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Refactor Difficulty Adjustment calc + unit test it
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junderw
parent
bb1adf41e7
commit
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2 changed files with 137 additions and 52 deletions
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@ -137,4 +137,62 @@ describe('Mempool Backend Config', () => {
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});
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});
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test('should calculate Difficulty Adjustments properly', () => {
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jest.isolateModules(() => {
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const { calcDifficultyAdjustment } = jest.requireActual('../api/difficulty-adjustment');
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const dt = dtString => Math.floor(new Date(dtString).getTime() / 1000);
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const vectors = [
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[ // Vector 1
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[ // Inputs
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dt('2022-08-18T11:07:00.000Z'), // Last DA time (in seconds)
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dt('2022-08-19T14:03:53.000Z'), // Current time (now) (in seconds)
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750134, // Current block height
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0.6280047707459726, // Previous retarget % (Passed through)
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'mainnet', // Network (if testnet, next value is non-zero)
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0, // If not testnet, not used
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],
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{ // Expected Result
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progressPercent: 9.027777777777777,
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difficultyChange: 12.562233927411782,
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estimatedRetargetDate: 1661895424692,
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remainingBlocks: 1834,
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remainingTime: 977591692,
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previousRetarget: 0.6280047707459726,
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nextRetargetHeight: 751968,
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timeAvg: 533038,
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timeOffset: 0,
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},
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],
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[ // Vector 2 (testnet)
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[ // Inputs
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dt('2022-08-18T11:07:00.000Z'), // Last DA time (in seconds)
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dt('2022-08-19T14:03:53.000Z'), // Current time (now) (in seconds)
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750134, // Current block height
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0.6280047707459726, // Previous retarget % (Passed through)
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'testnet', // Network
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dt('2022-08-19T13:52:46.000Z'), // Latest block timestamp in seconds
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],
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{ // Expected Result is same other than timeOffset
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progressPercent: 9.027777777777777,
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difficultyChange: 12.562233927411782,
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estimatedRetargetDate: 1661895424692,
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remainingBlocks: 1834,
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remainingTime: 977591692,
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previousRetarget: 0.6280047707459726,
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nextRetargetHeight: 751968,
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timeAvg: 533038,
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timeOffset: -667000, // 11 min 7 seconds since last block (testnet only)
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// If we add time avg to abs(timeOffset) it makes exactly 1200000 ms, or 20 minutes
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},
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],
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] as [[number, number, number, number, string, number], any][];
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for (const vector of vectors) {
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const result = calcDifficultyAdjustment(...vector[0]);
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// previousRetarget is passed through untouched
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expect(result.previousRetarget).toStrictEqual(vector[0][3]);
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expect(result).toStrictEqual(vector[1]);
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}
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});
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});
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});
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@ -2,69 +2,96 @@ import config from '../config';
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import { IDifficultyAdjustment } from '../mempool.interfaces';
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import blocks from './blocks';
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export interface DifficultyAdjustment {
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progressPercent: number; // Percent: 0 to 100
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difficultyChange: number; // Percent: -75 to 300
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estimatedRetargetDate: number; // Unix time in ms
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remainingBlocks: number; // Block count
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remainingTime: number; // Duration of time in ms
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previousRetarget: number; // Percent: -75 to 300
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nextRetargetHeight: number; // Block Height
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timeAvg: number; // Duration of time in ms
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timeOffset: number; // (Testnet) Time since last block (cap @ 20min) in ms
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}
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export function calcDifficultyAdjustment(
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DATime: number,
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nowSeconds: number,
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blockHeight: number,
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previousRetarget: number,
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network: string,
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latestBlockTimestamp: number,
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): DifficultyAdjustment {
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const ESTIMATE_LAG_BLOCKS = 146; // For first 7.2% of epoch, don't estimate.
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const EPOCH_BLOCK_LENGTH = 2016;
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const diffSeconds = nowSeconds - DATime;
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const blocksInEpoch = (blockHeight >= 0) ? blockHeight % EPOCH_BLOCK_LENGTH : 0;
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const progressPercent = (blockHeight >= 0) ? blocksInEpoch / EPOCH_BLOCK_LENGTH * 100 : 100;
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const remainingBlocks = EPOCH_BLOCK_LENGTH - blocksInEpoch;
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const nextRetargetHeight = (blockHeight >= 0) ? blockHeight + remainingBlocks : 0;
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let difficultyChange = 0;
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// Only calculate the estimate once we have 7.2% of blocks in current epoch
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if (blocksInEpoch >= ESTIMATE_LAG_BLOCKS) {
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difficultyChange = (600 / (diffSeconds / blocksInEpoch) - 1) * 100;
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// Max increase is x4 (+300%)
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if (difficultyChange > 300) {
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difficultyChange = 300;
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}
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// Max decrease is /4 (-75%)
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if (difficultyChange < -75) {
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difficultyChange = -75;
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}
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}
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let timeAvgMins = blocksInEpoch >= ESTIMATE_LAG_BLOCKS ? diffSeconds / blocksInEpoch / 60 : 10;
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// Testnet difficulty is set to 1 after 20 minutes of no blocks,
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// therefore the time between blocks will always be below 20 minutes (1200s).
