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Review comment: ensure <transact! after <close is rejected.

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This commit is contained in:
Nick Alexander 2016-10-13 12:45:29 -07:00
parent b20c70fc2a
commit f02d508370
2 changed files with 39 additions and 9 deletions
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27
src/common/datomish/transact.cljc
View file

@ -35,7 +35,9 @@
(defprotocol IConnection (defprotocol IConnection
(close (close
[conn] [conn]
"Close this connection. Returns a pair channel of [nil error].") "Close this connection. Returns a pair channel of [nil error].
Closing a closed connection is a no-op.")
(db (db
[conn] [conn]
@ -45,11 +47,15 @@
[conn] [conn]
"Get the full transaction history DB associated with this connection.")) "Get the full transaction history DB associated with this connection."))
(defrecord Connection [current-db transact-chan] (defrecord Connection [closed? current-db transact-chan]
IConnection IConnection
(close [conn] (close [conn]
(a/close! (:transact-chan conn)) (if (compare-and-set! (:closed? conn) false true)
(db/close-db @(:current-db conn))) (do
;; This immediately stops <transact! enqueueing new work.
(a/close! (:transact-chan conn))
(db/close-db @(:current-db conn)))
(go [nil nil])))
(db [conn] @(:current-db conn)) (db [conn] @(:current-db conn))
@ -112,7 +118,8 @@
(a/mult listener-source) ;; Just for tapping. (a/mult listener-source) ;; Just for tapping.
connection connection
(map->Connection {:current-db (atom db) (map->Connection {:closed? (atom false)
:current-db (atom db)
:listener-source listener-source :listener-source listener-source
:listener-mult listener-mult :listener-mult listener-mult
:transact-chan (a/chan (util/unlimited-buffer)) :transact-chan (a/chan (util/unlimited-buffer))
@ -576,10 +583,12 @@
{:pre [(conn? conn)]} {:pre [(conn? conn)]}
;; Any race to put! is a real race between callers of <transact!. We can't just park on put!, ;; Any race to put! is a real race between callers of <transact!. We can't just park on put!,
;; because the parked putter that is woken is non-deterministic. ;; because the parked putter that is woken is non-deterministic.
(a/put! (:transact-chan conn) [tx-data result close?]) (let [closed? (not (a/put! (:transact-chan conn) [tx-data result close?]))]
(go-pair (go-pair
;; We want to return a pair-chan, no matter what kind of channel result is. ;; We want to return a pair-chan, no matter what kind of channel result is.
(<? result)))) (if closed?
(raise "Connection is closed" {:error :transact/connection-closed})
(<? result))))))
(defn- start-transactor [conn] (defn- start-transactor [conn]
(let [token-chan (a/chan 1)] (let [token-chan (a/chan 1)]

21
test/datomish/transact_test.cljc
View file

@ -221,4 +221,25 @@
(is (= (<? (<datoms-after (d/db conn) tx0)) (is (= (<? (<datoms-after (d/db conn) tx0))
#{[101 :name "Petr"]}))))) #{[101 :name "Petr"]})))))
;; We don't use deftest-db in order to be able to close the connection ourselves.
(deftest-async test-transact-after-close
(with-tempfile [t (tempfile)]
(let [conn (<? (d/<connect t))
{tx0 :tx} (<? (d/<transact! conn test-schema))]
(try
(testing "transaction before close is applied"
(<? (d/<transact! conn [{:db/id 101 :name "Petr"}]))
(is (= (<? (<datoms-after (d/db conn) tx0))
#{[101 :name "Petr"]})))
(finally
(<? (d/<close conn))))
(testing "transact after close throws"
(is (thrown-with-msg?
ExceptionInfo #"Connection is closed"
(<? (d/<transact! conn [{:db/id (d/id-literal :db.part/user -1) :name "Petr"}])))))
;; Closing a closed connection is a no-op.
(<? (d/<close conn)))))
#_ (time (t/run-tests)) #_ (time (t/run-tests))