Merge pull request #482 from nats-io/kv-create-after-del

[FEAT] [KV] create now re-attempts if the last entry in the KV is deleted or purged

nats-base-client/kv.ts

@@ -460,8 +460,29 @@ export class Bucket implements KV, KvRemove {
     } as KvEntry;
   }
 
-  create(k: string, data: Uint8Array): Promise<number> {
-    return this.put(k, data, { previousSeq: 0 });
+  async create(k: string, data: Uint8Array): Promise<number> {
+    let firstErr;
+    try {
+      const n = await this.put(k, data, { previousSeq: 0 });
+      return Promise.resolve(n);
+    } catch (err) {
+      firstErr = err;
+      if (err?.api_error?.err_code !== 10071) {
+        return Promise.reject(err);
+      }
+    }
+    let rev = 0;
+    try {
+      const e = await this.get(k);
+      if (e?.operation === "DEL" || e?.operation === "PURGE") {
+        rev = e !== null ? e.revision : 0;
+        return this.update(k, data, rev);
+      } else {
+        return Promise.reject(firstErr);
+      }
+    } catch (err) {
+      return Promise.reject(err);
+    }
   }
 
   update(k: string, data: Uint8Array, version: number): Promise<number> {

nats-base-client/types.ts

@@ -2787,7 +2787,8 @@ export interface RoKV {
 
 export interface KV extends RoKV {
   /**
-   * Creates a new entry ensuring that the entry does not exist.
+   * Creates a new entry ensuring that the entry does not exist (or
+   * the current version is deleted or the key is purged)
    * If the entry already exists, this operation fails.
    * @param k
    * @param data

tests/kv_test.ts

@@ -1681,3 +1681,20 @@ Deno.test("kv - mirror cross domain", async () => {
 
   await cleanup(lns, lnc);
 });
+
+Deno.test("kv - create after delete", async () => {
+  const { ns, nc } = await setup(jetstreamServerConf({}, true));
+
+  const js = nc.jetstream();
+  const kv = await js.views.kv("K");
+  await kv.create("a", Empty);
+
+  await assertRejects(async () => {
+    await kv.create("a", Empty);
+  });
+  await kv.delete("a");
+  await kv.create("a", Empty);
+  await kv.purge("a");
+  await kv.create("a", Empty);
+  await cleanup(ns, nc);
+});