public-pool/src/models/StratumV1ClientStatistics.ts

import { ClientEntity } from '../ORM/client/client.entity';

const CACHE_SIZE = 30;
const MIN_DIFF = 0.001;
export class StratumV1ClientStatistics {

    public targetSubmitShareEveryNSeconds: number = 30;
    public hashRate = 0;

    private submissionCacheStart: Date;
    private submissionCache: { time: Date, difficulty: number }[] = [];
    private submissionCacheDifficultySum = 0;

    constructor() {
        this.submissionCacheStart = new Date();
    }

    public async addShares(_client: ClientEntity, targetDifficulty: number) {
        var date = new Date();

        if (this.submissionCache.length > CACHE_SIZE) {
            this.submissionCacheDifficultySum -= this.submissionCache[0].difficulty;
            this.submissionCache.shift();
        }
        this.submissionCache.push({
            time: date,
            difficulty: targetDifficulty,
        });
        this.submissionCacheDifficultySum += targetDifficulty;

        const time = new Date().getTime() - this.submissionCache[0].time.getTime();
        if(time > 60000 && this.submissionCache.length > 2) { 
            this.hashRate = (this.submissionCacheDifficultySum * 4294967296) / (time / 1000);
        }
    }


    public getSuggestedDifficulty(clientDifficulty: number) {

        // miner hasn't submitted shares in one minute
        if (this.submissionCache.length < 5) {
            if ((new Date().getTime() - this.submissionCacheStart.getTime()) / 5000 > 60) {
                return this.nearestPowerOfTwo(clientDifficulty / 6);
            } else {
                return null;
            }
        }

        const sum = this.submissionCache.reduce((pre, cur) => {
            pre += cur.difficulty;
            return pre;
        }, 0);
        const diffSeconds = (this.submissionCache[this.submissionCache.length - 1].time.getTime() - this.submissionCache[0].time.getTime()) / 1000;

        const difficultyPerSecond = sum / diffSeconds;

        const targetDifficulty = difficultyPerSecond * this.targetSubmitShareEveryNSeconds;

        if ((clientDifficulty * 2) < targetDifficulty || (clientDifficulty / 2) > targetDifficulty) {
            return this.nearestPowerOfTwo(targetDifficulty)
        }

        return null;
    }

    private nearestPowerOfTwo(val): number {
        if (val === 0) {
            return null;
        }
        if (val < MIN_DIFF) {
            return MIN_DIFF;
        }
        let x = val | (val >> 1);
        x = x | (x >> 2);
        x = x | (x >> 4);
        x = x | (x >> 8);
        x = x | (x >> 16);
        x = x | (x >> 32);
        const res = x - (x >> 1);
        if (res == 0 && val * 100 < MIN_DIFF) {
            return MIN_DIFF;
        }
        if (res == 0) {
            return this.nearestPowerOfTwo(val * 100) / 100;
        }
        return res;
    }

}