/**
    *
    * 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.wal;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.NavigableMap;
  import java.util.TreeMap;
  import java.util.UUID;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.hadoop.hbase.regionserver.MultiVersionConcurrencyControl;
  import org.apache.hadoop.hbase.regionserver.MultiVersionConcurrencyControl.WriteEntry;
  import org.apache.hadoop.hbase.util.ByteStringer;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.exceptions.TimeoutIOException;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  import org.apache.hadoop.hbase.protobuf.generated.WALProtos.FamilyScope;
  import org.apache.hadoop.hbase.protobuf.generated.WALProtos.ScopeType;
  import org.apache.hadoop.hbase.regionserver.SequenceId;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.protobuf.ByteString;
  
  
  
  // imports for things that haven't moved from regionserver.wal yet.
  import org.apache.hadoop.hbase.regionserver.wal.CompressionContext;
  import org.apache.hadoop.hbase.regionserver.wal.WALCellCodec;
  
  /**
   * A Key for an entry in the change log.
   *
   * The log intermingles edits to many tables and rows, so each log entry
   * identifies the appropriate table and row.  Within a table and row, they're
   * also sorted.
   *
   * <p>Some Transactional edits (START, COMMIT, ABORT) will not have an
   * associated row.
   *
   * Note that protected members marked @InterfaceAudience.Private are only protected
   * to support the legacy HLogKey class, which is in a different package.
   * 
   * <p>
   */
  // TODO: Key and WALEdit are never used separately, or in one-to-many relation, for practical
  //       purposes. They need to be merged into WALEntry.
  // TODO: Cleanup. We have logSeqNum and then WriteEntry, both are sequence id'ing. Fix.
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION)
  public class WALKey implements SequenceId, Comparable<WALKey> {
    private static final Log LOG = LogFactory.getLog(WALKey.class);
  
    @InterfaceAudience.Private // For internal use only.
    public MultiVersionConcurrencyControl getMvcc() {
      return mvcc;
    }
  
    /**
     * Will block until a write entry has been assigned by they WAL subsystem.
     * @return A WriteEntry gotten from local WAL subsystem. Must be completed by calling
     * mvcc#complete or mvcc#completeAndWait.
     * @throws InterruptedIOException
     * @see
     * #setWriteEntry(org.apache.hadoop.hbase.regionserver.MultiVersionConcurrencyControl.WriteEntry)
     */
    @InterfaceAudience.Private // For internal use only.
    public MultiVersionConcurrencyControl.WriteEntry getWriteEntry() throws InterruptedIOException {
      assert this.writeEntry != null;
      return this.writeEntry;
   }
 
   @InterfaceAudience.Private // For internal use only.
   public void setWriteEntry(MultiVersionConcurrencyControl.WriteEntry writeEntry) {
     assert this.writeEntry == null;
     this.writeEntry = writeEntry;
     // Set our sequenceid now using WriteEntry.
     this.logSeqNum = writeEntry.getWriteNumber();
   }
 
   // should be < 0 (@see HLogKey#readFields(DataInput))
   // version 2 supports WAL compression
   // public members here are only public because of HLogKey
   @InterfaceAudience.Private
   protected enum Version {
     UNVERSIONED(0),
     // Initial number we put on WALKey when we introduced versioning.
     INITIAL(-1),
     // Version -2 introduced a dictionary compression facility.  Only this
     // dictionary-based compression is available in version -2.
     COMPRESSED(-2);
 
     public final int code;
     static final Version[] byCode;
     static {
       byCode = Version.values();
       for (int i = 0; i < byCode.length; i++) {
         if (byCode[i].code != -1 * i) {
           throw new AssertionError("Values in this enum should be descending by one");
         }
       }
     }
 
     Version(int code) {
       this.code = code;
     }
 
     public boolean atLeast(Version other) {
       return code <= other.code;
     }
 
     public static Version fromCode(int code) {
       return byCode[code * -1];
     }
   }
 
   /*
    * This is used for reading the log entries created by the previous releases
    * (0.94.11) which write the clusters information to the scopes of WALEdit.
    */
   private static final String PREFIX_CLUSTER_KEY = ".";
 
 
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected static final Version VERSION = Version.COMPRESSED;
 
   /** Used to represent when a particular wal key doesn't know/care about the sequence ordering. */
   public static final long NO_SEQUENCE_ID = -1;
 
 
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected byte [] encodedRegionName;
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected TableName tablename;
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected long logSeqNum;
   private long origLogSeqNum = 0;
   // Time at which this edit was written.
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected long writeTime;
 
   // The first element in the list is the cluster id on which the change has originated
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected List<UUID> clusterIds;
 
   private NavigableMap<byte[], Integer> scopes;
 
   private long nonceGroup = HConstants.NO_NONCE;
   private long nonce = HConstants.NO_NONCE;
   private MultiVersionConcurrencyControl mvcc;
   private MultiVersionConcurrencyControl.WriteEntry writeEntry;
   public static final List<UUID> EMPTY_UUIDS = Collections.unmodifiableList(new ArrayList<UUID>());
 
   // visible for deprecated HLogKey
   @InterfaceAudience.Private
   protected CompressionContext compressionContext;
 
   public WALKey() {
     init(null, null, 0L, HConstants.LATEST_TIMESTAMP,
         new ArrayList<UUID>(), HConstants.NO_NONCE, HConstants.NO_NONCE, null);
   }
 
   @VisibleForTesting
   public WALKey(final byte[] encodedRegionName, final TableName tablename,
                 long logSeqNum,
       final long now, UUID clusterId) {
     List<UUID> clusterIds = new ArrayList<UUID>();
     clusterIds.add(clusterId);
     init(encodedRegionName, tablename, logSeqNum, now, clusterIds,
         HConstants.NO_NONCE, HConstants.NO_NONCE, null);
   }
 
   public WALKey(final byte[] encodedRegionName, final TableName tablename) {
     this(encodedRegionName, tablename, System.currentTimeMillis());
   }
 
   public WALKey(final byte[] encodedRegionName, final TableName tablename, final long now) {
     init(encodedRegionName,
         tablename,
         NO_SEQUENCE_ID,
         now,
         EMPTY_UUIDS,
         HConstants.NO_NONCE,
         HConstants.NO_NONCE,
         null);
   }
 
   public WALKey(final byte[] encodedRegionName,
                 final TableName tablename,
                 final long now,
                 MultiVersionConcurrencyControl mvcc) {
     init(encodedRegionName,
         tablename,
         NO_SEQUENCE_ID,
         now,
         EMPTY_UUIDS,
         HConstants.NO_NONCE,
         HConstants.NO_NONCE,
         mvcc);
   }
 
   /**
    * Create the log key for writing to somewhere.
    * We maintain the tablename mainly for debugging purposes.
    * A regionName is always a sub-table object.
    * <p>Used by log splitting and snapshots.
    *
    * @param encodedRegionName Encoded name of the region as returned by
    *                          <code>HRegionInfo#getEncodedNameAsBytes()</code>.
    * @param tablename         - name of table
    * @param logSeqNum         - log sequence number
    * @param now               Time at which this edit was written.
    * @param clusterIds        the clusters that have consumed the change(used in Replication)
    */
   public WALKey(final byte[] encodedRegionName,
                 final TableName tablename,
                 long logSeqNum,
                 final long now,
                 List<UUID> clusterIds,
                 long nonceGroup,
                 long nonce,
                 MultiVersionConcurrencyControl mvcc) {
     init(encodedRegionName, tablename, logSeqNum, now, clusterIds, nonceGroup, nonce, mvcc);
   }
 
   /**
    * Create the log key for writing to somewhere.
    * We maintain the tablename mainly for debugging purposes.
    * A regionName is always a sub-table object.
    *
    * @param encodedRegionName Encoded name of the region as returned by
    *                          <code>HRegionInfo#getEncodedNameAsBytes()</code>.
    * @param tablename
    * @param now               Time at which this edit was written.
    * @param clusterIds        the clusters that have consumed the change(used in Replication)
    * @param nonceGroup
    * @param nonce
    * @param mvcc mvcc control used to generate sequence numbers and control read/write points
    */
   public WALKey(final byte[] encodedRegionName, final TableName tablename,
                 final long now, List<UUID> clusterIds, long nonceGroup,
                 final long nonce, final MultiVersionConcurrencyControl mvcc) {
     init(encodedRegionName, tablename, NO_SEQUENCE_ID, now, clusterIds, nonceGroup, nonce, mvcc);
   }
 
