{-# LANGUAGE DoAndIfThenElse #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
module Main
where
-- System imports.
import Control.Arrow ( (&&&), (>>^), arr, returnA )
import Control.Concurrent ( threadDelay )
import Control.Exception ( SomeException, catch )
import Control.Monad ( when )
import Database.Groundhog.Generic ( runDbConn )
import Database.Groundhog.Sqlite (
withSqliteConn )
import Database.Groundhog.Postgresql (
withPostgresqlConn )
import Data.Monoid ( (<>) )
import Network.Services.TSN.Logging ( init_logging )
import System.Console.CmdArgs ( def )
import System.Directory ( removeFile )
import System.Exit ( exitWith, ExitCode (ExitFailure) )
import System.IO.Error ( catchIOError )
import Text.XML.HXT.Core (
ArrowXml,
IOStateArrow,
XmlTree,
(>>>),
(/>),
getAttrl,
getText,
hasName,
readDocument,
runX,
unpickleDoc )
-- Local imports.
import Backend ( Backend(..) )
import CommandLine ( get_args )
import Configuration ( Configuration(..), merge_optional )
import ConnectionString ( ConnectionString(..) )
import ExitCodes ( exit_no_xml_files )
import qualified OptionalConfiguration as OC (
OptionalConfiguration ( xml_files ),
from_rc )
import Network.Services.TSN.Report (
report_info,
report_error )
import TSN.DbImport ( DbImport(..), ImportResult(..) )
import qualified TSN.XML.Heartbeat as Heartbeat ( verify )
import qualified TSN.XML.Injuries as Injuries ( pickle_message )
import qualified TSN.XML.InjuriesDetail as InjuriesDetail ( pickle_message )
import qualified TSN.XML.News as News ( pickle_message )
import qualified TSN.XML.Odds as Odds ( pickle_message )
import qualified TSN.XML.Weather as Weather ( pickle_message )
import Xml ( DtdName(..), parse_opts )
-- | This is where most of the work happens. This function is called
-- on every file that we would like to import. It determines which
-- importer to use based on the DTD, attempts to process the file,
-- and then returns whether or not it was successful. If the file
-- was processed, 'True' is returned. Otherwise, 'False' is
-- returned.
--
-- The implementation is straightforward with one exception: since
-- we are already in arrow world with HXT, the @import_with_dtd@
-- function is lifted to an 'Arrow' as well with 'arr'. This
-- prevents us from having to do a bunch of unwrapping and
-- rewrapping with the associated error checking.
--
import_file :: Configuration -- ^ A configuration object needed for the
-- 'backend' and 'connection_string'.
-> FilePath -- ^ The path of the XML file to import.
-> IO Bool -- ^ True if we processed the file, False otherwise.
import_file cfg path = do
results <- parse_and_import `catch` exception_handler
case results of
[] -> do
-- One of the arrows returned "nothing."
report_error $ "Unable to determine DTD for file " ++ path ++ "."
return False
(ImportFailed errmsg:_) -> do
report_error errmsg
return False
(ImportSkipped infomsg:_) -> do
-- We processed the message but didn't import anything. Return
-- "success" so that the XML file is deleted.
report_info infomsg
return True
(ImportSucceeded:_) -> do
report_info $ "Successfully imported " ++ path ++ "."
return True
(ImportUnsupported infomsg:_) -> do
-- For now we return "success" for these too, since we know we don't
-- support a bunch of DTDs and we want them to get deleted.
report_info infomsg
return True
where
-- | This will catch *any* exception, even the ones thrown by
-- Haskell's 'error' (which should never occur under normal
-- circumstances).
exception_handler :: SomeException -> IO [ImportResult]
exception_handler e = do
report_error (show e)
let errdesc = "Failed to import file " ++ path ++ "."
-- Return a nonempty list so we don't claim incorrectly that
-- we couldn't parse the DTD.
return [ImportFailed errdesc]
-- | An arrow that reads a document into an 'XmlTree'.
readA :: IOStateArrow s a XmlTree
readA = readDocument parse_opts path
-- | An arrow which parses the doctype "SYSTEM" of an 'XmlTree'.
-- We use these to determine the parser to use.
dtdnameA :: ArrowXml a => a XmlTree DtdName
dtdnameA = getAttrl >>> hasName "doctype-SYSTEM" /> getText >>^ DtdName
-- | Combine the arrows above as well as the function below
-- (arrowized with 'arr') into an IO action that does everything
-- (parses and then runs the import on what was parsed).
