Difficulty adjustment refactor

fixes #1157

backend/src/api/difficulty-adjustment.ts

@@ -0,0 +1,71 @@
+import config from '../config';
+import { IDifficultyAdjustment } from '../mempool.interfaces';
+import blocks from './blocks';
+
+class DifficultyAdjustmentApi {
+  constructor() { }
+
+  public getDifficultyAdjustment(): IDifficultyAdjustment {
+    const DATime = blocks.getLastDifficultyAdjustmentTime();
+    const previousRetarget = blocks.getPreviousDifficultyRetarget();
+    const blockHeight = blocks.getCurrentBlockHeight();
+    const blocksCache = blocks.getBlocks();
+    const latestBlock = blocksCache[blocksCache.length - 1];
+
+    const now = new Date().getTime() / 1000;
+    const diff = now - DATime;
+    const blocksInEpoch = blockHeight % 2016;
+    const progressPercent = (blocksInEpoch >= 0) ? blocksInEpoch / 2016 * 100 : 100;
+    const remainingBlocks = 2016 - blocksInEpoch;
+    const nextRetargetHeight = blockHeight + remainingBlocks;
+
+    let difficultyChange = 0;
+    if (remainingBlocks < 1870) {
+      if (blocksInEpoch > 0) {
+        difficultyChange = (600 / (diff / blocksInEpoch ) - 1) * 100;
+      }
+      if (difficultyChange > 300) {
+        difficultyChange = 300;
+      }
+      if (difficultyChange < -75) {
+        difficultyChange = -75;
+      }
+    }
+
+    const timeAvgDiff = difficultyChange * 0.1;
+
+    let timeAvgMins = 10;
+
+    if (timeAvgDiff > 0) {
+      timeAvgMins -= Math.abs(timeAvgDiff);
+    } else {
+      timeAvgMins += Math.abs(timeAvgDiff);
+    }
+
+    // Testnet difficulty is set to 1 after 20 minutes of no blockSize,
+    // therefore the time between blocks will always be below 20 minutes (1200s).
+    let timeOffset = 0;
+    if (config.MEMPOOL.NETWORK === 'testnet' && now - latestBlock.timestamp + timeAvgMins * 60 > 1200) {
+      timeOffset = -Math.min(now - latestBlock.timestamp, 1200) * 1000;
+      timeAvgMins = 20;
+    }
+
+    const timeAvg = timeAvgMins * 60 * 1000 ;
+    const remainingTime = (remainingBlocks * timeAvg) + (now * 1000);
+    const estimatedRetargetDate = remainingTime + now;
+
+    return {
+      progressPercent,
+      difficultyChange,
+      estimatedRetargetDate,
+      remainingBlocks,
+      remainingTime,
+      previousRetarget,
+      nextRetargetHeight,
+      timeAvg,
+      timeOffset,
+    };
+  }
+}
+
+export default new DifficultyAdjustmentApi();

backend/src/api/websocket-handler.ts

@@ -12,6 +12,7 @@ import loadingIndicators from './loading-indicators';
 import config from '../config';
 import transactionUtils from './transaction-utils';
 import rbfCache from './rbf-cache';
+import difficultyAdjustment from './difficulty-adjustment';
 
 class WebsocketHandler {
   private wss: WebSocket.Server | undefined;
@@ -191,14 +192,13 @@ class WebsocketHandler {
     return {
       'mempoolInfo': memPool.getMempoolInfo(),
       'vBytesPerSecond': memPool.getVBytesPerSecond(),
-      'lastDifficultyAdjustment': blocks.getLastDifficultyAdjustmentTime(),
-      'previousRetarget': blocks.getPreviousDifficultyRetarget(),
       'blocks': _blocks,
       'conversions': fiatConversion.getConversionRates(),
       'mempool-blocks': mempoolBlocks.getMempoolBlocks(),
       'transactions': memPool.getLatestTransactions(),
       'backendInfo': backendInfo.getBackendInfo(),
       'loadingIndicators': loadingIndicators.getLoadingIndicators(),
+      'da': difficultyAdjustment.getDifficultyAdjustment(),
       ...this.extraInitProperties
     };
   }
@@ -234,6 +234,7 @@ class WebsocketHandler {
     const mempoolInfo = memPool.getMempoolInfo();
     const vBytesPerSecond = memPool.getVBytesPerSecond();
     const rbfTransactions = Common.findRbfTransactions(newTransactions, deletedTransactions);
+    const da = difficultyAdjustment.getDifficultyAdjustment();
     memPool.handleRbfTransactions(rbfTransactions);
 
