fetch-parse-json-bench.ts

import { summary, run, bench, do_not_optimize } from "mitata";
import { LimitedBytesTransformStream } from "@std/streams";

const register = (name: string, fn: (list: Request[]) => any) =>
  bench(name, function* () {
    yield {
      [0]: () => reqs.map((t) => t.clone()),
      bench: fn,
    };
  });

const reqs = new Array(1000).fill(0).map(
  (_, i) =>
    new Request("http://localhost", {
      method: "POST",
      body: new Blob([
        "{",
        ...new Array(Math.floor(10 + i / 20))
          .fill(0)
          .map(() => '"' + crypto.randomUUID() + '":0,'),
        '"_":"a"}',
      ]),
    }),
);

// Example benchmark
summary(() => {
  register("req.json", async (list) => {
    for (let i = 0; i < list.length; i++) do_not_optimize(await list[i].json());
  });

  register("parse req.text", async (list) => {
    for (let i = 0; i < list.length; i++)
      do_not_optimize(JSON.parse(await list[i].text()));
  });
});

summary(() => {
  const LIMIT = 300;
  const decoder = new TextDecoder();

  register("manual stream", async (list) => {
    for (let i = 0; i < list.length; i++) {
      const stream = list[i].body;
      if (stream != null) {
        try {
          let remainingBytes = LIMIT;
          let chunks = "";

          for (
            let reader = stream.getReader(), data = await reader.read();
            !data.done;
            data = await reader.read()
          ) {
            remainingBytes -= data.value.byteLength;
            if (remainingBytes < 0)
              throw new RangeError(`Exceeded byte size limit of '${LIMIT}'`);

            chunks += decoder.decode(data.value);
          }

          do_not_optimize(JSON.parse(chunks));
        } catch {}
      }
    }
  });

  register("LimitedBytesTransformStream", async (list) => {
    for (let i = 0; i < list.length; i++) {
      const stream = list[i].body;
      if (stream != null)
        try {
          do_not_optimize(
            await new Response(
              stream.pipeThrough(new LimitedBytesTransformStream(LIMIT)),
            ).json(),
          );
        } catch {}
    }
  });
});

// Start the benchmark
run();