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Diffstat (limited to 'doc/zmq_getsockopt.3')
| -rw-r--r-- | doc/zmq_getsockopt.3 | 445 |
1 files changed, 438 insertions, 7 deletions
diff --git a/doc/zmq_getsockopt.3 b/doc/zmq_getsockopt.3 index d1ea10b..9ab4ec9 100644 --- a/doc/zmq_getsockopt.3 +++ b/doc/zmq_getsockopt.3 @@ -2,12 +2,12 @@ .\" Title: zmq_getsockopt .\" Author: [see the "AUTHORS" section] .\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/> -.\" Date: 10/15/2010 +.\" Date: 03/15/2011 .\" Manual: 0MQ Manual -.\" Source: 0MQ 2.0.10 +.\" Source: 0MQ 2.1.3 .\" Language: English .\" -.TH "ZMQ_GETSOCKOPT" "3" "10/15/2010" "0MQ 2\&.0\&.10" "0MQ Manual" +.TH "ZMQ_GETSOCKOPT" "3" "03/15/2011" "0MQ 2\&.1\&.3" "0MQ Manual" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- @@ -37,6 +37,45 @@ zmq_getsockopt \- get 0MQ socket options 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 parts to follow" .sp The \fIZMQ_RCVMORE\fR option shall return a boolean value indicating if the multi\-part message currently being read from the specified \fIsocket\fR has more message parts to follow\&. If there are no message parts to follow or if the message currently being read is not a multi\-part message a value of zero shall be returned\&. Otherwise, a value of 1 shall be returned\&. @@ -207,7 +246,7 @@ T} .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 determines if existing 0MQ infastructure (\fImessage queues\fR, \fIforwarding devices\fR) shall be identified with a specific application and persist across multiple runs of the application\&. +The \fIZMQ_IDENTITY\fR option shall retrieve the identity of the specified \fIsocket\fR\&. Socket identity determines if existing 0MQ infrastructure (\fImessage queues\fR, \fIforwarding devices\fR) shall be identified with a specific application and persist across multiple runs of the application\&. .sp If the socket has no identity, each run of an application is completely separate from other runs\&. However, with identity set the socket shall re\-use any existing 0MQ infrastructure configured by the previous run(s)\&. Thus the application may receive messages that were sent in the meantime, \fImessage queue\fR limits shall be shared with previous run(s) and so on\&. .sp @@ -326,9 +365,50 @@ all, when using multicast transports T} .TE .sp 1 -.SS "ZMQ_MCAST_LOOP: Control multicast loopback" +.SS "ZMQ_RECOVERY_IVL_MSEC: Get multicast recovery interval in milliseconds" +.sp +The \fIZMQ_RECOVERY_IVL\(cq_MSEC option shall retrieve the recovery interval, in milliseconds, for multicast transports using the specified \*(Aqsocket\fR\&. The recovery interval determines the maximum time in seconds that a receiver can be absent from a multicast group before unrecoverable data loss will occur\&. .sp -The \fIZMQ_MCAST_LOOP\fR option controls whether data sent via multicast transports can also be received by the sending host via loopback\&. A value of zero indicates that the loopback functionality is disabled, while the default value of 1 indicates that the loopback functionality is enabled\&. Leaving multicast loopback enabled when it is not required can have a negative impact on performance\&. Where possible, disable \fIZMQ_MCAST_LOOP\fR in production environments\&. +For backward compatibility, the default value of \fIZMQ_RECOVERY_IVL_MSEC\fR is \-1 indicating that the recovery interval should be obtained from the \fIZMQ_RECOVERY_IVL\fR option\&. However, if the \fIZMQ_RECOVERY_IVL_MSEC\fR value is not zero, then it will take precedence, and be used\&. +.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 +milliseconds +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_MCAST_LOOP: Control multicast loop\-back" +.sp +The \fIZMQ_MCAST_LOOP\fR option controls whether data sent via multicast transports can also be received by the sending host via loop\-back\&. A value of zero indicates that the loop\-back functionality is disabled, while the default value of 1 indicates that the loop\-back functionality is enabled\&. Leaving multicast loop\-back enabled when it is not required can have a negative impact on performance\&. Where possible, disable \fIZMQ_MCAST_LOOP\fR in production environments\&. .TS tab(:); lt lt @@ -443,6 +523,352 @@ 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\&. +.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_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 +\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 +uint32_t +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 .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\&. @@ -476,6 +902,11 @@ The provided \fIsocket\fR was not valid (NULL)\&. .RE +.PP +\fBEINTR\fR +.RS 4 +The operation was interrupted by delivery of a signal\&. +.RE .SH "EXAMPLE" .PP \fBRetrieving the high water mark\fR. @@ -499,7 +930,7 @@ assert (rc == 0); \fBzmq_setsockopt\fR(3) \fBzmq_socket\fR(3) \fBzmq\fR(7) .SH "AUTHORS" .sp -The 0MQ documentation was written by Martin Sustrik <\m[blue]\fBsustrik@250bpm\&.com\fR\m[]\&\s-2\u[1]\d\s+2> and Martin Lucina <\m[blue]\fBmato@kotelna\&.sk\fR\m[]\&\s-2\u[2]\d\s+2>\&. +This 0MQ manual page was written by Martin Sustrik <\m[blue]\fBsustrik@250bpm\&.com\fR\m[]\&\s-2\u[1]\d\s+2> and Martin Lucina <\m[blue]\fBmato@kotelna\&.sk\fR\m[]\&\s-2\u[2]\d\s+2>\&. .SH "NOTES" .IP " 1." 4 sustrik@250bpm.com |