Provided by: libxs-dev_1.2.0-2_amd64 bug

NAME

       xs_setsockopt - set Crossroads socket options

SYNOPSIS

       int xs_setsockopt (void *socket, int option_name, const void *option_value, size_t
       option_len);

       Caution: All options, with the exception of XS_SUBSCRIBE, XS_UNSUBSCRIBE and XS_LINGER,
       only take effect for subsequent socket bind/connects.

DESCRIPTION

       The xs_setsockopt() function shall set the option specified by the option_name argument to
       the value pointed to by the option_value argument for the Crossroads socket pointed to by
       the socket argument. The option_len argument is the size of the option value in bytes.

       The following socket options can be set with the xs_setsockopt() function:

   XS_SNDHWM: Set high water mark for outbound messages
       The XS_SNDHWM option shall set the high water mark for outbound messages on the specified
       socket. The high water mark is a hard limit on the maximum number of outstanding messages
       the library shall queue in memory for any single peer that the specified socket is
       communicating with.

       If this limit has been reached the socket shall enter an exceptional state and depending
       on the socket type, the library shall take appropriate action such as blocking or dropping
       sent messages. Refer to the individual socket descriptions in xs_socket(3) for details on
       the exact action taken for each socket type.

       Option value type         int

       Option value unit         messages

       Default value             1000

       Applicable socket types   all

   XS_RCVHWM: Set high water mark for inbound messages
       The XS_RCVHWM option shall set the high water mark for inbound messages on the specified
       socket. The high water mark is a hard limit on the maximum number of outstanding messages
       the libray shall queue in memory for any single peer that the specified socket is
       communicating with.

       If this limit has been reached the socket shall enter an exceptional state and depending
       on the socket type, the library shall take appropriate action such as blocking or dropping
       sent messages. Refer to the individual socket descriptions in xs_socket(3) for details on
       the exact action taken for each socket type.

       Option value type         int

       Option value unit         messages

       Default value             1000

       Applicable socket types   all

   XS_AFFINITY: Set I/O thread affinity
       The XS_AFFINITY option shall set the I/O thread affinity for newly created connections on
       the specified socket.

       Affinity determines which threads from the Crossroads I/O thread pool associated with the
       socket’s context shall handle newly created connections. A value of zero specifies no
       affinity, meaning that work shall be distributed fairly among all Crossroads I/O threads
       in the thread pool. For non-zero values, the lowest bit corresponds to thread 1, second
       lowest bit to thread 2 and so on. For example, a value of 3 specifies that subsequent
       connections on socket shall be handled exclusively by I/O threads 1 and 2.

       See also xs_init(3) for details on allocating the number of I/O threads for a specific
       context.

       Option value type         uint64_t

       Option value unit         N/A (bitmap)

       Default value             0

       Applicable socket types   N/A

   XS_SUBSCRIBE: Establish message filter
       The XS_SUBSCRIBE option shall establish a new message filter on a XS_SUB socket. Newly
       created XS_SUB sockets shall filter out all incoming messages, therefore you should call
       this option to establish an initial message filter.

       An empty option_value of length zero shall subscribe to all incoming messages. A non-empty
       option_value shall subscribe to all messages beginning with the specified prefix. Multiple
       filters may be attached to a single XS_SUB socket, in which case a message shall be
       accepted if it matches at least one filter.

       Option value type         binary data

       Option value unit         N/A

       Default value             N/A

       Applicable socket types   XS_SUB

   XS_UNSUBSCRIBE: Remove message filter
       The XS_UNSUBSCRIBE option shall remove an existing message filter on a XS_SUB socket. The
       filter specified must match an existing filter previously established with the
       XS_SUBSCRIBE option. If the socket has several instances of the same filter attached the
       XS_UNSUBSCRIBE option shall remove only one instance, leaving the rest in place and
       functional.

       Option value type         binary data

       Option value unit         N/A

       Default value             N/A

       Applicable socket types   XS_SUB

   XS_IDENTITY: Set socket identity
       The XS_IDENTITY option shall set the identity of the specified socket. Socket identity is
       used only by request/reply pattern. Namely, it can be used in tandem with a XS_XREP socket
       to route messages to the peer with specific identity.

       Identity should be at least one byte and at most 255 bytes long. Identities starting with
       binary zero are reserved for use by Crossroads infrastructure.

       Option value type         binary data

       Option value unit         N/A

       Default value             NULL

       Applicable socket types   all

   XS_RATE: Set multicast data rate
       The XS_RATE option shall set the maximum send or receive data rate for multicast
       transports such as xs_pgm(7) using the specified socket.

