@ceramicnetwork/core/lib/pubsub/pubsub-keepalive.js

Typescript implementation of the Ceramic protocol

import { Observable, interval } from 'rxjs';
import { concatMap } from 'rxjs/operators';
import { MsgType } from './pubsub-message.js';
import { version } from '../version.js';
export class PubsubKeepalive extends Observable {
    constructor(pubsub, ipfs, maxPubsubPublishInterval, maxIntervalWithoutKeepalive) {
        super((subscriber) => {
            pubsub.subscribe(subscriber);
            const pubsubKeepaliveInterval = interval(Math.min(this.maxPubsubPublishInterval / 2, this.maxIntervalWithoutKeepalive / 2))
                .pipe(concatMap(async () => {
                if (!this._ipfsVersion) {
                    this._ipfsVersion = await ipfs.version().then((_) => _.version);
                }
                return this._ipfsVersion;
            }))
                .subscribe((ipfsVersion) => {
                this.publishPubsubKeepaliveIfNeeded(ipfsVersion);
            });
            return () => {
                pubsubKeepaliveInterval.unsubscribe();
            };
        });
        this.pubsub = pubsub;
        this.ipfs = ipfs;
        this.maxPubsubPublishInterval = maxPubsubPublishInterval;
        this.maxIntervalWithoutKeepalive = maxIntervalWithoutKeepalive;
        this.lastPublishedMessageDate = Date.now() - this.maxPubsubPublishInterval;
        this.lastPublishedKeepAliveMessageDate = 0;
        this._ipfsVersion = undefined;
    }
    next(message) {
        const now = Date.now();
        this.lastPublishedMessageDate = now;
        if (message.typ === MsgType.KEEPALIVE)
            this.lastPublishedKeepAliveMessageDate = now;
        return this.pubsub.next(message);
    }
    publishPubsubKeepaliveIfNeeded(ipfsVersion) {
        const now = Date.now();
        const needToPublishKeepaliveOnceADay = now - this.lastPublishedKeepAliveMessageDate > this.maxIntervalWithoutKeepalive;
        const needToPublishKeepaliveInactivity = now - this.lastPublishedMessageDate >= this.maxPubsubPublishInterval / 2;
        if (!needToPublishKeepaliveInactivity && !needToPublishKeepaliveOnceADay) {
            return;
        }
        const message = {
            typ: MsgType.KEEPALIVE,
            ts: now,
            ver: version,
            ipfsVer: ipfsVersion,
        };
        this.next(message);
    }
}
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