Revert "Revert "HBASE-23705 Add CellComparator to HFileContext (#1062)""

Revert of a revert, i.e., putting this patch back.

This reverts commit f4b0ad9.

hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparator.java

@@ -17,8 +17,9 @@
  */
 package org.apache.hadoop.hbase;
 
+import java.nio.ByteBuffer;
 import java.util.Comparator;
-
+import org.apache.hadoop.hbase.util.ByteBufferUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.yetus.audience.InterfaceStability;
 
@@ -31,11 +32,12 @@
 public interface CellComparator extends Comparator<Cell> {
   /**
    * A comparator for ordering cells in user-space tables. Useful when writing cells in sorted
-   * order as necessary for bulk import (i.e. via MapReduce)
+   * order as necessary for bulk import (i.e. via MapReduce).
    * <p>
    * CAUTION: This comparator may provide inaccurate ordering for cells from system tables,
    * and should not be relied upon in that case.
    */
+  // For internal use, see CellComparatorImpl utility methods.
   static CellComparator getInstance() {
     return CellComparatorImpl.COMPARATOR;
   }
@@ -80,6 +82,24 @@ static CellComparator getInstance() {
    */
   int compareRows(Cell cell, byte[] bytes, int offset, int length);
 
+  /**
+   * @param row ByteBuffer that wraps a row; will read from current position and will reading all
+   *            remaining; will not disturb the ByteBuffer internal state.
+   * @return greater than 0 if leftCell is bigger, less than 0 if rightCell is bigger, 0 if both
+   *         cells are equal
+   */
+  default int compareRows(ByteBuffer row, Cell cell) {
+    if (cell instanceof ByteBufferExtendedCell) {
+      return ByteBufferUtils.compareTo(row, row.position(), row.remaining(),
+        ((ByteBufferExtendedCell) cell).getRowByteBuffer(),
+        ((ByteBufferExtendedCell) cell).getRowPosition(),
+        cell.getRowLength());
+    }
+    return ByteBufferUtils.compareTo(row, row.position(), row.remaining(),
+      cell.getRowArray(), cell.getRowOffset(),
+      cell.getRowLength());
+  }
+
   /**
    * Lexographically compares the two cells excluding the row part. It compares family, qualifier,
    * timestamp and the type

hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparatorImpl.java

@@ -17,16 +17,15 @@
  */
 package org.apache.hadoop.hbase;
 
+import java.nio.ByteBuffer;
 import java.util.Comparator;
-
 import org.apache.hadoop.hbase.KeyValue.Type;
 import org.apache.hadoop.hbase.util.ByteBufferUtils;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.yetus.audience.InterfaceStability;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.apache.hbase.thirdparty.com.google.common.primitives.Longs;
 
 /**
@@ -377,6 +376,26 @@ private static int compareRows(byte[] left, int loffset, int llength, byte[] rig
       return result;
     }
 
+    @Override
+    public int compareRows(ByteBuffer row, Cell cell) {
+      byte [] array;
+      int offset;
+      int len = row.remaining();
+      if (row.hasArray()) {
+        array = row.array();
+        offset = row.position() + row.arrayOffset();
+      } else {
+        // We copy the row array if offheap just so we can do a compare. We do this elsewhere too
+        // in BBUtils when Cell is backed by an offheap ByteBuffer. Needs fixing so no copy. TODO.
+        array = new byte[len];
+        offset = 0;
+        ByteBufferUtils.copyFromBufferToArray(array, row, row.position(),
+          0, len);
+      }
+      // Reverse result since we swap the order of the params we pass below.
+      return -compareRows(cell, array, offset, len);
+    }
+
     @Override
     public Comparator getSimpleComparator() {
       return this;
@@ -387,4 +406,24 @@ public Comparator getSimpleComparator() {
   public Comparator getSimpleComparator() {
     return new BBKVComparator(this);
   }
+
+  /**
+   * Utility method that makes a guess at comparator to use based off passed tableName.
+   * Use in extreme when no comparator specified.
+   * @return CellComparator to use going off the {@code tableName} passed.
+   */
+  public static CellComparator getCellComparator(TableName tableName) {
+    return getCellComparator(tableName.toBytes());
+  }
+
+  /**
+   * Utility method that makes a guess at comparator to use based off passed tableName.
+   * Use in extreme when no comparator specified.
+   * @return CellComparator to use going off the {@code tableName} passed.
+   */
+  public static CellComparator getCellComparator(byte [] tableName) {
+    // FYI, TableName.toBytes does not create an array; just returns existing array pointer.
+    return Bytes.equals(tableName, TableName.META_TABLE_NAME.toBytes())?
+      CellComparatorImpl.META_COMPARATOR: CellComparatorImpl.COMPARATOR;
+  }
 }

