Support for neshClassicCache

packages/nextjs-cache-handler/package.json

@@ -31,6 +31,10 @@
       "require": "./dist/handlers/*.cjs",
       "import": "./dist/handlers/*.js"
     },
+    "./functions": {
+      "require": "./dist/functions/functions.cjs",
+      "import": "./dist/functions/functions.js"
+    },
     "./instrumentation": {
       "require": "./dist/instrumentation/instrumentation.cjs",
       "import": "./dist/instrumentation/instrumentation.js"
@@ -41,6 +45,9 @@
       "*": [
         "dist/handlers/cache-handler.d.ts"
       ],
+      "functions": [
+        "dist/functions/functions.d.ts"
+      ],
       "instrumentation": [
         "dist/instrumentation/instrumentation.d.ts"
       ],

packages/nextjs-cache-handler/src/functions/functions.ts

@@ -0,0 +1 @@
+export { neshClassicCache } from "./nesh-classic-cache";

packages/nextjs-cache-handler/src/functions/nesh-classic-cache.ts

@@ -0,0 +1,350 @@
+import assert from "node:assert/strict";
+import { createHash } from "node:crypto";
+import { Revalidate } from "../handlers/cache-handler.types";
+import { workAsyncStorage } from "next/dist/server/app-render/work-async-storage.external.js";
+import type { IncrementalCache } from "next/dist/server/lib/incremental-cache";
+import { CacheHandler } from "../handlers/cache-handler";
+import { CACHE_ONE_YEAR } from "next/dist/lib/constants";
+import { CachedRouteKind } from "next/dist/server/response-cache";
+
+declare global {
+  var __incrementalCache: IncrementalCache | undefined;
+}
+
+function hashCacheKey(url: string): string {
+  // this should be bumped anytime a fix is made to cache entries
+  // that should bust the cache
+  const MAIN_KEY_PREFIX = "nesh-pages-cache-v1";
+
+  const cacheString = JSON.stringify([MAIN_KEY_PREFIX, url]);
+
+  return createHash("sha256").update(cacheString).digest("hex");
+}
+
+/**
+ * Serializes the given arguments into a string representation.
+ *
+ * @param object - The arguments to be serialized.
+ *
+ * @returns The serialized string representation of the arguments.
+ */
+function serializeArguments(object: object): string {
+  return JSON.stringify(object);
+}
+
+/**
+ * Serializes the given object into a string representation.
+ *
+ * @param object - The object to be serialized.
+ *
+ * @returns The serialized string representation of the object.
+ */
+function serializeResult(object: object): string {
+  return Buffer.from(JSON.stringify(object), "utf-8").toString("base64");
+}
+
+/**
+ * Deserializes a string representation of an object into its original form.
+ *
+ * @param string - The string representation of the object.
+ *
+ * @returns The deserialized object.
+ */
+function deserializeResult<T>(string: string): T {
+  return JSON.parse(Buffer.from(string, "base64").toString("utf-8"));
+}
+
+/**
+ * @template Arguments - The type of the arguments passed to the callback function.
+ *
+ * @template Result - The type of the value returned by the callback function.
+ */
+type Callback<Arguments extends unknown[], Result> = (
+  ...args: Arguments
+) => Result;
+
+/**
+ * An object containing options for the cache.
+ */
+type NeshClassicCacheOptions<Arguments extends unknown[], Result> = {
+  /**
+   * The response context object.
+   * It is used to set the cache headers.
+   */
+  responseContext?: object & {
+    setHeader(
+      name: string,
+      value: number | string | readonly string[],
+    ): unknown;
+  };
+  /**
+   * An array of tags to associate with the cached result.
+   * Tags are used to revalidate the cache using the `revalidateTag` function.
+   */
+  tags?: string[];
+  /**
+   * The revalidation interval in seconds.
+   * Must be a positive integer or `false` to disable revalidation.
+   *
+   * @default revalidate // of the current route
+   */
+  revalidate?: Revalidate;
+  /**
+   * A custom cache key to be used instead of creating one from the arguments.
+   */
+  cacheKey?: string;
+  /**
+   * A function that serializes the arguments passed to the callback function.
+   * Use it to create a cache key.
+   *
+   * @default (args) => JSON.stringify(args)
+   *
