pbdZMQ (version 0.2-6)

New Poll Functions: New Poll Functions

Description

New poll functions

Usage

zmq.poll2(socket, type, timeout = -1L, MC = .pbd_env$ZMQ.MC)
zmq.poll2.interrupt(socket, type, timeout = -1L, MC = .pbd_env$ZMQ.MC)
zmq.poll2.get.revents(index = 1L, poller)

Arguments

socket

a vector of ZMQ sockets

type

a vector of socket types corresponding to socket argument

timeout

timeout for poll, see ZeroMQ manual for details

MC

a message control, see ZMQ.MC() for details

index

an index of ZMQ poll items to obtain revents

poller

a pointer of ZMQ poller

Value

zmq.poll2() returns a ZMQ code, an errno, and a pollitem pointer. No error/warning/interrupt in this R function, but some error/warning/interrupt may catch by the C function zmq_poll(). See ZeroMQ manual for details.

zmq.poll.get.revents.new() returns the revent type.

Details

zmq.poll2() initials ZMQ poll items given ZMQ socket's and ZMQ poll type's. Both socket and type are in vectors of the same length, while socket contains socket pointers and type contains types of poll. See ZMQ.PO() for the possible values of type. ZMQ defines several poll types and utilize them to poll multiple sockets.

zmq.poll2.interrupt() call zmq.poll2() and raise an interrupt signal if ret$pollret[1] == -1 and ret$pollret[2] == 4.

zmq.poll2.get.revents() obtains revent types from ZMQ poll item by the input index..

References

ZeroMQ/4.1.0 API Reference: http://api.zeromq.org/4-1:_start

Programming with Big Data in R Website: http://r-pbd.org/

See Also

zmq.recv(), zmq.send().

Examples

# NOT RUN {
### Multiple socket reader as in the ZeroMQ guide.
# SHELL> Rscript wuserver.r &
# SHELL> Rscript taskvent.r &
# SHELL> Rscript mspoller2.r
# SHELL> rm weather.ipc

library(pbdZMQ, quietly = TRUE)

### Initial.
context <- zmq.ctx.new()
receiver <- zmq.socket(context, .pbd_env$ZMQ.ST$PULL)
zmq.connect(receiver, "tcp://localhost:5557")
subscriber <- zmq.socket(context, .pbd_env$ZMQ.ST$SUB)
zmq.connect(subscriber, "tcp://localhost:5556")
zmq.setsockopt(subscriber, .pbd_env$ZMQ.SO$SUBSCRIBE, "20993")

### Process messages from both sockets.
cat("Press Ctrl+C or Esc to stop mspoller.\n")
i.rec <- 0
i.sub <- 0
while(TRUE){
  ### Set poller.
  poller <- zmq.poll2(c(receiver, subscriber),
                      c(.pbd_env$ZMQ.PO$POLLIN, .pbd_env$ZMQ.PO$POLLIN))

  ### Check receiver.
  if(bitwAnd(zmq.poll2.get.revents(1, poller),
             .pbd_env$ZMQ.PO$POLLIN)){
    ret <- zmq.recv(receiver)
    if(ret$len != -1){
      cat("task ventilator:", ret$buf, "at", i.rec, "\n")
      i.rec <- i.rec + 1
    }
  }

  ### Check subscriber.
  if(bitwAnd(zmq.poll2.get.revents(2, poller),
             .pbd_env$ZMQ.PO$POLLIN)){
    ret <- zmq.recv(subscriber)
    if(ret$len != -1){
      cat("weather update:", ret$buf, "at", i.sub, "\n")
      i.sub <- i.sub + 1
    }
  }

  if(i.rec >= 5 & i.sub >= 5){
    break
  }

  Sys.sleep(runif(1, 0.5, 1))
}

### Finish.
zmq.close(receiver)
zmq.close(subscriber)
zmq.ctx.destroy(context)
# }
# NOT RUN {
# }