hbase-common/src/main/java/org/apache/hadoop/hbase/TableName.java

@@ -286,6 +286,9 @@ public String getQualifierAsString() {
     return qualifierAsString;
   }
 
+  /**
+   * @return A pointer to TableName as String bytes.
+   */
   public byte[] toBytes() {
     return name;
   }

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/AbstractDataBlockEncoder.java

@@ -18,10 +18,8 @@
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
-
 import org.apache.hadoop.hbase.ByteBufferKeyOnlyKeyValue;
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.CellComparator;
 import org.apache.hadoop.hbase.KeyValue;
 import org.apache.hadoop.hbase.io.hfile.BlockType;
 import org.apache.hadoop.hbase.io.hfile.HFileContext;
@@ -59,14 +57,13 @@ protected Cell createFirstKeyCell(ByteBuffer key, int keyLength) {
     }
   }
 
-  protected abstract static class AbstractEncodedSeeker implements
-      EncodedSeeker {
+  /**
+   * Decorates EncodedSeeker with a {@link HFileBlockDecodingContext}
+   */
+  protected abstract static class AbstractEncodedSeeker implements EncodedSeeker {
     protected HFileBlockDecodingContext decodingCtx;
-    protected final CellComparator comparator;
 
-    public AbstractEncodedSeeker(CellComparator comparator,
-        HFileBlockDecodingContext decodingCtx) {
-      this.comparator = comparator;
+    public AbstractEncodedSeeker(HFileBlockDecodingContext decodingCtx) {
       this.decodingCtx = decodingCtx;
     }
 
@@ -77,7 +74,5 @@ protected boolean includesMvcc() {
     protected boolean includesTags() {
       return this.decodingCtx.getHFileContext().isIncludesTags();
     }
-
   }
-
 }

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/BufferedDataBlockEncoder.java

@@ -732,9 +732,8 @@ protected abstract static class BufferedEncodedSeeker<STATE extends SeekerState>
     protected final ObjectIntPair<ByteBuffer> tmpPair = new ObjectIntPair<>();
     protected STATE current, previous;
 
-    public BufferedEncodedSeeker(CellComparator comparator,
-        HFileBlockDecodingContext decodingCtx) {
-      super(comparator, decodingCtx);
+    public BufferedEncodedSeeker(HFileBlockDecodingContext decodingCtx) {
+      super(decodingCtx);
       if (decodingCtx.getHFileContext().isCompressTags()) {
         try {
           tagCompressionContext = new TagCompressionContext(LRUDictionary.class, Byte.MAX_VALUE);
@@ -1008,11 +1007,7 @@ protected STATE createSeekerState() {
   }
 
