Add support for gzip compression through libdeflate

ixwebsocket/IXGzipCodec.cpp

@@ -6,6 +6,7 @@
 
 #include "IXGzipCodec.h"
 
+#include "IXBench.h"
 #include <array>
 #include <string.h>
 
@@ -13,11 +14,52 @@
 #include <zlib.h>
 #endif
 
+#ifdef IXWEBSOCKET_USE_DEFLATE
+#include <libdeflate.h>
+#endif
+
 namespace ix
 {
 #ifdef IXWEBSOCKET_USE_ZLIB
     std::string gzipCompress(const std::string& str)
     {
+#ifdef IXWEBSOCKET_USE_DEFLATE
+        int compressionLevel = 6;
+        struct libdeflate_compressor* compressor;
+
+        compressor = libdeflate_alloc_compressor(compressionLevel);
+
+        const void* uncompressed_data = str.data();
+        size_t uncompressed_size = str.size();
+        void* compressed_data;
+        size_t actual_compressed_size;
+        size_t max_compressed_size;
+
+        max_compressed_size = libdeflate_gzip_compress_bound(compressor, uncompressed_size);
+        compressed_data = malloc(max_compressed_size);
+
+        if (compressed_data == NULL)
+        {
+            return std::string();
+        }
+
+        actual_compressed_size = libdeflate_gzip_compress(
+            compressor, uncompressed_data, uncompressed_size, compressed_data, max_compressed_size);
+
+        libdeflate_free_compressor(compressor);
+
+        if (actual_compressed_size == 0)
+        {
+            free(compressed_data);
+            return std::string();
+        }
+
+        std::string out;
+        out.assign(reinterpret_cast<char*>(compressed_data), actual_compressed_size);
+        free(compressed_data);
+
+        return out;
+#else
         z_stream zs; // z_stream is zlib's control structure
         memset(&zs, 0, sizeof(zs));
 
@@ -57,6 +99,7 @@ namespace ix
         deflateEnd(&zs);
 
         return outstring;
+#endif
     }
 
     bool gzipDecompress(const std::string& in, std::string& out)