1 files changed, 40 insertions, 0 deletions
diff --git a/src/Erebos/Storage/Backend.hs b/src/Erebos/Storage/Backend.hs
new file mode 100644
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+++ b/src/Erebos/Storage/Backend.hs
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+{-|
+Description: Implement custom storage backend
+
+Exports type class, which can be used to create custom 'Storage' backend.
+-}
+
+module Erebos.Storage.Backend (
+    StorageBackend(..),
+    Complete, Partial,
+    Storage, PartialStorage,
+    newStorage,
+    withStorageBackend,
+
+    refDigestBytes,
+
+    WatchID, startWatchID, nextWatchID,
+) where
+
+import Control.Concurrent.MVar
+
+import Data.ByteArray qualified as BA
+import Data.ByteString (ByteString)
+import Data.HashTable.IO qualified as HT
+
+import Erebos.Object.Internal
+import Erebos.Storage.Internal
+
+
+newStorage :: StorageBackend bck => bck -> IO (Storage' (BackendCompleteness bck))
+newStorage stBackend = do
+    stRefGeneration <- newMVar =<< HT.new
+    stRefRoots <- newMVar =<< HT.new
+    return Storage {..}
+
+withStorageBackend :: Storage' c -> (forall bck. (StorageBackend bck, BackendCompleteness bck ~ c) => bck -> IO a) -> IO a
+withStorageBackend Storage {..} f = f stBackend
+
+
+refDigestBytes :: RefDigest -> ByteString
+refDigestBytes = BA.convert