/// <summary>
/// Create a Data Block and obtain an output stream for adding data into the
/// block.
/// </summary>
/// <remarks>
/// Create a Data Block and obtain an output stream for adding data into the
/// block. There can only be one BlockAppender stream active at any time.
/// Data Blocks may not be created after the first Meta Blocks. The caller
/// must call BlockAppender.close() to conclude the block creation.
/// </remarks>
/// <returns>The BlockAppender stream</returns>
/// <exception cref="System.IO.IOException"/>
public virtual BCFile.Writer.BlockAppender PrepareDataBlock()
{
if (blkInProgress == true)
{
throw new InvalidOperationException("Cannot create Data Block until previous block is closed."
);
}
if (metaBlkSeen == true)
{
throw new InvalidOperationException("Cannot create Data Block after Meta Blocks."
);
}
BCFile.Writer.DataBlockRegister dbr = new BCFile.Writer.DataBlockRegister(this);
BCFile.Writer.WBlockState wbs = new BCFile.Writer.WBlockState(GetDefaultCompressionAlgorithm
(), @out, fsOutputBuffer, conf);
BCFile.Writer.BlockAppender ba = new BCFile.Writer.BlockAppender(this, dbr, wbs);
blkInProgress = true;
return(ba);
}
/// <exception cref="System.IO.IOException"/>
/// <exception cref="Org.Apache.Hadoop.IO.File.Tfile.MetaBlockAlreadyExists"/>
private BCFile.Writer.BlockAppender PrepareMetaBlock(string name, Compression.Algorithm
compressAlgo)
{
if (blkInProgress == true)
{
throw new InvalidOperationException("Cannot create Meta Block until previous block is closed."
);
}
if (metaIndex.GetMetaByName(name) != null)
{
throw new MetaBlockAlreadyExists("name=" + name);
}
BCFile.Writer.MetaBlockRegister mbr = new BCFile.Writer.MetaBlockRegister(this, name
, compressAlgo);
BCFile.Writer.WBlockState wbs = new BCFile.Writer.WBlockState(compressAlgo, @out,
fsOutputBuffer, conf);
BCFile.Writer.BlockAppender ba = new BCFile.Writer.BlockAppender(this, mbr, wbs);
blkInProgress = true;
metaBlkSeen = true;
return(ba);
}
/// <summary>Close the BCFile Writer.</summary>
/// <remarks>
/// Close the BCFile Writer. Attempting to use the Writer after calling
/// <code>close</code> is not allowed and may lead to undetermined results.
/// </remarks>
/// <exception cref="System.IO.IOException"/>
public virtual void Close()
{
if (closed == true)
{
return;
}
try
{
if (errorCount == 0)
{
if (blkInProgress == true)
{
throw new InvalidOperationException("Close() called with active block appender.");
}
// add metaBCFileIndex to metaIndex as the last meta block
BCFile.Writer.BlockAppender appender = PrepareMetaBlock(BCFile.DataIndex.BlockName
, GetDefaultCompressionAlgorithm());
try
{
dataIndex.Write(appender);
}
finally
{
appender.Close();
}
long offsetIndexMeta = @out.GetPos();
metaIndex.Write(@out);
// Meta Index and the trailing section are written out directly.
@out.WriteLong(offsetIndexMeta);
ApiVersion.Write(@out);
BCFile.Magic.Write(@out);
@out.Flush();
}
}
finally
{
closed = true;
}
}
