add KeyVariety type

Where before the "name" of a key and a backend was a string, this makes
it a concrete data type.

This is groundwork for allowing some varieties of keys to be disabled
in file2key, so git-annex won't use them at all.

Benchmarks ran in my big repo:

old git-annex info:

real	0m3.338s
user	0m3.124s
sys	0m0.244s

new git-annex info:

real	0m3.216s
user	0m3.024s
sys	0m0.220s

new git-annex find:

real	0m7.138s
user	0m6.924s
sys	0m0.252s

old git-annex find:

real	0m7.433s
user	0m7.240s
sys	0m0.232s

Surprising result; I'd have expected it to be slower since it now parses
all the key varieties. But, the parser is very simple and perhaps
sharing KeyVarieties uses less memory or something like that.

This commit was supported by the NSF-funded DataLad project.

1 files changed, 2 insertions, 1 deletions

diff --git a/Test.hs b/Test.hs
index 1b724b5af..7ef0cb5f0 100644
--- a/Test.hs
+++ b/Test.hs
@@ -64,6 +64,7 @@ import qualified Logs.PreferredContent
 import qualified Types.MetaData
 import qualified Remote
 import qualified Key
+import qualified Types.Key
 import qualified Types.Messages
 import qualified Config
 import qualified Config.Cost
@@ -2152,7 +2153,7 @@ backendWORM :: Types.Backend
 backendWORM = backend_ "WORM"
 
 backend_ :: String -> Types.Backend
-backend_ = Backend.lookupBackendName
+backend_ = Backend.lookupBackendVariety . Types.Key.parseKeyVariety
 
 getKey :: Types.Backend -> FilePath -> IO Types.Key
 getKey b f = fromJust <$> annexeval go