finish io

src/sp/extensions/Compress.cpp

@@ -0,0 +1,85 @@
+#include <sp/extensions/Compress.h>
+
+#include <cassert>
+#include <sp/common/VarInt.h>
+#include <zlib.h>
+
+namespace sp {
+namespace zlib {
+
+static DataBuffer Inflate(const std::uint8_t* source, std::size_t size, std::size_t uncompressedSize) {
+	DataBuffer result;
+	result.Resize(uncompressedSize);
+
+	uncompress(static_cast<Bytef*>(result.data()), reinterpret_cast<uLongf*>(&uncompressedSize), static_cast<const Bytef*>(source),
+		static_cast<uLong>(size));
+
+	assert(result.GetSize() == uncompressedSize);
+	return result;
+}
+
+static DataBuffer Deflate(const std::uint8_t* source, std::size_t size) {
+	DataBuffer result;
+	uLongf compressedSize = size;
+
+	result.Resize(size);  // Resize for the compressed data to fit into
+	compress(static_cast<Bytef*>(result.data()), &compressedSize, static_cast<const Bytef*>(source), static_cast<uLong>(size));
+	result.Resize(compressedSize);	// Resize to cut useless data
+
+	return result;
+}
+
+DataBuffer Compress(const DataBuffer& buffer, std::size_t a_CompressionThreshold) {
+	DataBuffer packet;
+
+	if (buffer.GetSize() < a_CompressionThreshold) {
+		// Don't compress since it's a small packet
+		packet << VarInt{0};
+		packet << buffer;
+		return packet;
+	}
+
+	DataBuffer compressedData = Deflate(buffer.data(), buffer.GetSize());
+	VarInt uncompressedDataLength = buffer.GetSize();
+
+	if (compressedData.GetSize() >= buffer.GetSize()) {
+		// the compression is overkill so we don't send the compressed buffer
+		packet << VarInt{0};
+		packet << buffer;
+	} else {
+		packet << uncompressedDataLength;
+		packet << compressedData;
+	}
+
+	return packet;
+}
+
+DataBuffer Decompress(DataBuffer& buffer, std::uint64_t packetLength) {
+	VarInt uncompressedLength;
+	buffer >> uncompressedLength;
+
+	std::uint64_t compressedLength = packetLength - uncompressedLength.GetSerializedLength();
+
+	if (uncompressedLength.GetValue() == 0) {
+		// Data already uncompressed. Nothing to do
+		DataBuffer ret;
+		buffer.ReadSome(ret, compressedLength);
+		return ret;
+	}
+
+	assert(buffer.GetReadOffset() + compressedLength <= buffer.GetSize());
+
+	return Inflate(buffer.data() + buffer.GetReadOffset(), compressedLength, uncompressedLength.GetValue());
+}
+
+}  // namespace zlib
+
+DataBuffer ZlibCompress::EncapsulateImpl(const DataBuffer& a_Data)  {
+	return zlib::Compress(a_Data, m_CompressionThreshold);
+}
+
+DataBuffer ZlibCompress::DecapsulateImpl(DataBuffer& a_Data) {
+	return zlib::Decompress(a_Data, a_Data.GetSize());
+}
+
+}  // namespace sp