fluence-js/src/fluenceConnection.ts

/*
 * Copyright 2020 Fluence Labs Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import Websockets from 'libp2p-websockets';
import Mplex from 'libp2p-mplex';
import SECIO from 'libp2p-secio';
import Peer from 'libp2p';
import { decode, encode } from 'it-length-prefixed';
import pipe from 'it-pipe';
import Multiaddr from 'multiaddr';
import PeerId from 'peer-id';
import * as log from 'loglevel';
import { build, parseParticle, Particle, stringifyParticle } from './particle';

export const PROTOCOL_NAME = '/fluence/faas/1.0.0';

enum Status {
    Initializing = 'Initializing',
    Connected = 'Connected',
    Disconnected = 'Disconnected',
}

export class FluenceConnection {
    private readonly selfPeerId: PeerId;
    private node: LibP2p;
    private readonly address: Multiaddr;
    readonly nodePeerId: PeerId;
    private readonly selfPeerIdStr: string;
    private readonly handleCall: (call: Particle) => void;

    constructor(multiaddr: Multiaddr, hostPeerId: PeerId, selfPeerId: PeerId, handleCall: (call: Particle) => void) {
        this.selfPeerId = selfPeerId;
        this.handleCall = handleCall;
        this.selfPeerIdStr = selfPeerId.toB58String();
        this.address = multiaddr;
        this.nodePeerId = hostPeerId;
    }

    async connect() {
        let peerInfo = this.selfPeerId;
        this.node = await Peer.create({
            peerId: peerInfo,
            config: {},
            modules: {
                transport: [Websockets],
                streamMuxer: [Mplex],
                connEncryption: [SECIO],
                peerDiscovery: [],
            },
        });

        await this.startReceiving();
    }

    isConnected() {
        return this.status === Status.Connected;
    }

    // connection status. If `Disconnected`, it cannot be reconnected
    private status: Status = Status.Initializing;

    private async startReceiving() {
        if (this.status === Status.Initializing) {
            await this.node.start();

            log.debug(`dialing to the node with client's address: ` + this.node.peerId.toB58String());

            await this.node.dial(this.address);

            let _this = this;

            this.node.handle([PROTOCOL_NAME], async ({ connection, stream }) => {
                pipe(stream.source, decode(), async function (source: AsyncIterable<string>) {
                    for await (const msg of source) {
                        try {
                            let particle = parseParticle(msg);
                            log.debug('Particle is received:');
                            log.debug(JSON.stringify(particle, undefined, 2));
                            _this.handleCall(particle);
                        } catch (e) {
                            log.error('error on handling a new incoming message: ' + e);
                        }
                    }
                });
            });

            this.status = Status.Connected;
        } else {
            throw Error(`can't start receiving. Status: ${this.status}`);
        }
    }

    private checkConnectedOrThrow() {
        if (this.status !== Status.Connected) {
            throw Error(`connection is in ${this.status} state`);
        }
    }

    async disconnect() {
        await this.node.stop();
        this.status = Status.Disconnected;
    }

    async buildParticle(script: string, data: Map<string, any>, ttl?: number): Promise<Particle> {
        return build(this.selfPeerId, script, data, ttl);
    }

    async sendParticle(particle: Particle): Promise<void> {
        this.checkConnectedOrThrow();

        let particleStr = stringifyParticle(particle);
        log.debug('send particle: \n' + JSON.stringify(particle, undefined, 2));

        // create outgoing substream
        const conn = (await this.node.dialProtocol(this.address, PROTOCOL_NAME)) as {
            stream: Stream;
            protocol: string;
        };

        pipe(
            [Buffer.from(particleStr, 'utf8')],
            // at first, make a message varint
            encode(),
            conn.stream.sink,
        );
    }
}