Simplify websocket mempool delta handling

frontend/src/app/components/mempool-block-overview/mempool-block-overview.component.ts

@@ -1,11 +1,10 @@
-import { Component, ComponentRef, ViewChild, HostListener, Input, Output, EventEmitter,
+import { Component, ViewChild, Input, Output, EventEmitter,
   OnInit, OnDestroy, OnChanges, ChangeDetectionStrategy, ChangeDetectorRef, AfterViewInit } from '@angular/core';
 import { StateService } from '../../services/state.service';
-import { MempoolBlockDelta } from '../../interfaces/websocket.interface';
+import { MempoolBlockDelta, isMempoolDelta } from '../../interfaces/websocket.interface';
 import { TransactionStripped } from '../../interfaces/node-api.interface';
 import { BlockOverviewGraphComponent } from '../../components/block-overview-graph/block-overview-graph.component';
-import { Subscription, BehaviorSubject, merge, of, timer } from 'rxjs';
+import { Subscription, BehaviorSubject } from 'rxjs';
-import { switchMap, filter, concatMap, map } from 'rxjs/operators';
 import { WebsocketService } from '../../services/websocket.service';
 import { RelativeUrlPipe } from '../../shared/pipes/relative-url/relative-url.pipe';
 import { Router } from '@angular/router';
@@ -39,10 +38,6 @@ export class MempoolBlockOverviewComponent implements OnInit, OnDestroy, OnChang
   poolDirection: string = 'left';
 
   blockSub: Subscription;
-  rateLimit = 1000;
-  private lastEventTime = Date.now() - this.rateLimit;
-  private subId = 0;
-
   firstLoad: boolean = true;
 
   constructor(
@@ -62,39 +57,13 @@ export class MempoolBlockOverviewComponent implements OnInit, OnDestroy, OnChang
   }
 
   ngAfterViewInit(): void {
-    this.blockSub = merge(
+    this.blockSub = this.stateService.mempoolBlockUpdate$.subscribe((update) => {
-      this.stateService.mempoolBlockTransactions$,
-      this.stateService.mempoolBlockDelta$,
-    ).pipe(
-      concatMap(update => {
-        const now = Date.now();
-        const timeSinceLastEvent = now - this.lastEventTime;
-        this.lastEventTime = Math.max(now, this.lastEventTime + this.rateLimit);
-
-        const subId = this.subId;
-
-        // If time since last event is less than X seconds, delay this event
-        if (timeSinceLastEvent < this.rateLimit) {
-          return timer(this.rateLimit - timeSinceLastEvent).pipe(
-            // Emit the event after the timer
-            map(() => ({ update, subId }))
-          );
-        } else {
-          // If enough time has passed, emit the event immediately
-          return of({ update, subId });
-        }
-      })
-    ).subscribe(({ update, subId }) => {
-      // discard stale updates after a block transition
-      if (subId !== this.subId) {
-        return;
-      }
       // process update
-      if (update['added']) {
+      if (isMempoolDelta(update)) {
         // delta
-        this.updateBlock(update as MempoolBlockDelta);
+        this.updateBlock(update);
       } else {
-        const transactionsStripped = update as TransactionStripped[];
+        const transactionsStripped = update.transactions;
         // new transactions
         if (this.firstLoad) {
           this.replaceBlock(transactionsStripped);
@@ -137,7 +106,6 @@ export class MempoolBlockOverviewComponent implements OnInit, OnDestroy, OnChang
 
   ngOnChanges(changes): void {
     if (changes.index) {
-      this.subId++;
       this.firstLoad = true;
       if (this.blockGraph) {
         this.blockGraph.clear(changes.index.currentValue > changes.index.previousValue ? this.chainDirection : this.poolDirection);

frontend/src/app/interfaces/websocket.interface.ts

@@ -75,6 +75,16 @@ export interface MempoolBlockDelta {
   removed: string[];
   changed: { txid: string, rate: number, flags: number, acc: boolean }[];
 }
+export interface MempoolBlockState {
+  transactions: TransactionStripped[];
+}
+export type MempoolBlockUpdate = MempoolBlockDelta | MempoolBlockState;
+export function isMempoolState(update: MempoolBlockUpdate): update is MempoolBlockState {
+  return update['transactions'] !== undefined;
+}
+export function isMempoolDelta(update: MempoolBlockUpdate): update is MempoolBlockDelta {
+  return update['transactions'] === undefined;
+}
 
 export interface MempoolBlockDeltaCompressed {
   added: TransactionCompressed[];

