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|
{-# LANGUAGE DeriveGeneric #-}
module Log where
import Types
import Hash
import Memory
import GHC.Generics (Generic)
import Data.Aeson
import Data.Char
import Data.Either
import Data.Time.Clock.POSIX
import qualified Data.ByteString.Lazy as L
import System.IO
-- | A log of Activity both Entered and Seen, which can be recorded to
-- prove what happened in a debug-me session.
--
-- Note that the time stamp is included to allow replaying logs, but
-- it's not part of the provable session.
--
-- Note that changing this in ways that change the JSON serialization
-- changes debug-me's log file format.
data ActivityLog = ActivityLog
{ loggedActivity :: SomeActivity
, loggedHash :: Hash
, loggedTimestamp :: Timestamp
}
deriving (Show, Generic)
instance DataSize ActivityLog where
dataSize l = dataSize (loggedActivity l) + dataSize (loggedHash l) + 2
instance ToJSON (ActivityLog)
instance FromJSON (ActivityLog)
data SomeActivity
= ActivitySeen (Activity Seen)
| ActivityEntered (Activity Entered)
deriving (Show, Generic)
instance DataSize SomeActivity where
dataSize (ActivitySeen a) = dataSize a
dataSize (ActivityEntered a) = dataSize a
instance ToJSON SomeActivity where
toJSON = genericToJSON sumOptions
toEncoding = genericToEncoding sumOptions
instance FromJSON SomeActivity where
parseJSON = genericParseJSON sumOptions
mkActivityLog :: SomeActivity -> POSIXTime -> ActivityLog
mkActivityLog a now = ActivityLog
{ loggedActivity = a
, loggedHash = case a of
ActivitySeen s -> hash s
ActivityEntered e -> hash e
, loggedTimestamp = now
}
type Timestamp = POSIXTime
type Logger = SomeActivity -> IO ()
withLogger :: FilePath -> (Logger -> IO a) -> IO a
withLogger logfile a = withFile logfile WriteMode (a . mkLogger)
mkLogger :: Handle -> Logger
mkLogger h a = do
l <- mkActivityLog a <$> getPOSIXTime
L.hPut h (encode l)
hPutStr h "\n"
hFlush h
parseLog :: L.ByteString -> [Either String ActivityLog]
parseLog = map eitherDecode'
. filter (not . L.null)
. L.split (fromIntegral (ord '\n'))
-- | Throws exception on unparsable log.
loadLog :: FilePath -> IO [ActivityLog]
loadLog f = do
parsed <- parseLog <$> L.readFile f
case lefts parsed of
[] -> return (rights parsed)
errs -> error $ unlines errs
|
