connectionRetry.ts

import {sleep} from "./sleep";

const RETRY_COUNT: number = 1000;
const RETRY_DELAY_INCREASE: number = 500;

export class ConnectionRetry {

    private _isConnected: boolean = false;
    private _connectionAttempts: number = 0;
    private _retryDelay: number = 0;

    constructor(public connectable: IConnectable, public serviceName: string) {

    }

    public async init(): Promise<IConnectable> {
        this._isConnected = await this.connect();
        while (!this._isConnected) {
            await this.init();
        }
        return this.connectable;
    }

    public async connect(): Promise<boolean> {
        await sleep(this._retryDelay += RETRY_DELAY_INCREASE);
        if (!this.isConnected && this._connectionAttempts < RETRY_COUNT) {
            this._connectionAttempts++;
            try {
                console.log(`Service ${this.serviceName}: Making attempt ` + (this._connectionAttempts) + ` to connect...`);
                return await this.connectable.establish();
            } catch (e) {
                console.error(`Cannot establish connection with ${this.serviceName}`, e);
                return false;
            }
        } else if (this.isConnected === false && RETRY_COUNT) {
            console.error(`Failed: Could not establish connection to ${this.serviceName} after ${RETRY_COUNT} attempts.`);
            return false;
        }
    }

    public get isConnected(): boolean {
        return this._isConnected;
    }
}


export interface IConnectable {
    start(): Promise<IConnectable>;
    establish: () => Promise<boolean>;
}