An initial implementation of the cache API

[penalosa]

To test this, build workerd on the expose-cache-api branch, copy the binary into the right directory within node_modules for your system, and run miniflare with cache: true. The following test worker should demonstrate the cache behaviour:

test-cache.worker.js

export default {
  async fetch(request) {
    let res = "Running test cases...\n";
    const assert = (cond, message) => {
      if (!cond) {
        res += "❌ " + message + "\n";
      } else {
        res += "✅ " + message + "\n";
      }
    };
    const put = async (
      str,
      { df = null, reqHeaders = {}, resHeaders = {}, url = "" } = {}
    ) => {
      await (df == null ? caches.default : await caches.open(df)).put(
        new Request("https://example.com" + url, { headers: reqHeaders }),
        new Response(str, { headers: resHeaders })
      );
    };
    const del = async ({ df = null, reqHeaders = {}, url = "" } = {}) => {
      await (df == null ? caches.default : await caches.open(df)).delete(
        new Request("https://example.com" + url, { headers: reqHeaders })
      );
    };
    const get = async ({ df = null, reqHeaders = {}, url = "" } = {}) => {
      return await (df == null ? caches.default : await caches.open(df)).match(
        new Request("https://example.com" + url, { headers: reqHeaders })
      );
    };
    const test = async (name, cb) => {
      let incr = 1;
      let assertions = [];
      await cb((cond) => assertions.push(cond));
      if (assertions.length === 1) {
        assert(assertions[0], name);
      } else {
        assertions.forEach((cond) => {
          assert(cond, `(#${incr++}) ${name}`);
        });
      }
    };
    // Tests
    await test("Caches are not shared between namespaces", async (assert) => {
      await put("cached", { url: "/ns" });
      assert((await get({ url: "/ns", df: "test" })) === undefined);
    });

    await test("Cache item persisted", async (assert) => {
      await put("test-cached");
      assert((await get().then((r) => r.text())) === "test-cached");
    });

    await test("Etag is persisted", async (assert) => {
      await put("test-etag", { resHeaders: { ETag: "abc" } });
      assert((await get()).headers.get("ETag") === "abc");
    });

    await test("Expires is persisted", async (assert) => {
      await put("expires", { resHeaders: { Expires: "abc" } });
      assert((await get()).headers.get("Expires") === "abc");
    });

    await test("Last-Modified is persisted", async (assert) => {
      await put("last-modified", { resHeaders: { "Last-Modified": "abc" } });
      assert((await get()).headers.get("Last-Modified") === "abc");
    });

    await test("Cache-Control is persisted", async (assert) => {
      await put("cache-control", { resHeaders: { "Cache-Control": "abc" } });
      assert((await get()).headers.get("Cache-Control") === "abc");
    });

    await test("Set-Cookie causes no storage", async (assert) => {
      await put("set-cookie", {
        url: "/set-cookie",
        resHeaders: { "Set-Cookie": "abc=cde" },
      });
      assert(!(await get({ url: "/set-cookie" })));
    });

    await test("Set-Cookie is filtered with private=Set-Cookie", async (assert) => {
      await put("set-cookie-filter", {
        url: "/set-cookie-filter",
        resHeaders: {
          "Set-Cookie": "abc=cde",
          "Cache-Control": "private=Set-Cookie",
        },
      });
      assert(
        (await get({ url: "/set-cookie-filter" }).then((r) => r.text())) ===
          "set-cookie-filter"
      );
    });

    await test("Etag If-None-Match matches", async (assert) => {
      await put("test-etag", {
        url: "/etag-if-none-match",
        resHeaders: { ETag: '"abc"' },
      });
      assert(
        (
          await get({
            url: "/etag-if-none-match",
            reqHeaders: {
              "If-None-Match": '"abc"',
            },
          })
        ).status === 304
      );
    });

    await test("Etag If-None-Match doesn't match", async (assert) => {
      await put("test-etag", {
        url: "/etag-if-none-match-mismatch",
        resHeaders: { ETag: '"abc"' },
      });

      assert(
        (
          await get({
            url: "/etag-if-none-match-mismatch",
            reqHeaders: {
              "If-None-Match": '"cde"',
            },
          })
        ).headers.get("Cf-Cache-Status") == "HIT"
      );
    });

    await test("Last-Modified If-Modified-Since too late", async (assert) => {
      await put("last-modified", {
        url: "/last-modified-too-late",
        resHeaders: { "Last-Modified": "Wed, 21 Oct 2015 07:28:00 GMT" },
      });

      assert(
        (
          await get({
            url: "/last-modified-too-late",
            reqHeaders: {
              "If-Modified-Since": "Wed, 21 Oct 2016 07:28:00 GMT",
            },
          })
        ).status == 304
      );
    });
    await test("Last-Modified If-Modified-Since in time", async (assert) => {
      await put("last-modified", {
        url: "/last-modified-in-time",
        resHeaders: { "Last-Modified": "Wed, 21 Oct 2015 07:28:00 GMT" },
      });

      assert(
        (
          await get({
            url: "/last-modified-in-time",
            reqHeaders: {
              "If-Modified-Since": "Wed, 21 Oct 2014 07:28:00 GMT",
            },
          })
        ).headers.get("Cf-Cache-Status") == "HIT"
      );
    });

    await test("Range 1-", async (assert) => {
      await put("range", {
        url: "/range",
      });

      assert(
        (await get({
          url: "/range",
          reqHeaders: {
            Range: "bytes=1-",
          },
        }).then((r) => r.text())) === "ange"
      );
    });

    await test("Cache item is gone after purge ", async (assert) => {
      await put("test-cached-del");
      assert((await get().then((r) => r.text())) === "test-cached-del");
      await del();
      assert((await get()) === undefined);
    });

    return new Response(res);
  },
};

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[mrbbot]

Awesome! 😃 Added some comments, but looks really good, and especially like the README for the cache plugin.

[mrbbot]

We should do this for R2Error too, but this should probably extend MiniflareError (or HttpError?), and use code instead of status. MiniflareError will automatically set the name correctly too based off new.target.

[penalosa]

I copied this over from R2Error, but the reason it uses status rather than code is because it is the http status code. R2Error has another property v4Code (or v4code depending on context, the API is maddeningly inconsistent), so using code there would be a bit confusing, I think. For consistency, it might make sense to keep this as status. I'll have a look at extending from MiniflareError though

[mrbbot]

Super nit-picky, but given we're not using node: prefixes throughout the rest of the codebase (we probably should tbh), could we change this to just http? Whatever we end up deciding, probably best to add an eslint rule.

[penalosa]

What about adding an eslint rule to enforce it? (In a separate PR, so as not to mess up the diff of this one?) I'll remove it for this PR

[mrbbot]

Yep, that sounds good, I'd make the switch to node: in that PR too. 👍

[penalosa]

@mrbbot is this good to go?

[mrbbot]

Yep! 😊 LGTM!