frontend/src/app/services/state.service.ts

@@ -1,7 +1,7 @@
 import { Inject, Injectable, PLATFORM_ID, LOCALE_ID } from '@angular/core';
 import { ReplaySubject, BehaviorSubject, Subject, fromEvent, Observable, merge } from 'rxjs';
 import { Transaction } from '../interfaces/electrs.interface';
-import { HealthCheckHost, IBackendInfo, MempoolBlock, MempoolBlockDelta, MempoolInfo, Recommendedfees, ReplacedTransaction, ReplacementInfo } from '../interfaces/websocket.interface';
+import { HealthCheckHost, IBackendInfo, MempoolBlock, MempoolBlockDelta, MempoolBlockUpdate, MempoolInfo, Recommendedfees, ReplacedTransaction, ReplacementInfo, isMempoolState } from '../interfaces/websocket.interface';
 import { BlockExtended, CpfpInfo, DifficultyAdjustment, MempoolPosition, OptimizedMempoolStats, RbfTree, TransactionStripped } from '../interfaces/node-api.interface';
 import { Router, NavigationStart } from '@angular/router';
 import { isPlatformBrowser } from '@angular/common';
@@ -127,8 +127,7 @@ export class StateService {
   bsqPrice$ = new ReplaySubject<number>(1);
   mempoolInfo$ = new ReplaySubject<MempoolInfo>(1);
   mempoolBlocks$ = new ReplaySubject<MempoolBlock[]>(1);
-  mempoolBlockTransactions$ = new Subject<TransactionStripped[]>();
+  mempoolBlockUpdate$ = new Subject<MempoolBlockUpdate>();
-  mempoolBlockDelta$ = new Subject<MempoolBlockDelta>();
   liveMempoolBlockTransactions$: Observable<{ [txid: string]: TransactionStripped}>;
   txConfirmed$ = new Subject<[string, BlockExtended]>();
   txReplaced$ = new Subject<ReplacedTransaction>();
@@ -215,25 +214,25 @@ export class StateService {
       this.router.navigate(['/tracker/' + window.location.pathname.slice(4)]);
     }
 
-    this.liveMempoolBlockTransactions$ = merge(
+    this.liveMempoolBlockTransactions$ = this.mempoolBlockUpdate$.pipe(scan((transactions: { [txid: string]: TransactionStripped }, change: MempoolBlockUpdate): { [txid: string]: TransactionStripped } => {
-      this.mempoolBlockTransactions$.pipe(map(transactions => { return { transactions }; })),
+      if (isMempoolState(change)) {
-      this.mempoolBlockDelta$.pipe(map(delta => { return { delta }; })),
+        const txMap = {};
-    ).pipe(scan((transactions: { [txid: string]: TransactionStripped }, change: any): { [txid: string]: TransactionStripped } => {
-      if (change.transactions) {
-        const txMap = {}
         change.transactions.forEach(tx => {
           txMap[tx.txid] = tx;
-        })
+        });
         return txMap;
       } else {
-        change.delta.changed.forEach(tx => {
+        change.added.forEach(tx => {
-          transactions[tx.txid].rate = tx.rate;
+          transactions[tx.txid] = tx;
-        })
+        });
-        change.delta.removed.forEach(txid => {
+        change.removed.forEach(txid => {
           delete transactions[txid];
         });
-        change.delta.added.forEach(tx => {
+        change.changed.forEach(tx => {
-          transactions[tx.txid] = tx;
+          if (transactions[tx.txid]) {
+            transactions[tx.txid].rate = tx.rate;
+            transactions[tx.txid].acc = tx.acc;
+          }
         });
         return transactions;
       }

frontend/src/app/services/websocket.service.ts

@@ -401,14 +401,16 @@ export class WebsocketService {
       if (response['projected-block-transactions'].index == this.trackingMempoolBlock) {
         if (response['projected-block-transactions'].blockTransactions) {
           this.stateService.mempoolSequence = response['projected-block-transactions'].sequence;
-          this.stateService.mempoolBlockTransactions$.next(response['projected-block-transactions'].blockTransactions.map(uncompressTx));
+          this.stateService.mempoolBlockUpdate$.next({
+            transactions: response['projected-block-transactions'].blockTransactions.map(uncompressTx),
+          });
         } else if (response['projected-block-transactions'].delta) {
           if (this.stateService.mempoolSequence && response['projected-block-transactions'].sequence !== this.stateService.mempoolSequence + 1) {
             this.stateService.mempoolSequence = 0;
             this.startTrackMempoolBlock(this.trackingMempoolBlock, true);
           } else {
             this.stateService.mempoolSequence = response['projected-block-transactions'].sequence;
-            this.stateService.mempoolBlockDelta$.next(uncompressDeltaChange(response['projected-block-transactions'].delta));
+            this.stateService.mempoolBlockUpdate$.next(uncompressDeltaChange(response['projected-block-transactions'].delta));
           }
         }
       }