+   * @param callbackArguments - The arguments passed to the callback function.
+   */
+  argumentsSerializer?(callbackArguments: Arguments): string;
+  /**
+   *
+   * A function that serializes the result of the callback function.
+   *
+   * @default (result) => Buffer.from(JSON.stringify(result)).toString('base64')
+   *
+   * @param result - The result of the callback function.
+   */
+  resultSerializer?(result: Result): string;
+  /**
+   * A function that deserializes the string representation of the result of the callback function.
+   *
+   * @default (string) => JSON.parse(Buffer.from(string, 'base64').toString('utf-8'))
+   *
+   * @param string - The string representation of the result of the callback function.
+   */
+  resultDeserializer?(string: string): Result;
+};
+
+/**
+ * An object containing common options for the cache.
+ */
+type CommonNeshClassicCacheOptions<Arguments extends unknown[], Result> = Omit<
+  NeshClassicCacheOptions<Arguments, Result>,
+  "cacheKey" | "responseContext"
+>;
+
+/**
+ * Experimental implementation of the "`unstable_cache`" for classic Next.js Pages Router.
+ * It allows to cache data in the `getServerSideProps` and API routes.
+ *
+ * The API may change in the future. Use with caution.
+ *
+ * Caches the result of a callback function and returns a cached version if available.
+ * If not available, it executes the callback function, caches the result, and returns it.
+ *
+ * @param callback - The callback function to be cached.
+ *
+ * @param options - An object containing options for the cache.
+ *
+ * @param options.responseContext - The response context object.
+ * It is used to set the cache headers.
+ *
+ * @param options.tags - An array of tags to associate with the cached result.
+ * Tags are used to revalidate the cache using the `revalidateTag` function.
+ *
+ * @param options.revalidate - The revalidation interval in seconds.
+ * Must be a positive integer or `false` to disable revalidation.
+ * Defaults to `export const revalidate = time;` in the current route.
+ *
+ * @param options.argumentsSerializer - A function that serializes the arguments passed to the callback function.
+ * Use it to create a cache key. Defaults to `JSON.stringify(args)`.
+ *
+ * @param options.resultSerializer - A function that serializes the result of the callback function.
+ * Defaults to `Buffer.from(JSON.stringify(data)).toString('base64')`.
+ *
+ * @param options.resultDeserializer - A function that deserializes the string representation of the result of the callback function.
+ * Defaults to `JSON.parse(Buffer.from(data, 'base64').toString('utf-8'))`.
+ *
+ * @returns The callback wrapped in a caching function.
+ * First argument is the cache options which can be used to override the common options.
+ * In addition, there is a `cacheKey` option that can be used to provide a custom cache key.
+ *
+ * @throws If the `neshClassicCache` function is not used in a Next.js Pages directory or if the `revalidate` option is invalid.
+ *
+ * @example file: `src/pages/api/api-example.js`
+ *
+ * ```js
+ * import { neshClassicCache } from '@neshca/cache-handler/functions';
+ * import axios from 'axios';
+ *
+ * export const config = {
+ *   runtime: 'nodejs',
+ * };
+ *
+ * async function getViaAxios(url) {
+ *   try {
+ *     return (await axios.get(url.href)).data;
+ *   } catch (_error) {
+ *     return null;
+ *   }
+ * }
+ *
+ * const cachedAxios = neshClassicCache(getViaAxios);
+ *
+ * export default async function handler(request, response) {
+ *   if (request.method !== 'GET') {
+ *     return response.status(405).send(null);
+ *   }
+ *
+ *   const revalidate = 5;
+ *
+ *   const url = new URL('https://api.example.com/data.json');
+ *
+ *   // Add tags to be able to revalidate the cache
+ *   const data = await cachedAxios({ revalidate, tags: [url.pathname], responseContext: response }, url);
+ *
+ *   if (!data) {
+ *     response.status(404).send('Not found');
+ *
+ *     return;
+ *   }
+ *
+ *   response.json(data);
+ * }
+ * ```
+ *
+ * @remarks
+ * - This function is intended to be used in a Next.js Pages directory.
+ *
+ * @since 1.8.0
+ */
+export function neshClassicCache<
