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diff --git a/doc/zmq_getsockopt.3 b/doc/zmq_getsockopt.3 new file mode 100644 index 0000000..766db57 --- /dev/null +++ b/doc/zmq_getsockopt.3 @@ -0,0 +1,1645 @@ +'\" t +.\" Title: zmq_getsockopt +.\" Author: [see the "AUTHORS" section] +.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/> +.\" Date: 10/14/2014 +.\" Manual: 0MQ Manual +.\" Source: 0MQ 4.0.5 +.\" Language: English +.\" +.TH "ZMQ_GETSOCKOPT" "3" "10/14/2014" "0MQ 4\&.0\&.5" "0MQ Manual" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +zmq_getsockopt \- get 0MQ socket options +.SH "SYNOPSIS" +.sp +\fBint zmq_getsockopt (void \fR\fB\fI*socket\fR\fR\fB, int \fR\fB\fIoption_name\fR\fR\fB, void \fR\fB\fI*option_value\fR\fR\fB, size_t \fR\fB\fI*option_len\fR\fR\fB);\fR +.SH "DESCRIPTION" +.sp +The \fIzmq_getsockopt()\fR function shall retrieve the value for the option specified by the \fIoption_name\fR argument for the 0MQ socket pointed to by the \fIsocket\fR argument, and store it in the buffer pointed to by the \fIoption_value\fR argument\&. The \fIoption_len\fR argument is the size in bytes of the buffer pointed to by \fIoption_value\fR; upon successful completion \fIzmq_getsockopt()\fR shall modify the \fIoption_len\fR argument to indicate the actual size of the option value stored in the buffer\&. +.sp +The following options can be retrieved with the \fIzmq_getsockopt()\fR function: +.SS "ZMQ_TYPE: Retrieve socket type" +.sp +The \fIZMQ_TYPE\fR option shall retrieve the socket type for the specified \fIsocket\fR\&. The socket type is specified at socket creation time and cannot be modified afterwards\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +N/A +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_RCVMORE: More message data parts to follow" +.sp +The \fIZMQ_RCVMORE\fR option shall return True (1) if the message part last received from the \fIsocket\fR was a data part with more parts to follow\&. If there are no data parts to follow, this option shall return False (0)\&. +.sp +Refer to \fBzmq_send\fR(3) and \fBzmq_recv\fR(3) for a detailed description of multi\-part messages\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +boolean +T} +T{ +.sp +Default value +T}:T{ +.sp +N/A +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_SNDHWM: Retrieves high water mark for outbound messages" +.sp +The \fIZMQ_SNDHWM\fR option shall return the high water mark for outbound messages on the specified \fIsocket\fR\&. The high water mark is a hard limit on the maximum number of outstanding messages 0MQ shall queue in memory for any single peer that the specified \fIsocket\fR is communicating with\&. A value of zero means no limit\&. +.sp +If this limit has been reached the socket shall enter an exceptional state and depending on the socket type, 0MQ shall take appropriate action such as blocking or dropping sent messages\&. Refer to the individual socket descriptions in \fBzmq_socket\fR(3) for details on the exact action taken for each socket type\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +messages +T} +T{ +.sp +Default value +T}:T{ +.sp +1000 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_RCVHWM: Retrieve high water mark for inbound messages" +.sp +The \fIZMQ_RCVHWM\fR option shall return the high water mark for inbound messages on the specified \fIsocket\fR\&. The high water mark is a hard limit on the maximum number of outstanding messages 0MQ shall queue in memory for any single peer that the specified \fIsocket\fR is communicating with\&. A value of zero means no limit\&. +.sp +If this limit has been reached the socket shall enter an exceptional state and depending on the socket type, 0MQ shall take appropriate action such as blocking or dropping sent messages\&. Refer to the individual socket descriptions in \fBzmq_socket\fR(3) for details on the exact action taken for each socket type\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +messages +T} +T{ +.sp +Default value +T}:T{ +.sp +1000 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_AFFINITY: Retrieve I/O thread affinity" +.sp +The \fIZMQ_AFFINITY\fR option shall retrieve the I/O thread affinity for newly created connections on the specified \fIsocket\fR\&. +.sp +Affinity determines which threads from the 0MQ I/O thread pool associated with the socket\(cqs \fIcontext\fR shall handle newly created connections\&. A value of zero specifies no affinity, meaning that work shall be distributed fairly among all 0MQ 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 \fIsocket\fR shall be handled exclusively by I/O threads 1 and 2\&. +.sp +See also \fBzmq_init\fR(3) for details on allocating the number of I/O threads for a specific \fIcontext\fR\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +uint64_t +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A (bitmap) +T} +T{ +.sp +Default value +T}:T{ +.sp +0 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +N/A +T} +.TE +.sp 1 +.SS "ZMQ_IDENTITY: Retrieve socket identity" +.sp +The \fIZMQ_IDENTITY\fR option shall retrieve the identity of the specified \fIsocket\fR\&. Socket identity is used only by request/reply pattern\&. Namely, it can be used in tandem with ROUTER socket to route messages to the peer with specific identity\&. +.sp +Identity should be at least one byte and at most 255 bytes long\&. Identities starting with binary zero are reserved for use by 0MQ infrastructure\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +binary data +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +NULL +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +ZMQ_REP, ZMQ_REQ, ZMQ_ROUTER, ZMQ_DEALER\&. +T} +.TE +.sp 1 +.SS "ZMQ_RATE: Retrieve multicast data rate" +.sp +The \fIZMQ_RATE\fR option shall retrieve the maximum send or receive data rate for multicast transports using the specified \fIsocket\fR\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +kilobits per second +T} +T{ +.sp +Default value +T}:T{ +.sp +100 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using multicast transports +T} +.TE +.sp 1 +.SS "ZMQ_RECOVERY_IVL: Get multicast recovery interval" +.sp +The \fIZMQ_RECOVERY_IVL\fR option shall retrieve the recovery interval for multicast transports using the specified \fIsocket\fR\&. 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\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +milliseconds +T} +T{ +.sp +Default value +T}:T{ +.sp +10000 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using multicast transports +T} +.TE +.sp 1 +.SS "ZMQ_SNDBUF: Retrieve kernel transmit buffer size" +.sp +The \fIZMQ_SNDBUF\fR option shall retrieve the underlying kernel transmit buffer size for the specified \fIsocket\fR\&. A value of zero means that the OS default is in effect\&. For details refer to your operating system documentation for the \fISO_SNDBUF\fR socket option\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +bytes +T} +T{ +.sp +Default value +T}:T{ +.sp +0 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_RCVBUF: Retrieve kernel receive buffer size" +.sp +The \fIZMQ_RCVBUF\fR option shall retrieve the underlying kernel receive buffer size for the specified \fIsocket\fR\&. A value of zero means that the OS default is in effect\&. For details refer to your operating system documentation for the \fISO_RCVBUF\fR socket option\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +bytes +T} +T{ +.sp +Default value +T}:T{ +.sp +0 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_LINGER: Retrieve linger period for socket shutdown" +.sp +The \fIZMQ_LINGER\fR option shall retrieve the linger period for the specified \fIsocket\fR\&. 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 \fBzmq_close\fR(3), and further affects the termination of the socket\(cqs context with \fBzmq_term\fR(3)\&. The following outlines the different behaviours: +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +The default value of +\fI\-1\fR +specifies an infinite linger period\&. Pending messages shall not be discarded after a call to +\fIzmq_close()\fR; attempting to terminate the socket\(cqs context with +\fIzmq_term()\fR +shall block until all pending messages have been sent to a peer\&. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +The value of +\fI0\fR +specifies no linger period\&. Pending messages shall be discarded immediately when the socket is closed with +\fIzmq_close()\fR\&. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +Positive values specify an upper bound for the linger period in milliseconds\&. Pending messages shall not be discarded after a call to +\fIzmq_close()\fR; attempting to terminate the socket\(cqs context with +\fIzmq_term()\fR +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\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +Option value type +T}:T{ +int +T} +T{ +Option value unit +T}:T{ +milliseconds +T} +T{ +Default value +T}:T{ +\-1 (infinite) +T} +T{ +Applicable socket types +T}:T{ +all +T} +.TE +.sp 1 +.RE +.SS "ZMQ_RECONNECT_IVL: Retrieve reconnection interval" +.sp +The \fIZMQ_RECONNECT_IVL\fR option shall retrieve the initial reconnection interval for the specified \fIsocket\fR\&. The reconnection interval is the period 0MQ shall wait between attempts to reconnect disconnected peers when using connection\-oriented transports\&. The value \-1 means no reconnection\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +.sp +The reconnection interval may be randomized by 0MQ to prevent reconnection storms in topologies with a large number of peers per socket\&. +.sp .5v +.RE +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +milliseconds +T} +T{ +.sp +Default value +T}:T{ +.sp +100 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, only for connection\-oriented transports +T} +.TE +.sp 1 +.SS "ZMQ_RECONNECT_IVL_MAX: Retrieve maximum reconnection interval" +.sp +The \fIZMQ_RECONNECT_IVL_MAX\fR option shall retrieve the maximum reconnection interval for the specified \fIsocket\fR\&. This is the maximum period 0MQ shall wait between attempts to reconnect\&. On each reconnect attempt, the previous interval shall be doubled untill ZMQ_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 ZMQ_RECONNECT_IVL\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +.sp +Values less than ZMQ_RECONNECT_IVL will be ignored\&. +.sp .5v +.RE +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +milliseconds +T} +T{ +.sp +Default value +T}:T{ +.sp +0 (only use ZMQ_RECONNECT_IVL) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, only for connection\-oriented transport +T} +.TE +.sp 1 +.SS "ZMQ_BACKLOG: Retrieve maximum length of the queue of outstanding connections" +.sp +The \fIZMQ_BACKLOG\fR option shall retrieve the maximum length of the queue of outstanding peer connections for the specified \fIsocket\fR; this only applies to connection\-oriented transports\&. For details refer to your operating system documentation for the \fIlisten\fR function\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +connections +T} +T{ +.sp +Default value +T}:T{ +.sp +100 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, only for connection\-oriented transports +T} +.TE +.sp 1 +.SS "ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size" +.sp +The option shall retrieve limit for the inbound messages\&. If a peer sends a message larger than ZMQ_MAXMSGSIZE it is disconnected\&. Value of \-1 means \fIno limit\fR\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int64_t +T} +T{ +.sp +Option value unit +T}:T{ +.sp +bytes +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets" +.sp +The option shall retrieve time\-to\-live used for outbound multicast packets\&. The default of 1 means that the multicast packets don\(cqt leave the local network\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +network hops +T} +T{ +.sp +Default value +T}:T{ +.sp +1 +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using multicast transports +T} +.TE +.sp 1 +.SS "ZMQ_RCVTIMEO: Maximum time before a socket operation returns with EAGAIN" +.sp +Retrieve the timeout for recv operation on the socket\&. If the value is 0, \fIzmq_recv(3)\fR 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\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +milliseconds +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (infinite) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_SNDTIMEO: Maximum time before a socket operation returns with EAGAIN" +.sp +Retrieve the timeout for send operation on the socket\&. If the value is 0, \fIzmq_send(3)\fR 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\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +milliseconds +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (infinite) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_IPV6: Retrieve IPv6 socket status" +.sp +Retrieve the IPv6 option for the socket\&. A value of 1 means IPv6 is enabled on the socket, while 0 means the socket will use only IPv4\&. When IPv6 is enabled the socket will connect to, or accept connections from, both IPv4 and IPv6 hosts\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +boolean +T} +T{ +.sp +Default value +T}:T{ +.sp +0 (false) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_IPV4ONLY: Retrieve IPv4\-only socket override status" +.sp +Retrieve the IPv4\-only option for the socket\&. This option is deprecated\&. Please use the ZMQ_IPV6 option\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +boolean +T} +T{ +.sp +Default value +T}:T{ +.sp +1 (true) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_IMMEDIATE: Retrieve attach\-on\-connect value" +.sp +Retrieve the state of the attach on connect value\&. If set to 1, will delay the attachment of a pipe on connect until the underlying connection has completed\&. This will cause the socket to block if there are no other connections, but will prevent queues from filling on pipes awaiting connection\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +boolean +T} +T{ +.sp +Default value +T}:T{ +.sp +0 (false) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, primarily when using TCP/IPC transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_FD: Retrieve file descriptor associated with the socket" +.sp +The \fIZMQ_FD\fR option shall retrieve the file descriptor associated with the specified \fIsocket\fR\&. The returned file descriptor can be used to integrate the socket into an existing event loop; the 0MQ library shall signal any pending events on the socket in an \fIedge\-triggered\fR fashion by making the file descriptor become ready for reading\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +.sp +The ability to read