feat: memo, add keyHash option (#54)

* apply a custom hashing func or use the default

Author: cdcabrera

src/__tests__/__snapshots__/server.caching.test.ts.snap

@@ -720,6 +720,124 @@ exports[`memo should fire "onCacheRollout" callback on cache rollout, one entry
 ]
 `;
 
+exports[`memo should memoize a function, allow custom key hashing: async 1`] = `
+[
+  {
+    "cacheKeys": [
+      "custom-hash-",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "[EMPTY]",
+    "type": "memo promise",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "[EMPTY]",
+    "type": "memo promise",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-1",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "1",
+    "type": "memo promise",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-1",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "1",
+    "type": "memo promise",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-2,true",
+    ],
+    "cacheLength": 2,
+    "errorValue": "2",
+    "successValue": undefined,
+    "type": "memo promise",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-2,true",
+    ],
+    "cacheLength": 2,
+    "errorValue": "2",
+    "successValue": undefined,
+    "type": "memo promise",
+  },
+]
+`;
+
+exports[`memo should memoize a function, allow custom key hashing: sync 1`] = `
+[
+  {
+    "cacheKeys": [
+      "custom-hash-",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "[EMPTY]",
+    "type": "memo",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "[EMPTY]",
+    "type": "memo",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-1",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "1",
+    "type": "memo",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-1",
+    ],
+    "cacheLength": 2,
+    "errorValue": undefined,
+    "successValue": "1",
+    "type": "memo",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-2,true",
+    ],
+    "cacheLength": 2,
+    "errorValue": "2",
+    "successValue": undefined,
+    "type": "memo error",
+  },
+  {
+    "cacheKeys": [
+      "custom-hash-2,true",
+    ],
+    "cacheLength": 2,
+    "errorValue": "2",
+    "successValue": undefined,
+    "type": "memo error",
+  },
+]
+`;
+
 exports[`memo should memoize a function, cacheLimit: async 1`] = `
 [
   {

src/__tests__/server.caching.test.ts

@@ -34,6 +34,13 @@ describe('memo', () => {
       description: 'disable memoization when cacheLimit is zero',
       options: { cacheLimit: 0 },
       params: [[], [], [1], [1], [2, true], [2, true]]
+    },
+    {
+      description: 'allow custom key hashing',
+      options: {
+        keyHash: (value: unknown) => `custom-hash-${value}`
+      },
+      params: [[], [], [1], [1], [2, true], [2, true]]
     }
   ])('should memoize a function, $description', async ({ options, params }) => {
     const log: any[] = [];

src/server.caching.ts

@@ -56,6 +56,7 @@ type MemoDebugHandler<TReturn = unknown> = (info: { type: string; value: unknown
  * @property [cacheLimit] Number of entries to cache before overwriting previous entries (default: 1)
  * @property {MemoDebugHandler<TReturn>} [debug] Debug callback function
  * @property [expire] Expandable milliseconds until cache expires
+ * @property [keyHash] Function to generate a predictable hash key from the provided arguments. Defaults to internal `generateHash`.
  * @property {OnMemoCacheHandler<TReturn>} [onCacheExpire] Callback when cache expires. Only fires when the `expire` option is set.
  * @property {OnMemoCacheHandler<TReturn>} [onCacheRollout] Callback when cache entries are rolled off due to cache limit.
  */
@@ -64,6 +65,7 @@ interface MemoOptions<TReturn = unknown> {
   cacheLimit?: number;
   debug?: MemoDebugHandler<TReturn>;
   expire?: number;
+  keyHash?: (args: unknown[]) => unknown;
   onCacheExpire?: OnMemoCacheHandler<TReturn>;
   onCacheRollout?: OnMemoCacheHandler<TReturn>;
 }
@@ -93,6 +95,7 @@ const memo = <TArgs extends unknown[], TReturn = unknown>(
     cacheLimit = 1,
     debug = () => {},
     expire,
+    keyHash = generateHash,
     onCacheExpire,
     onCacheRollout
   }: MemoOptions<TReturn> = {}
@@ -104,6 +107,9 @@ const memo = <TArgs extends unknown[], TReturn = unknown>(
   const isOnCacheRolloutPromise = isPromise(onCacheRollout);
   const isOnCacheRollout = typeof onCacheRollout === 'function' || isOnCacheRolloutPromise;
   const updatedExpire = Number.parseInt(String(expire), 10) || undefined;
+  const setKey = function (value: unknown[]): unknown {
+    return keyHash.call(null, value);
+  };
 
   const ized = function () {
     const cache: MemoCache<TReturn> = [];
@@ -159,7 +165,7 @@ const memo = <TArgs extends unknown[], TReturn = unknown>(
         return bypassValue;
       }
 
-      const key = generateHash(args);
+      const key = setKey(args);
 
       // Parse, memoize and return the original value
       if (cache.indexOf(key) < 0) {