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Diffstat (limited to 'man/man3/zmq_setsockopt.3')
| -rw-r--r-- | man/man3/zmq_setsockopt.3 | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/man/man3/zmq_setsockopt.3 b/man/man3/zmq_setsockopt.3 index da528cf..a79f879 100644 --- a/man/man3/zmq_setsockopt.3 +++ b/man/man3/zmq_setsockopt.3 @@ -4,9 +4,112 @@ zmq_setsockopt \- sets a specified option on a 0MQ socket .SH SYNOPSIS .B int zmq_setsockopt (void *s, int option, const void *optval, size_t optvallen); .SH DESCRIPTION +Sets an option on the socket. +.IR option +argument specifies the option from the list below. +.IR optval +is a pointer to the value to set, +.IR optvallen +is the size of the value in bytes. + +.IP "\fBZMQ_HWM\fP" +High watermark for the message pipes associated with the socket. The water +mark cannot be exceeded. If the messages don't fit into the pipe emergency +mechanisms of the particular socket type are used (block, drop etc.) If HWM +is set to zero, there are no limits for the content of the pipe. +Type: int64_t Unit: bytes Default: 0 + +.IP "\fBZMQ_LWM\fP" +Low watermark makes sense only if high watermark is defined (i.e. is non-zero). +When the emergency state is reached when messages overflow the pipe, the +emergency lasts till the size of the pipe decreases to low watermark. +At that point normal state is resumed. +Type: int64_t Unit: bytes Default: 0 + +.IP "\fBZMQ_SWAP\fP" +Swap allows the pipe to exceed high watermark. However, the data are written +to the disk rather than held in the memory. Until high watermark is +exceeded there is no disk activity involved though. The value of the option +defines maximal size of the swap file. +Type: int64_t Unit: bytes Default: 0 + +.IP "\fBZMQ_AFFINITY\fP" +Affinity defines which threads in the thread pool will be used to handle +newly created sockets. This way you can dedicate some of the threads (CPUs) +to a specific work. Value of 0 means no affinity. Work is distributed +fairly among the threads in the thread pool. For non-zero values, the lowest +bit corresponds to the thread 1, second lowest bit to the thread 2 etc. +Thus, value of 3 means that from now on newly created sockets will handle +I/O activity exclusively using threads no. 1 and 2. +Type: int64_t Unit: N/A (bitmap) Default: 0 + +.IP "\fBZMQ_IDENTITY\fP" +Identity of the socket. Identity is important when restarting applications. +If the socket has no identity, each run of the application is completely +separated from other runs. However, with identity application reconnects to +existing infrastructure left by the previous run. Thus it may receive +messages that were sent in the meantime, it shares pipe limits with the +previous run etc. +Type: string Unit: N/A Default: NULL + +.IP "\fBZMQ_SUBSCRIBE\fP" +Applicable only to ZMQ_SUB socket type. It establishes new message filter. +When ZMQ_SUB socket is created all the incoming messages are filtered out. +This option allows you to subscribe for all messages ("*"), messages with +specific topic ("x.y.z") and/or messages with specific topic prefix +("x.y.*"). Topic is one-byte-size-prefixed string located at +the very beginning of the message. Multiple filters can be attached to +a single 'sub' socket. In that case message passes if it matches at least +one of the filters. +Type: string Unit: N/A Default: N/A + +.IP "\fBZMQ_UNSUBSCRIBE\fP" +Applicable only to ZMQ_SUB socket type. Removes existing message filter. +The filter specified must match the string passed to ZMQ_SUBSCRIBE options +exactly. If there were several instances of the same filter created, +this options removes only one of them, leaving the rest in place +and functional. +Type: string Unit: N/A Default: N/A + +.IP "\fBZMQ_RATE\fP" +This option applies only to sending side of multicast transports (pgm & udp). +It specifies maximal outgoing data rate that an individual sender socket +can send. +Type: uint64_t Unit: kilobits/second Default: 100 + +.IP "\fBZMQ_RECOVERY_IVL\fP" +This option applies only to multicast transports (pgm & udp). It specifies +how long can the receiver socket survive when the sender is inaccessible. +Keep in mind that large recovery intervals at high data rates result in +very large recovery buffers, meaning that you can easily overload your box +by setting say 1 minute recovery interval at 1Gb/s rate (requires +7GB in-memory buffer). +Type: uint64_t Unit: seconds Default: 10 + +.IP "\fBZMQ_MCAST_LOOP\fP" +This option applies only to multicast transports (pgm & udp). Value of 1 +means that the mutlicast packets can be received on the box they were sent +from. Setting the value to 0 disables the loopback functionality which +can have negative impact on the performance. If possible, disable +the loopback in production environments. +Type: uint64_t Unit: N/A (boolean value) Default: 1 + .SH RETURN VALUE +In case of success the function returns zero. Otherwise it returns -1 and +sets +.IR errno +to the appropriate value. .SH ERRORS +.IP "\fBEINVAL\fP" +unknown option, a value with incorrect length or invalid value. .SH EXAMPLE +.nf +int rc = zmq_setsockopt (s, ZMQ_SUBSCRIBE, "*", 1); +assert (rc == 0); +.fi .SH SEE ALSO +.BR zmq_socket (3) +.BR zmq (7) + .SH AUTHOR Martin Sustrik <sustrik at 250bpm dot com> |