stall detection is working

New config annex.stalldetection, remote.name.annex-stalldetection, which
can be used to deal with remotes that stall during transfers, or are
sometimes too slow to want to use.

This commit was sponsored by Luke Shumaker on Patreon.

Types/StallDetection.hs

@@ -0,0 +1,29 @@
+{- types for stall detection
+ -
+ - Copyright 2020 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+module Types.StallDetection where
+
+import Utility.DataUnits
+import Utility.HumanTime
+import Utility.Misc
+
+-- Unless the given number of bytes have been sent over the given
+-- amount of time, there's a stall.
+data StallDetection = StallDetection ByteSize Duration
+	deriving (Show)
+
+-- Parse eg, "0KiB/60s"
+parseStallDetection :: String -> Either String StallDetection
+parseStallDetection s = 
+	let (bs, ds) = separate (== '/') s
+	in do
+		b <- maybe 
+			(Left $ "Unable to parse stall detection amount " ++ bs)
+			Right
+			(readSize dataUnits bs)
+		d <- parseDuration ds
+		return (StallDetection b d)