Introduce dbval.store: pluggable tuple storage behind a protocol

README.md

@@ -40,6 +40,15 @@ dbval only needs the key portion. Consequently, you are dealing with a sorted
 set and Datascript's core is a
 [persistent-sorted-set](https://github.com/tonsky/persistent-sorted-set).
 
+The storage layer is pluggable via the `dbval.store` protocol: a store only
+has to provide ordered range scans over committed keys and atomic batch
+commits. `dbval.store.sqlite` is the default backend and
+`dbval.store.memory` provides an in-memory store for tests. Note that dbval
+ships no storage driver — to use the default SQLite store, add
+`org.xerial/sqlite-jdbc` to your dependencies (like with
+[next.jdbc](https://github.com/seancorfield/next-jdbc), you bring the driver
+for the store you pick).
+
 I first assumed that I need to make one part of a datom mutable, so that I can
 mark it as retracted. Until I discovered that the sorting of `t` in the Datomic
 indexes `:eavt`, `:aevt`, `:avet` and `:vaet` allows to figure out what the

deps.edn

@@ -1,6 +1,5 @@
 {:deps
  {org.foundationdb/fdb-java {:mvn/version "7.3.47"}
-  org.xerial/sqlite-jdbc {:mvn/version "3.47.1.0"}
   com.yetanalytics/colossal-squuid {:mvn/version "0.1.5"
                                     :exclusions
                                     [ ;; important to avoid `java.lang.NoSuchMethodError: 'boolean com.google.protobuf.GeneratedMessageV3.isStringEmpty(java.lang.Object)'         at com.google.cloud.secretmanager.v1.ListSecretsRequest.getSerializedSize(ListSecretsRequest.java:355)`
@@ -30,7 +29,8 @@
    :jvm-opts    ["-ea" "-Ddbval.debug" "-Dclojure.main.report=stderr" "-Djdk.attach.allowAttachSelf"]
    :extra-deps
    {io.github.tonsky/duti      {:git/sha "e36d65296a4f9758664309ec35b00887e88c405a"}
-    com.cognitect/transit-clj  {:mvn/version "1.0.324"}}}
+    com.cognitect/transit-clj  {:mvn/version "1.0.324"}
+    org.xerial/sqlite-jdbc     {:mvn/version "3.47.1.0"}}}
 
   :bench
   {:extra-paths ["bench"]
@@ -39,4 +39,5 @@
               "-Djdk.attach.allowAttachSelf"
               "-XX:+DebugNonSafepoints"]
    :extra-deps
-   {io.github.tonsky/duti {:git/sha "e36d65296a4f9758664309ec35b00887e88c405a"}}}}}
+   {io.github.tonsky/duti {:git/sha "e36d65296a4f9758664309ec35b00887e88c405a"}
+    org.xerial/sqlite-jdbc {:mvn/version "3.47.1.0"}}}}}

src/dbval/core.clj

@@ -159,8 +159,11 @@
 
    Options are:
 
-   :db-file <string>  Path to the SQLite file backing this database.
-                      Defaults to a fresh temporary file."
+   :store   <dbval.store/ITupleStore>  The tuple store backing this database.
+                      Defaults to a SQLite store (see dbval.store.sqlite);
+                      dbval.store.memory provides an in-memory store.
+   :db-file <string>  Path to the SQLite file backing this database, when no
+                      :store is given. Defaults to a fresh temporary file."
   ([]
    (db/empty-db nil {}))
   ([schema]