hyperstate.js

import Hypercore from 'hypercore';
import Hyperbee from 'hyperbee';

class Hyperstate extends Hypercore {
  constructor(storage, key, opts) {
    super(storage, key, opts);
    this.state = {};

    this.opening = this._open();
    this.opening.catch(noop);
    this.opened = false;
  }

  async _open() {
    await super.ready();
    if (this.length > 0) this.state = await this.get(this.length - 1);
  }

  async ready() {
    return this.opening;
  }

  async put(key, value) {
    const snapshot = this.snapshot({ valueEncoding: this.valueEncoding });
    const payload = { [key]: value };

    if (snapshot.length === 0) {
      return super.append(payload);
    }

    const state = (await snapshot.get(snapshot.length - 1)) || {};

    await snapshot.clear(0, snapshot.length);

    this.state = { ...state, ...payload };

    return super.append(this.state);
  }
}

function noop() {}

const OVERHEAD_SIZE = 1000;

async function test(db) {
  await db.put(
    'overhead',
    Buffer.alloc(OVERHEAD_SIZE).fill('overhead').toString(),
  );
  for (let i = 0; i < 100; i++) {
    await db.put('foo', 'bar' + i);
  }
}

const lightdb = new Hyperstate('./storage/hyperstate', {
  valueEncoding: 'json',
});
await lightdb.ready();
await test(lightdb);

const bee = new Hyperbee(new Hypercore('./storage/hyperbee'), {
  keyEncoding: 'utf8',
  valueEncoding: 'json',
});
await test(bee);

console.log(lightdb.state.foo);