Method ExportImpl

lib/otel/otel.cpp:366–421

}

void OTel::ExportImpl(boost::asio::yield_context& yc) const
{
	AsioProtobufOutStream outputS{*m_Stream, m_ConnInfo, yc};
	[[maybe_unused]] auto serialized = m_Request->SerializeToZeroCopyStream(&outputS);
	ASSERT(serialized);
	// Must have completed chunk writing successfully, otherwise reading the response will hang forever.
	if (!outputS.WriterDone()) {
		BOOST_THROW_EXCEPTION(std::runtime_error("BUG: Protobuf output stream writer did not complete successfully."));
	}

	IncomingHttpResponse responseMsg{*m_Stream};
	responseMsg.Parse(yc);

	if (auto ct = responseMsg[http::field::content_type]; ct != "application/x-protobuf") {
		if (responseMsg.result() == http::status::ok) {
			// Some OpenTelemetry Collector compatible backends (e.g., Prometheus OTLP Receiver) respond with 200 OK
			// but without the expected Protobuf content type. So, don't do anything here since the request succeeded.
			return;
		}
		Log(LogWarning, "OTelExporter")
			<< "Unexpected Content-Type from OpenTelemetry backend '" << ct << "' (" << responseMsg.reason() << "):\n"
			<< responseMsg.body();
	} else if (responseMsg.result_int() >= 200 && responseMsg.result_int() <= 299) {
		// We've got a valid Protobuf response, so we've to deserialize the body to check for partial success.
		// See https://opentelemetry.io/docs/specs/otlp/#partial-success-1.
		google::protobuf::Arena arena;
		auto* response = MetricsResponse::default_instance().New(&arena);
		[[maybe_unused]] auto deserialized = response->ParseFromString(responseMsg.body());
		ASSERT(deserialized);

		if (response->has_partial_success()) {
			const auto& ps = response->partial_success();
			const auto& msg = ps.error_message();
			if (ps.rejected_data_points() > 0 || !msg.empty()) {
				Log(LogWarning, "OTelExporter")
					<< "OpenTelemetry backend reported partial success: " << (msg.empty() ? "<none>" : msg)
					<< " (" << ps.rejected_data_points() << " metric data points rejected).";
			}
		}
	} else if (IsRetryableExportError(responseMsg.result())) {
		uint64_t throttleSeconds = 0;
		if (auto throttle = responseMsg[http::field::retry_after]; !throttle.empty()) {
			try {
				throttleSeconds = boost::lexical_cast<uint64_t>(throttle);
			} catch (const std::exception& ex) {
				Log(LogWarning, "OTelExporter")
					<< "Failed to parse 'Retry-After' header from OpenTelemetry backend response: " << ex.what();
			}
		}
		BOOST_THROW_EXCEPTION(RetryableExportError{throttleSeconds});
	} else {
		Log(LogWarning, "OTelExporter")
			<< "OpenTelemetry backend responded with non-success and non-retryable status code "
			<< responseMsg.result_int() << " (" << responseMsg.reason() << ").\n" << responseMsg.body();
	}
}

/**