       Option value type         int

       Option value unit         kilobits per second

       Default value             100

       Applicable socket types   all, when using multicast
                                 transports

   XS_RECOVERY_IVL: Set multicast recovery interval
       The XS_RECOVERY_IVL option shall set the recovery interval for multicast transports using
       the specified socket. The recovery interval determines the maximum time in milliseconds
       that a receiver can be absent from a multicast group before unrecoverable data loss will
       occur.

           Caution
           Exercise care when setting large recovery intervals as the data needed for recovery
           will be held in memory. For example, a 1 minute recovery interval at a data rate of
           1Gbps requires a 7GB in-memory buffer.

       Option value type         int

       Option value unit         milliseconds

       Default value             10000

       Applicable socket types   all, when using multicast
                                 transports

   XS_SNDBUF: Set kernel transmit buffer size
       The XS_SNDBUF option shall set the underlying kernel transmit buffer size for the socket
       to the specified size in bytes. A value of zero means leave the OS default unchanged. For
       details please refer to your operating system documentation for the SO_SNDBUF socket
       option.

       Option value type         int

       Option value unit         bytes

       Default value             0

       Applicable socket types   all

   XS_RCVBUF: Set kernel receive buffer size
       The XS_RCVBUF option shall set the underlying kernel receive buffer size for the socket to
       the specified size in bytes. A value of zero means leave the OS default unchanged. For
       details refer to your operating system documentation for the SO_RCVBUF socket option.

       Option value type         int

       Option value unit         bytes

       Default value             0

       Applicable socket types   all

   XS_LINGER: Set linger period for socket shutdown
       The XS_LINGER option shall set the linger period for the specified socket. The linger
       period determines how long pending messages which have yet to be sent to a peer shall
       linger in memory after a socket is closed with xs_close(3), and further affects the
       termination of the socket’s context with xs_term(3). The following outlines the different
       behaviours:

       ·   The default value of -1 specifies an infinite linger period. Pending messages shall
           not be discarded after a call to xs_close(); attempting to terminate the socket’s
           context with xs_term() shall block until all pending messages have been sent to a
           peer.

       ·   The value of 0 specifies no linger period. Pending messages shall be discarded
           immediately when the socket is closed with xs_close().

       ·   Positive values specify an upper bound for the linger period in milliseconds. Pending
           messages shall not be discarded after a call to xs_close(); attempting to terminate
           the socket’s context with xs_term() shall block until either all pending messages have
           been sent to a peer, or the linger period expires, after which any pending messages
           shall be discarded.

           Option value type         int
           Option value unit         milliseconds
           Default value             -1 (infinite)
           Applicable socket types   all

   XS_RECONNECT_IVL: Set reconnection interval
       The XS_RECONNECT_IVL option shall set the initial reconnection interval for the specified
       socket. The reconnection interval is the period the library shall wait between attempts to
       reconnect disconnected peers when using connection-oriented transports.

           Note
           The reconnection interval may be randomized by the library to prevent reconnection
           storms in topologies with a large number of peers per socket.

       Option value type         int

       Option value unit         milliseconds

       Default value             100

       Applicable socket types   all, only for
                                 connection-oriented transports

   XS_RECONNECT_IVL_MAX: Set maximum reconnection interval
       The XS_RECONNECT_IVL_MAX option shall set the maximum reconnection interval for the
       specified socket. This is the maximum period the library shall wait between attempts to
       reconnect. On each reconnect attempt, the previous interval shall be doubled untill
       XS_RECONNECT_IVL_MAX is reached. This allows for exponential backoff strategy. Default
       value means no exponential backoff is performed and reconnect interval calculations are
       only based on XS_RECONNECT_IVL.

           Note
           Values less than XS_RECONNECT_IVL will be ignored.

       Option value type         int

       Option value unit         milliseconds

       Default value             0 (only use XS_RECONNECT_IVL)

       Applicable socket types   all, only for
                                 connection-oriented transports

   XS_BACKLOG: Set maximum length of the queue of outstanding connections
       The XS_BACKLOG option shall set the maximum length of the queue of outstanding peer
       connections for the specified socket; this only applies to connection-oriented transports.
       For details refer to your operating system documentation for the listen function.

       Option value type         int

       Option value unit         connections

       Default value             100

       Applicable socket types   all, only for
                                 connection-oriented transports.

