earlect/dist/viking.js

Leader Election Generic Implementation for TypeScript

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const crypto_1 = __importDefault(require("crypto"));
const events_1 = require("events");
const pino_1 = __importDefault(require("pino"));
const logger = pino_1.default();
var VikingState;
(function (VikingState) {
    VikingState["WANDERER"] = "Wanderer";
    VikingState["FOLLOWER"] = "Follower";
    VikingState["CHALLENGER"] = "Challenger";
    VikingState["LEADER"] = "Leader";
})(VikingState = exports.VikingState || (exports.VikingState = {}));
var VikingEvent;
(function (VikingEvent) {
    VikingEvent["LEADER_SHOUT"] = "Leader Shout";
    VikingEvent["CHALLENGE"] = "Challenge";
    VikingEvent["CHALLENGE_RUMOUR"] = "Challenge Rumour";
})(VikingEvent = exports.VikingEvent || (exports.VikingEvent = {}));
class Viking {
    constructor(hall) {
        this.hall = hall;
        this.name = crypto_1.default.randomBytes(13).toString("hex");
        this.leaderName = Viking.NO_LEADER_NAME;
        this.state = VikingState.WANDERER;
        this.comm = new events_1.EventEmitter();
        this.challengerHP = 0;
        this.leaderWatchers = [];
    }
    static async createInHall(hall) {
        const viking = new Viking(hall);
        hall.registerViking(viking);
        viking.setLeaderShoutTimeout();
        viking.comm.on(VikingEvent.LEADER_SHOUT, (leaderShout) => {
            viking.resetLeaderShoutTimeout();
            if (viking.state === VikingState.WANDERER ||
                viking.state === VikingState.CHALLENGER) {
                viking.setLeaderName(leaderShout.leaderName);
                viking.changeStateTo(VikingState.FOLLOWER);
            }
            else if (viking.state === VikingState.FOLLOWER) {
                viking.setLeaderName(leaderShout.leaderName);
            }
            else if (viking.state === VikingState.LEADER && leaderShout.leaderName !== viking.name) {
                logger.debug(`We have another leader '${leaderShout.leaderName}'. Going rogue...`);
                viking.setLeaderName(Viking.NO_LEADER_NAME);
                viking.changeStateTo(VikingState.CHALLENGER);
            }
        });
        viking.comm.on(VikingEvent.CHALLENGE, (challenge) => {
            if (viking.state === VikingState.CHALLENGER) {
                viking.resetChallengeTimeout();
                logger.debug(`I still have ${viking.challengerHP} ...`);
                viking.challengerHP -= challenge.power;
                if (viking.challengerHP <= 0) {
                    logger.debug("... and I lose all my force");
                    viking.changeStateTo(VikingState.FOLLOWER);
                }
                else {
                    logger.debug("... and I still fight");
                }
            }
        });
        viking.comm.on(VikingEvent.CHALLENGE_RUMOUR, (challenge) => {
            if (viking.state === VikingState.CHALLENGER && viking.name !== challenge.challengerName) {
                logger.debug("Hearing noise of battle...");
                viking.resetChallengeTimeout();
            }
        });
        setInterval(() => {
            if (viking.state === VikingState.LEADER) {
                const leaderShout = { leaderName: viking.name };
                hall.sendLeaderShout(leaderShout);
            }
        }, Viking.LEADER_SHOUT_INTERVAL_MS);
        setInterval(() => {
            if (viking.state === VikingState.CHALLENGER) {
                const challenge = {
                    challengerName: viking.name,
                    power: Viking.generateChallengePower(),
                };
                hall.sendChallenge(challenge);
            }
        }, Viking.CHALLENGE_SEND_INTERVAL_MS);
        return viking;
    }
    static generateChallengePower() {
        return Viking.MIN_CHALLENGE_HP