   /**
    * Create the log key for writing to somewhere.
    * We maintain the tablename mainly for debugging purposes.
    * A regionName is always a sub-table object.
    *
    * @param encodedRegionName Encoded name of the region as returned by
    *                          <code>HRegionInfo#getEncodedNameAsBytes()</code>.
    * @param tablename
    * @param logSeqNum
    * @param nonceGroup
    * @param nonce
    */
   public WALKey(final byte[] encodedRegionName,
                 final TableName tablename,
                 long logSeqNum,
                 long nonceGroup,
                 long nonce,
                 final MultiVersionConcurrencyControl mvcc) {
     init(encodedRegionName,
         tablename,
         logSeqNum,
         EnvironmentEdgeManager.currentTime(),
         EMPTY_UUIDS,
         nonceGroup,
         nonce,
         mvcc);
   }
 
   @InterfaceAudience.Private
   protected void init(final byte[] encodedRegionName,
                       final TableName tablename,
                       long logSeqNum,
                       final long now,
                       List<UUID> clusterIds,
                       long nonceGroup,
                       long nonce,
                       MultiVersionConcurrencyControl mvcc) {
     this.logSeqNum = logSeqNum;
     this.writeTime = now;
     this.clusterIds = clusterIds;
     this.encodedRegionName = encodedRegionName;
     this.tablename = tablename;
     this.nonceGroup = nonceGroup;
     this.nonce = nonce;
     this.mvcc = mvcc;
   }
 
   /**
    * @param compressionContext Compression context to use
    */
   public void setCompressionContext(CompressionContext compressionContext) {
     this.compressionContext = compressionContext;
   }
 
   /** @return encoded region name */
   public byte [] getEncodedRegionName() {
     return encodedRegionName;
   }
 
   /** @return table name */
   public TableName getTablename() {
     return tablename;
   }
 
   /** @return log sequence number */
   public long getLogSeqNum() {
     return this.logSeqNum;
   }
 
   /**
    * Used to set original seq Id for WALKey during wal replay
    * @param seqId
    */
   public void setOrigLogSeqNum(final long seqId) {
     this.origLogSeqNum = seqId;
   }
   
   /**
    * Return a positive long if current WALKey is created from a replay edit
    * @return original sequence number of the WALEdit
    */
   public long getOrigLogSeqNum() {
     return this.origLogSeqNum;
   }
   
   /**
    * Wait for sequence number to be assigned &amp; return the assigned value
    * @return long the new assigned sequence number
    * @throws IOException
    */
   @Override
   public long getSequenceId() throws IOException {
     return this.logSeqNum;
   }
 
   /**
    * @return the write time
    */
   public long getWriteTime() {
     return this.writeTime;
   }
 
   public NavigableMap<byte[], Integer> getScopes() {
     return scopes;
   }
 
   /** @return The nonce group */
   public long getNonceGroup() {
     return nonceGroup;
   }
 
   /** @return The nonce */
   public long getNonce() {
     return nonce;
   }
 
   public void setScopes(NavigableMap<byte[], Integer> scopes) {
     this.scopes = scopes;
   }
 
   public void readOlderScopes(NavigableMap<byte[], Integer> scopes) {
     if (scopes != null) {
       Iterator<Map.Entry<byte[], Integer>> iterator = scopes.entrySet()
           .iterator();
       while (iterator.hasNext()) {
         Map.Entry<byte[], Integer> scope = iterator.next();
         String key = Bytes.toString(scope.getKey());
         if (key.startsWith(PREFIX_CLUSTER_KEY)) {
           addClusterId(UUID.fromString(key.substring(PREFIX_CLUSTER_KEY
               .length())));
           iterator.remove();
         }
       }
       if (scopes.size() > 0) {
         this.scopes = scopes;
       }
     }
   }
 
   /**
    * Marks that the cluster with the given clusterId has consumed the change
    */
   public void addClusterId(UUID clusterId) {
     if (!clusterIds.contains(clusterId)) {
       clusterIds.add(clusterId);
     }
   }
 
   /**
    * @return the set of cluster Ids that have consumed the change
    */
   public List<UUID> getClusterIds() {
     return clusterIds;
   }
 
   /**
    * @return the cluster id on which the change has originated. It there is no such cluster, it
    *         returns DEFAULT_CLUSTER_ID (cases where replication is not enabled)
    */
   public UUID getOriginatingClusterId(){
     return clusterIds.isEmpty() ? HConstants.DEFAULT_CLUSTER_ID : clusterIds.get(0);
   }
 
   @Override
   public String toString() {
     return tablename + "/" + Bytes.toString(encodedRegionName) + "/" +
       logSeqNum;
   }
 
   /**
    * Produces a string map for this key. Useful for programmatic use and
    * manipulation of the data stored in an WALKey, for example, printing
    * as JSON.
    *
    * @return a Map containing data from this key
    */
   public Map<String, Object> toStringMap() {
     Map<String, Object> stringMap = new HashMap<String, Object>();
     stringMap.put("table", tablename);
     stringMap.put("region", Bytes.toStringBinary(encodedRegionName));
     stringMap.put("sequence", logSeqNum);
     return stringMap;
   }
 
   @Override
   public boolean equals(Object obj) {
     if (this == obj) {
       return true;
     }
     if (obj == null || getClass() != obj.getClass()) {
       return false;
     }
     return compareTo((WALKey)obj) == 0;
   }
 
   @Override
   public int hashCode() {
     int result = Bytes.hashCode(this.encodedRegionName);
     result = (int) (result ^ this.logSeqNum);
     result = (int) (result ^ this.writeTime);
     return result;
   }
 
   @Override
   public int compareTo(WALKey o) {
     int result = Bytes.compareTo(this.encodedRegionName, o.encodedRegionName);
     if (result == 0) {
       if (this.logSeqNum < o.logSeqNum) {
         result = -1;
       } else if (this.logSeqNum  > o.logSeqNum) {
         result = 1;
       }
       if (result == 0) {
         if (this.writeTime < o.writeTime) {
           result = -1;
         } else if (this.writeTime > o.writeTime) {
           return 1;
         }
       }
     }
     // why isn't cluster id accounted for?
     return result;
   }
 
   /**
    * Drop this instance's tablename byte array and instead
    * hold a reference to the provided tablename. This is not
    * meant to be a general purpose setter - it's only used
    * to collapse references to conserve memory.
    */
   void internTableName(TableName tablename) {
     // We should not use this as a setter - only to swap
     // in a new reference to the same table name.
     assert tablename.equals(this.tablename);
     this.tablename = tablename;
   }
 
   /**
    * Drop this instance's region name byte array and instead
    * hold a reference to the provided region name. This is not
    * meant to be a general purpose setter - it's only used
    * to collapse references to conserve memory.
    */
   void internEncodedRegionName(byte []encodedRegionName) {
     // We should not use this as a setter - only to swap
     // in a new reference to the same table name.
     assert Bytes.equals(this.encodedRegionName, encodedRegionName);
     this.encodedRegionName = encodedRegionName;
   }
 