     this.wss.clients.forEach(async (client: WebSocket) => {
@@ -247,6 +248,7 @@ class WebsocketHandler {
         response['mempoolInfo'] = mempoolInfo;
         response['vBytesPerSecond'] = vBytesPerSecond;
         response['transactions'] = newTransactions.slice(0, 6).map((tx) => Common.stripTransaction(tx));
+        response['da'] = da;
       }
 
       if (client['want-mempool-blocks']) {
@@ -410,8 +412,7 @@ class WebsocketHandler {
       const response = {
         'block': block,
         'mempoolInfo': memPool.getMempoolInfo(),
-        'lastDifficultyAdjustment': blocks.getLastDifficultyAdjustmentTime(),
-        'previousRetarget': blocks.getPreviousDifficultyRetarget(),
+        'da': difficultyAdjustment.getDifficultyAdjustment(),
       };
 
       if (mBlocks && client['want-mempool-blocks']) {

backend/src/mempool.interfaces.ts

@@ -197,3 +197,15 @@ export interface IBackendInfo {
   gitCommit: string;
   version: string;
 }
+
+export interface IDifficultyAdjustment {
+  progressPercent: number;
+  difficultyChange: number;
+  estimatedRetargetDate: number;
+  remainingBlocks: number;
+  remainingTime: number;
+  previousRetarget: number;
+  nextRetargetHeight: number;
+  timeAvg: number;
+  timeOffset: number;
+}

backend/src/routes.ts

@@ -25,6 +25,7 @@ import axios from 'axios';
 import mining from './api/mining';
 import BlocksRepository from './repositories/BlocksRepository';
 import HashratesRepository from './repositories/HashratesRepository';
+import difficultyAdjustment from './api/difficulty-adjustment';
 
 class Routes {
   constructor() {}
@@ -847,55 +848,7 @@ class Routes {
 
   public getDifficultyChange(req: Request, res: Response) {
     try {
-      const DATime = blocks.getLastDifficultyAdjustmentTime();
-      const previousRetarget = blocks.getPreviousDifficultyRetarget();
-      const blockHeight = blocks.getCurrentBlockHeight();
-
-      const now = new Date().getTime() / 1000;
-      const diff = now - DATime;
-      const blocksInEpoch = blockHeight % 2016;
-      const progressPercent = (blocksInEpoch >= 0) ? blocksInEpoch / 2016 * 100 : 100;
-      const remainingBlocks = 2016 - blocksInEpoch;
-      const nextRetargetHeight = blockHeight + remainingBlocks;
-
-      let difficultyChange = 0;
-      if (remainingBlocks < 1870) {
-        if (blocksInEpoch > 0) {
-          difficultyChange = (600 / (diff / blocksInEpoch ) - 1) * 100;
-        }
-        if (difficultyChange > 300) {
-          difficultyChange = 300;
-        }
-        if (difficultyChange < -75) {
-          difficultyChange = -75;
-        }
-      }
-
-      const timeAvgDiff = difficultyChange * 0.1;
-
-      let timeAvgMins = 10;
-      if (timeAvgDiff > 0) {
-        timeAvgMins -= Math.abs(timeAvgDiff);
-      } else {
-        timeAvgMins += Math.abs(timeAvgDiff);
-      }
-
-      const timeAvg = timeAvgMins * 60;
-      const remainingTime =  remainingBlocks * timeAvg;
-      const estimatedRetargetDate = remainingTime + now;
-
-      const result = {
-        progressPercent,
-        difficultyChange,
-        estimatedRetargetDate,
-        remainingBlocks,
-        remainingTime,
-        previousRetarget,
-        nextRetargetHeight,
-        timeAvg,
-      };
-      res.json(result);
-
+      res.json(difficultyAdjustment.getDifficultyAdjustment());
     } catch (e) {
       res.status(500).send(e instanceof Error ? e.message : e);
     }