Namespace containing the net_flow module's extension of boost.system error conventions, so that Flow network protocol API can return codes/messages from within its own new set of error codes/messages. More...

Enumerations
enum class	Code { S_NODE_NOT_RUNNING = 1 , S_CANNOT_CONNECT_TO_IP_ANY , S_INVALID_SERVICE_PORT_NUMBER , S_PORT_TAKEN , S_INTERNAL_ERROR_PORT_NOT_TAKEN , S_OUT_OF_PORTS , S_INTERNAL_ERROR_PORT_COLLISION , S_CONN_RESET_BAD_PEER_BEHAVIOR , S_CONN_REFUSED , S_INTERNAL_ERROR_SYSTEM_ERROR_ASIO_TIMER , S_CONN_TIMEOUT , S_CONN_RESET_BY_OTHER_SIDE , S_CONN_RESET_TOO_MANY_REXMITS , S_SEQ_NUM_ARITHMETIC_FAILURE , S_SEQ_NUM_IMPLIES_CONNECTION_COLLISION , S_NODE_SHUTTING_DOWN , S_USER_CLOSED_ABRUPTLY , S_EVENT_SET_CLOSED , S_EVENT_SET_IMMUTABLE_WHEN_WAITING , S_EVENT_SET_EVENT_ALREADY_EXISTS , S_EVENT_SET_EVENT_DOES_NOT_EXIST , S_EVENT_SET_DOUBLE_WAIT_OR_POLL , S_EVENT_SET_NO_EVENTS , S_EVENT_SET_RESULT_CHECK_WHEN_WAITING , S_CONN_METADATA_TOO_LARGE , S_STATIC_OPTION_CHANGED , S_OPTION_CHECK_FAILED , S_WAIT_INTERRUPTED , S_WAIT_USER_TIMEOUT }
	All possible errors returned (via flow::Error_code arguments) by flow::net_flow functions/methods. More...

Functions
Error_code	make_error_code (Code err_code)
	Given a `Code` `enum` value, creates a lightweight flow::Error_code (a/k/a boost.system `error_code`) representing that error. More...

Detailed Description

Namespace containing the net_flow module's extension of boost.system error conventions, so that Flow network protocol API can return codes/messages from within its own new set of error codes/messages.

Synopsis

// Assign a code from net_flow's custom error code set -- to a *general* Error_code.
flow::Error_code code = flow::net_flow::error::Code::S_CONN_REFUSED;
// code contains the int equivalent of S_CONN_REFUSED enum value; and a category pointer for your new
// new code set to which S_CONN_REFUSED belonds.  So it's about the size of errno plus a pointer.
 
// Yet we have nice OO access to the equivalents of `errno` and `strerror(errno)`:
std::cout << "General error value = [" << code.value() << "]; msg = [" << code.message() << "].\n";
// And we can throw an std::exception (`catch{}` can log the exception's .what() which will contain
// the numeric value, the human message, and the optional context string).
throw flow::error::Runtime_error(code, "Additional context info here!");

Discussion

The contents of this namespace is one instance (and model example) for how one can easily create their own simple error code set enum (and corresponding string messages) and hook it into the flexible, yet maximally fast, boost.system error facility. Another example (a peer of ours) would be boost.asio's error code set. See flow::Error_code doc header for a top-down summary of the Flow-used-and-recommended error reporting system.

For boost.system experts wondering whether there is support for error_condition equivalence (i.e., the ability to compare a given flow::error::error_code to a more general boost::system::error_condition), currently the answer is no, there isn't. We may add error_conditions as Error_code usage patterns emerge over time.

Enumeration Type Documentation

◆ Code

enum class flow::net_flow::error::Code

strong

All possible errors returned (via flow::Error_code arguments) by flow::net_flow functions/methods.

These values are convertible to flow::Error_code (a/k/a boost::system::error_code) and thus extend the set of errors that flow::Error_code can represent.

Enumerator
S_NODE_NOT_RUNNING	Node not running.
S_CANNOT_CONNECT_TO_IP_ANY	Cannot ask to connect to "any" IP address. Use specific IP address.
S_INVALID_SERVICE_PORT_NUMBER	Flow port number is not in the valid service port number range.
S_PORT_TAKEN	Flow port already reserved.
S_INTERNAL_ERROR_PORT_NOT_TAKEN	Internal error: Tried to return Flow port which had not been reserved.
S_OUT_OF_PORTS	No more ephemeral Flow ports available.
S_INTERNAL_ERROR_PORT_COLLISION	Internal error: Ephemeral port double reservation allowed.
S_CONN_RESET_BAD_PEER_BEHAVIOR	Connection reset because of unexpected/illegal behavior by the other side.
S_CONN_REFUSED	Other side refused connection.
S_INTERNAL_ERROR_SYSTEM_ERROR_ASIO_TIMER	Internal error: System error: Something went wrong with boost.asio timer subsystem.
S_CONN_TIMEOUT	Other side did not complete connection handshake within the allowed time; perhaps no one is listening.
S_CONN_RESET_BY_OTHER_SIDE	Other side reset an established connection.
S_CONN_RESET_TOO_MANY_REXMITS	Connection reset because a packet has been retransmitted too many times.
S_SEQ_NUM_ARITHMETIC_FAILURE	Other side has sent packets with inconsistent sequence numbers.
S_SEQ_NUM_IMPLIES_CONNECTION_COLLISION	Other side has sent packet with sequence number that implies a port collision between two connections over time.
S_NODE_SHUTTING_DOWN	Node shutting down.
S_USER_CLOSED_ABRUPTLY	User code on this side abruptly closed connection; other side may be informed of this.
S_EVENT_SET_CLOSED	Attempted operation on an event set, when that event set was closed.
S_EVENT_SET_IMMUTABLE_WHEN_WAITING	Attempted to write to an event set, while a wait operation was pending on that event set.
S_EVENT_SET_EVENT_ALREADY_EXISTS	Attempted to add an event into an event set, but that event already exists.
S_EVENT_SET_EVENT_DOES_NOT_EXIST	Attempted to work with an event that does not exist in the event set.
S_EVENT_SET_DOUBLE_WAIT_OR_POLL	Attempted to wait on or poll an event set while already waiting on that event set.
S_EVENT_SET_NO_EVENTS	Attempted to wait on an event set without specifying event on which to wait.
S_EVENT_SET_RESULT_CHECK_WHEN_WAITING	Attempted to check wait results while still waiting.
S_CONN_METADATA_TOO_LARGE	During connection user supplied metadata that is too large.
S_STATIC_OPTION_CHANGED	When setting options, tried to set an unchangeable (static) option.
S_OPTION_CHECK_FAILED	When setting options, at least one option's value violates a required condition on that option.
S_WAIT_INTERRUPTED	A blocking (`sync_`) or background-blocking (`async_`) operation was interrupted, such as by a signal.
S_WAIT_USER_TIMEOUT	A blocking (`sync_`) or background-blocking (`async_`) operation timed out versus user-supplied time limit.

Function Documentation

◆ make_error_code()

Error_code flow::net_flow::error::make_error_code ( Code err_code )

Given a Code enum value, creates a lightweight flow::Error_code (a/k/a boost.system error_code) representing that error.

This is needed to make the boost::system::error_code::error_code<Code>() template implementation work. Or, slightly more in English, it glues the (completely general) flow::Error_code to the (net_flow-specific) error code set flow::net_flow::error::Code, so that one can implicitly covert from the latter to the former.

Parameters

err_code The enum value.

Returns: A corresponding flow::Error_code.

Enumerations