🎉 Add initial redis client foundation.

backend/src/uxbox/util/redis.clj

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+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) 2019 Andrey Antukh <niwi@niwi.nz>
+
+(ns uxbox.util.redis
+  "Asynchronous posgresql client."
+  (:refer-clojure :exclude [get set run!])
+  (:require
+   [promesa.core :as p])
+  (:import
+   io.lettuce.core.RedisClient
+   io.lettuce.core.RedisURI
+   io.lettuce.core.codec.StringCodec
+   io.lettuce.core.api.async.RedisAsyncCommands
+   io.lettuce.core.api.StatefulRedisConnection
+   ))
+
+(defrecord Client [conn uri]
+  java.lang.AutoCloseable
+  (close [_]
+    (.shutdown ^RedisClient conn)))
+
+(defrecord Connection [cmd conn]
+  java.lang.AutoCloseable
+  (close [_]
+    (.close ^StatefulRedisConnection conn)))
+
+(defn client
+  [uri]
+  (->Client (RedisClient/create) (RedisURI/create uri)))
+
+(defn connect
+  [client]
+  (let [^RedisURI uri (:uri client)
+        ^RedisClient conn (:conn client)
+        ^StatefulRedisConnection conn' (.connect conn StringCodec/UTF8 uri)]
+    (->Connection (.async conn') conn')))
+
+(declare impl-with-conn)
+
+(defmacro with-conn
+  [[csym sym] & body]
+  `(impl-with-conn ~sym (fn [~csym] ~@body)))
+
+(defn impl-with-conn
+  [client f]
+  (let [^RedisURI uri (:uri client)
+        ^RedisClient conn (:conn client)]
+    (-> (.connectAsync conn StringCodec/UTF8 uri)
+        (p/then (fn [^StatefulRedisConnection conn]
+                  (let [cmd  (.async conn)
+                        conn (->Connection cmd conn)]
+                    (-> (p/do! (f conn))
+                        (p/handle (fn [v e]
+                                    (.close conn)
+                                    (if e
+                                      (throw e)
+                                      v))))))))))
+
+(defn- resolve-to-bool
+  [v]
+  (if (= v 1)
+    true
+    false))
+
+(defmulti impl-run (fn [conn cmd parmas] cmd))
+
+(defn run!
+  [conn cmd params]
+  (let [^RedisAsyncCommands conn (:cmd conn)]
+    (impl-run conn cmd params)))
+
+(defmethod impl-run :get
+  [conn _ {:keys [key]}]
+  (.get ^RedisAsyncCommands conn ^String key))
+
+(defmethod impl-run :set
+  [conn _ {:keys [key val]}]
+  (.set ^RedisAsyncCommands conn ^String key ^String val))
+
+(defmethod impl-run :smembers
+  [conn _ {:keys [key]}]
+  (-> (.smembers ^RedisAsyncCommands conn ^String key)
+      (p/then' #(into #{} %))))
+
+(defmethod impl-run :sadd
+  [conn _ {:keys [key val]}]
+  (let [keys (into-array String [val])]
+    (-> (.sadd ^RedisAsyncCommands conn ^String key ^"[S;" keys)
+        (p/then resolve-to-bool))))
+
+(defmethod impl-run :srem
+  [conn _ {:keys [key val]}]
+  (let [keys (into-array String [val])]
+    (-> (.srem ^RedisAsyncCommands conn ^String key ^"[S;" keys)
+        (p/then resolve-to-bool))))
+