R/mongoResp.r

In strongh/mongor: A driver for MongoDB

##' Eagerly await mongo's reponse
##'
##' Polls the socket connection for non-null value.
##' Assume that the first 4 bytes are a int32 describing the message length.
##' Attempt to read the message length.
##'
##' @param connection an open socket 
##' @param timeout how many tries to get a non-null

mongoResp <-
  function(conn, timeout=10){
    socketSelect(list(conn), c(FALSE), timeout=timeout)
    
    first.raw <- readBin(con=conn, what='raw', n=4)
    
    msg.len <- decode_int32(first.raw)
    
    if (msg.len == 0){
      stop("No word from mongo!")
    } else {            
      msg <- readBin(
                     con=conn,
                     what='raw',
                     n=(msg.len-4)) # msg.len counts itself in the total message length
      
      c(first.raw, msg)
    }
  }