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let timeOffset = 0;
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if (network === 'testnet') {
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if (timeAvgMins > 20) {
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timeAvgMins = 20;
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}
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if (nowSeconds - latestBlockTimestamp + timeAvgMins * 60 > 1200) {
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timeOffset = -Math.min(nowSeconds - latestBlockTimestamp, 1200) * 1000;
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}
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}
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const timeAvg = Math.floor(timeAvgMins * 60 * 1000);
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const remainingTime = remainingBlocks * timeAvg;
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const estimatedRetargetDate = remainingTime + nowSeconds * 1000;
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return {
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progressPercent,
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difficultyChange,
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estimatedRetargetDate,
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remainingBlocks,
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remainingTime,
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previousRetarget,
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nextRetargetHeight,
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timeAvg,
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timeOffset,
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};
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}
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class DifficultyAdjustmentApi {
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constructor() { }
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public getDifficultyAdjustment(): IDifficultyAdjustment {
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const ESTIMATE_LAG_BLOCKS = 146; // For first 7.2% of epoch, don't estimate.
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const EPOCH_BLOCK_LENGTH = 2016;
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const DATime = blocks.getLastDifficultyAdjustmentTime();
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const previousRetarget = blocks.getPreviousDifficultyRetarget();
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const blockHeight = blocks.getCurrentBlockHeight();
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const blocksCache = blocks.getBlocks();
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const latestBlock = blocksCache[blocksCache.length - 1];
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const nowSeconds = Math.floor(new Date().getTime() / 1000);
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const diffSeconds = nowSeconds - DATime;
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const blocksInEpoch = (blockHeight >= 0) ? blockHeight % EPOCH_BLOCK_LENGTH : 0;
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const progressPercent = (blockHeight >= 0) ? blocksInEpoch / EPOCH_BLOCK_LENGTH * 100 : 100;
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const remainingBlocks = EPOCH_BLOCK_LENGTH - blocksInEpoch;
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const nextRetargetHeight = (blockHeight >= 0) ? blockHeight + remainingBlocks : 0;
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let difficultyChange = 0;
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// Only calculate the estimate once we have 7.2% of blocks in current epoch
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if (blocksInEpoch >= ESTIMATE_LAG_BLOCKS) {
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difficultyChange = (600 / (diffSeconds / blocksInEpoch) - 1) * 100;
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// Max increase is x4 (+300%)
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if (difficultyChange > 300) {
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difficultyChange = 300;
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}
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// Max decrease is /4 (-75%)
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if (difficultyChange < -75) {
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difficultyChange = -75;
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}
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}
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let timeAvgMins = blocksInEpoch >= ESTIMATE_LAG_BLOCKS ? diffSeconds / blocksInEpoch / 60 : 10;
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// Testnet difficulty is set to 1 after 20 minutes of no blocks,
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// therefore the time between blocks will always be below 20 minutes (1200s).
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let timeOffset = 0;
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if (config.MEMPOOL.NETWORK === 'testnet') {
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if (timeAvgMins > 20) {
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timeAvgMins = 20;
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}
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if (nowSeconds - latestBlock.timestamp + timeAvgMins * 60 > 1200) {
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timeOffset = -Math.min(nowSeconds - latestBlock.timestamp, 1200) * 1000;
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}
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}
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const timeAvg = Math.floor(timeAvgMins * 60 * 1000);
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const remainingTime = remainingBlocks * timeAvg;
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const estimatedRetargetDate = remainingTime + nowSeconds * 1000;
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return {
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progressPercent,
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difficultyChange,
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estimatedRetargetDate,
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remainingBlocks,
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remainingTime,
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previousRetarget,
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nextRetargetHeight,
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timeAvg,
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timeOffset,
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};
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return calcDifficultyAdjustment(
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DATime, nowSeconds, blockHeight, previousRetarget,
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config.MEMPOOL.NETWORK, latestBlock.timestamp
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);
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}
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}
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