[commit: ghc] master: ghc-pkg: Consider .conf files when computing package db mtime (30d69f4)
git at git.haskell.org
git at git.haskell.org
Tue Mar 7 18:32:51 UTC 2017
Repository : ssh://git@git.haskell.org/ghc
On branch : master
Link : http://ghc.haskell.org/trac/ghc/changeset/30d69f404ba102da94423836f86fbec2fb4adaf9/ghc
>---------------------------------------------------------------
commit 30d69f404ba102da94423836f86fbec2fb4adaf9
Author: Andrzej Rybczak <electricityispower at gmail.com>
Date: Tue Mar 7 09:55:02 2017 -0500
ghc-pkg: Consider .conf files when computing package db mtime
We can no longer use the mtime of the containing directory since it now
contains a lock file in addition to the .cache and .conf files.
Fixes #13375.
Test Plan: Validate on Windows
Reviewers: austin, arybczak
Subscribers: rwbarton, thomie
Differential Revision: https://phabricator.haskell.org/D3289
>---------------------------------------------------------------
30d69f404ba102da94423836f86fbec2fb4adaf9
utils/ghc-pkg/Main.hs | 85 +++++++++++++--------------------------------------
1 file changed, 21 insertions(+), 64 deletions(-)
diff --git a/utils/ghc-pkg/Main.hs b/utils/ghc-pkg/Main.hs
index c5ecbf2..ed73c29 100644
--- a/utils/ghc-pkg/Main.hs
+++ b/utils/ghc-pkg/Main.hs
@@ -832,14 +832,15 @@ readParseDatabase verbosity mb_user_conf mode use_cache path
Right fs
| not use_cache -> ignore_cache (const $ return ())
| otherwise -> do
- tdir <- getModificationTime path
e_tcache <- tryIO $ getModificationTime cache
case e_tcache of
Left ex -> do
whenReportCacheErrors $
if isDoesNotExistError ex
then
- when (verbosity >= Verbose) $ do
+ -- It's fine if the cache is not there as long as the
+ -- database is empty.
+ when (not $ null confs) $ do
warn ("WARNING: cache does not exist: " ++ cache)
warn ("ghc will fail to read this package db. " ++
recacheAdvice)
@@ -848,21 +849,13 @@ readParseDatabase verbosity mb_user_conf mode use_cache path
warn "ghc will fail to read this package db."
ignore_cache (const $ return ())
Right tcache -> do
- let compareTimestampToCache file =
- when (verbosity >= Verbose) $ do
- tFile <- getModificationTime file
- compareTimestampToCache' file tFile
- compareTimestampToCache' file tFile = do
- let rel = case tcache `compare` tFile of
- LT -> " (NEWER than cache)"
- GT -> " (older than cache)"
- EQ -> " (same as cache)"
- warn ("Timestamp " ++ show tFile
- ++ " for " ++ file ++ rel)
when (verbosity >= Verbose) $ do
warn ("Timestamp " ++ show tcache ++ " for " ++ cache)
- compareTimestampToCache' path tdir
- if tcache >= tdir
+ -- If any of the .conf files is newer than package.cache, we
+ -- assume that cache is out of date.
+ cache_outdated <- (`anyM` confs) $ \conf ->
+ (tcache <) <$> getModificationTime conf
+ if not cache_outdated
then do
when (verbosity > Normal) $
infoLn ("using cache: " ++ cache)
@@ -873,18 +866,27 @@ readParseDatabase verbosity mb_user_conf mode use_cache path
warn ("WARNING: cache is out of date: " ++ cache)
warn ("ghc will see an old view of this " ++
"package db. " ++ recacheAdvice)
- ignore_cache compareTimestampToCache
+ ignore_cache $ \file -> do
+ when (verbosity >= Verbose) $ do
+ tFile <- getModificationTime file
+ let rel = case tcache `compare` tFile of
+ LT -> " (NEWER than cache)"
+ GT -> " (older than cache)"
+ EQ -> " (same as cache)"
+ warn ("Timestamp " ++ show tFile
+ ++ " for " ++ file ++ rel)
where
+ confs = map (path </>) $ filter (".conf" `isSuffixOf`) fs
+
ignore_cache :: (FilePath -> IO ()) -> IO (PackageDB mode)
ignore_cache checkTime = do
-- If we're opening for modification, we need to acquire a
-- lock even if we don't open the cache now, because we are
-- going to modify it later.
lock <- F.mapM (const $ GhcPkg.lockPackageDb cache) mode
- let confs = filter (".conf" `isSuffixOf`) fs
- doFile f = do checkTime f
+ let doFile f = do checkTime f
parseSingletonPackageConf verbosity f
- pkgs <- mapM doFile $ map (path </>) confs
+ pkgs <- mapM doFile confs
mkPackageDB pkgs lock
-- We normally report cache errors for read-only commands,
@@ -1215,16 +1217,6 @@ updateDBCache verbosity db = do
then die $ filename ++ ": you don't have permission to modify this file"
else ioError e
- -- See Note [writeAtomic leaky abstraction]
- -- Cross-platform "touch". This only works if filename is not empty, and
- -- not open for writing already.
- -- TODO. When the Win32 or directory packages have either a touchFile or a
- -- setModificationTime function, use one of those.
- withBinaryFile filename ReadWriteMode $ \handle -> do
- c <- hGetChar handle
- hSeek handle AbsoluteSeek 0
- hPutChar handle c
-
case packageDbLock db of
GhcPkg.DbOpenReadWrite lock -> GhcPkg.unlockPackageDb lock
@@ -2180,38 +2172,3 @@ removeFileSafe fn =
-- absolute path.
absolutePath :: FilePath -> IO FilePath
absolutePath path = return . normalise . (</> path) =<< getCurrentDirectory
-
-
-{- Note [writeAtomic leaky abstraction]
-GhcPkg.writePackageDb calls writeAtomic, which first writes to a temp file,
-and then moves the tempfile to its final destination. This all happens in the
-same directory (package.conf.d).
-Moving a file doesn't change its modification time, but it *does* change the
-modification time of the directory it is placed in. Since we compare the
-modification time of the cache file to that of the directory it is in to
-decide whether the cache is out-of-date, it will be instantly out-of-date
-after creation, if the renaming takes longer than the smallest time difference
-that the getModificationTime can measure.
-
-The solution we opt for is a "touch" of the cache file right after it is
-created. This resets the modification time of the cache file and the directory
-to the current time.
-
-Other possible solutions:
- * backdate the modification time of the directory to the modification time
- of the cachefile. This is what we used to do on posix platforms. An
- observer of the directory would see the modification time of the directory
- jump back in time. Not nice, although in practice probably not a problem.
- Also note that a cross-platform implementation of setModificationTime is
- currently not available.
- * set the modification time of the cache file to the modification time of
- the directory (instead of the curent time). This could also work,
- given that we are the only ones writing to this directory. It would also
- require a high-precision getModificationTime (lower precision times get
- rounded down it seems), or the cache would still be out-of-date.
- * change writeAtomic to create the tempfile outside of the target file's
- directory.
- * create the cachefile outside of the package.conf.d directory in the first
- place. But there are tests and there might be tools that currently rely on
- the package.conf.d/package.cache format.
--}
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