X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMain.hs;h=de0e28e53ea9dfa48fa4d8cb202216b1e9b67788;hb=HEAD;hp=dcb38b23e338eb3bc93524aec2d84173b4dd51d0;hpb=60aea8c7765bf2382b1d24d039f3951e00434e3c;p=dead%2Fhtsn.git

diff --git a/src/Main.hs b/src/Main.hs
index dcb38b2..de0e28e 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -5,6 +5,7 @@ module Main
 where
 
 -- System imports.
+import Control.Applicative ( (<$>) )
 import Control.Concurrent ( threadDelay )
 import Control.Exception ( bracket, throw )
 import Control.Monad ( when )
@@ -71,12 +72,17 @@ recv_line h = do
 --   This can fail, but we don't purposefully throw any exceptions. If
 --   something goes wrong, we would rather log it and keep going.
 --
+--   And in fact the only \"error\" that can occur is from
+--   'parse_xmlfid' if TSN sends us a non-integer XML File ID. But
+--   this is expected from time to time, and is merely unsupported. So
+--   we report any failures as info instead of as errors.
+--
 save_document :: Configuration
               -> String -- ^ String representation of an XML document
               -> IO ()
 save_document cfg doc =
   case either_path of
-    Left err -> report_error err
+    Left err -> report_info err -- Can only be non-integer XML File ID
     Right path -> do
       already_exists <- doesFileExist path
       when already_exists $ do
@@ -85,10 +91,10 @@ save_document cfg doc =
       writeFile path doc
       report_info $ "Wrote file: " ++ path ++ "."
   where
-    -- All the fmaps are because we're working inside a Maybe.
-    xmlfid = fmap show (parse_xmlfid doc)
-    filename = fmap (++ ".xml") xmlfid
-    either_path = fmap ((output_directory cfg) </>) filename
+    -- All the <$> are because we're working inside an Either.
+    xmlfid = show <$> (parse_xmlfid doc)
+    filename = (++ ".xml") <$> xmlfid
+    either_path = ((output_directory cfg) </>) <$> filename
 
 
 -- | Loop forever, writing the @buffer@ to file whenever a
@@ -105,28 +111,46 @@ save_document cfg doc =
 --   The bang pattern at least on @buffer@ is necessary for
 --   performance reasons.
 --
+--   We specify a timeout of fifteen minutes on the 'recv_line'
+--   function, after which we will return to our caller. This should
+--   cause the connection to be dropped, and a new one initiated. The
+--   timeout is in response to observed behavior where the feed
+--   eventually stops transmitting data entirely without closing the
+--   connection.
+--
 loop :: Configuration
      -> Handle -- ^ Handle to the feed (network connection)
      -> [String] -- ^ Current XML document buffer, line-by-line, in reverse
      -> IO ()
 loop !cfg !h !buffer = do
-  line <- recv_line h
-  let new_buffer = line : buffer
-
-  -- Use isPrefixOf to avoid line-ending issues. Hopefully they won't
-  -- send invalid junk (on the same line) after closing the root
-  -- element.
-  if "</message>" `isPrefixOf` line
-  then do
-    -- The buffer is in reverse (newest first) order, though, so we
-    -- have to reverse it first. We then concatenate all of its lines
-    -- into one big string.
-    let document = concat $ reverse new_buffer
-    save_document cfg document
-    loop cfg h [] -- Empty the buffer before looping again.
-  else
-    -- Append line to the head of the buffer and loop.
-    loop cfg h new_buffer
+  line' <- timeout fifteen_minutes $ recv_line h
+  case line' of
+    -- If we haven't received anything in fifteen minutes, return back
+    -- to the calling function. This should only happen in the case of
+    -- an error, and our caller should be prepared to handle it.
+    Nothing -> report_warning "No data received for 15 minutes."
+
+    Just line -> do
+      -- If the recv didn't timeout, proceed normally.
+      let new_buffer = line : buffer
+
+      -- Use isPrefixOf to avoid line-ending issues. Hopefully they won't
+      -- send invalid junk (on the same line) after closing the root
+      -- element.
+      if "</message>" `isPrefixOf` line
+      then do
+        -- The buffer is in reverse (newest first) order, though, so we
+        -- have to reverse it first. We then concatenate all of its lines
+        -- into one big string.
+        let document = concat $ reverse new_buffer
+        save_document cfg document
+        loop cfg h [] -- Empty the buffer before looping again.
+      else
+        -- Append line to the head of the buffer and loop.
+        loop cfg h new_buffer
+  where
+    fifteen_minutes :: Int
+    fifteen_minutes = 15 * 60 * 1000000
 
 
 -- | Once we're connected to a feed, we need to log in. There's no
@@ -207,16 +231,20 @@ log_in cfg h = do
 connect_and_parse :: Configuration
                   -> String -- ^ Hostname to connect to
                   -> IO ()
-connect_and_parse cfg host = do
-  report_info $ "Connecting to " ++ host ++ "."
+connect_and_parse cfg host =
   bracket acquire_handle release_handle action
-  return ()
   where
     five_seconds :: Int
-    five_seconds = 5000000
+    five_seconds = 5 * 1000000
+
+    acquire_handle = do
+      report_info $ "Connecting to " ++ host ++ "."
+      connectTo host (PortNumber 4500)
+
+    release_handle h = do
+      report_info $ "Closing connection to " ++ host ++ "."
+      hClose h
 
-    acquire_handle = connectTo host (PortNumber 4500)
-    release_handle = hClose
     action h = do
       -- No buffering anywhere.
       hSetBuffering h NoBuffering
@@ -240,6 +268,10 @@ connect_and_parse cfg host = do
       case login_worked of
         Nothing -> report_info $ "Login timed out (5 seconds). "
                                    ++ "Waiting 5 seconds to reconnect."
+
+        -- If loop returns (due to its timeout), it will pop out right
+        -- here and the action will terminate causing 'release_handle'
+        -- to trigger.
         Just _ ->  loop cfg h []
 
 
@@ -271,15 +303,7 @@ main = do
   let cfg = (def :: Configuration) `merge_optional` opt_config
   init_logging (log_level cfg) (log_file cfg) (syslog cfg)
 
-  -- Check the optional config for missing required options. 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 was merged from a default
-  -- Configuration above).
-  when (null $ get_feed_hosts (OC.feed_hosts opt_config)) $ do
-    report_error "No feed hosts supplied."
-    exitWith (ExitFailure exit_no_feed_hosts)
-
+  -- Check the optional config for missing required options.
   when (isNothing (OC.password opt_config)) $ do
     report_error "No password supplied."
     exitWith (ExitFailure exit_no_password)
@@ -288,6 +312,18 @@ main = do
     report_error "No username supplied."
     exitWith (ExitFailure exit_no_username)
 
+  -- This should be impossible. We had a choice to make: since the
+  -- command-line feed_hosts are usually not supplied, we don't want
+  -- to take the empty list supplied on the command-line and use
+  -- that. But that means that we need to do the same thing if the
+  -- user supplies an empty list in the config file. That "same thing"
+  -- is to use the default list. So, this should never be empty,
+  -- because if the optional config has no feed hosts, we use the
+  -- default list.
+  when (null $ get_feed_hosts (feed_hosts cfg)) $ do
+    report_error "No feed hosts supplied."
+    exitWith (ExitFailure exit_no_feed_hosts)
+
   when (daemonize cfg) $ do
     -- Old PID files can be left around after an unclean shutdown. We
     -- only care if we're running as a daemon.