Method handleRequest

src/Server/HTTPHandler.cpp:925–994

void HTTPHandler::handleRequest(HTTPServerRequest & request, HTTPServerResponse & response)
{
    setThreadName("HTTPHandler");
    ThreadStatus thread_status;

    SCOPE_EXIT({
        // If there is no request_credentials instance waiting for the next round, then the request is processed,
        // so no need to preserve request_context either.
        // Needs to be performed with respect to the other destructors in the scope though.
        if (!request_credentials)
            request_context.reset();
    });

    if (!request_context)
    {
        // Context should be initialized before anything, for correct memory accounting.
        request_context = Context::createCopy(server.context());
        request_credentials.reset();
    }

    /// Cannot be set here, since query_id is unknown.
    std::optional<CurrentThread::QueryScope> query_scope;
    Output used_output;

    /// In case of exception, send stack trace to client.
    bool with_stacktrace = false;

    try
    {
        response.setContentType("text/plain; charset=UTF-8");
        response.set("X-ClickHouse-Server-Display-Name", server_display_name);
        /// For keep-alive to work.
        if (request.getVersion() == HTTPServerRequest::HTTP_1_1)
            response.setChunkedTransferEncoding(true);

        HTMLForm params(request_context->getSettingsRef(), request);
        with_stacktrace = params.getParsed<bool>("stacktrace", false);

        /// FIXME: maybe this check is already unnecessary.
        /// Workaround. Poco does not detect 411 Length Required case.
        if (request.getMethod() == HTTPRequest::HTTP_POST && !request.getChunkedTransferEncoding() && !request.hasContentLength())
        {
            throw Exception(
                "The Transfer-Encoding is not chunked and there is no Content-Length header for POST request",
                ErrorCodes::HTTP_LENGTH_REQUIRED);
        }

        processQuery(request_context, request, params, response, used_output, query_scope);
        LOG_DEBUG(log, (request_credentials ? "Authentication in progress..." : "Done processing query"));
    }
    catch (...)
    {
        SCOPE_EXIT({
            request_credentials.reset(); // ...so that the next requests on the connection have to always start afresh in case of exceptions.
        });

        tryLogCurrentException(log);