   public org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey.Builder getBuilder(
       WALCellCodec.ByteStringCompressor compressor) throws IOException {
     org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey.Builder builder =
         org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey.newBuilder();
     if (compressionContext == null) {
       builder.setEncodedRegionName(ByteStringer.wrap(this.encodedRegionName));
       builder.setTableName(ByteStringer.wrap(this.tablename.getName()));
     } else {
       builder.setEncodedRegionName(compressor.compress(this.encodedRegionName,
           compressionContext.regionDict));
       builder.setTableName(compressor.compress(this.tablename.getName(),
           compressionContext.tableDict));
     }
     builder.setLogSequenceNumber(this.logSeqNum);
     builder.setWriteTime(writeTime);
     if (this.origLogSeqNum > 0) {
       builder.setOrigSequenceNumber(this.origLogSeqNum);
     }
     if (this.nonce != HConstants.NO_NONCE) {
       builder.setNonce(nonce);
     }
     if (this.nonceGroup != HConstants.NO_NONCE) {
       builder.setNonceGroup(nonceGroup);
     }
     HBaseProtos.UUID.Builder uuidBuilder = HBaseProtos.UUID.newBuilder();
     for (UUID clusterId : clusterIds) {
       uuidBuilder.setLeastSigBits(clusterId.getLeastSignificantBits());
       uuidBuilder.setMostSigBits(clusterId.getMostSignificantBits());
       builder.addClusterIds(uuidBuilder.build());
     }
     if (scopes != null) {
       for (Map.Entry<byte[], Integer> e : scopes.entrySet()) {
         ByteString family = (compressionContext == null) ? ByteStringer.wrap(e.getKey())
             : compressor.compress(e.getKey(), compressionContext.familyDict);
         builder.addScopes(FamilyScope.newBuilder()
             .setFamily(family).setScopeType(ScopeType.valueOf(e.getValue())));
       }
     }
     return builder;
   }
 
   public void readFieldsFromPb(org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey walKey,
                                WALCellCodec.ByteStringUncompressor uncompressor)
       throws IOException {
     if (this.compressionContext != null) {
       this.encodedRegionName = uncompressor.uncompress(
           walKey.getEncodedRegionName(), compressionContext.regionDict);
       byte[] tablenameBytes = uncompressor.uncompress(
           walKey.getTableName(), compressionContext.tableDict);
       this.tablename = TableName.valueOf(tablenameBytes);
     } else {
       this.encodedRegionName = walKey.getEncodedRegionName().toByteArray();
       this.tablename = TableName.valueOf(walKey.getTableName().toByteArray());
     }
     clusterIds.clear();
     if (walKey.hasClusterId()) {
       //When we are reading the older log (0.95.1 release)
       //This is definitely the originating cluster
       clusterIds.add(new UUID(walKey.getClusterId().getMostSigBits(), walKey.getClusterId()
           .getLeastSigBits()));
     }
     for (HBaseProtos.UUID clusterId : walKey.getClusterIdsList()) {
       clusterIds.add(new UUID(clusterId.getMostSigBits(), clusterId.getLeastSigBits()));
     }
     if (walKey.hasNonceGroup()) {
       this.nonceGroup = walKey.getNonceGroup();
     }
     if (walKey.hasNonce()) {
       this.nonce = walKey.getNonce();
     }
     this.scopes = null;
     if (walKey.getScopesCount() > 0) {
       this.scopes = new TreeMap<byte[], Integer>(Bytes.BYTES_COMPARATOR);
       for (FamilyScope scope : walKey.getScopesList()) {
         byte[] family = (compressionContext == null) ? scope.getFamily().toByteArray() :
           uncompressor.uncompress(scope.getFamily(), compressionContext.familyDict);
         this.scopes.put(family, scope.getScopeType().getNumber());
       }
     }
     this.logSeqNum = walKey.getLogSequenceNumber();
     this.writeTime = walKey.getWriteTime();
     if(walKey.hasOrigSequenceNumber()) {
       this.origLogSeqNum = walKey.getOrigSequenceNumber();
     }
   }
 
   public long estimatedSerializedSizeOf() {
     long size = encodedRegionName != null ? encodedRegionName.length : 0;
     size += tablename != null ? tablename.toBytes().length : 0;
     if (clusterIds != null) {
       size += 16 * clusterIds.size();
     }
     if (nonceGroup != HConstants.NO_NONCE) {
       size += Bytes.SIZEOF_LONG; // nonce group
     }
     if (nonce != HConstants.NO_NONCE) {
       size += Bytes.SIZEOF_LONG; // nonce
     }
     if (scopes != null) {
       for (Map.Entry<byte[], Integer> scope: scopes.entrySet()) {
         size += scope.getKey().length;
         size += Bytes.SIZEOF_INT;
       }
     }
     size += Bytes.SIZEOF_LONG; // sequence number
     size += Bytes.SIZEOF_LONG; // write time
     if (origLogSeqNum > 0) {
       size += Bytes.SIZEOF_LONG; // original sequence number
     }
     return size;
   }
 }