NN_GETSOCKOPT(3) nanomsg manual NN_GETSOCKOPT(3)NAMEnn_getsockopt - retrieve a socket option
SYNOPSIS
#include <nanomsg/nn.h>
int nn_getsockopt (int s, int level, int option, void *optval, size_t
*optvallen);
DESCRIPTION
Retrieves the value for 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 value is stored in the buffer pointed to by optval argument. Size
of the buffer is specified by the optvallen argument. If the size of
the option is greater than size of the buffer, the value will be
silently truncated. Otherwise, the optvallen will be modified to
indicate the actual length of the option.
<nanomsg/nn.h> header defines generic socket-level options
(NN_SOL_SOCKET level). The options are as follows:
NN_DOMAIN
Returns the domain constant as it was passed to nn_socket().
NN_PROTOCOL
Returns the protocol constant as it was passed to nn_socket().
NN_LINGER
Specifies how long the socket should try to send pending outbound
messages after nn_close() have been called, in milliseconds.
Negative value means infinite linger. The type of the option is
int. Default value is 1000 (1 second).
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, EAGAIN 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, EAGAIN
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
Retrieves outbound priority currently set on 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_SNDFD
Retrieves a file descriptor that is readable when a message can be
sent to the socket. The descriptor should be used only for polling
and never read from or written to. The type of the option is same
as the type of file descriptor on the platform. That is, int on
POSIX-complaint platforms and SOCKET on Windows. The descriptor
becomes invalid and should not be used any more once the socket is
closed. This socket option is not available for unidirectional
recv-only socket types.
NN_RCVFD
Retrieves a file descriptor that is readable when a message can be
received from the socket. The descriptor should be used only for
polling and never read from or written to. The type of the option
is same as the type of file descriptor on the platform. That is,
int on POSIX-complaint platforms and SOCKET on Windows. The
descriptor becomes invalid and should not be used any more once the
socket is closed. This socket option is not available for
unidirectional send-only socket types.
NN_SOCKET_NAME
Socket name for error reporting and statistics. The type of the
option is string. Default value is "N" where N is socket integer.
This option is experimental, see nn_env(7) for details
RETURN VALUE
If the function succeeds zero is returned. Otherwise, -1 is returned
and errno is set to to one of the values defined below.
ERRORS
EBADF
The provided socket is invalid.
ENOPROTOOPT
The option is unknown at the level indicated.
ETERM
The library is terminating.
EXAMPLE
int linger;
size_t sz = sizeof (linger);
nn_getsockopt (s, NN_SOL_SOCKET, NN_LINGER, &linger, &sz);
SEE ALSOnn_socket(3)nn_setsockopt(3)nanomsg(7)AUTHORS
Martin Sustrik <sustrik@250bpm.com[1]>
NOTES
1. sustrik@250bpm.com
mailto:sustrik@250bpm.com
nanomsg Unknown 12/23/2015 NN_GETSOCKOPT(3)
