fixed close after locking

This commit is contained in:
Joey Hess 2010-10-10 11:08:40 -04:00
parent 11ad93f023
commit f98fa53d7f
3 changed files with 16 additions and 8 deletions

View file

@ -12,6 +12,11 @@
-
- A line of the log will look like: "date N reponame"
- Where N=1 when the repo has the file, and 0 otherwise.
-
- TOOD: compact logs, by storing only current presence infomation when
- writing them.
-
- TODO: use ByteString
-}
module LocationLog where
@ -67,9 +72,8 @@ readLog file = do
exists <- doesFileExist file
if exists
then do
h <- openLocked file ReadMode
s <- hGetContentsStrict h
hClose h
s <- withFileLocked file ReadMode $ \h ->
hGetContentsStrict h
-- filter out any unparsable lines
return $ filter (\l -> (status l) /= Undefined )
$ map read $ lines s
@ -80,9 +84,8 @@ readLog file = do
writeLog :: String -> LogLine -> IO ()
writeLog file line = do
createDirectoryIfMissing True (parentDir file)
h <- openLocked file AppendMode
hPutStrLn h $ show line
hClose h
withFileLocked file AppendMode $ \h ->
hPutStrLn h $ show line
{- Generates a new LogLine with the current date. -}
logNow :: LogStatus -> String -> IO LogLine

View file

@ -9,12 +9,15 @@ import Data.String.Utils
{- Let's just say that Haskell makes reading/writing a file with
- file locking excessively difficult. -}
openLocked file mode = do
withFileLocked file mode action = do
-- TODO: find a way to use bracket here
handle <- openFile file mode
lockfd <- handleToFd handle -- closes handle
waitToSetLock lockfd (lockType mode, AbsoluteSeek, 0, 0)
handle' <- fdToHandle lockfd
return handle'
ret <- action handle'
hClose handle'
return ret
where
lockType ReadMode = ReadLock
lockType _ = WriteLock

View file

@ -6,3 +6,5 @@ import GitRepo
main = do
gitPrep
l <- readLog "demo.log"
writeLog "demo2.log" $ l !! 0