static constexpr char tbl[] =

"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

std::string out;

out.reserve(((len + 2) / 3) * 4);

size_t i = 0;

for (; i + 3 <= len; i += 3) {

uint32_t n = (static_cast<uint32_t>(data[i]) << 16) |

(static_cast<uint32_t>(data[i + 1]) << 8) |

static_cast<uint32_t>(data[i + 2]);

out.push_back(tbl[(n >> 18) & 0x3F]);

out.push_back(tbl[(n >> 12) & 0x3F]);

out.push_back(tbl[(n >> 6) & 0x3F]);

out.push_back(tbl[n & 0x3F]);

}

if (i + 1 == len) {

uint32_t n = static_cast<uint32_t>(data[i]) << 16;

out.push_back(tbl[(n >> 18) & 0x3F]);

out.push_back(tbl[(n >> 12) & 0x3F]);

out.push_back('=');

out.push_back('=');

} else if (i + 2 == len) {

uint32_t n = (static_cast<uint32_t>(data[i]) << 16) |

(static_cast<uint32_t>(data[i + 1]) << 8);

out.push_back(tbl[(n >> 18) & 0x3F]);

out.push_back(tbl[(n >> 12) & 0x3F]);

out.push_back(tbl[(n >> 6) & 0x3F]);

out.push_back('=');

}

return out;

auto now = std::chrono::system_clock::now();

auto since_epoch = now.time_since_epoch();

auto secs = std::chrono::duration_cast<std::chrono::seconds>(since_epoch);

auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(since_epoch - secs);

std::time_t t = static_cast<std::time_t>(secs.count());

std::tm tm_utc{};

#ifdef _WIN32

gmtime_s(&tm_utc, &t);

#else

gmtime_r(&t, &tm_utc);

#endif

char buf[32];

std::strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%S", &tm_utc);

char out[40];

std::snprintf(out, sizeof(out), "%s.%03dZ", buf, static_cast<int>(ms.count()));

return std::string(out);

std::string server_id,

std::string protocol_name,

std::string protocol_hash)

: server_id_(std::move(server_id))

, protocol_name_(std::move(protocol_name))

, protocol_hash_(std::move(protocol_hash)) {

if (path.empty()) return;

out_.open(path, std::ios::out | std::ios::app);

enabled_ = out_.is_open();

if (!enabled_) return;

nlohmann::json j;

j["timestamp"] = utc_timestamp_ms();

j["level"] = "INFO";

j["logger"] = "vgi_rpc.access";

j["message"] =

protocol_name_ + "." + rec.method + (rec.status == "ok" ? " ok" : " error");

j["server_id"] = server_id_;

j["protocol"] = protocol_name_;

j["protocol_hash"] = protocol_hash_;

j["method"] = rec.method;

j["method_type"] = rec.is_stream ? "stream" : "unary";

j["principal"] = "";

j["auth_domain"] = "";

j["authenticated"] = false;

j["remote_addr"] = "";

j["duration_ms"] = std::round(rec.duration_ms * 100.0) / 100.0;

j["status"] = rec.status;

j["error_type"] = rec.error_type;

if (rec.status == "error") {

j["error_message"] =

rec.error_message.empty() ? std::string("error") : rec.error_message;

}

if (rec.is_stream) {

j["stream_id"] = rec.stream_id;

if (rec.cancelled) j["cancelled"] = true;

}

if (rec.has_request_data) {

j["request_data"] = rec.request_data_b64;

}

out_ << j.dump() << '\n';

out_.flush();