   XS_MAXMSGSIZE: Maximum acceptable inbound message size
       Limits the size of the inbound message. If a peer sends a message larger than
       XS_MAXMSGSIZE it is disconnected.

       Option value type         uint64_t

       Option value unit         bytes

       Default value             2^64-1

       Applicable socket types   all

   XS_MULTICAST_HOPS: Maximum network hops for multicast packets
       Sets the time-to-live field in every multicast packet sent from this socket. The default
       is 1 which means that the multicast packets don’t leave the local network.

       Option value type         int

       Option value unit         network hops

       Default value             1

       Applicable socket types   all, when using multicast
                                 transports

   XS_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN
       Sets the timeout for receive operation on the socket. If the value is 0, xs_recv(3) will
       return immediately, with a EAGAIN error if there is no message to receive. If the value is
       -1, it will block until a message is available. For all other values, it will wait for a
       message for that amount of time before returning with an EAGAIN error.

       Option value type         int

       Option value unit         milliseconds

       Default value             -1 (infinite)

       Applicable socket types   all

   XS_SNDTIMEO: Maximum time before a send operation returns with EAGAIN
       Sets the timeout for send operation on the socket. If the value is 0, xs_send(3) will
       return immediately, with a EAGAIN error if the message cannot be sent. If the value is -1,
       it will block until the message is sent. For all other values, it will try to send the
       message for that amount of time before returning with an EAGAIN error.

       Option value type         int

       Option value unit         milliseconds

       Default value             -1 (infinite)

       Applicable socket types   all

   XS_IPV4ONLY: Use IPv4-only sockets
       Sets the underlying native socket type. A value of 1 will use IPv4 sockets, while the
       value of 0 will use IPv6 sockets. An IPv6 socket lets applications connect to and accept
       connections from both IPv4 and IPv6 hosts.

       Option value type         int

       Option value unit         boolean

       Default value             1 (true)

       Applicable socket types   all, when using TCP transport.

   XS_KEEPALIVE: Enable transport keepalives
       When set to 1, this option enables use of protocol keepalives on the socket, if supported
       by the underlying transport protocol.

       Option value type         int

       Option value unit         boolean

       Default value             0 (false)

       Applicable socket types   all, when using TCP transport.

   XS_SURVEY_TIMEOUT: Sets the deadline for the survey
       Specifies how long to wait for responses to the survey. After the interval expires, any
       firther calls to xs_recv() will return EAGAIN error. All the responses received later on
       will be silently discarded. Value of -1 means infinite.

       Option value type         int

       Option value unit         milliseconds

       Default value             -1 (infinite)

       Applicable socket types   XS_SURVEYOR

RETURN VALUE

       The xs_setsockopt() function shall return zero if successful. Otherwise it shall return -1
       and set errno to one of the values defined below.

ERRORS

       EINVAL
           The requested option option_name is unknown, or the requested option_len or
           option_value is invalid.

       ETERM
           The context associated with the specified socket was terminated.

       ENOTSOCK
           The provided socket was invalid.

       EINTR
           The operation was interrupted by delivery of a signal.

EXAMPLE

       Subscribing to messages on a XS_SUB socket.

           /* Subscribe to all messages */
           rc = xs_setsockopt (socket, XS_SUBSCRIBE, "", 0);
           assert (rc == 0);
           /* Subscribe to messages prefixed with "ANIMALS.CATS" */
           rc = xs_setsockopt (socket, XS_SUBSCRIBE, "ANIMALS.CATS", 12);

       Setting I/O thread affinity.

           int64_t affinity;
           /* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
           affinity = 1;
           rc = xs_setsockopt (socket, XS_AFFINITY, &affinity, sizeof affinity);
           assert (rc == 0);
           rc = xs_bind (socket, "tcp://lo:5555");
           assert (rc != -1);
           /* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
           affinity = 2;
           rc = xs_setsockopt (socket, XS_AFFINITY, &affinity, sizeof affinity);
           assert (rc == 0);
           rc = xs_bind (socket, "tcp://lo:5556");
           assert (rc != -1);

SEE ALSO

       xs_getsockopt(3) xs_socket(3) xs(7)

AUTHORS

       The Crossroads documentation was written by Martin Sustrik <sustrik@250bpm.com[1]> and
       Martin Lucina <martin@lucina.net[2]>.

NOTES

        1. sustrik@250bpm.com
           mailto:sustrik@250bpm.com

        2. martin@lucina.net
           mailto:martin@lucina.net