40ecf58d4b
This does not change the overall license of the git-annex program, which was already AGPL due to a number of sources files being AGPL already. Legally speaking, I'm adding a new license under which these files are now available; I already released their current contents under the GPL license. Now they're dual licensed GPL and AGPL. However, I intend for all my future changes to these files to only be released under the AGPL license, and I won't be tracking the dual licensing status, so I'm simply changing the license statement to say it's AGPL. (In some cases, others wrote parts of the code of a file and released it under the GPL; but in all cases I have contributed a significant portion of the code in each file and it's that code that is getting the AGPL license; the GPL license of other contributors allows combining with AGPL code.)
53 lines
1.6 KiB
Haskell
53 lines
1.6 KiB
Haskell
{- git-annex bloom filter
|
|
-
|
|
- Copyright 2010-2015 Joey Hess <id@joeyh.name>
|
|
-
|
|
- Licensed under the GNU AGPL version 3 or higher.
|
|
-}
|
|
|
|
module Annex.BloomFilter where
|
|
|
|
import Annex.Common
|
|
import qualified Annex
|
|
import Utility.Bloom
|
|
|
|
import Control.Monad.ST
|
|
|
|
{- A bloom filter capable of holding half a million keys with a
|
|
- false positive rate of 1 in 10000000 uses around 16 mb of memory,
|
|
- so will easily fit on even my lowest memory systems.
|
|
-}
|
|
bloomCapacity :: Annex Int
|
|
bloomCapacity = fromMaybe 500000 . annexBloomCapacity <$> Annex.getGitConfig
|
|
bloomAccuracy :: Annex Int
|
|
bloomAccuracy = fromMaybe 10000000 . annexBloomAccuracy <$> Annex.getGitConfig
|
|
bloomBitsHashes :: Annex (Int, Int)
|
|
bloomBitsHashes = do
|
|
capacity <- bloomCapacity
|
|
accuracy <- bloomAccuracy
|
|
case safeSuggestSizing capacity (1 / fromIntegral accuracy) of
|
|
Left e -> do
|
|
warning $ "bloomfilter " ++ e ++ "; falling back to sane value"
|
|
-- precaulculated value for 500000 (1/10000000)
|
|
return (16777216,23)
|
|
Right v -> return v
|
|
|
|
{- Creates a bloom filter, and runs an action to populate it.
|
|
-
|
|
- The action is passed a callback that it can use to feed values into the
|
|
- bloom filter.
|
|
-
|
|
- Once the action completes, the mutable filter is frozen
|
|
- for later use.
|
|
-}
|
|
genBloomFilter :: Hashable v => ((v -> Annex ()) -> Annex ()) -> Annex (Bloom v)
|
|
genBloomFilter populate = do
|
|
(numbits, numhashes) <- bloomBitsHashes
|
|
bloom <- lift $ newMB (cheapHashes numhashes) numbits
|
|
populate $ \v -> lift $ insertMB bloom v
|
|
lift $ unsafeFreezeMB bloom
|
|
where
|
|
lift = liftIO . stToIO
|
|
|
|
bloomFilter :: [v] -> Bloom v -> [v]
|
|
bloomFilter l bloom = filter (\v -> v `notElemB` bloom) l
|