1 files changed, 177 insertions, 168 deletions

diff --git a/src/StringCompression.cpp b/src/StringCompression.cpp
index ff434bbb1..6678fe1bd 100644
--- a/src/StringCompression.cpp
+++ b/src/StringCompression.cpp
@@ -1,242 +1,251 @@
 
 // StringCompression.cpp
 
-// Implements the wrapping functions for compression and decompression using AString as their data
+// Implements the wrapping functions for compression and decompression
 
 #include "Globals.h"
+#include "ByteBuffer.h"
 #include "StringCompression.h"
 
+#include <libdeflate.h>
 
 
 
 
-int CompressString(const char * a_Data, size_t a_Length, AString & a_Compressed, int a_Factor)
+
+std::string_view Compression::Result::GetStringView() const
 {
-	uLongf CompressedSize = compressBound(static_cast<uLong>(a_Length));
-
-	// HACK: We're assuming that AString returns its internal buffer in its data() call and we're overwriting that buffer!
-	// It saves us one allocation and one memcpy of the entire compressed data
-	// It may not work on some STL implementations! (Confirmed working on all currently used MSVC, GCC and Clang versions)
-	a_Compressed.resize(CompressedSize);
-	int errorcode = compress2(reinterpret_cast<Bytef *>(const_cast<char *>(a_Compressed.data())), &CompressedSize, reinterpret_cast<const Bytef *>(a_Data), static_cast<uLong>(a_Length), a_Factor);
-	if (errorcode != Z_OK)
+	const auto View = GetView();
+	return { reinterpret_cast<const char *>(View.data()), View.size() };
+}
+
+
+
+
+
+ContiguousByteBufferView Compression::Result::GetView() const
+{
+	// Get a generic std::byte * to what the variant is currently storing:
+	return
 	{
-		return errorcode;
-	}
-	a_Compressed.resize(CompressedSize);
-	return Z_OK;
+		std::visit([](const auto & Buffer) -> const std::byte *
+		{
+			using Variant = std::decay_t<decltype(Buffer)>;
+
+			if constexpr (std::is_same_v<Variant, Compression::Result::Static>)
+			{
+				return Buffer.data();
+			}
+			else
+			{
+				return Buffer.get();
+			}
+		}, Storage), Size
+	};
 }
 
 
 
 
 
-int UncompressString(const char * a_Data, size_t a_Length, AString & a_Uncompressed, size_t a_UncompressedSize)
+Compression::Compressor::Compressor(int CompressionFactor)
 {
-	// HACK: We're assuming that AString returns its internal buffer in its data() call and we're overwriting that buffer!
-	// It saves us one allocation and one memcpy of the entire compressed data
-	// It may not work on some STL implementations! (Confirmed working on all currently used MSVC, GCC and Clang versions)
-	a_Uncompressed.resize(a_UncompressedSize);
-	uLongf UncompressedSize = static_cast<uLongf>(a_UncompressedSize);  // On some architectures the uLongf is different in size to int, that may be the cause of the -5 error
-	int errorcode = uncompress(reinterpret_cast<Bytef *>(const_cast<char *>(a_Uncompressed.data())), &UncompressedSize, reinterpret_cast<const Bytef *>(a_Data), static_cast<uLong>(a_Length));
-	if (errorcode != Z_OK)
+	m_Handle = libdeflate_alloc_compressor(CompressionFactor);
+
+	if (m_Handle == nullptr)
 	{
-		return errorcode;
+		throw std::bad_alloc();
 	}
-	a_Uncompressed.resize(UncompressedSize);
-	return Z_OK;
 }
 
 
 
 
 
-int CompressStringGZIP(const char * a_Data, size_t a_Length, AString & a_Compressed)
+Compression::Compressor::~Compressor()
 {
-	// Compress a_Data into a_Compressed using GZIP; return Z_XXX error constants same as zlib's compress2()
+	libdeflate_free_compressor(m_Handle);
+}
+
+
 
-	a_Compressed.reserve(a_Length);
 
-	char Buffer[64 KiB];
-	z_stream strm;
-	memset(&strm, 0, sizeof(strm));
-	strm.next_in = reinterpret_cast<Bytef *>(const_cast<char *>(a_Data));
-	strm.avail_in = static_cast<uInt>(a_Length);
-	strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-	strm.avail_out = sizeof(Buffer);
 
-	int res = deflateInit2(&strm, 9, Z_DEFLATED, 31, 9, Z_DEFAULT_STRATEGY);
-	if (res != Z_OK)
+template <auto Algorithm>
+Compression::Result Compression::Compressor::Compress(const void * const Input, const size_t Size)
+{
+	// First see if the stack buffer has enough space:
 	{
-		LOG("%s: compression initialization failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-		return res;
+		Result::Static Buffer;
+		const auto BytesWrittenOut = Algorithm(m_Handle, Input, Size, Buffer.data(), Buffer.size());
+
+		if (BytesWrittenOut != 0)
+		{
+			return { Buffer, BytesWrittenOut };
+		}
 	}
 
