Store state and 9p filesystem in IndexedDB

[krishenriksen]

An example would be to initialize V86Starter without defining initial_state

Then Load or Store the state using IndexedDB

let db;

// open db
const request = indexedDB.open('storage', 1);

// create the object store and indexes
request.onupgradeneeded = (e) => {

	db = e.target.result;

	let store = db.createObjectStore('Storage', {
		autoIncrement: true
	});

	// create an index on the property
	store.createIndex('id', 'id', {
		unique: true
	});
};

request.onsuccess = (e) => {
	
	db = e.target.result;
};

const get = globalThis.get = (id) => {

	return new Promise(resolve => {

		const txn = db.transaction('Storage', 'readonly');
		const store = txn.objectStore('Storage');
	
		const query = store.get(id);
	
		query.onsuccess = (e) => {
	
			resolve(e.target.result);
		};
	});
};

const put = globalThis.put = (id, arrayBuffer) => {

	return new Promise(resolve => {

		// create a new transaction
		const txn = db.transaction('Storage', 'readwrite');

		// get the object store
		const store = txn.objectStore('Storage');

		// store for 1 day
		const expire = new Date();
		expire.setDate(expire.getDate() + 1);

		let query = store.put({
			arrayBuffer: arrayBuffer,
			timestamp: expire.getTime()
		}, id);

		// handle success case
		query.onsuccess = (e) => {

			resolve(e.target.result);
		};
	});
}

get('blockstate').then(async (data) => {

	let arrayBuffer;

	if (data && data.timestamp > new Date().getTime()) {

		// get from indexedDB

		arrayBuffer = data.arrayBuffer;
	}
	else {

		// get from server

		const rawResponse = await fetch(`http://localhost:8080/v86/images/blockstate.bin.zst`);
		arrayBuffer = await rawResponse.arrayBuffer();

		put('blockstate', arrayBuffer);
	}

	await emulator.restore_state(arrayBuffer);
}

[Darin755]

I personally use localForage because it simplifies the complexity of IndexDB

[ProgrammerIn-wonderland]

My fork uses filer.js (a node like FS library in the browser with unix permissions and all the jazz) for the filesystem (code taken from humphd's browser shell) for 9p persistence. It works pretty well

https://github.com/MercuryWorkshop/v86/blob/master/lib/9p-filer.js