFile that are the result of major compaction
    * @return the timestamp of the oldest HFile for all stores of this region
    */
   long getOldestHfileTs(boolean majorCompactioOnly) throws IOException;
 
   /**
    * @return map of column family names to max sequence id that was read from storage when this
    * region was opened
    */
   public Map<byte[], Long> getMaxStoreSeqId();
 
   /** @return true if loading column families on demand by default */
   boolean isLoadingCfsOnDemandDefault();
 
   /** @return readpoint considering given IsolationLevel */
   long getReadpoint(IsolationLevel isolationLevel);
 
   /**
    * @return The earliest time a store in the region was flushed. All
    *         other stores in the region would have been flushed either at, or
    *         after this time.
    */
   long getEarliestFlushTimeForAllStores();
 
   ///////////////////////////////////////////////////////////////////////////
   // Metrics
 
   /** @return read requests count for this region */
   long getReadRequestsCount();
 
   /**
    * Update the read request count for this region
    * @param i increment
    */
   void updateReadRequestsCount(long i);
 
   /** @return write request count for this region */
   long getWriteRequestsCount();
 
   /**
    * Update the write request count for this region
    * @param i increment
    */
   void updateWriteRequestsCount(long i);
 
   /** @return memstore size for this region, in bytes */
   long getMemstoreSize();
 
   /** @return the number of mutations processed bypassing the WAL */
   long getNumMutationsWithoutWAL();
 
   /** @return the size of data processed bypassing the WAL, in bytes */
   long getDataInMemoryWithoutWAL();
 
   /** @return the number of blocked requests */
   long getBlockedRequestsCount();
 
   /** @return the number of checkAndMutate guards that passed */
   long getCheckAndMutateChecksPassed();
 
   /** @return the number of failed checkAndMutate guards */
   long getCheckAndMutateChecksFailed();
 
   /** @return the MetricsRegion for this region */
   MetricsRegion getMetrics();
 
   /** @return the block distribution for all Stores managed by this region */
   HDFSBlocksDistribution getHDFSBlocksDistribution();
 
   ///////////////////////////////////////////////////////////////////////////
   // Locking
 
   // Region read locks
 
   /**
    * Operation enum is used in {@link Region#startRegionOperation} to provide context for
    * various checks before any region operation begins.
    */
   enum Operation {
     ANY, GET, PUT, DELETE, SCAN, APPEND, INCREMENT, SPLIT_REGION, MERGE_REGION, BATCH_MUTATE,
     REPLAY_BATCH_MUTATE, COMPACT_REGION, REPLAY_EVENT
   }
 
   /**
    * This method needs to be called before any public call that reads or
    * modifies data.
    * Acquires a read lock and checks if the region is closing or closed.
    * <p>{@link #closeRegionOperation} MUST then always be called after
    * the operation has completed, whether it succeeded or failed.
    * @throws IOException
    */
   void startRegionOperation() throws IOException;
 
   /**
    * This method needs to be called before any public call that reads or
    * modifies data.
    * Acquires a read lock and checks if the region is closing or closed.
    * <p>{@link #closeRegionOperation} MUST then always be called after
    * the operation has completed, whether it succeeded or failed.
    * @param op The operation is about to be taken on the region
    * @throws IOException
    */
   void startRegionOperation(Operation op) throws IOException;
 
   /**
    * Closes the region operation lock.
    * @throws IOException
    */
   void closeRegionOperation() throws IOException;
 
   // Row write locks
 
   /**
    * Row lock held by a given thread.
    * One thread may acquire multiple locks on the same row simultaneously.
    * The locks must be released by calling release() from the same thread.
    */
   public interface RowLock {
     /**
      * Release the given lock.  If there are no remaining locks held by the current thread
      * then unlock the row and allow other threads to acquire the lock.
      * @throws IllegalArgumentException if called by a different thread than the lock owning
      *     thread
      */
     void release();
   }
 
   /**
    * Tries to acquire a lock on the given row.
    * @param waitForLock if true, will block until the lock is available.
    *        Otherwise, just tries to obtain the lock and returns
    *        false if unavailable.
    * @return the row lock if acquired,
    *   null if waitForLock was false and the lock was not acquired
    * @throws IOException if waitForLock was true and the lock could not be acquired after waiting
    */
   RowLock getRowLock(byte[] row, boolean waitForLock) throws IOException;
 
   /**
    * If the given list of row locks is not null, releases all locks.
    */
   void releaseRowLocks(List<RowLock> rowLocks);
 