-	for (;;)
+	// No it doesn't. Allocate space on the heap to write the compression result, increasing in powers of 2.
+	// This will either succeed, or except with bad_alloc.
+
+	auto DynamicCapacity = Result::StaticCapacity * 2;
+	while (true)
 	{
-		res = deflate(&strm, Z_FINISH);
-		switch (res)
+		auto Dynamic = cpp20::make_unique_for_overwrite<Result::Dynamic::element_type[]>(DynamicCapacity);
+		const auto BytesWrittenOut = Algorithm(m_Handle, Input, Size, Dynamic.get(), DynamicCapacity);
+
+		if (BytesWrittenOut != 0)
 		{
-			case Z_OK:
-			{
-				// Some data has been compressed. Consume the buffer and continue compressing
-				a_Compressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-				strm.avail_out = sizeof(Buffer);
-				if (strm.avail_in == 0)
-				{
-					// All data has been compressed
-					deflateEnd(&strm);
-					return Z_OK;
-				}
-				break;
-			}
+			return { std::move(Dynamic), BytesWrittenOut };
+		}
 
-			case Z_STREAM_END:
-			{
-				// Finished compressing. Consume the rest of the buffer and return
-				a_Compressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				deflateEnd(&strm);
-				return Z_OK;
-			}
+		DynamicCapacity *= 2;
+	}
+}
 
-			default:
-			{
-				// An error has occurred, log it and return the error value
-				LOG("%s: compression failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-				deflateEnd(&strm);
-				return res;
-			}
-		}  // switch (res)
-	}  // while (true)
+
+
+
+
+Compression::Result Compression::Compressor::CompressGZip(const ContiguousByteBufferView Input)
+{
+	return Compress<&libdeflate_gzip_compress>(Input.data(), Input.size());
 }
 
 
 
 
 
-extern int UncompressStringGZIP(const char * a_Data, size_t a_Length, AString & a_Uncompressed)
+Compression::Result Compression::Compressor::CompressZLib(const ContiguousByteBufferView Input)
 {
-	// Uncompresses a_Data into a_Uncompressed using GZIP; returns Z_OK for success or Z_XXX error constants same as zlib
+	return Compress<&libdeflate_zlib_compress>(Input.data(), Input.size());
+}
 
-	a_Uncompressed.reserve(a_Length);
 
-	char Buffer[64 KiB];
-	z_stream strm;
-	memset(&strm, 0, sizeof(strm));
-	strm.next_in = reinterpret_cast<Bytef *>(const_cast<char *>(a_Data));
-	strm.avail_in = static_cast<uInt>(a_Length);
-	strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-	strm.avail_out = sizeof(Buffer);
 
-	int res = inflateInit2(&strm, 31);  // Force GZIP decoding
-	if (res != Z_OK)
+
+
+Compression::Result Compression::Compressor::CompressZLib(const void * const Input, const size_t Size)
+{
+	return Compress<&libdeflate_zlib_compress>(Input, Size);
+}
+
+
+
+
+
+Compression::Extractor::Extractor()
+{
+	m_Handle = libdeflate_alloc_decompressor();
+
+	if (m_Handle == nullptr)
 	{
-		LOG("%s: uncompression initialization failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-		return res;
+		throw std::bad_alloc();
 	}
+}
 
-	for (;;)
-	{
-		res = inflate(&strm, Z_NO_FLUSH);
-		switch (res)
-		{
-			case Z_OK:
-			{
-				// Some data has been uncompressed. Consume the buffer and continue uncompressing
-				a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-				strm.avail_out = sizeof(Buffer);
-				if (strm.avail_in == 0)
-				{
-					// All data has been uncompressed
-					inflateEnd(&strm);
-					return Z_OK;
-				}
-				break;
-			}
 
-			case Z_STREAM_END:
-			{
-				// Finished uncompressing. Consume the rest of the buffer and return
-				a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				inflateEnd(&strm);
-				return Z_OK;
-			}
 
-			default:
-			{
-				// An error has occurred, log it and return the error value
-				LOG("%s: uncompression failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-				inflateEnd(&strm);
-				return res;
-			}
-		}  // switch (res)
-	}  // while (true)
+
+
+Compression::Extractor::~Extractor()
+{
+	libdeflate_free_decompressor(m_Handle);
+}
+
+
+
+
+
+Compression::Result Compression::Extractor::ExtractGZip(ContiguousByteBufferView Input)
+{
+	return Extract<&libdeflate_gzip_decompress>(Input);
+}
+
+
+
+
+
+Compression::Result Compression::Extractor::ExtractZLib(ContiguousByteBufferView Input)
+{
+	return Extract<&libdeflate_zlib_decompress>(Input);
 }
 
