From 4cc3972cba42d0ec420c7508c358c90d6294b5df Mon Sep 17 00:00:00 2001
From: Ruben Deyhle <deyhle@users.noreply.github.com>
Date: Tue, 21 Mar 2023 03:55:04 +0100
Subject: [PATCH] feat: add mget(), mset(), mdel() to multiCache (#367)

---
 README.md                  | 23 ++++++++++++++++++
 src/multi-caching.ts       | 25 ++++++++++++++++++-
 test/multi-caching.test.ts | 50 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 7802b1d6..345d91b9 100644
--- a/README.md
+++ b/README.md
@@ -98,6 +98,29 @@ console.log(await multiCache.get('foo2'));
 
 // Delete from all caches
 await multiCache.del('foo2');
+
+// Sets multiple keys in all caches.
+// You can pass as many key, value tuples as you want
+await multiCache.mset(
+  [
+    ['foo', 'bar'],
+    ['foo2', 'bar2'],
+  ],
+  ttl
+);
+
+// mget() fetches from highest priority cache.
+// If the first cache does not return all the keys,
+// the next cache is fetched with the keys that were not found.
+// This is done recursively until either:
+// - all have been found
+// - all caches has been fetched
+console.log(await multiCache.mget('key', 'key2');
+// >> ['bar', 'bar2']
+
+// Delete keys with mdel() passing arguments...
+await multiCache.mdel('foo', 'foo2');
+
 ```
 
 See unit tests in [`test/multi-caching.test.ts`](./test/multi-caching.test.ts) for more information.
diff --git a/src/multi-caching.ts b/src/multi-caching.ts
index 57b86936..19a7ec33 100644
--- a/src/multi-caching.ts
+++ b/src/multi-caching.ts
@@ -1,6 +1,10 @@
 import { Cache, Milliseconds } from './caching';
 
-export type MultiCache = Omit<Cache, 'store'>;
+export type MultiCache = Omit<Cache, 'store'> & {
+  mset(args: [string, unknown][], ttl?: Milliseconds): Promise<void>;
+  mget(...args: string[]): Promise<unknown[]>;
+  mdel(...args: string[]): Promise<void>;
+};
 
 /**
  * Module that lets you specify a hierarchy of caches.
@@ -56,5 +60,24 @@ export function multiCaching<Caches extends Cache[]>(
     reset: async () => {
       await Promise.all(caches.map((x) => x.reset()));
     },
+    mget: async (...keys: string[]) => {
+      const values = new Array(keys.length).fill(undefined);
+      for (const cache of caches) {
+        if (values.every((x) => x !== undefined)) break;
+        try {
+          const val = await cache.store.mget(...keys);
+          val.forEach((v, i) => {
+            if (values[i] === undefined && v !== undefined) values[i] = v;
+          });
+        } catch (e) {}
+      }
+      return values;
+    },
+    mset: async (args: [string, unknown][], ttl?: Milliseconds) => {
+      await Promise.all(caches.map((cache) => cache.store.mset(args, ttl)));
+    },
+    mdel: async (...keys: string[]) => {
+      await Promise.all(caches.map((cache) => cache.store.mdel(...keys)));
+    },
   };
 }
diff --git a/test/multi-caching.test.ts b/test/multi-caching.test.ts
index ba39958a..8bdab292 100644
--- a/test/multi-caching.test.ts
+++ b/test/multi-caching.test.ts
@@ -91,6 +91,56 @@ describe('multiCaching', () => {
       });
     });
 
+    describe('mset()', () => {
+      it('lets us set multiple keys in all caches', async () => {
+        const keys = [faker.datatype.string(20), faker.datatype.string(20)];
+        const values = [faker.datatype.string(), faker.datatype.string()];
+        await multiCache.mset(
+          [
+            [keys[0], values[0]],
+            [keys[1], values[1]],
+          ],
+          defaultTtl,
+        );
+        await expect(memoryCache.get(keys[0])).resolves.toEqual(values[0]);
+        await expect(memoryCache2.get(keys[0])).resolves.toEqual(values[0]);
+        await expect(memoryCache3.get(keys[0])).resolves.toEqual(values[0]);
+        await expect(memoryCache.get(keys[1])).resolves.toEqual(values[1]);
+        await expect(memoryCache2.get(keys[1])).resolves.toEqual(values[1]);
+        await expect(memoryCache3.get(keys[1])).resolves.toEqual(values[1]);
+      });
+    });
+
+    describe('mget()', () => {
+      it('lets us get multiple keys', async () => {
+        const keys = [faker.datatype.string(20), faker.datatype.string(20)];
+        const values = [faker.datatype.string(), faker.datatype.string()];
+        await multiCache.set(keys[0], values[0], defaultTtl);
+        await memoryCache3.set(keys[1], values[1], defaultTtl);
+        await expect(multiCache.mget(...keys)).resolves.toStrictEqual(values);
+      });
+    });
+
+    describe('mdel()', () => {
+      it('lets us delete multiple keys', async () => {
+        const keys = [faker.datatype.string(20), faker.datatype.string(20)];
+        const values = [faker.datatype.string(), faker.datatype.string()];
+        await multiCache.mset(
+          [
+            [keys[0], values[0]],
+            [keys[1], values[1]],
+          ],
+          defaultTtl,
+        );
+        await expect(multiCache.mget(...keys)).resolves.toStrictEqual(values);
+        await multiCache.mdel(...keys);
+        await expect(multiCache.mget(...keys)).resolves.toStrictEqual([
+          undefined,
+          undefined,
+        ]);
+      });
+    });
+
     describe('when cache fails', () => {
       // eslint-disable-next-line @typescript-eslint/no-empty-function
       const empty = (async () => {}) as never;