On 11/27/21 5:24 PM, Ben Engbers wrote:
Op 27-11-2021 om 17:03 schreef Jeff Newmiller:
This is a null-terminated message protocol [1]. It has to be
processed one byte at a time.
[1] https://docs.basex.org/wiki/Server_Protocol
The message may contain embedded 0x00's. To distinguish these embedded
0x00's (and 0xFF's) from a terminating 0x00, embedded 0x00's and
0xFFare prefixed with a 0xFF byte. This means that when you process
one byte at a time you have to perform a check on every byte. This
results in totally unacceptable response times (My first version of
this client was based on this approach)
The only alternative solution I can think off is to use C++ to create
a socket and a function that reads from the socket. But since I have
hardly any experience with C++ programming nor using the rcpp package....
I think you could use non-blocking read. Read what is available in
chunks (e.g. up to 1024 bytes long). And based on what is read already,
figure out whether it is all data or not. Something along the lines as
the demo below. The demo, though, is polling too much (re-running
readBin to only find out no data is available yet). It should be
possible to improve with socketSelect().
Best
Tomas
# the client
con2 <- socketConnection("localhost", port = 6011, open = "rb")
cat("Connected...\n")
total <- 0
done <- function(n) {
n >= 1e8
}
while(!done(total)) {
r <- readBin(con2, "raw", 1024)
total <- total + length(r)
cat("Read", length(r), "bytes (total ", total, ").\n")
}
close(con2)
# the server
n <- 1e8
w <- as.raw(runif(n, 0, 255))
con1 <- socketConnection(port = 6011, blocking = TRUE, server = TRUE,
open="a+b")
cat("Connected...\n")
writeBin(w, con1)
cat("Data sent to client...\n")
close(con1)
Ben
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