   /**
-   * @param cell
-   * @param out
-   * @param encodingCtx
    * @return unencoded size added
-   * @throws IOException
    */
   protected final int afterEncodingKeyValue(Cell cell, DataOutputStream out,
       HFileBlockDefaultEncodingContext encodingCtx) throws IOException {
@@ -1102,7 +1097,7 @@ protected static void ensureSpace(ByteBuffer out, int length)
   public void startBlockEncoding(HFileBlockEncodingContext blkEncodingCtx, DataOutputStream out)
       throws IOException {
     if (blkEncodingCtx.getClass() != HFileBlockDefaultEncodingContext.class) {
-      throw new IOException (this.getClass().getName() + " only accepts "
+      throw new IOException(this.getClass().getName() + " only accepts "
           + HFileBlockDefaultEncodingContext.class.getName() + " as the " +
           "encoding context.");
     }
@@ -1154,8 +1149,8 @@ public void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputSt
         .getEncodingState();
     // Write the unencodedDataSizeWritten (with header size)
     Bytes.putInt(uncompressedBytesWithHeader,
-      HConstants.HFILEBLOCK_HEADER_SIZE + DataBlockEncoding.ID_SIZE, state.unencodedDataSizeWritten
-        );
+      HConstants.HFILEBLOCK_HEADER_SIZE + DataBlockEncoding.ID_SIZE,
+      state.unencodedDataSizeWritten);
     postEncoding(encodingCtx);
   }
 

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/CopyKeyDataBlockEncoder.java

@@ -20,9 +20,7 @@
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.CellComparator;
 import org.apache.hadoop.hbase.nio.ByteBuff;
 import org.apache.hadoop.hbase.util.ByteBufferUtils;
 import org.apache.hadoop.hbase.util.Bytes;
@@ -48,7 +46,8 @@ public void startBlockEncoding(HFileBlockEncodingContext blkEncodingCtx,
           + "encoding context.");
     }
 
-    HFileBlockDefaultEncodingContext encodingCtx = (HFileBlockDefaultEncodingContext) blkEncodingCtx;
+    HFileBlockDefaultEncodingContext encodingCtx =
+      (HFileBlockDefaultEncodingContext) blkEncodingCtx;
     encodingCtx.prepareEncoding(out);
 
     NoneEncoder encoder = new NoneEncoder(out, encodingCtx);
@@ -81,9 +80,8 @@ public String toString() {
   }
 
   @Override
-  public EncodedSeeker createSeeker(CellComparator comparator,
-      final HFileBlockDecodingContext decodingCtx) {
-    return new BufferedEncodedSeeker<SeekerState>(comparator, decodingCtx) {
+  public EncodedSeeker createSeeker(final HFileBlockDecodingContext decodingCtx) {
+    return new BufferedEncodedSeeker<SeekerState>(decodingCtx) {
       @Override
       protected void decodeNext() {
         current.keyLength = currentBuffer.getInt();

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoder.java

@@ -20,7 +20,6 @@
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-
 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.CellComparator;
 import org.apache.hadoop.hbase.io.hfile.HFileContext;
@@ -45,39 +44,27 @@ public interface DataBlockEncoder {
    * Starts encoding for a block of KeyValues. Call
    * {@link #endBlockEncoding(HFileBlockEncodingContext, DataOutputStream, byte[])} to finish
    * encoding of a block.
-   * @param encodingCtx
-   * @param out
-   * @throws IOException
    */
   void startBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out)
       throws IOException;
 
   /**
    * Encodes a KeyValue.
-   * @param cell
-   * @param encodingCtx
-   * @param out
    * @return unencoded kv size written
-   * @throws IOException
    */
   int encode(Cell cell, HFileBlockEncodingContext encodingCtx, DataOutputStream out)
       throws IOException;
 
   /**
    * Ends encoding for a block of KeyValues. Gives a chance for the encoder to do the finishing
    * stuff for the encoded block. It must be called at the end of block encoding.
-   * @param encodingCtx
-   * @param out
-   * @param uncompressedBytesWithHeader
-   * @throws IOException
    */
   void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out,
       byte[] uncompressedBytesWithHeader) throws IOException;
 
   /**
    * Decode.
    * @param source Compressed stream of KeyValues.
-   * @param decodingCtx
    * @return Uncompressed block of KeyValues.
    * @throws IOException If there is an error in source.
    */
@@ -96,11 +83,9 @@ ByteBuffer decodeKeyValues(DataInputStream source, HFileBlockDecodingContext dec
 