from the returned file descriptor does not necessarily indicate that messages are available to be read from, or can be written to, the underlying socket; applications must retrieve the actual event state with a subsequent retrieval of the \fIZMQ_EVENTS\fR option\&. +.sp .5v +.RE +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +.sp +The returned file descriptor is also used internally by the \fIzmq_send\fR and \fIzmq_recv\fR functions\&. As the descriptor is edge triggered, applications must update the state of \fIZMQ_EVENTS\fR after each invocation of \fIzmq_send\fR or \fIzmq_recv\fR\&.To be more explicit: after calling \fIzmq_send\fR the socket may become readable (and vice versa) without triggering a read event on the file descriptor\&. +.sp .5v +.RE +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBCaution\fR +.ps -1 +.br +.sp +The returned file descriptor is intended for use with a \fIpoll\fR or similar system call only\&. Applications must never attempt to read or write data to it directly, neither should they try to close it\&. +.sp .5v +.RE +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int on POSIX systems, SOCKET on Windows +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +N/A +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_EVENTS: Retrieve socket event state" +.sp +The \fIZMQ_EVENTS\fR option shall retrieve the event state for the specified \fIsocket\fR\&. The returned value is a bit mask constructed by OR\(cqing a combination of the following event flags: +.PP +\fBZMQ_POLLIN\fR +.RS 4 +Indicates that at least one message may be received from the specified socket without blocking\&. +.RE +.PP +\fBZMQ_POLLOUT\fR +.RS 4 +Indicates that at least one message may be sent to the specified socket without blocking\&. +.RE +.sp +The combination of a file descriptor returned by the \fIZMQ_FD\fR option being ready for reading but no actual events returned by a subsequent retrieval of the \fIZMQ_EVENTS\fR option is valid; applications should simply ignore this case and restart their polling operation/event loop\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A (flags) +T} +T{ +.sp +Default value +T}:T{ +.sp +N/A +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all +T} +.TE +.sp 1 +.SS "ZMQ_LAST_ENDPOINT: Retrieve the last endpoint set" +.sp +The \fIZMQ_LAST_ENDPOINT\fR option shall retrieve the last endpoint bound for TCP and IPC transports\&. The returned value will be a string in the form of a ZMQ DSN\&. Note that if the TCP host is INADDR_ANY, indicated by a *, then the returned address will be 0\&.0\&.0\&.0 (for IPv4)\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +NULL\-terminated character string +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +NULL +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when binding TCP or IPC transports +T} +.TE +.sp 1 +.SS "ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option" +.sp +Override \fISO_KEEPALIVE\fR socket option(where supported by OS)\&. The default value of \-1 means to skip any overrides and leave it to OS default\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +\-1,0,1 +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (leave to OS default) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT(or TCP_KEEPALIVE on some OS)" +.sp +Override \fITCP_KEEPCNT\fR(or \fITCP_KEEPALIVE\fR on some OS) socket option (where supported by OS)\&. The default value of \-1 means to skip any overrides and leave it to OS default\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +\-1,>0 +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (leave to OS default) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option" +.sp +Override \fITCP_KEEPCNT\fR socket option(where supported by OS)\&. The default value of \-1 means to skip any overrides and leave it to OS default\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +\-1,>0 +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (leave to OS default) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option" +.sp +Override \fITCP_KEEPINTVL\fR socket option(where supported by OS)\&. The default value of \-1 means to skip any overrides and leave it to OS default\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +\-1,>0 +T} +T{ +.sp +Default value +T}:T{ +.sp +\-1 (leave to OS default) +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transports\&. +T} +.TE +.sp 1 +.SS "ZMQ_MECHANISM: Retrieve current security mechanism" +.sp +The \fIZMQ_MECHANISM\fR option shall retrieve the current security mechanism for the socket\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +ZMQ_NULL, ZMQ_PLAIN, or ZMQ_CURVE +T} +T{ +.sp +Default value +T}:T{ +.sp +ZMQ_NULL +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP or IPC transports +T} +.TE +.sp 1 +.SS "ZMQ_PLAIN_SERVER: Retrieve current PLAIN server role" +.sp +Returns the \fIZMQ_PLAIN_SERVER\fR option, if