/// <summary>
/// Copies compressed contents from <paramref name="source"/> into the <paramref name="target"/> from the <paramref name="targetOffset"/>
/// </summary>
/// <param name="target">The <see cref="ByteBuffer"/> that will be written to.</param>
/// <param name="source">The source <see cref="ByteBuffer"/> to read the data from.</param>
/// <param name="targetOffset">The <paramref name="target"/> buffer's offset to start writing from.</param>
/// <returns>The number of bytes written.</returns>
public static int CompressedCopy(this ByteBuffer target, ByteBuffer source, int targetOffset)
{
byte[] compressed;
using (var ms = new MemoryStream(source.ToArray()))
{
compressed = Compress(ms);
}
target.BlockCopy(compressed, 0, targetOffset, compressed.Length);
return compressed.Length;
}
/// <summary>
/// Construct a new histogram by decoding it from a compressed form in a ByteBuffer.
/// </summary>
/// <param name="buffer">The buffer to decode from</param>
/// <param name="minBarForHighestTrackableValue">Force highestTrackableValue to be set at least this high</param>
/// <returns>The newly constructed histogram</returns>
public static HistogramBase DecodeFromCompressedByteBuffer(ByteBuffer buffer, long minBarForHighestTrackableValue)
{
var cookie = buffer.GetInt();
var headerSize = GetHeaderSize(cookie);
var lengthOfCompressedContents = buffer.GetInt();
HistogramBase histogram;
//Skip the first two bytes (from the RFC 1950 specification) and move to the deflate specification (RFC 1951)
// http://george.chiramattel.com/blog/2007/09/deflatestream-block-length-does-not-match.html
using (var inputStream = new MemoryStream(buffer.ToArray(), buffer.Position + Rfc1950HeaderLength, lengthOfCompressedContents - Rfc1950HeaderLength))
using (var decompressor = new DeflateStream(inputStream, CompressionMode.Decompress, leaveOpen: true))
{
var headerBuffer = ByteBuffer.Allocate(headerSize);
headerBuffer.ReadFrom(decompressor, headerSize);
histogram = DecodeFromByteBuffer(headerBuffer, minBarForHighestTrackableValue, decompressor);
}
return histogram;
}
