Function ToHex

src/brpc/progressive_attachment.cpp:73–73

static char s_hex_map[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
                            '9', 'A', 'B', 'C', 'D', 'E', 'F' };
inline char ToHex(uint32_t size/*0-15*/) { return s_hex_map[size]; }

inline void AppendChunkHead(butil::IOBuf* buf, uint32_t size) {
    char tmp[32];