optimise read and write for Keys database (untested)
Writes are optimised by queueing up multiple writes when possible. The queue is flushed after the Annex monad action finishes. That makes it happen on program termination, and also whenever a nested Annex monad action finishes. Reads are optimised by checking once (per AnnexState) if the database exists. If the database doesn't exist yet, all reads return mempty. Reads also cause queued writes to be flushed, so reads will always be consistent with writes (as long as they're made inside the same Annex monad). A future optimisation path would be to determine when that's not necessary, which is probably most of the time, and avoid flushing unncessarily. Design notes for this commit: - separate reads from writes - reuse a handle which is left open until program exit or until the MVar goes out of scope (and autoclosed then) - writes are queued - queue is flushed periodically - immediate queue flush before any read - auto-flush queue when database handle is garbage collected - flush queue on exit from Annex monad (Note that this may happen repeatedly for a single database connection; or a connection may be reused for multiple Annex monad actions, possibly even concurrent ones.) - if database does not exist (or is empty) the handle is not opened by reads; reads instead return empty results - writes open the handle if it was not open previously
This commit is contained in:
parent
959b060e26
commit
4224fae71f
10 changed files with 213 additions and 91 deletions
|
@ -78,10 +78,6 @@ openDb u = do
|
|||
rename tmpdbdir dbdir
|
||||
lockFileCached =<< fromRepo (gitAnnexFsckDbLock u)
|
||||
h <- liftIO $ H.openDbQueue db "fscked"
|
||||
|
||||
-- work around https://github.com/yesodweb/persistent/issues/474
|
||||
liftIO setConsoleEncoding
|
||||
|
||||
return $ FsckHandle h u
|
||||
|
||||
closeDb :: FsckHandle -> Annex ()
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue