limiting files based on metadata

Note that there is currently no caching, so
	--metadata foo=bar --metadata tag=blah
will currently read the log 2x per file.

Annex/FileMatcher.hs

@@ -83,6 +83,7 @@ parseToken checkpresent checkpreferreddir groupmap t
 			, ("inbackend", limitInBackend)
 			, ("largerthan", limitSize (>))
 			, ("smallerthan", limitSize (<))
+			, ("metadata", limitMetaData)
 			, ("inallgroup", limitInAllGroup groupmap)
 			]
   where

CmdLine/GitAnnex/Options.hs

@@ -54,6 +54,8 @@ gitAnnexOptions = commonOptions ++
 		"match files larger than a size"
 	, Option [] ["smallerthan"] (ReqArg Limit.addSmallerThan paramSize)
 		"match files smaller than a size"
+	, Option [] ["metadata"] (ReqArg Limit.addMetaData "FIELD=VALUE")
+		"match files with attached metadata"
 	, Option [] ["want-get"] (NoArg Limit.Wanted.addWantGet)
 		"match files the repository wants to get"
 	, Option [] ["want-drop"] (NoArg Limit.Wanted.addWantDrop)

Command/MetaData.hs

@@ -21,7 +21,7 @@ def = [withOptions [setOption] $ command "metadata" paramPaths seek
 	SectionUtility "sets metadata of a file"]
 
 setOption :: Option
-setOption = Option ['s'] ["set"] (ReqArg mkmod "field[+-]=value") "set metadata"
+setOption = Option ['s'] ["set"] (ReqArg mkmod "FIELD[+-]=VALUE") "set metadata"
   where
 	mkmod p = case parseModMeta p of
 		Left e -> error e

Limit.hs

@@ -23,6 +23,8 @@ import Types.Key
 import Types.Group
 import Types.FileMatcher
 import Types.Limit
+import Types.MetaData
+import Logs.MetaData
 import Logs.Group
 import Logs.Unused
 import Logs.Location
@@ -262,6 +264,16 @@ limitSize vs s = case readSize dataUnits s of
 				<$> getFileStatus (relFile fi)
 		return $ filesize `vs` Just sz
 
+addMetaData :: String -> Annex ()
+addMetaData = addLimit . limitMetaData
+
+limitMetaData :: MkLimit
+limitMetaData s = case parseMetaData s of
+	Left e -> Left e
+	Right (f, v) -> Right $ const $ checkKey (check f v)
+  where
+  	check f v k = S.member v . metaDataValues f <$> getCurrentMetaData k
+
 addTimeLimit :: String -> Annex ()
 addTimeLimit s = do
 	let seconds = maybe (error "bad time-limit") durationToPOSIXTime $

Types/MetaData.hs

@@ -28,10 +28,11 @@ module Types.MetaData (
 	differenceMetaData,
 	currentMetaData,
 	currentMetaDataValues,
-	getAllMetaData,
+	metaDataValues,
 	ModMeta(..),
 	modMeta,
 	parseModMeta,
+	parseMetaData,
 	prop_metadata_sane,
 	prop_metadata_serialize
 ) where
@@ -170,7 +171,7 @@ isSet (MetaValue (CurrentlySet isset) _) = isset
 
 {- Gets only currently set values -}
 currentMetaDataValues :: MetaField -> MetaData -> S.Set MetaValue
-currentMetaDataValues f m = S.filter isSet (getAllMetaData f m)
+currentMetaDataValues f m = S.filter isSet (metaDataValues f m)
 
 currentMetaData :: MetaData -> MetaData
 currentMetaData (MetaData m) = removeEmptyFields $ MetaData $
@@ -180,8 +181,8 @@ removeEmptyFields :: MetaData -> MetaData
 removeEmptyFields (MetaData m) = MetaData $ M.filter (not . S.null) m
 
 {- Gets currently set values, but also values that have been unset. -}
-getAllMetaData :: MetaField -> MetaData -> S.Set MetaValue
+metaDataValues :: MetaField -> MetaData -> S.Set MetaValue
-getAllMetaData f (MetaData m) = fromMaybe S.empty (M.lookup f m)
+metaDataValues f (MetaData m) = fromMaybe S.empty (M.lookup f m)
 
 {- Ways that existing metadata can be modified -}
 data ModMeta
@@ -202,15 +203,27 @@ modMeta m (SetMeta f v) = updateMetaData f v $
 {- Parses field=value, field+=value, field-=value -}
 parseModMeta :: String -> Either String ModMeta
 parseModMeta p = case lastMaybe f of
-	Just '+' -> AddMeta <$> mkf f' <*> v
+	Just '+' -> AddMeta <$> mkMetaField f' <*> v
-	Just '-' -> DelMeta <$> mkf f' <*> v
+	Just '-' -> DelMeta <$> mkMetaField f' <*> v
-	_ -> SetMeta <$> mkf f <*> v
+	_ -> SetMeta <$> mkMetaField f <*> v
   where
 	(f, sv) = separate (== '=') p
 	f' = beginning f
 	v = pure (toMetaValue sv)
-	mkf fld = maybe (Left $ badfield fld) Right (toMetaField fld)
+
-	badfield fld = "Illegal metadata field name, \"" ++ fld ++ "\""
+{- Parses field=value -}
+parseMetaData :: String -> Either String (MetaField, MetaValue)
+parseMetaData p = (,)
+	<$> mkMetaField f
+	<*> pure (toMetaValue v)
+  where
+	(f, v) = separate (== '=') p
+
+mkMetaField :: String -> Either String MetaField
+mkMetaField f = maybe (Left $ badField f) Right (toMetaField f)
+
+badField :: String -> String
+badField f = "Illegal metadata field name, \"" ++ f ++ "\""
 
 {- Avoid putting too many fields in the map; extremely large maps make
  - the seriaization test slow due to the sheer amount of data.
@@ -228,7 +241,7 @@ instance Arbitrary MetaField where
 
 prop_metadata_sane :: MetaData -> MetaField -> MetaValue -> Bool
 prop_metadata_sane m f v = and
-	[ S.member v $ getAllMetaData f m'
+	[ S.member v $ metaDataValues f m'
 	, not (isSet v) || S.member v (currentMetaDataValues f m')
 	, differenceMetaData m' newMetaData == m'
 	]

debian/changelog

@@ -1,5 +1,10 @@
 git-annex (5.20140211) UNRELEASED; urgency=medium
 
+  * metadata: New command that can attach metadata to files.
+  * --metadata can be used to limit commands to acting on files
+    that have particular metadata.
+  * Preferred content expressions can use metadata=field=value
+    to limit them to acting on files that have particular metadata.
   * Add progress display for transfers to/from external special remotes.
   * Windows webapp: Can set up box.com, Amazon S3 remotes.
   * Windows webapp: Can create repos on removable drives.

doc/git-annex.mdwn

@@ -1082,6 +1082,11 @@ file contents are present at either of two repositories.
   The size can be specified with any commonly used units, for example,
   "0.5 gb" or "100 KiloBytes"
 
+* `--metadata field=value`
+
+  Matches only files that have a metadata field attached with the specified
+  value.
+
 * `--want-get`
 
   Matches files that the preferred content settings for the repository