Interface for the storage layer

11 files changed, 65 insertions, 0 deletions

diff --git a/lib/abstract/Storage.ml b/lib/abstract/Storage.ml
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+++ b/lib/abstract/Storage.ml
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+module type STORAGE = sig
+  type connection
+  type transaction
+
+  val connect: Concepts.Configuration.configuration -> connection
+
+  (** begin a transaction within `connection` *)
+  val start: connection -> transaction
+  (** `commit` the current transaction *)
+  val commit: transaction -> ()
+  (** `abort` the current transaction *)
+  val abort: transaction -> ()
+
+  (** within a transaction, fetch a blob from disk *)
+  val get: transaction -> Concepts.Hash.hash -> Concepts.Representation.blob
+  (** within a transaction, associate a hash with a blob on disk *)
+  val put: transaction -> Concepts.Hash.hash -> Concepts.Representation.blob -> ()
+end
diff --git a/lib/backend/storage/LMDB.ml b/lib/backend/storage/LMDB.ml
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+++ b/lib/backend/storage/LMDB.ml
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+type connection = unit
+type transaction = unit
+
+let connect (_: Concepts.Configuration.configuration) = failwith "TODO"
+
+let start (_: connection) = failwith "TODO"
+let commit (_: transaction) = failwith "TODO"
+let abort (_: transaction) = failwith "TODO"
+
+let get (_: transaction) (_: Concepts.Hash.hash) = failwith "TODO"
+let put (_: transaction) (_: Concepts.Hash.hash) (_: Concepts.Representation.blob) = failwith "TODO"
diff --git a/lib/backend/storage/LMDB.mli b/lib/backend/storage/LMDB.mli
new file mode 100644
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+++ b/lib/backend/storage/LMDB.mli
@@ -0,0 +1 @@
+include Abstract.Storage
diff --git a/lib/concepts/Configuration.ml b/lib/concepts/Configuration.ml
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+++ b/lib/concepts/Configuration.ml
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+type configuration = unit
diff --git a/lib/concepts/Configuration.mli b/lib/concepts/Configuration.mli
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+++ b/lib/concepts/Configuration.mli
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+(** an abstract representation for a system configuration *)
+type configuration
diff --git a/lib/concepts/Hash.ml b/lib/concepts/Hash.ml
new file mode 100644
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+++ b/lib/concepts/Hash.ml
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+type hash = ()
+
+val hash_of_value (_: Value.value) = failwith "TODO"
+
+val hash_equals (_: hash) (_: hash) = failwith "TODO"
diff --git a/lib/concepts/Hash.mli b/lib/concepts/Hash.mli
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+++ b/lib/concepts/Hash.mli
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+(** An abstract value representing a hash *)
+type hash
+
+(** Given a value, compute it's hash *)
+val hash_of_value: Value.value -> hash
+
+(** Given two hashes, are they the same? *)
+val hash_equals: hash -> hash -> bool
diff --git a/lib/concepts/Representation.ml b/lib/concepts/Representation.ml
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+++ b/lib/concepts/Representation.ml
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+type blob = unit
+
+let blob_of_value (_: Value.value) = failwith "TODO"
+
+let value_of_blob (_: blob) = failwith "TODO"
diff --git a/lib/concepts/Representation.mli b/lib/concepts/Representation.mli
new file mode 100644
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+++ b/lib/concepts/Representation.mli
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+(** an abstract representation of an encoded value *)
+type blob
+
+(** encode a blob into a value *)
+val blob_of_value: Value.value -> blob
+(** decode a value from a blob *)
+val value_of_blob: blob -> Value.value
diff --git a/lib/concepts/Value.ml b/lib/concepts/Value.ml
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+++ b/lib/concepts/Value.ml
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+type value
+  = String of string
+  | Integer of int
diff --git a/lib/concepts/Value.mli b/lib/concepts/Value.mli
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+++ b/lib/concepts/Value.mli
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+(** A tagged concrete value *)
+type value
+  = String of string
+  | Integer of int