An in-progress asynchronous manifold interface to the synchronous java.jdbc using a dirigiste thread pool. This library is not yet ready for serious use.
[jdbca "0.1.0-SNAPSHOT"](require '[jdbca :as j])
(require '[manifold.stream :as s])
;; db would be a connection pool in production code
(def db {:subprotocol "postgresql"
:subname "//localhost:5432/bts"
:user "bts"
:password ""})
(-> (j/query db ["select *, pg_sleep(1) from dogs where name = ?" "abe"])
(d/chain
(partial s/map :name)
s/take!)
(d/catch
(fn [e] "caught: " e)))
;=> << … >>
*1
;=> << "abe" >>This project currently only contains the JDBC functionality I need in another project. Contributions are welcome.
Next on the list is transaction support. I'm currently considering a faux-monadic interface that's a blend of let-flow and postgres.async's dosql, where each of the bindings will be made sequentially, and any failure will result in the entire form realizing an error-deferred:
(j/do [tx (j/begin {:isolation :serializable})
rs1 (j/execute! tx ["insert into dogs (name) values (?)" "new dog"])
rs2 (j/execute! tx ["insert into cats (name) values (?)" "new cat"])
_ (j/commit!)]
(concat rs1 rs1))To simplify transaction semantics, I think the current j/query function should probably be changed to just return a deferred yielding a clojure sequence instead of a manifold stream.
Copyright © 2015 Brian Schroeder
Distributed under the MIT License.