   ///////////////////////////////////////////////////////////////////////////
   // Region operations
 
   /**
    * Perform one or more append operations on a row.
    * @param append
    * @param nonceGroup
    * @param nonce
    * @return result of the operation
    * @throws IOException
    */
   Result append(Append append, long nonceGroup, long nonce) throws IOException;
 
   /**
    * Perform a batch of mutations.
    * <p>
    * Note this supports only Put and Delete mutations and will ignore other types passed.
    * @param mutations the list of mutations
    * @param nonceGroup
    * @param nonce
    * @return an array of OperationStatus which internally contains the
    *         OperationStatusCode and the exceptionMessage if any.
    * @throws IOException
    */
   OperationStatus[] batchMutate(Mutation[] mutations, long nonceGroup, long nonce)
       throws IOException;
 
   /**
    * Replay a batch of mutations.
    * @param mutations mutations to replay.
    * @param replaySeqId
    * @return an array of OperationStatus which internally contains the
    *         OperationStatusCode and the exceptionMessage if any.
    * @throws IOException
    */
    OperationStatus[] batchReplay(MutationReplay[] mutations, long replaySeqId) throws IOException;
 
   /**
    * Atomically checks if a row/family/qualifier value matches the expected val
    * If it does, it performs the row mutations.  If the passed value is null, t
    * is for the lack of column (ie: non-existence)
    * @param row to check
    * @param family column family to check
    * @param qualifier column qualifier to check
    * @param compareOp the comparison operator
    * @param comparator
    * @param mutation
    * @param writeToWAL
    * @return true if mutation was applied, false otherwise
    * @throws IOException
    */
   boolean checkAndMutate(byte [] row, byte [] family, byte [] qualifier, CompareOp compareOp,
       ByteArrayComparable comparator, Mutation mutation, boolean writeToWAL) throws IOException;
 
   /**
    * Atomically checks if a row/family/qualifier value matches the expected val
    * If it does, it performs the row mutations.  If the passed value is null, t
    * is for the lack of column (ie: non-existence)
    * @param row to check
    * @param family column family to check
    * @param qualifier column qualifier to check
    * @param compareOp the comparison operator
    * @param comparator
    * @param mutations
    * @param writeToWAL
    * @return true if mutation was applied, false otherwise
    * @throws IOException
    */
   boolean checkAndRowMutate(byte [] row, byte [] family, byte [] qualifier, CompareOp compareOp,
       ByteArrayComparable comparator, RowMutations mutations, boolean writeToWAL)
       throws IOException;
 
   /**
    * Deletes the specified cells/row.
    * @param delete
    * @throws IOException
    */
   void delete(Delete delete) throws IOException;
 
   /**
    * Do a get based on the get parameter.
    * @param get query parameters
    * @return result of the operation
    */
   Result get(Get get) throws IOException;
 
   /**
    * Do a get based on the get parameter.
    * @param get query parameters
    * @param withCoprocessor invoke coprocessor or not. We don't want to
    * always invoke cp.
    * @return list of cells resulting from the operation
    */
   List<Cell> get(Get get, boolean withCoprocessor) throws IOException;
 
   /**
    * Return an iterator that scans over the HRegion, returning the indicated
    * columns and rows specified by the {@link Scan}.
    * <p>
    * This Iterator must be closed by the caller.
    *
    * @param scan configured {@link Scan}
    * @return RegionScanner
    * @throws IOException read exceptions
    */
   RegionScanner getScanner(Scan scan) throws IOException;
 
   /** The comparator to be used with the region */
   CellComparator getCellCompartor();
 
   /**
    * Perform one or more increment operations on a row.
    * @param increment
    * @param nonceGroup
    * @param nonce
    * @return result of the operation
    * @throws IOException
    */
   Result increment(Increment increment, long nonceGroup, long nonce) throws IOException;
 
   /**
    * Performs multiple mutations atomically on a single row. Currently
    * {@link Put} and {@link Delete} are supported.
    *
    * @param mutations object that specifies the set of mutations to perform atomically
    * @throws IOException
    */
   void mutateRow(RowMutations mutations) throws IOException;
 
   /**
    * Perform atomic mutations within the region.
    *
    * @param mutations The list of mutations to perform.
    * <code>mutations</code> can contain operations for multiple rows.
    * Caller has to ensure that all rows are contained in this region.
    * @param rowsToLock Rows to lock
    * @param nonceGroup Optional nonce group of the operation (client Id)
    * @param nonce Optional nonce of the operation (unique random id to ensure "more idempotence")
    * If multiple rows are locked care should be taken that
    * <code>rowsToLock</code> is sorted in order to avoid deadlocks.
    * @throws IOException
    */
   void mutateRowsWithLocks(Collection<Mutation> mutations, Collection<byte[]> rowsToLock,
       long nonceGroup, long nonce) throws IOException;
 
