git-annex/Database/RepoSize/Handle.hs

{- Sqlite database used to track the sizes of repositories.
 -
 - Copyright 2024 Joey Hess <id@joeyh.name>
 -:
 - Licensed under the GNU AGPL version 3 or higher.
 -}

module Database.RepoSize.Handle where

import qualified Database.Handle as H
import Utility.LockPool (LockHandle)

import Control.Concurrent
import Data.Time.Clock.POSIX

data RepoSizeHandle = RepoSizeHandle
	(Maybe H.DbHandle)
	-- ^ Nothing if the database was not able to be opened due to
	-- permissions.
	(MVar (Maybe (LockHandle, POSIXTime)))
	-- ^ Live update lock and time of last check for stale live
	-- updates.
plumb in LiveUpdate (WIP) Each command that first checks preferred content (and/or required content) and then does something that can change the sizes of repositories needs to call prepareLiveUpdate, and plumb it through the preferred content check and the location log update. So far, only Command.Drop is done. Many other commands that don't need to do this have been updated to keep working. There may be some calls to NoLiveUpdate in places where that should be done. All will need to be double checked. Not currently in a compilable state. 2024-08-23 20:35:12 +00:00			`{- Sqlite database used to track the sizes of repositories.`
			`-`
			`- Copyright 2024 Joey Hess <id@joeyh.name>`
			`-:`
			`- Licensed under the GNU AGPL version 3 or higher.`
			`-}`

			`module Database.RepoSize.Handle where`

			`import qualified Database.Handle as H`
remove stale live changes from reposize database Reorganized the reposize database directory, and split up a column. checkStaleSizeChanges needs to run before needLiveUpdate, otherwise the process won't be holding a lock on its pid file, and another process could go in and expire the live update it records. It just so happens that they do get called in the correct order, since checking balanced preferred content calls getLiveRepoSizes before needLiveUpdate. The 1 minute delay between checks is arbitrary, but will avoid excess work. The downside of it is that, if a process is dropping a file and gets interrupted, for 1 minute another process can expect a repository will soon be smaller than it is. And so a process might send data to a repository when a file is not really going to be dropped from it. But note that can already happen if a drop takes some time in eg locking and then fails. So it seems possible that live updates should only be allowed to increase, rather than decrease the size of a repository. 2024-08-28 17:52:59 +00:00			`import Utility.LockPool (LockHandle)`
plumb in LiveUpdate (WIP) Each command that first checks preferred content (and/or required content) and then does something that can change the sizes of repositories needs to call prepareLiveUpdate, and plumb it through the preferred content check and the location log update. So far, only Command.Drop is done. Many other commands that don't need to do this have been updated to keep working. There may be some calls to NoLiveUpdate in places where that should be done. All will need to be double checked. Not currently in a compilable state. 2024-08-23 20:35:12 +00:00
remove stale live changes from reposize database Reorganized the reposize database directory, and split up a column. checkStaleSizeChanges needs to run before needLiveUpdate, otherwise the process won't be holding a lock on its pid file, and another process could go in and expire the live update it records. It just so happens that they do get called in the correct order, since checking balanced preferred content calls getLiveRepoSizes before needLiveUpdate. The 1 minute delay between checks is arbitrary, but will avoid excess work. The downside of it is that, if a process is dropping a file and gets interrupted, for 1 minute another process can expect a repository will soon be smaller than it is. And so a process might send data to a repository when a file is not really going to be dropped from it. But note that can already happen if a drop takes some time in eg locking and then fails. So it seems possible that live updates should only be allowed to increase, rather than decrease the size of a repository. 2024-08-28 17:52:59 +00:00			`import Control.Concurrent`
			`import Data.Time.Clock.POSIX`

			`data RepoSizeHandle = RepoSizeHandle`
			`(Maybe H.DbHandle)`
			`-- ^ Nothing if the database was not able to be opened due to`
			`-- permissions.`
			`(MVar (Maybe (LockHandle, POSIXTime)))`
			`-- ^ Live update lock and time of last check for stale live`
			`-- updates.`