8025decc7f
This will allow special remotes to eg, open a http connection and reuse it, while checking if chunks are present, or removing chunks. S3 and WebDAV both need this to support chunks with reasonable speed. Note that a special remote might want to cache a http connection across multiple requests. A simple case of this is that CheckPresent is typically called before Store or Remove. A remote using this interface can certianly use a Preparer that eg, uses a MVar to cache a http connection. However, it's up to the remote to then deal with things like stale or stalled http connections when eg, doing a series of downloads from a remote and other places. There could be long delays between calls to a remote, which could lead to eg, http connection stalls; the machine might even move to a new network, etc. It might be nice to improve this interface later to allow the simple case without needing to handle the full complex case. One way to do it would be to have a `Transaction SpecialRemote cache`, where SpecialRemote contains methods for Storer, Retriever, Remover, and CheckPresent, that all expect to be passed a `cache`.
27 lines
652 B
Haskell
27 lines
652 B
Haskell
{- git-annex remote messages
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-
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- Copyright 2013 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Remote.Helper.Messages where
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import Common.Annex
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import qualified Git
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import qualified Types.Remote as Remote
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showChecking :: Git.Repo -> Annex ()
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showChecking r = showAction $ "checking " ++ Git.repoDescribe r
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class Checkable a where
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descCheckable :: a -> String
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instance Checkable Git.Repo where
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descCheckable = Git.repoDescribe
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instance Checkable (Remote.RemoteA a) where
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descCheckable = Remote.name
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cantCheck :: Checkable a => a -> e
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cantCheck v = error $ "unable to check " ++ descCheckable v
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