   /**
    * Performs atomic multiple reads and writes on a given row.
    *
    * @param processor The object defines the reads and writes to a row.
    */
   void processRowsWithLocks(RowProcessor<?,?> processor) throws IOException;
 
   /**
    * Performs atomic multiple reads and writes on a given row.
    *
    * @param processor The object defines the reads and writes to a row.
    * @param nonceGroup Optional nonce group of the operation (client Id)
    * @param nonce Optional nonce of the operation (unique random id to ensure "more idempotence")
    */
   void processRowsWithLocks(RowProcessor<?,?> processor, long nonceGroup, long nonce)
       throws IOException;
 
   /**
    * Performs atomic multiple reads and writes on a given row.
    *
    * @param processor The object defines the reads and writes to a row.
    * @param timeout The timeout of the processor.process() execution
    *                Use a negative number to switch off the time bound
    * @param nonceGroup Optional nonce group of the operation (client Id)
    * @param nonce Optional nonce of the operation (unique random id to ensure "more idempotence")
    */
   void processRowsWithLocks(RowProcessor<?,?> processor, long timeout, long nonceGroup, long nonce)
       throws IOException;
 
   /**
    * Puts some data in the table.
    * @param put
    * @throws IOException
    */
   void put(Put put) throws IOException;
 
   /**
    * Listener class to enable callers of
    * bulkLoadHFile() to perform any necessary
    * pre/post processing of a given bulkload call
    */
   interface BulkLoadListener {
 
     /**
      * Called before an HFile is actually loaded
      * @param family family being loaded to
      * @param srcPath path of HFile
      * @return final path to be used for actual loading
      * @throws IOException
      */
     String prepareBulkLoad(byte[] family, String srcPath) throws IOException;
 
     /**
      * Called after a successful HFile load
      * @param family family being loaded to
      * @param srcPath path of HFile
      * @throws IOException
      */
     void doneBulkLoad(byte[] family, String srcPath) throws IOException;
 
     /**
      * Called after a failed HFile load
      * @param family family being loaded to
      * @param srcPath path of HFile
      * @throws IOException
      */
     void failedBulkLoad(byte[] family, String srcPath) throws IOException;
   }
 
   /**
    * Attempts to atomically load a group of hfiles.  This is critical for loading
    * rows with multiple column families atomically.
    *
    * @param familyPaths List of Pair&lt;byte[] column family, String hfilePath&gt;
    * @param bulkLoadListener Internal hooks enabling massaging/preparation of a
    * file about to be bulk loaded
    * @param assignSeqId
    * @return true if successful, false if failed recoverably
    * @throws IOException if failed unrecoverably.
    */
   boolean bulkLoadHFiles(Collection<Pair<byte[], String>> familyPaths, boolean assignSeqId,
       BulkLoadListener bulkLoadListener) throws IOException;
 
   ///////////////////////////////////////////////////////////////////////////
   // Coprocessors
 
   /** @return the coprocessor host */
   RegionCoprocessorHost getCoprocessorHost();
 
   /**
    * Executes a single protocol buffer coprocessor endpoint {@link Service} method using
    * the registered protocol handlers.  {@link Service} implementations must be registered via the
    * {@link Region#registerService(com.google.protobuf.Service)}
    * method before they are available.
    *
    * @param controller an {@code RpcContoller} implementation to pass to the invoked service
    * @param call a {@code CoprocessorServiceCall} instance identifying the service, method,
    *     and parameters for the method invocation
    * @return a protocol buffer {@code Message} instance containing the method's result
    * @throws IOException if no registered service handler is found or an error
    *     occurs during the invocation
    * @see org.apache.hadoop.hbase.regionserver.Region#registerService(com.google.protobuf.Service)
    */
   Message execService(RpcController controller, CoprocessorServiceCall call) throws IOException;
 
