DESCRIPTION¶
Sets the value of the option. The level argument
specifies the protocol level at which the option resides. For generic
socket-level options use NN_SOL_SOCKET level. For
socket-type-specific options use socket type for level argument (e.g.
NN_SUB). For transport-specific options use ID of the transport as
the level argument (e.g. NN_TCP).
The new value is pointed to by optval argument. Size of the
option is specified by the optvallen argument.
<nanomsg/nn.h> header defines generic socket-level
options (NN_SOL_SOCKET level). The options are as follows:
NN_SNDBUF
Size of the send buffer, in bytes. To prevent blocking
for messages larger than the buffer, exactly one message may be buffered in
addition to the data in the send buffer. The type of this option is int.
Default value is 128kB.
NN_RCVBUF
Size of the receive buffer, in bytes. To prevent blocking
for messages larger than the buffer, exactly one message may be buffered in
addition to the data in the receive buffer. The type of this option is int.
Default value is 128kB.
NN_RCVMAXSIZE
Maximum message size that can be received, in bytes.
Negative value means that the received size is limited only by available
addressable memory. The type of this option is int. Default is 1024kB.
NN_SNDTIMEO
The timeout for send operation on the socket, in
milliseconds. If message cannot be sent within the specified timeout,
ETIMEDOUT error is returned. Negative value means infinite timeout. The type
of the option is int. Default value is -1.
NN_RCVTIMEO
The timeout for recv operation on the socket, in
milliseconds. If message cannot be received within the specified timeout,
ETIMEDOUT error is returned. Negative value means infinite timeout. The type
of the option is int. Default value is -1.
NN_RECONNECT_IVL
For connection-based transports such as TCP, this option
specifies how long to wait, in milliseconds, when connection is broken before
trying to re-establish it. Note that actual reconnect interval may be
randomised to some extent to prevent severe reconnection storms. The type of
the option is int. Default value is 100 (0.1 second).
NN_RECONNECT_IVL_MAX
This option is to be used only in addition to
NN_RECONNECT_IVL option. It specifies maximum reconnection interval. On
each reconnect attempt, the previous interval is doubled until
NN_RECONNECT_IVL_MAX is reached. Value of zero means that no
exponential backoff is performed and reconnect interval is based only on
NN_RECONNECT_IVL. If NN_RECONNECT_IVL_MAX is less than
NN_RECONNECT_IVL, it is ignored. The type of the option is int. Default
value is 0.
NN_SNDPRIO
Sets outbound priority for endpoints subsequently added
to the socket. This option has no effect on socket types that send messages to
all the peers. However, if the socket type sends each message to a single peer
(or a limited set of peers), peers with high priority take precedence over
peers with low priority. The type of the option is int. Highest priority is 1,
lowest priority is 16. Default value is 8.
NN_RCVPRIO
Sets inbound priority for endpoints subsequently added to
the socket. This option has no effect on socket types that are not able to
receive messages. When receiving a message, messages from peer with higher
priority are received before messages from peer with lower priority. The type
of the option is int. Highest priority is 1, lowest priority is 16. Default
value is 8.
NN_IPV4ONLY
If set to 1, only IPv4 addresses are used. If set to 0,
both IPv4 and IPv6 addresses are used. The type of the option is int. Default
value is 1.
NN_SOCKET_NAME
Socket name for error reporting and statistics. The type
of the option is string. Default value is "socket.N" where N is
socket integer.
This option is experimental, see nn_env(7) for
detailsNN_MAXTTL
Sets the maximum number of "hops" a message can
go through before it is dropped. Each time the message is received (for
example via the
nn_device(3) function) counts as a single hop. This provides a
form of protection against inadvertent loops.
NN_LINGER
This option is not implemented, and should not be used in
new code. Applications which need to be sure that their messages are delivered
to a remote peer should either use an acknowledgement (implied when receiving
a reply on NN_REQ sockets), or insert a suitable delay before calling
nn_close(3) or exiting the application.
