37 lines
1.2 KiB
Haskell
37 lines
1.2 KiB
Haskell
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{- Lock pool.
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-
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- This avoids a problem with unix fcntl locks: They are not composition-safe.
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-
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- For example, if one thread is holding a lock, and another thread opens the
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- lock file (to attempt to take or check the lock), and then closes it,
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- the lock will be released, despite the first thread still having the
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- lockfile open.
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-
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- Or, if a process is already holding an exclusive lock on a file, an
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- re-opens it and tries to take another exclusive lock, it won't block
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- on the first lock.
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-
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- To avoid these problems, this implements a lock pool. This keeps track
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- of which lock files are being used by the process, and avoids
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- re-opening them. Instead, if a lockfile is in use by the current
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- process, STM is used to handle further concurrent uses of that lock
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- file.
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-
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- Note that, like Utility.LockFile, this does *not* attempt to be a
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- portability shim; the native locking of the OS is used.
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-
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- Copyright 2015 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE CPP #-}
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module Utility.LockPool (module X) where
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#ifndef mingw32_HOST_OS
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import Utility.LockPool.Posix as X
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#else
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import Utility.LockPool.Windows as X
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#endif
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