   /**
    * Registers a new protocol buffer {@link Service} subclass as a coprocessor endpoint to
    * be available for handling
    * {@link Region#execService(com.google.protobuf.RpcController,
    *    org.apache.hadoop.hbase.protobuf.generated.ClientProtos.CoprocessorServiceCall)}} calls.
    *
    * <p>
    * Only a single instance may be registered per region for a given {@link Service} subclass (the
    * instances are keyed on {@link com.google.protobuf.Descriptors.ServiceDescriptor#getFullName()}.
    * After the first registration, subsequent calls with the same service name will fail with
    * a return value of {@code false}.
    * </p>
    * @param instance the {@code Service} subclass instance to expose as a coprocessor endpoint
    * @return {@code true} if the registration was successful, {@code false}
    * otherwise
    */
   boolean registerService(Service instance);
 
   ///////////////////////////////////////////////////////////////////////////
   // RowMutation processor support
 
   /**
    * Check the collection of families for validity.
    * @param families
    * @throws NoSuchColumnFamilyException
    */
   void checkFamilies(Collection<byte[]> families) throws NoSuchColumnFamilyException;
 
   /**
    * Check the collection of families for valid timestamps
    * @param familyMap
    * @param now current timestamp
    * @throws FailedSanityCheckException
    */
   void checkTimestamps(Map<byte[], List<Cell>> familyMap, long now)
       throws FailedSanityCheckException;
 
   /**
    * Prepare a delete for a row mutation processor
    * @param delete The passed delete is modified by this method. WARNING!
    * @throws IOException
    */
   void prepareDelete(Delete delete) throws IOException;
 
   /**
    * Set up correct timestamps in the KVs in Delete object.
    * <p>Caller should have the row and region locks.
    * @param mutation
    * @param familyCellMap
    * @param now
    * @throws IOException
    */
   void prepareDeleteTimestamps(Mutation mutation, Map<byte[], List<Cell>> familyCellMap,
       byte[] now) throws IOException;
 
   /**
    * Replace any cell timestamps set to {@link org.apache.hadoop.hbase.HConstants#LATEST_TIMESTAMP}
    * provided current timestamp.
    * @param values
    * @param now
    */
   void updateCellTimestamps(final Iterable<List<Cell>> values, final byte[] now)
       throws IOException;
 
   ///////////////////////////////////////////////////////////////////////////
   // Flushes, compactions, splits, etc.
   // Wizards only, please
 
   interface FlushResult {
     enum Result {
       FLUSHED_NO_COMPACTION_NEEDED,
       FLUSHED_COMPACTION_NEEDED,
       // Special case where a flush didn't run because there's nothing in the memstores. Used when
       // bulk loading to know when we can still load even if a flush didn't happen.
       CANNOT_FLUSH_MEMSTORE_EMPTY,
       CANNOT_FLUSH
     }
 
     /** @return the detailed result code */
     Result getResult();
 
     /** @return true if the memstores were flushed, else false */
     boolean isFlushSucceeded();
 
     /** @return True if the flush requested a compaction, else false */
     boolean isCompactionNeeded();
   }
 
   /**
    * Flush the cache.
    *
    * <p>When this method is called the cache will be flushed unless:
    * <ol>
    *   <li>the cache is empty</li>
    *   <li>the region is closed.</li>
    *   <li>a flush is already in progress</li>
    *   <li>writes are disabled</li>
    * </ol>
    *
    * <p>This method may block for some time, so it should not be called from a
    * time-sensitive thread.
    * @param force whether we want to force a flush of all stores
    * @return FlushResult indicating whether the flush was successful or not and if
    * the region needs compacting
    *
    * @throws IOException general io exceptions
    * because a snapshot was not properly persisted.
    */
   FlushResult flush(boolean force) throws IOException;
 
   /**
    * Synchronously compact all stores in the region.
    * <p>This operation could block for a long time, so don't call it from a
    * time-sensitive thread.
    * <p>Note that no locks are taken to prevent possible conflicts between
    * compaction and splitting activities. The regionserver does not normally compact
    * and split in parallel. However by calling this method you may introduce
    * unexpected and unhandled concurrency. Don't do this unless you know what
    * you are doing.
    *
    * @param majorCompaction True to force a major compaction regardless of thresholds
    * @throws IOException
    */
   void compact(final boolean majorCompaction) throws IOException;
 
   /**
    * Trigger major compaction on all stores in the region.
    * <p>
    * Compaction will be performed asynchronously to this call by the RegionServer's
    * CompactSplitThread. See also {@link Store#triggerMajorCompaction()}
    * @throws IOException
    */
   void triggerMajorCompaction() throws IOException;
 
   /**
    * @return if a given region is in compaction now.
    */
   CompactionState getCompactionState();
 
   /** Wait for all current flushes and compactions of the region to complete */
   void waitForFlushesAndCompactions();
 
 }