HBASE-17757 Unify blocksize after encoding to decrease memory fragment

Signed-off-by: anoopsamjohn <anoopsamjohn@gmail.com>

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java

@@ -871,6 +871,10 @@ public class HFileBlock implements Cacheable {
     // includes the header size also.
     private int unencodedDataSizeWritten;
 
+    // Size of actual data being written. considering the block encoding. This
+    // includes the header size also.
+    private int encodedDataSizeWritten;
+
     /**
      * Bytes to be written to the file system, including the header. Compressed
      * if compression is turned on. It also includes the checksum data that
@@ -958,6 +962,7 @@ public class HFileBlock implements Cacheable {
         this.dataBlockEncoder.startBlockEncoding(dataBlockEncodingCtx, userDataStream);
       }
       this.unencodedDataSizeWritten = 0;
+      this.encodedDataSizeWritten = 0;
       return userDataStream;
     }
 
@@ -968,8 +973,10 @@ public class HFileBlock implements Cacheable {
      */
     void write(Cell cell) throws IOException{
       expectState(State.WRITING);
+      int posBeforeEncode = this.userDataStream.size();
       this.unencodedDataSizeWritten +=
           this.dataBlockEncoder.encode(cell, dataBlockEncodingCtx, this.userDataStream);
+      this.encodedDataSizeWritten += this.userDataStream.size() - posBeforeEncode;
     }
 
     /**
@@ -1197,6 +1204,19 @@ public class HFileBlock implements Cacheable {
       return state == State.WRITING;
     }
 
+    /**
+     * Returns the number of bytes written into the current block so far, or
+     * zero if not writing the block at the moment. Note that this will return
+     * zero in the "block ready" state as well.
+     *
+     * @return the number of bytes written
+     */
+    public int encodedBlockSizeWritten() {
+      if (state != State.WRITING)
+        return 0;
+      return this.encodedDataSizeWritten;
+    }
+
     /**
      * Returns the number of bytes written into the current block so far, or
      * zero if not writing the block at the moment. Note that this will return

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterImpl.java

@@ -63,6 +63,12 @@ public class HFileWriterImpl implements HFile.Writer {
 
   private static final long UNSET = -1;
 
+  /** if this feature is enabled, preCalculate encoded data size before real encoding happens*/
+  public static final String UNIFIED_ENCODED_BLOCKSIZE_RATIO = "hbase.writer.unified.encoded.blocksize.ratio";
+
+  /** Block size limit after encoding, used to unify encoded block Cache entry size*/
+  private final int encodedBlockSizeLimit;
+
   /** The Cell previously appended. Becomes the last cell in the file.*/
   protected Cell lastCell = null;
 
@@ -174,6 +180,8 @@ public class HFileWriterImpl implements HFile.Writer {
 
     closeOutputStream = path != null;
     this.cacheConf = cacheConf;
+    float encodeBlockSizeRatio = conf.getFloat(UNIFIED_ENCODED_BLOCKSIZE_RATIO, 1f);
+    this.encodedBlockSizeLimit = (int)(hFileContext.getBlocksize() * encodeBlockSizeRatio);
     finishInit(conf);
     if (LOG.isTraceEnabled()) {
       LOG.trace("Writer" + (path != null ? " for " + path : "") +
@@ -306,10 +314,14 @@ public class HFileWriterImpl implements HFile.Writer {
    * @throws IOException
    */
   protected void checkBlockBoundary() throws IOException {
-    if (blockWriter.blockSizeWritten() < hFileContext.getBlocksize()) return;
-    finishBlock();
-    writeInlineBlocks(false);
-    newBlock();
+    //for encoder like prefixTree, encoded size is not available, so we have to compare both encoded size
+    //and unencoded size to blocksize limit.
+    if (blockWriter.encodedBlockSizeWritten() >= encodedBlockSizeLimit
+        || blockWriter.blockSizeWritten() >= hFileContext.getBlocksize()) {
+      finishBlock();
+      writeInlineBlocks(false);
+      newBlock();
+    }
   }
 
   /** Clean up the data block that is currently being written.*/