separate handles for cat-file and cat-file --batch-check

This avoids starting one process when only the other one is needed.
Eg in git-annex smudge --clean, this reduces the total number of
cat-file processes that are started from 4 to 2.

The only performance penalty is that when both are needed, it has to do
twice as much work to maintain the two Maps. But both are very small,
consisting of 1 or 2 items, so that work is negligible.

Sponsored-by: Dartmouth College's Datalad project

Types/CatFileHandles.hs

@@ -1,6 +1,6 @@
 {- git-cat file handles pools
  -
- - Copyright 2020 Joey Hess <id@joeyh.name>
+ - Copyright 2020-2021 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -9,22 +9,30 @@ module Types.CatFileHandles (
 	CatFileHandles(..),
 	catFileHandlesNonConcurrent,
 	catFileHandlesPool,
+	CatMap(..),
+	emptyCatMap,
 ) where
 
 import Control.Concurrent.STM
 import qualified Data.Map as M
 
 import Utility.ResourcePool
-import Git.CatFile (CatFileHandle)
+import Git.CatFile (CatFileHandle, CatFileMetaDataHandle)
 
 data CatFileHandles
 	= CatFileHandlesNonConcurrent CatMap
 	| CatFileHandlesPool (TMVar CatMap)
 
-type CatMap = M.Map FilePath (ResourcePool CatFileHandle)
+data CatMap = CatMap
+	{ catFileMap :: M.Map FilePath (ResourcePool CatFileHandle)
+	, catFileMetaDataMap :: M.Map FilePath (ResourcePool CatFileMetaDataHandle)
+	}
+
+emptyCatMap :: CatMap
+emptyCatMap = CatMap M.empty M.empty
 
 catFileHandlesNonConcurrent :: CatFileHandles
-catFileHandlesNonConcurrent = CatFileHandlesNonConcurrent M.empty
+catFileHandlesNonConcurrent = CatFileHandlesNonConcurrent emptyCatMap
 
 catFileHandlesPool :: IO CatFileHandles
-catFileHandlesPool = CatFileHandlesPool <$> newTMVarIO M.empty
+catFileHandlesPool = CatFileHandlesPool <$> newTMVarIO emptyCatMap