   /**
    * Create a HFileBlock seeker which find KeyValues within a block.
-   * @param comparator what kind of comparison should be used
-   * @param decodingCtx
    * @return A newly created seeker.
    */
-  EncodedSeeker createSeeker(CellComparator comparator, HFileBlockDecodingContext decodingCtx);
+  EncodedSeeker createSeeker(HFileBlockDecodingContext decodingCtx);
 
   /**
    * Creates a encoder specific encoding context
@@ -188,8 +173,6 @@ interface EncodedSeeker {
 
     /**
      * Compare the given key against the current key
-     * @param comparator
-     * @param key
      * @return -1 is the passed key is smaller than the current key, 0 if equal and 1 if greater
      */
     public int compareKey(CellComparator comparator, Cell key);

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/DiffKeyDeltaEncoder.java

@@ -20,9 +20,7 @@
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.CellComparator;
 import org.apache.hadoop.hbase.KeyValue;
 import org.apache.hadoop.hbase.KeyValueUtil;
 import org.apache.hadoop.hbase.PrivateCellUtil;
@@ -382,9 +380,8 @@ protected void copyFromNext(SeekerState that) {
   }
 
   @Override
-  public EncodedSeeker createSeeker(CellComparator comparator,
-      HFileBlockDecodingContext decodingCtx) {
-    return new BufferedEncodedSeeker<DiffSeekerState>(comparator, decodingCtx) {
+  public EncodedSeeker createSeeker(HFileBlockDecodingContext decodingCtx) {
+    return new BufferedEncodedSeeker<DiffSeekerState>(decodingCtx) {
       private byte[] familyNameWithSize;
       private static final int TIMESTAMP_WITH_TYPE_LENGTH =
           Bytes.SIZEOF_LONG + Bytes.SIZEOF_BYTE;

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/FastDiffDeltaEncoder.java

@@ -21,9 +21,7 @@
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.CellComparator;
 import org.apache.hadoop.hbase.KeyValue;
 import org.apache.hadoop.hbase.KeyValueUtil;
 import org.apache.hadoop.hbase.PrivateCellUtil;
@@ -397,9 +395,8 @@ protected void copyFromNext(SeekerState that) {
   }
 
   @Override
-  public EncodedSeeker createSeeker(CellComparator comparator,
-      final HFileBlockDecodingContext decodingCtx) {
-    return new BufferedEncodedSeeker<FastDiffSeekerState>(comparator, decodingCtx) {
+  public EncodedSeeker createSeeker(final HFileBlockDecodingContext decodingCtx) {
+    return new BufferedEncodedSeeker<FastDiffSeekerState>(decodingCtx) {
       private void decode(boolean isFirst) {
         byte flag = currentBuffer.get();
         if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {

hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/HFileBlockDecodingContext.java

@@ -17,20 +17,18 @@
 package org.apache.hadoop.hbase.io.encoding;
 
 import java.io.IOException;
-
 import org.apache.hadoop.hbase.io.hfile.HFileContext;
 import org.apache.hadoop.hbase.nio.ByteBuff;
 import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * A decoding context that is created by a reader's encoder, and is shared
- * across the reader's all read operations.
+ * across all of the reader's read operations.
  *
  * @see HFileBlockEncodingContext for encoding
  */
 @InterfaceAudience.Private
 public interface HFileBlockDecodingContext {
-
   /**
    * Perform all actions that need to be done before the encoder's real decoding
    * process. Decompression needs to be done if
@@ -46,7 +44,6 @@ public interface HFileBlockDecodingContext {
    *          ByteBuffer pointed after the header but before the data
    * @param onDiskBlock
    *          on disk data to be decoded
-   * @throws IOException
    */
   void prepareDecoding(
     int onDiskSizeWithoutHeader,