+module Logging (
+ init_logging,
+ log_debug,
+ log_error,
+ log_info,
+ log_warning )
+where
+
+import Control.Monad ( when )
+import System.Log.Formatter ( simpleLogFormatter )
+import System.Log.Handler ( setFormatter )
+import System.Log.Handler.Simple ( GenericHandler, fileHandler )
+import System.Log.Handler.Syslog (
+ Facility ( USER ),
+ openlog )
+import System.Log.Logger (
+ Priority ( INFO ),
+ addHandler,
+ debugM,
+ errorM,
+ infoM,
+ rootLoggerName,
+ setHandlers,
+ setLevel,
+ updateGlobalLogger,
+ warningM )
+
+
+-- | Log a message at the DEBUG level.
+log_debug :: String -> IO ()
+log_debug = debugM rootLoggerName
+
+-- | Log a message at the ERROR level.
+log_error :: String -> IO ()
+log_error = errorM rootLoggerName
+
+-- | Log a message at the INFO level.
+log_info :: String -> IO ()
+log_info = infoM rootLoggerName
+
+-- | Log a message at the WARNING level.
+log_warning :: String -> IO ()
+log_warning = warningM rootLoggerName
+
+
+-- | Set up the logging. All logs are handled by the global "root"
+-- logger provided by HSLogger. We remove all of its handlers so
+-- that it does nothing; then we conditionally add back two handlers
+-- -- one for syslog, and one for a normal file -- dependent upon
+-- the 'syslog' and 'log_file' configuration items.
+--
+-- Why don't we take a Configuration as an argument? Because it
+-- would create circular imports!
+init_logging :: Maybe FilePath -> Priority -> Bool -> IO ()
+init_logging log_file log_level syslog = do
+ -- First set the global log level and clear the default handler.
+ let no_handlers = [] :: [GenericHandler a]
+ updateGlobalLogger rootLoggerName (setLevel log_level .
+ setHandlers no_handlers)
+
+ when syslog $ do
+ let min_level = INFO
+ let sl_level = if log_level < min_level then min_level else log_level
+
+ -- The syslog handle gets its own level which will cowardly refuse
+ -- to log all debug info (i.e. the entire feed) to syslog.
+ sl_handler' <- openlog rootLoggerName [] USER sl_level
+
+ -- Syslog should output the date by itself.
+ let sl_formatter = simpleLogFormatter "htsn-import[$pid] $prio: $msg"
+ let sl_handler = setFormatter sl_handler' sl_formatter
+
+ updateGlobalLogger rootLoggerName (addHandler sl_handler)
+
+ case log_file of
+ Nothing -> return ()
+ Just lf -> do
+ lf_handler' <- fileHandler lf log_level
+ let lf_formatter = simpleLogFormatter
+ "$time: htsn-import[$pid] $prio: $msg"
+ let lf_handler = setFormatter lf_handler' lf_formatter
+ updateGlobalLogger rootLoggerName (addHandler lf_handler)