any, previously set on the socket\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +int +T} +T{ +.sp +Option value unit +T}:T{ +.sp +0, 1 +T} +T{ +.sp +Default value +T}:T{ +.sp +int +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP or IPC transports +T} +.TE +.sp 1 +.SS "ZMQ_PLAIN_USERNAME: Retrieve current PLAIN username" +.sp +The \fIZMQ_PLAIN_USERNAME\fR option shall retrieve the last username set for the PLAIN security mechanism\&. The returned value shall be a NULL\-terminated string and MAY be empty\&. The returned size SHALL include the terminating null byte\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +NULL\-terminated character string +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +null string +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP or IPC transports +T} +.TE +.sp 1 +.SS "ZMQ_PLAIN_PASSWORD: Retrieve current password" +.sp +The \fIZMQ_PLAIN_PASSWORD\fR option shall retrieve the last password set for the PLAIN security mechanism\&. The returned value shall be a NULL\-terminated string and MAY be empty\&. The returned size SHALL include the terminating null byte\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +NULL\-terminated character string +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +null string +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP or IPC transports +T} +.TE +.sp 1 +.SS "ZMQ_CURVE_PUBLICKEY: Retrieve current CURVE public key" +.sp +Retrieves the current long term public key for the socket\&. You can provide either a 32 byte buffer, to retrieve the binary key value, or a 41 byte buffer, to retrieve the key in a printable Z85 format\&. NOTE: to fetch a printable key, the buffer must be 41 bytes large to hold the 40\-char key value and one null byte\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +binary data or Z85 text string +T} +T{ +.sp +Option value size +T}:T{ +.sp +32 or 41 +T} +T{ +.sp +Default value +T}:T{ +.sp +null +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transport +T} +.TE +.sp 1 +.SS "ZMQ_CURVE_SECRETKEY: Retrieve current CURVE secret key" +.sp +Retrieves the current long term secret key for the socket\&. You can provide either a 32 byte buffer, to retrieve the binary key value, or a 41 byte buffer, to retrieve the key in a printable Z85 format\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +binary data or Z85 text string +T} +T{ +.sp +Option value size +T}:T{ +.sp +32 or 41 +T} +T{ +.sp +Default value +T}:T{ +.sp +null +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transport +T} +.TE +.sp 1 +.SS "ZMQ_CURVE_SERVERKEY: Retrieve current CURVE server key" +.sp +Retrieves the current server key for the client socket\&. You can provide either a 32 byte buffer, to retrieve the binary key value, or a 40 byte buffer, to retrieve the key in a printable Z85 format\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +binary data or Z85 text string +T} +T{ +.sp +Option value size +T}:T{ +.sp +32 or 41 +T} +T{ +.sp +Default value +T}:T{ +.sp +null +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transport +T} +.TE +.sp 1 +.SS "ZMQ_ZAP_DOMAIN: Retrieve RFC 27 authentication domain" +.sp +The \fIZMQ_ZAP_DOMAIN\fR option shall retrieve the last ZAP domain set for the socket\&. The returned value shall be a NULL\-terminated string and MAY be empty\&. The returned size SHALL include the terminating null byte\&. +.TS +tab(:); +lt lt +lt lt +lt lt +lt lt. +T{ +.sp +Option value type +T}:T{ +.sp +character string +T} +T{ +.sp +Option value unit +T}:T{ +.sp +N/A +T} +T{ +.sp +Default value +T}:T{ +.sp +not set +T} +T{ +.sp +Applicable socket types +T}:T{ +.sp +all, when using TCP transport +T} +.TE +.sp 1 +.SH "RETURN VALUE" +.sp +The \fIzmq_getsockopt()\fR function shall return zero if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&. +.SH "ERRORS" +.PP +\fBEINVAL\fR +.RS 4 +The requested option +\fIoption_name\fR +is unknown, or the requested +\fIoption_len\fR +or +\fIoption_value\fR +is invalid, or the size of the buffer pointed to by +\fIoption_value\fR, as specified by +\fIoption_len\fR, is insufficient for storing the option value\&. +.RE +.PP +\fBETERM\fR +.RS 4 +The 0MQ +\fIcontext\fR +associated with the specified +\fIsocket\fR +was terminated\&. +.RE +.PP +\fBENOTSOCK\fR +.RS 4 +The provided +\fIsocket\fR +was invalid\&. +.RE +.PP +\fBEINTR\fR +.RS 4 +The operation was interrupted by delivery of a signal\&. +.RE +.SH "EXAMPLE" +.PP +\fBRetrieving the high water mark for outgoing messages\fR. +.sp +.if n \{\ +.RS 4 +.\} +.nf +/* Retrieve high water mark into sndhwm */ +int sndhwm; +size_t sndhwm_size = sizeof (sndhwm); +rc = zmq_getsockopt (socket, ZMQ_SNDHWM, &sndhwm, &sndhwm_size); +assert (rc == 0); +.fi +.if n \{\ +.RE +.\} +.sp +.SH "SEE ALSO" +.sp +\fBzmq_setsockopt\fR(3) \fBzmq_socket\fR(3) \fBzmq\fR(7) +.SH "AUTHORS" +.sp +This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&. |