            + Math.floor((Viking.MAX_CHALLENGE_HP - Viking.MIN_CHALLENGE_HP) * Math.random());
    }
    receiveLeaderShout(leaderShout) {
        const viking = this;
        viking.comm.emit(VikingEvent.LEADER_SHOUT, leaderShout);
    }
    receiveChallenge(challenge) {
        const viking = this;
        if (challenge.challengerName !== viking.name) {
            viking.comm.emit(VikingEvent.CHALLENGE, challenge);
        }
    }
    receiveChallengeRumour(challenge) {
        const viking = this;
        viking.comm.emit(VikingEvent.CHALLENGE_RUMOUR, challenge);
    }
    addLeaderWatcher(leaderWatcher) {
        const viking = this;
        viking.leaderWatchers.push(leaderWatcher);
        if (viking.state === VikingState.LEADER) {
            leaderWatcher.becomeLeader();
        }
        else {
            leaderWatcher.dropLeader();
        }
    }
    setLeaderName(leaderName) {
        const viking = this;
        viking.leaderName = leaderName;
    }
    changeStateTo(newState) {
        const viking = this;
        logger.debug(`${viking.state} => ${newState}`);
        // Before state change actions
        if (viking.state === VikingState.CHALLENGER) {
            viking.cancelChallengeTimeout();
        }
        else if (viking.state === VikingState.LEADER) {
            for (const leaderWatcher of viking.leaderWatchers) {
                leaderWatcher.dropLeader();
            }
        }
        // State change
        viking.state = newState;
        // After state change actions
        if (viking.state === VikingState.CHALLENGER) {
            viking.challengerHP = Viking.INITIAL_HP;
            viking.setChallengeTimeout();
        }
        else if (viking.state === VikingState.LEADER) {
            for (const leaderWatcher of viking.leaderWatchers) {
                leaderWatcher.becomeLeader();
            }
        }
    }
    setLeaderShoutTimeout() {
        const viking = this;
        viking.leaderShoutTimeout = setTimeout(() => {
            if (viking.state === VikingState.WANDERER
                || viking.state === VikingState.FOLLOWER) {
                logger.debug(viking.state + ": No leader viking around => becoming a Challenger");
                viking.changeStateTo(VikingState.CHALLENGER);
            }
            else if (viking.state === VikingState.LEADER) {
                logger.debug(viking.state + ": Can't hear any leader shout... Not even my own... Have I been raptured??? => becoming a Wanderer");
                viking.changeStateTo(VikingState.WANDERER);
            }
        }, Viking.LEADER_SHOUT_TIMEOUT_MS);
    }
    cancelLeaderShoutTimeout() {
        const viking = this;
        if (viking.leaderShoutTimeout) {
            clearTimeout(viking.leaderShoutTimeout);
        }
    }
    resetLeaderShoutTimeout() {
        const viking = this;
        viking.cancelLeaderShoutTimeout();
        viking.setLeaderShoutTimeout();
    }
    setChallengeTimeout() {
        const viking = this;
        viking.challengeTimeout = setTimeout(() => {
            logger.debug(viking.state + ": No other viking challenged me => becoming a Leader");
            viking.changeStateTo(VikingState.LEADER);
        }, Viking.CHALLENGE_TIMEOUT_MS);
    }
    cancelChallengeTimeout() {
        const viking = this;
        if (viking.challengeTimeout) {
            clearTimeout(viking.challengeTimeout);
        }
    }
    resetChallengeTimeout() {
        const viking = this;
        viking.cancelChallengeTimeout();
        viking.setChallengeTimeout();
    }
}
exports.Viking = Viking;
Viking.INITIAL_HP = 100;
Viking.MIN_CHALLENGE_HP = 30;
Viking.MAX_CHALLENGE_HP = 50;
Viking.LEADER_SHOUT_INTERVAL_MS = 100;
Viking.LEADER_SHOUT_TIMEOUT_MS = 2000;
Viking.CHALLENGE_SEND_INTERVAL_MS = 100;
Viking.CHALLENGE_TIMEOUT_MS = 1000;
Viking.NO_LEADER_NAME = "";