[FEAT] added support for Consumers to set mem_storage.

nats-base-client/jsconsumeropts.ts

@@ -255,6 +255,11 @@ export class ConsumerOptsBuilderImpl implements ConsumerOptsBuilder {
     this.config.max_expires = nanos(millis);
     return this;
   }
+
+  memory() {
+    this.config.mem_storage = true;
+    return this;
+  }
 }
 
 export function isConsumerOptsBuilder(

nats-base-client/types.ts

@@ -1227,6 +1227,12 @@ export interface ConsumerOptsBuilder {
    * @param millis
    */
   inactiveEphemeralThreshold(millis: number): this;
+
+  /**
+   * Force the consumer state to be kept in memory rather than inherit the setting from
+   * the Stream
+   */
+  memory(): this;
 }
 
 /**

tests/jetstream_test.ts

@@ -3510,3 +3510,38 @@ Deno.test("jetstream - republish", async () => {
 
   await cleanup(ns, nc);
 });
+
+Deno.test("jetstream - mem_storage consumer option", async () => {
+  const { ns, nc } = await setup(jetstreamServerConf({}, true));
+  if (await notCompatible(ns, nc, "2.9.0")) {
+    return;
+  }
+
+  const { stream, subj } = await initStream(nc);
+  const jsm = await nc.jetstreamManager();
+  const si = await jsm.streams.info(stream);
+  assertEquals(si.config.storage, StorageType.File);
+
+  const opts = consumerOpts();
+  opts.ackExplicit();
+  opts.durable("opts");
+  opts.memory();
+
+  const js = nc.jetstream();
+  const sub = await js.pullSubscribe(subj, opts);
+  let ci = await sub.consumerInfo();
+  assertEquals(ci.config.mem_storage, true);
+
+  ci.config.mem_storage = false;
+  ci = await jsm.consumers.update(stream, "opts", ci.config);
+  assertEquals(ci.config.mem_storage, undefined);
+
+  ci = await jsm.consumers.add(stream, {
+    durable_name: "dopts",
+    mem_storage: true,
+    ack_policy: AckPolicy.Explicit,
+  });
+  assertEquals(ci.config.mem_storage, true);
+
+  await cleanup(ns, nc);
+});