 
 
 
 
-extern int InflateString(const char * a_Data, size_t a_Length, AString & a_Uncompressed)
+Compression::Result Compression::Extractor::ExtractZLib(ContiguousByteBufferView Input, size_t UncompressedSize)
 {
-	a_Uncompressed.reserve(a_Length);
-
-	char Buffer[64 KiB];
-	z_stream strm;
-	memset(&strm, 0, sizeof(strm));
-	strm.next_in = reinterpret_cast<Bytef *>(const_cast<char *>(a_Data));
-	strm.avail_in = static_cast<uInt>(a_Length);
-	strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-	strm.avail_out = sizeof(Buffer);
-
-	int res = inflateInit(&strm);  // Force GZIP decoding
-	if (res != Z_OK)
+	return Extract<&libdeflate_zlib_decompress>(Input, UncompressedSize);
+}
+
+
+
+
+
+template <auto Algorithm>
+Compression::Result Compression::Extractor::Extract(const ContiguousByteBufferView Input)
+{
+	// First see if the stack buffer has enough space:
 	{
-		LOG("%s: inflation initialization failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-		return res;
+		Result::Static Buffer;
+		size_t BytesWrittenOut;
+
+		switch (Algorithm(m_Handle, Input.data(), Input.size(), Buffer.data(), Buffer.size(), &BytesWrittenOut))
+		{
+			case LIBDEFLATE_SUCCESS: return { Buffer, BytesWrittenOut };
+			case LIBDEFLATE_INSUFFICIENT_SPACE: break;
+			default: throw std::runtime_error("Data extraction failed.");
+		}
 	}
 
-	for (;;)
+	// No it doesn't. Allocate space on the heap to write the compression result, increasing in powers of 2.
+
+	auto DynamicCapacity = Result::StaticCapacity * 2;
+	while (true)
 	{
-		res = inflate(&strm, Z_NO_FLUSH);
-		switch (res)
+		size_t BytesWrittenOut;
+		auto Dynamic = cpp20::make_unique_for_overwrite<Result::Dynamic::element_type[]>(DynamicCapacity);
+
+		switch (Algorithm(m_Handle, Input.data(), Input.size(), Dynamic.get(), DynamicCapacity, &BytesWrittenOut))
 		{
-			case Z_OK:
+			case libdeflate_result::LIBDEFLATE_SUCCESS: return { std::move(Dynamic), BytesWrittenOut };
+			case libdeflate_result::LIBDEFLATE_INSUFFICIENT_SPACE:
 			{
-				// Some data has been uncompressed. Consume the buffer and continue uncompressing
-				a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				strm.next_out = reinterpret_cast<Bytef *>(Buffer);
-				strm.avail_out = sizeof(Buffer);
-				if (strm.avail_in == 0)
-				{
-					// All data has been uncompressed
-					inflateEnd(&strm);
-					return Z_OK;
-				}
-				break;
+				DynamicCapacity *= 2;
+				continue;
 			}
+			default: throw std::runtime_error("Data extraction failed.");
+		}
+	}
+}
 
-			case Z_STREAM_END:
-			{
-				// Finished uncompressing. Consume the rest of the buffer and return
-				a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out);
-				inflateEnd(&strm);
-				return Z_OK;
-			}
 
-			default:
-			{
-				// An error has occurred, log it and return the error value
-				LOG("%s: inflation failed: %d (\"%s\").", __FUNCTION__, res, strm.msg);
-				inflateEnd(&strm);
-				return res;
-			}
-		}  // switch (res)
-	}  // while (true)
-}
 
 
 
+template <auto Algorithm>
+Compression::Result Compression::Extractor::Extract(const ContiguousByteBufferView Input, size_t UncompressedSize)
+{
+	// Here we have the expected size after extraction, so directly use a suitable buffer size:
+	if (UncompressedSize <= Result::StaticCapacity)
+	{
+		if (
+			Result::Static Buffer;
+			Algorithm(m_Handle, Input.data(), Input.size(), Buffer.data(), UncompressedSize, nullptr) == libdeflate_result::LIBDEFLATE_SUCCESS
+		)
+		{
+			return { Buffer, UncompressedSize };
+		}
+	}
+	else if (
+		auto Dynamic = cpp20::make_unique_for_overwrite<Result::Dynamic::element_type[]>(UncompressedSize);
+		Algorithm(m_Handle, Input.data(), Input.size(), Dynamic.get(), UncompressedSize, nullptr) == libdeflate_result::LIBDEFLATE_SUCCESS
+	)
+	{
+		return { std::move(Dynamic), UncompressedSize };
+	}
 
+	throw std::runtime_error("Data extraction failed.");
+}