+  Arguments extends unknown[],
+  Result extends Promise<unknown>,
+>(
+  callback: Callback<Arguments, Result>,
+  commonOptions?: CommonNeshClassicCacheOptions<Arguments, Result>,
+) {
+  if (commonOptions?.resultSerializer && !commonOptions?.resultDeserializer) {
+    throw new Error(
+      "neshClassicCache: if you provide a resultSerializer, you must provide a resultDeserializer.",
+    );
+  }
+
+  if (commonOptions?.resultDeserializer && !commonOptions?.resultSerializer) {
+    throw new Error(
+      "neshClassicCache: if you provide a resultDeserializer, you must provide a resultSerializer.",
+    );
+  }
+
+  const commonRevalidate = commonOptions?.revalidate ?? false;
+  const commonArgumentsSerializer =
+    commonOptions?.argumentsSerializer ?? serializeArguments;
+  const commonResultSerializer =
+    commonOptions?.resultSerializer ?? serializeResult;
+  const commonResultDeserializer =
+    commonOptions?.resultDeserializer ?? deserializeResult;
+
+  async function cachedCallback(
+    options: NeshClassicCacheOptions<Arguments, Result>,
+    ...args: Arguments
+  ): Promise<Result | null> {
+    const store = workAsyncStorage.getStore();
+
+    assert(
+      !store?.incrementalCache,
+      "neshClassicCache must be used in a Next.js Pages directory.",
+    );
+
+    const cacheHandler = globalThis?.__incrementalCache?.cacheHandler as
+      | InstanceType<typeof CacheHandler>
+      | undefined;
+
+    assert(
+      cacheHandler,
+      "neshClassicCache must be used in a Next.js Pages directory.",
+    );
+
+    const {
+      responseContext,
+      tags = [],
+      revalidate = commonRevalidate,
+      cacheKey,
+      argumentsSerializer = commonArgumentsSerializer,
+      resultDeserializer = commonResultDeserializer,
+      resultSerializer = commonResultSerializer,
+    } = options ?? {};
+
+    assert(
+      revalidate === false || (revalidate > 0 && Number.isInteger(revalidate)),
+      "neshClassicCache: revalidate must be a positive integer or false.",
+    );
+
+    responseContext?.setHeader(
+      "Cache-Control",
+      `public, s-maxage=${revalidate}, stale-while-revalidate`,
+    );
+
+    const uniqueTags = new Set<string>();
+
+    for (const tag of tags) {
+      if (typeof tag === "string") {
+        uniqueTags.add(tag);
+      } else {
+        console.warn(
+          `neshClassicCache: Invalid tag: ${tag}. Skipping it. Expected a string.`,
+        );
+      }
+    }
+
+    const allTags = Array.from(uniqueTags);
+
+    const key = hashCacheKey(
+      `nesh-classic-cache-${cacheKey ?? argumentsSerializer(args)}`,
+    );
+
+    const cacheData = await cacheHandler.get(key, {
+      revalidate,
+      tags: allTags,
+      kind: "FETCH" as unknown as any,
+      fetchUrl: "neshClassicCache",
+    });
+
+    if (
+      cacheData?.value?.kind === "FETCH" &&
+      cacheData.lifespan &&
+      cacheData.lifespan.staleAt > Date.now() / 1000
+    ) {
+      return resultDeserializer(cacheData.value.data.body);
+    }
+
+    const data: Result = await callback(...args);
+
+    cacheHandler.set(
+      key,
+      {
+        kind: "FETCH" as CachedRouteKind.FETCH,
+        data: {
+          body: resultSerializer(data),
+          headers: {},
+          url: "neshClassicCache",
+        },
+        revalidate: revalidate || CACHE_ONE_YEAR,
+      },
+      {
+        revalidate,
+        tags,
+        fetchCache: true,
+        fetchUrl: "neshClassicCache",
+      },
+    );
+
+    if (
+      cacheData?.value?.kind === "FETCH" &&
+      cacheData?.lifespan &&
+      cacheData.lifespan.expireAt > Date.now() / 1000
+    ) {
+      return resultDeserializer(cacheData.value.data.body);
+    }
+
+    return data;
+  }
+
+  return cachedCallback;
+}

packages/nextjs-cache-handler/tsup.config.ts

@@ -2,7 +2,11 @@ import { defineConfig } from "tsup";
 
 export const tsup = defineConfig({
   name: "Build cache-handler",
-  entry: ["src/handlers/*.ts", "src/instrumentation/*.ts"],
+  entry: [
+    "src/handlers/*.ts",
+    "src/functions/*.ts",
+    "src/instrumentation/*.ts",
+  ],
   splitting: false,
   outDir: "dist",
   clean: false,