From 92364f4e6e830e68a6e1ea1a017bf744ad6dfac0 Mon Sep 17 00:00:00 2001
From: Paula Gearon <pgearon@cisco.com>
Date: Sun, 10 Oct 2021 17:26:54 -0400
Subject: [PATCH] Clearing out connections that have been deleted

---
 src/asami/memory.cljc    | 13 ++++++++++---
 test/asami/api_test.cljc | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/asami/memory.cljc b/src/asami/memory.cljc
index f10f7ec..0157199 100644
--- a/src/asami/memory.cljc
+++ b/src/asami/memory.cljc
@@ -37,7 +37,8 @@
              (< 0 c) (recur low mid)))))))
 
 
-(declare as-of* as-of-t* as-of-time* since* since-t* graph* entity* next-tx* db* transact-update* transact-data*)
+(declare as-of* as-of-t* as-of-time* since* since-t* graph* entity*
+         next-tx* db* delete-database* transact-update* transact-data*)
 
 ;; graph is the wrapped graph
 ;; history is a seq of Databases, excluding this one
@@ -63,7 +64,7 @@
   (get-name [this] name)
   (next-tx [this] (next-tx* this))
   (db [this] (db* this))
-  (delete-database [this] true) ;; no-op for memory databases
+  (delete-database [this] (delete-database* this))
   (release [this]) ;; no-op for memory databases
   (transact-update [this update-fn] (transact-update* this update-fn))
   (transact-data [this updates! asserts retracts] (transact-data* this updates! asserts retracts))
@@ -73,7 +74,6 @@
 (def empty-graph mem/empty-graph)
 (def empty-multi-graph multi/empty-multi-graph)
 
-
 (s/defn new-connection :- ConnectionType
   "Creates a memory Connection object"
   [name :- s/Str
@@ -90,6 +90,13 @@
   [connection :- ConnectionType]
   (:db @(:state connection)))
 
+(s/defn delete-database* :- s/Bool
+  "Reverts the state of a connection to an empty database, resetting the initialization time."
+  [{:keys [state] :as connection} :- ConnectionType]
+  (let [db (->MemoryDatabase (-> state deref :history first :graph) [] (now) 0)]
+    (reset! state {:db db :history [db]})
+    true))
+
 (s/defn as-database :- DatabaseType
   "Creates a Database around an existing Graph.
    graph: The graph to build a database around. "
diff --git a/test/asami/api_test.cljc b/test/asami/api_test.cljc
index a033ed0..1931d4c 100644
--- a/test/asami/api_test.cljc
+++ b/test/asami/api_test.cljc
@@ -706,6 +706,24 @@
       (delete-database db-io)
       (delete-database db-new))))
 
+(deftest test-database-delete
+  (testing "Are deleted memory databases cleared"
+    (let [db-name "asami:mem://test-del"
+          conn (connect db-name)
+          {d :db-after} @(transact conn {:tx-data io-entities})
+          r (set (q '[:find ?e ?a ?v :where [?e ?a ?v]] d))]
+      (is (= 13 (count r)))
+
+      (delete-database db-name)
+
+      (let [d2 (db conn)
+            r2 (set (q '[:find ?e ?a ?v :where [?e ?a ?v]] d2))
+            r3 (set (q '[:find ?e ?a ?v :where [?e ?a ?v]] conn))
+            r-old (set (q '[:find ?e ?a ?v :where [?e ?a ?v]] d))]
+        (is (empty? r2))
+        (is (empty? r3))
+        (is (= 13 (count r-old)))))))
+
 (deftest test-update-unowned
   (testing "Doing an update on an attribute that references a top level entity"
     (let [c (connect "asami:mem://testupdate")