implement chunk logs

Slightly tricky as they are not normal UUIDBased logs, but are instead maps
from (uuid, chunksize) to chunkcount.

This commit was sponsored by Frank Thomas.

Logs/Chunk.hs

@@ -0,0 +1,44 @@
+{- Chunk logs.
+ -
+ - An object can be stored in chunked for on a remote; these logs keep
+ - track of the chunk size used, and the number of chunks.
+ -
+ - It's possible for a single object to be stored multiple times on the
+ - same remote using different chunk sizes. So, while this is a MapLog, it
+ - is not a normal UUIDBased log. Intead, it's a map from UUID and chunk
+ - size to number of chunks.
+ -
+ - Format: "timestamp uuid:chunksize chunkcount"
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs.Chunk where
+
+import Common.Annex
+import Logs
+import Logs.MapLog
+import qualified Annex.Branch
+import Logs.Chunk.Pure
+
+import qualified Data.Map as M
+import Data.Time.Clock.POSIX
+
+chunksStored :: UUID -> Key -> ChunkSize -> ChunkCount -> Annex ()
+chunksStored u k chunksize chunkcount = do
+	ts <- liftIO getPOSIXTime
+	Annex.Branch.change (chunkLogFile k) $
+		showLog . changeMapLog ts (u, chunksize) chunkcount . parseLog
+
+chunksRemoved :: UUID -> Key -> ChunkSize -> Annex ()
+chunksRemoved u k chunksize = chunksStored u k chunksize 0
+
+getCurrentChunks :: UUID -> Key -> Annex [(ChunkSize, ChunkCount)]
+getCurrentChunks u k = select . parseLog <$> Annex.Branch.get (chunkLogFile k)
+  where
+	select = filter (\(_sz, ct) -> ct > 0)
+		. map (\((_ku, sz), l) -> (sz, value l))
+		. M.toList
+		. M.filterWithKey (\(ku, _sz) _ -> ku == u)