bun.sh/test/js/bun/util/mmap.test.js

import { describe, expect, it } from "bun:test";
import { gcTick, isWindows, tmpdirSync } from "harness";
import { join } from "path";

// TODO: We do not support mmap() on Windows. Maybe we can add it later.
describe.skipIf(isWindows)("Bun.mmap", async () => {
  await gcTick();
  const path = join(tmpdirSync(), "bun-mmap-test.txt");
  await gcTick();
  await Bun.write(path, "hello");
  await gcTick();

  it("mmap finalizer", async () => {
    let map = Bun.mmap(path);
    await gcTick();
    const map2 = Bun.mmap(path);

    map = null;
    await gcTick();
  });

  it("mmap passed to other syscalls", async () => {
    const map = Bun.mmap(path);
    await gcTick();
    await Bun.write(path + "1", map);
    await gcTick();
    const text = await (await Bun.file(path + "1")).text();
    await gcTick();

    expect(text).toBe(new TextDecoder().decode(map));
  });

  it("mmap sync", async () => {
    const map = Bun.mmap(path);
    await gcTick();
    const map2 = Bun.mmap(path);
    await gcTick();

    const old = map[0];
    await gcTick();
    map[0] = 0;
    await gcTick();
    expect(map2[0]).toBe(0);

    map2[0] = old;
    await gcTick();
    expect(map[0]).toBe(old);
    await gcTick();
    await Bun.write(path, "olleh");
    await gcTick();
    expect(new TextDecoder().decode(map)).toBe("olleh");
    await gcTick();
  });

  it("mmap private", async () => {
    await gcTick();
    const map = Bun.mmap(path, { shared: true });
    await gcTick();
    const map2 = Bun.mmap(path, { shared: false });
    await gcTick();
    const old = map[0];

    await gcTick();
    map2[0] = 0;
    await gcTick();
    expect(map2[0]).toBe(0);
    await gcTick();
    expect(map[0]).toBe(old);
    await gcTick();
  });
});