where
import Control.Concurrent (threadDelay)
-import Control.DeepSeq (deepseq)
import Control.Exception.Base (bracket)
-import Control.Monad (forever, when)
+import Control.Monad (when)
import Data.List (isPrefixOf)
import Data.Maybe (isNothing)
import Data.Monoid ((<>))
stderr,
stdout )
import System.IO.Error (catchIOError)
+import System.Timeout (timeout)
import CommandLine (get_args)
import Configuration (Configuration(..), merge_optional)
exit_no_feed_hosts,
exit_no_password,
exit_no_username )
-import FeedHosts (FeedHosts(..))
import qualified OptionalConfiguration as OC (
OptionalConfiguration(..),
from_rc )
-import Terminal (hPutRedLn, putGreenLn)
+import Terminal (putGreenLn, report_error)
+import TSN.FeedHosts (FeedHosts(..))
import TSN.Xml (parse_xmlfid, xml_prologue)
-report_error :: String -> IO ()
-report_error = hPutRedLn stderr
-
-
+-- | Receive a single line of text from a Handle, echoing it to stdout
+-- in the process.
+--
recv_line :: Handle -> IO String
recv_line h = do
line <- hGetLine h
return line
+-- | Takes a Configuration, and an XML document (as a String). The XML
+-- document is written to the output directory, as specified by the
+-- Configuration.
+--
+-- This can fail, but we don't purposefully throw any exceptions. If
+-- something goes wrong, we would rather log it and keep going.
+--
save_document :: Configuration -> String -> IO ()
-save_document cfg doc = do
+save_document cfg doc =
case maybe_path of
Nothing ->
report_error "ERROR: document missing XML_File_ID element."
filename = fmap (++ ".xml") xmlfid
maybe_path = fmap ((output_directory cfg) </>) filename
+
-- | Loop forever, writing the buffer to file whenever a new XML
--- prologue is seen.
+-- prologue is seen. This is the low-level "loop forever" function
+-- that we stay in as long as we are connected to one feed.
+--
loop :: Configuration -> Handle -> [String] -> IO ()
loop !cfg !h !buffer = do
line <- recv_line h
save_document cfg document
loop cfg h [line] -- empty the buffer before looping again
else
- loop cfg h (line : buffer) -- append line to the head of the buffer and loop
+ -- append line to the head of the buffer and loop
+ loop cfg h (line : buffer)
log_in :: Configuration -> Handle -> IO ()
report_error "ERROR: didn't receive password prompt."
else do
send_line h (password cfg)
- banner <- recv_line h -- "The Sports Network"
- banner `deepseq` return ()
+ _ <- recv_line h -- "The Sports Network"
+ return ()
where
username_prompt = "Username: "
password_prompt = "Password: "
recv_prompt :: Handle -> IO String
recv_prompt = recv_chars 10
-connect_and_loop :: Configuration -> IO ()
-connect_and_loop cfg =
+connect_and_loop :: Configuration -> String -> IO ()
+connect_and_loop cfg host = do
+ putStrLn $ "Connecting to " ++ host ++ "..."
bracket acquire_handle release_handle action
+ return ()
where
- --acquire_handle = connectTo "feed1.sportsnetwork.com" (PortNumber 4500)
- acquire_handle = connectTo "feed2.sportsnetwork.com" (PortNumber 4500)
- --acquire_handle = connectTo "127.0.0.1" (PortNumber 13337)
+ five_seconds :: Int
+ five_seconds = 5000000
+
+ acquire_handle = connectTo host (PortNumber 4500)
release_handle = hClose
action h = do
-- No buffering anywhere.
hSetBuffering h NoBuffering
- log_in cfg h
- loop cfg h []
+
+ -- The feed is often unresponsive after we send out username. It
+ -- happens in a telnet session, too (albeit less frequently?),
+ -- so there might be a bug on their end.
+ --
+ -- If we dump the packets with tcpdump, it looks like their
+ -- software is getting confused: they send us some XML in
+ -- the middle of the log-in procedure. In any case, the easiest
+ -- fix is to disconnect and try again.
+ --
+ login_worked <- timeout five_seconds $ log_in cfg h
+ case login_worked of
+ Nothing -> putStrLn "Login timed out (5s)."
+ Just _ -> loop cfg h []
-- | A wrapper around threadDelay which takes seconds instead of
-- microseconds as its argument.
+--
thread_sleep :: Int -> IO ()
thread_sleep seconds = do
let microseconds = seconds * (10 ^ (6 :: Int))
threadDelay microseconds
+-- | The entry point of the program.
main :: IO ()
main = do
rc_cfg <- OC.from_rc
-- prefering the command-line ones.
let opt_config = rc_cfg <> cmd_cfg
+ -- This is necessary because if the user specifies an empty list of
+ -- hostnames in e.g. the config file, we want to bail rather than
+ -- fall back on the default list (which gets merged from a
+ -- Configuration below).
when (null $ get_feed_hosts (OC.feed_hosts opt_config)) $ do
report_error "ERROR: no feed hosts supplied."
exitWith (ExitFailure exit_no_feed_hosts)
-- set in either the config file or on the command-line.
let cfg = (def :: Configuration) `merge_optional` opt_config
+ -- This may be superstition (and I believe stderr is unbuffered),
+ -- but it can't hurt.
hSetBuffering stderr NoBuffering
hSetBuffering stdout NoBuffering
- forever $ do
- catchIOError (connect_and_loop cfg) (report_error . show)
- thread_sleep 10 -- Wait 10s before attempting to reconnect.
+ -- Begin connecting to our feed hosts, starting with the first one.
+ round_robin cfg 0
+
+ where
+ -- | This is the top-level "loop forever" function. If an
+ -- exception is thrown, it will propagate up to this point, where
+ -- it will be logged and ignored in style.
+ --
+ -- Afterwards, we recurse (call ourself) again to loop more forevers.
+ --
+ round_robin :: Configuration -> Int -> IO ()
+ round_robin cfg feed_host_idx = do
+ let hosts = get_feed_hosts $ feed_hosts cfg
+ let host = hosts !! feed_host_idx
+ catchIOError (connect_and_loop cfg host) (report_error . show)
+ thread_sleep 10 -- Wait 10s before attempting to reconnect.
+ round_robin cfg $ (feed_host_idx + 1) `mod` (length hosts)
projects / dead / htsn.git / blobdiff