147 lines
4.3 KiB
R
147 lines
4.3 KiB
R
chat_loop <- function(server, sockets, delay = 0.5) {
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repeat {
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Sys.sleep(delay) # Saves CPU resources
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## Exhausts queue each iteration
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while (in_queue(server))
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sockets <- new_socket_entry(server, sockets)
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## Update which sockets have sent messages
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sockets <- check_messages(sockets)
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## No sockets, nothing to do
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if (nrow(sockets) == 0)
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next
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## No new messages, nothing to do
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if (all(!sockets$message_ready))
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next
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sockets <- read_messages(sockets) # Messages are stored until sent
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sockets <- drop_dead(sockets) # Dead = ready to read, but no data
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## In case all sockets were dropped
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if (nrow(sockets) == 0)
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next
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sockets <- update_nicknames(sockets)
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sockets <- send_messages(sockets) # Only to users with nicknames
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}
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}
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check_messages <- function(sockets) {
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if (nrow(sockets) != 0)
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sockets$message_ready <- socketSelect(sockets$conn, timeout = 0)
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sockets
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}
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drop_dead <- function(sockets) {
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lapply(with(sockets, conn[!alive]), close)
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dropped <- with(sockets, nickname[nickname_exists(sockets) & !alive])
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sockets <- sockets[sockets$alive, ]
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if (length(dropped) != 0) {
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send_named(sockets, paste0(dropped, " has disconnected."))
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}
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sockets
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}
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in_queue <- function(server) socketSelect(list(server), timeout = 0)
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is_valid_name <- function(nicks) gsub("[A-Za-z0-9]*", "", nicks) == ""
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message_exists <- function(sockets) !is.na(sockets$message)
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new_row <- function(df) {
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df[nrow(df) + 1, ] <- NA
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df
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}
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new_socket_entry <- function(server, sockets) {
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sockets <- new_row(sockets)
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n <- nrow(sockets)
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within(sockets, {
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conn[[n]] <- new_user(server)
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alive[n] <- TRUE
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message_ready[n] <- FALSE
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})
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}
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new_user <- function(server) {
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conn <- socketAccept(server)
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writeLines("Hello! Please enter a nickname.", conn)
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conn
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}
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nickname_exists <- function(sockets) !is.na(sockets$nickname)
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read_messages <- function(sockets) {
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if (all(!sockets$message_ready))
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return(sockets)
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msgs <- lapply(with(sockets, conn[message_ready]), readLines, n = 1)
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empty_msgs <- sapply(msgs, identical, character(0))
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sockets <- within(sockets, alive[message_ready & empty_msgs] <- FALSE)
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msgs <- unlist(ifelse(empty_msgs, NA, msgs))
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within(sockets, message[message_ready] <- msgs)
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}
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send_messages <- function(sockets) {
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named_message <- message_exists(sockets) & nickname_exists(sockets)
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if (all(!named_message))
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return(sockets)
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rows <- which(named_message)
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socksub <- sockets[rows, ]
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time <- format(Sys.time(), "[%H:%M:%S] ")
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with(socksub, send_named(sockets, paste0(time, nickname, ": ", message)))
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within(sockets, message[rows] <- NA)
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}
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send_named <- function(sockets, msg) {
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has_nickname <- nickname_exists(sockets)
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invisible(lapply(sockets$conn[has_nickname], writeLines, text = msg))
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}
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start_chat_server <- function(port = 50525) {
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server <- serverSocket(port) # Start listening
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on.exit(closeAllConnections()) # Cleanup connections
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## All socket data is stored and passed using this object
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sockets <- data.frame(conn = I(list()), nickname = character(),
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message = character(), alive = logical(),
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message_ready = logical())
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## Main event loop
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chat_loop(server, sockets)
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}
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update_nicknames <- function(sockets) {
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sent_nickname <- message_exists(sockets) & !nickname_exists(sockets)
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nickname_valid <- is_valid_name(sockets$message)
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if (all(!sent_nickname))
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return(sockets)
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is_taken <- with(sockets, (tolower(message) %in% tolower(sockets$nickname)) &
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!is.na(message))
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sent_ok <- sent_nickname & nickname_valid & !is_taken
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sockets <- within(sockets, {
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nickname[sent_ok] <- message[sent_ok]
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message[sent_nickname] <- NA
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lapply(conn[sent_nickname & !nickname_valid], writeLines,
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text = "Alphanumeric characters only. Try again.")
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lapply(conn[is_taken], writeLines,
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text = "Name already taken. Try again.")
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})
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if (any(sent_ok))
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send_named(sockets, paste0(sockets$nickname[sent_ok], " has connected."))
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sockets
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}
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start_chat_server()
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