--
-- The result of runX has type IO [IO ImportResult]. We thus use
-- bind (>>=) and sequence to combine all of the IOs into one
-- big one outside of the list.
parse_and_import :: IO [ImportResult]
parse_and_import =
runX (readA >>> (dtdnameA &&& returnA) >>> (arr import_with_dtd))
>>=
sequence
-- | Takes a ('DtdName', 'XmlTree') pair and uses the 'DtdName'
-- to determine which function to call on the 'XmlTree'.
import_with_dtd :: (DtdName, XmlTree) -> IO ImportResult
import_with_dtd (DtdName dtd,xml)
-- We special-case the heartbeat so it doesn't have to run in
-- the database monad.
| dtd == "Heartbeat.dtd" = Heartbeat.verify xml
| otherwise =
-- We need NoMonomorphismRestriction here.
if backend cfg == Postgres
then withPostgresqlConn cs $ runDbConn importer
else withSqliteConn cs $ runDbConn importer
where
-- | Pull the real connection String out of the configuration.
cs :: String
cs = get_connection_string $ connection_string cfg
-- | Convenience; we use this everywhere below in 'importer'.
migrate_and_import m = dbmigrate m >> dbimport m
importer
| dtd == "injuriesxml.dtd" = do
let m = unpickleDoc Injuries.pickle_message xml
let errmsg = "Could not unpickle injuriesxml."
maybe (return $ ImportFailed errmsg) migrate_and_import m
| dtd == "Injuries_Detail_XML.dtd" = do
let m = unpickleDoc InjuriesDetail.pickle_message xml
let errmsg = "Could not unpickle Injuries_Detail_XML."
maybe (return $ ImportFailed errmsg) migrate_and_import m
| dtd == "newsxml.dtd" = do
let m = unpickleDoc News.pickle_message xml
let errmsg = "Could not unpickle newsxml."
maybe (return $ ImportFailed errmsg) migrate_and_import m
| dtd == "Odds_XML.dtd" = do
let m = unpickleDoc Odds.pickle_message xml
let errmsg = "Could not unpickle Odds_XML."
maybe (return $ ImportFailed errmsg) migrate_and_import m
| dtd == "weatherxml.dtd" = do
let m = unpickleDoc Weather.pickle_message xml
let errmsg = "Could not unpickle weatherxml."
maybe (return $ ImportFailed errmsg) migrate_and_import m
| otherwise = do
let infomsg =
"Unrecognized DTD in " ++ path ++ ": " ++ dtd ++ "."
return $ ImportUnsupported infomsg
-- | Entry point of the program. It twiddles some knobs for
-- configuration options and then calls 'import_file' on each XML
-- file given on the command-line.
--
-- Any file successfully processed is then optionally removed, and
-- we're done.
--
main :: IO ()
main = do
rc_cfg <- OC.from_rc
cmd_cfg <- get_args
-- Merge the config file options with the command-line ones,
-- prefering the command-line ones.
let opt_config = rc_cfg <> cmd_cfg
-- Update a default config with any options that have been set in
-- either the config file or on the command-line. We initialize
-- logging before the missing parameter checks below so that we can
-- log the errors.
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.
when (null $ OC.xml_files opt_config) $ do
report_error "No XML files given."
exitWith (ExitFailure exit_no_xml_files)
-- We don't do this in parallel (for now?) to keep the error
-- messages nice and linear.
results <- mapM (import_file cfg) (OC.xml_files opt_config)
-- Zip the results with the files list to find out which ones can be
-- deleted.
let result_pairs = zip (OC.xml_files opt_config) results
let victims = [ p | (p, True) <- result_pairs ]
let imported_count = length victims
report_info $ "Imported " ++ (show imported_count) ++ " document(s) total."
when (remove cfg) $ mapM_ (kill True) victims
where
-- | Wrap these two actions into one function so that we don't
-- report that the file was removed if the exception handler is
-- run.
remove_and_report path = do
removeFile path
report_info $ "Removed processed file " ++ path ++ "."
-- | Try to remove @path@ and potentially try again.
kill try_again path =
(remove_and_report path) `catchIOError` exception_handler
where
-- | 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
-- | If we can't remove the file, report that, and try once
-- more after waiting a few seconds.
exception_handler :: IOError -> IO ()
exception_handler e = do
report_error (show e)
report_error $ "Failed to remove imported file " ++ path ++ "."
if try_again then do
report_info "Waiting 5 seconds to attempt removal again..."
thread_sleep 5
kill False path
else
report_info $ "Giving up on " ++ path ++ "."