/// <summary>
/// Create an encoder with the target initial buffer size.
/// </summary>
/// <param name="compress">True to compress collated data.</param>
/// <param name="initialBufferSize">The initial buffer size (bytes).</param>
public CollatedPacketEncoder(bool compress, int initialBufferSize = 64 * 1024)
{
CollatedBytes = 0;
_collationStream = _dataStream = new CompressionBuffer(initialBufferSize);
_packet = new PacketBuffer();
// Prime the output stream, writing the initial header.
PacketHeader header = PacketHeader.Create((ushort)RoutingID.CollatedPacket, 0);
CollatedPacketMessage msg = new CollatedPacketMessage();
msg.Flags = (ushort)((compress) ? CollatedPacketFlag.GZipCompressed : 0u);
msg.Reserved = 0;
msg.UncompressedBytes = 0;
NetworkWriter writer = new NetworkWriter(_dataStream);
header.Write(writer);
msg.Write(writer);
_resetPosition = (int)_dataStream.Position;
CompressionEnabled = compress;
if (compress)
{
_collationStream = new GZipStream(_dataStream, CompressionMode.Compress, CompressionLevel.BestCompression);
}
}
/// <summary>
/// Finalise the collated packet before sending.
/// </summary>
/// <returns>True on successful finalisation, false if already finalised</returns>
public bool FinaliseEncoding()
{
if (_finalised)
{
return(false);
}
bool compressionSuccess = false;
if (CompressionEnabled)
{
// Compress the raw buffer into the compression buffer then validate it's smaller.
_finalisedBuffer.Position = 0;
// First write the standard header for this buffer.
// Prime the output stream, writing the initial header.
PacketHeader header = PacketHeader.Create((ushort)RoutingID.CollatedPacket, 0);
CollatedPacketMessage msg = new CollatedPacketMessage();
msg.Flags = (ushort)CollatedPacketFlag.GZipCompressed;
msg.Reserved = 0;
msg.UncompressedBytes = 0;
NetworkWriter writer = new NetworkWriter(_finalisedBuffer);
header.Write(writer);
msg.Write(writer);
int overhead = (int)_finalisedBuffer.Position;
// Now compress the collated packets.
GZipStream compressionStream = new GZipStream(_finalisedBuffer, CompressionLevel.Fastest);
compressionStream.Write(_collationBuffer.GetBuffer(), 0, (int)_collationBuffer.Position);
compressionStream.Close();
if (_finalisedBuffer.Position < _collationBuffer.Position + overhead)
{
// The compressed data are smaller, so we accept it.
SetPayloadSize((ushort)(Count - PacketHeader.Size));
// Update the payload and uncompressed sizes.
SetUncompressedBytesSize((ushort)CollatedBytes);
compressionSuccess = true;
}
}
if (!compressionSuccess)
{
// No compression or compression failed to reduce the data size. Write header then copy wrap packets.
PacketHeader header = PacketHeader.Create((ushort)RoutingID.CollatedPacket, 0);
_finalisedBuffer.Position = 0;
CollatedPacketMessage msg = new CollatedPacketMessage();
msg.Flags = 0;
msg.Reserved = 0;
msg.UncompressedBytes = 0;
NetworkWriter writer = new NetworkWriter(_finalisedBuffer);
header.Write(writer);
msg.Write(writer);
_finalisedBuffer.Write(_collationBuffer.GetBuffer(), 0, (int)_collationBuffer.Position);
// The compressed data are smaller, so we accept it.
SetPayloadSize((ushort)(Count - PacketHeader.Size));
// Update the payload and uncompressed sizes.
SetUncompressedBytesSize((ushort)CollatedBytes);
}
// Calculate the CRC
ushort crc = Crc16.Crc.Calculate(_finalisedBuffer.GetBuffer(), (uint)_finalisedBuffer.Position);
new NetworkWriter(_finalisedBuffer).Write(crc);
_finalised = true;
return(true);
}