/// <summary>
/// Create a new table builder.
/// - storageOptions define the options for the table buildup.
/// - dataStream is where the data for the table will be written to.
/// REQUIRES: Being able to read dataStream.Position
/// - tempStream is where temporary data is written to avoid holding too much in memory
/// REQUIRES: Being able to read tempStream.Position AND change tempStream.Position
/// </summary>
public TableBuilder(StorageState storageState,
Stream dataStream,
TemporaryFiles temporaryFiles)
{
_temporaryFiles = temporaryFiles;
try
{
_storageState = storageState;
_dataStream = dataStream;
_indexStream = temporaryFiles.Create();
_originalIndexStreamPosition = _indexStream.Position;
_lastKeyBuffer = _storageState.Options.BufferPool.Take(storageState.Options.MaximumExpectedKeySize);
_scratchBuffer = _storageState.Options.BufferPool.Take(storageState.Options.MaximumExpectedKeySize);
if (storageState.Options.FilterPolicy != null)
{
var filterBuilder = storageState.Options.FilterPolicy.CreateBuilder();
_filterBlockStream = temporaryFiles.Create();
_filterBuilder = new FilterBlockBuilder(_filterBlockStream, filterBuilder);
_filterBuilder.StartBlock(0);
}
_indexBlock = new BlockBuilder(_indexStream, storageState, _storageState.InternalKeyComparator,
blockRestartInterval: 1);
_dataBlock = new BlockBuilder(_dataStream, storageState, _storageState.InternalKeyComparator, _storageState.Options.BlockRestartInterval);
}
catch (Exception)
{
Dispose();
throw;
}
}
public void Finish()
{
Flush();
_closed = true;
BlockHandle filterBlockHandle = null;
//write filter block
if (_filterBuilder != null)
filterBlockHandle = _filterBuilder.Finish(_dataStream);
// write metadata block
var metaIndexBlock = new BlockBuilder(_dataStream, _storageState, _storageState.InternalKeyComparator, _storageState.Options.BlockRestartInterval);
if (filterBlockHandle != null)
{
metaIndexBlock.Add(("filter." + _storageState.Options.FilterPolicy.Name), filterBlockHandle.AsStream());
}
var metadIndexBlockHandle = WriteBlock(metaIndexBlock);
// write index block
if (_pendingIndexEntry)
{
var newKey = _storageState.InternalKeyComparator.FindShortestSuccessor(_lastKey, ref _scratchBuffer);
_indexBlock.Add(newKey, _pendingHandle.AsStream());
_pendingIndexEntry = false;
}
var indexBlockSize = _indexBlock.Finish();
_indexBlock.Stream.WriteByte(0);//write type, uncompressed
_indexBlock.Stream.WriteInt32(Crc.Mask(_indexBlock.Stream.WriteCrc));
_indexBlock.Stream.Position = _originalIndexStreamPosition;
var indexBlockHandler = new BlockHandle
{
Position = _dataStream.Position,
Count = indexBlockSize
};
_indexBlock.Stream.Stream.CopyTo(_dataStream);
// write footer
var footer = new Footer
{
IndexHandle = indexBlockHandler,
MetaIndexHandle = metadIndexBlockHandle
};
footer.EncodeTo(_dataStream);
}
private BlockHandle WriteBlock(BlockBuilder block)
{
// File format contains a sequence of blocks where each block has:
// block_data: uint8[n]
// type: uint8 - right now always uncompressed
// crc: uint32
var size = block.Finish();
var originalPosition = block.OriginalPosition;
var handle = new BlockHandle
{
Count = size,
Position = originalPosition
};
// write trailer
block.Stream.WriteByte(0); // type - uncompressed
_dataStream.WriteInt32(Crc.Mask(block.Stream.WriteCrc));
block.Dispose();
return handle;
}
/// <summary>
/// Advance: Forces the creation of a new block.
/// Client code should probably not call this method
/// </summary>
public void Flush()
{
if (_dataBlock.IsEmpty)
return;
if (_closed)
throw new InvalidOperationException("Cannot add after the table builder was closed");
if (_pendingIndexEntry)
throw new InvalidOperationException("Cannot call Flush when pending for an index entry");
_pendingHandle = WriteBlock(_dataBlock);
_dataBlock = new BlockBuilder(_dataStream, _storageState, _storageState.InternalKeyComparator, _storageState.Options.BlockRestartInterval);
_pendingIndexEntry = true;
_dataStream.Flush();
if (_filterBuilder != null)
_filterBuilder.StartBlock(_dataStream.Position);
}