Replace by fee storage

fixes #1222

backend/src/api/mempool.ts

@@ -8,6 +8,7 @@ import { IBitcoinApi } from './bitcoin/bitcoin-api.interface';
 import loadingIndicators from './loading-indicators';
 import bitcoinClient from './bitcoin/bitcoin-client';
 import bitcoinSecondClient from './bitcoin/bitcoin-second-client';
+import rbfCache from './rbf-cache';
 
 class Mempool {
   private static WEBSOCKET_REFRESH_RATE_MS = 10000;
@@ -200,6 +201,17 @@ class Mempool {
     logger.debug('Mempool updated in ' + time / 1000 + ' seconds');
   }
 
+  public handleRbfTransactions(rbfTransactions: { [txid: string]: TransactionExtended; }) {
+    for (const rbfTransaction in rbfTransactions) {
+      if (this.mempoolCache[rbfTransaction]) {
+        // Store replaced transactions
+        rbfCache.add(rbfTransaction, rbfTransactions[rbfTransaction].txid);
+        // Erase the replaced transactions from the local mempool
+        delete this.mempoolCache[rbfTransaction];
+      }
+    }
+  }
+
   private updateTxPerSecond() {
     const nowMinusTimeSpan = new Date().getTime() - (1000 * config.STATISTICS.TX_PER_SECOND_SAMPLE_PERIOD);
     this.txPerSecondArray = this.txPerSecondArray.filter((unixTime) => unixTime > nowMinusTimeSpan);

backend/src/api/rbf-cache.ts

@@ -0,0 +1,34 @@
+export interface CachedRbf {
+  txid: string;
+  expires: Date;
+}
+
+class RbfCache {
+  private cache: { [txid: string]: CachedRbf; } = {};
+
+  constructor() {
+    setInterval(this.cleanup.bind(this), 1000 * 60 * 60);
+  }
+
+  public add(replacedTxId: string, newTxId: string): void {
+    this.cache[replacedTxId] = {
+      expires: new Date(Date.now() + 1000 * 604800), // 1 week
+      txid: newTxId,
+    };
+  }
+
+  public get(txId: string): CachedRbf | undefined {
+    return this.cache[txId];
+  }
+
+  private cleanup(): void {
+    const currentDate = new Date();
+    for (const c in this.cache) {
+      if (this.cache[c].expires < currentDate) {
+        delete this.cache[c];
+      }
+    }
+  }
+}
+
+export default new RbfCache();

backend/src/api/websocket-handler.ts

@@ -11,6 +11,7 @@ import { Common } from './common';
 import loadingIndicators from './loading-indicators';
 import config from '../config';
 import transactionUtils from './transaction-utils';
+import rbfCache from './rbf-cache';
 
 class WebsocketHandler {
   private wss: WebSocket.Server | undefined;
@@ -48,29 +49,38 @@ class WebsocketHandler {
           if (parsedMessage && parsedMessage['track-tx']) {
             if (/^[a-fA-F0-9]{64}$/.test(parsedMessage['track-tx'])) {
               client['track-tx'] = parsedMessage['track-tx'];
-              // Client is telling the transaction wasn't found but it might have appeared before we had the time to start watching for it
+              // Client is telling the transaction wasn't found
               if (parsedMessage['watch-mempool']) {
-                const tx = memPool.getMempool()[client['track-tx']];
-                if (tx) {
-                  if (config.MEMPOOL.BACKEND === 'esplora') {
-                    response['tx'] = tx;
+                const rbfCacheTx = rbfCache.get(client['track-tx']);
+                if (rbfCacheTx) {
+                  response['txReplaced'] = {
+                    txid: rbfCacheTx.txid,
+                  };
+                  client['track-tx'] = null;
+                } else {
+                  // It might have appeared before we had the time to start watching for it
+                  const tx = memPool.getMempool()[client['track-tx']];
+                  if (tx) {
+                    if (config.MEMPOOL.BACKEND === 'esplora') {
+                      response['tx'] = tx;
+                    } else {
+                      // tx.prevout is missing from transactions when in bitcoind mode
+                      try {
+                        const fullTx = await transactionUtils.$getTransactionExtended(tx.txid, true);
+                        response['tx'] = fullTx;
+                      } catch (e) {
+                        logger.debug('Error finding transaction: ' + (e instanceof Error ? e.message : e));
+                      }
+                    }
                   } else {
-                    // tx.prevouts is missing from transactions when in bitcoind mode
                     try {
-                      const fullTx = await transactionUtils.$getTransactionExtended(tx.txid, true);
+                      const fullTx = await transactionUtils.$getTransactionExtended(client['track-tx'], true);
                       response['tx'] = fullTx;
                     } catch (e) {
-                      logger.debug('Error finding transaction: ' + (e instanceof Error ? e.message : e));
+                      logger.debug('Error finding transaction. ' + (e instanceof Error ? e.message : e));
+                      client['track-mempool-tx'] = parsedMessage['track-tx'];
                     }
                   }
-                } else {
-                  try {
-                    const fullTx = await transactionUtils.$getTransactionExtended(client['track-tx'], true);
-                    response['tx'] = fullTx;
-                  } catch (e) {
-                    logger.debug('Error finding transaction. ' + (e instanceof Error ? e.message : e));
-                    client['track-mempool-tx'] = parsedMessage['track-tx'];
-                  }
                 }
               }
             } else {
@@ -221,14 +231,10 @@ class WebsocketHandler {
 
     mempoolBlocks.updateMempoolBlocks(newMempool);
     const mBlocks = mempoolBlocks.getMempoolBlocks();
-    const mempool = memPool.getMempool();
     const mempoolInfo = memPool.getMempoolInfo();
     const vBytesPerSecond = memPool.getVBytesPerSecond();
     const rbfTransactions = Common.findRbfTransactions(newTransactions, deletedTransactions);
-
-    for (const rbfTransaction in rbfTransactions) {
-      delete mempool[rbfTransaction];
-    }
+    memPool.handleRbfTransactions(rbfTransactions);
 
     this.wss.clients.forEach(async (client: WebSocket) => {
       if (client.readyState !== WebSocket.OPEN) {