Detect RBF-transactions and offer to track them.

fixes #78

backend/src/api/common.ts

@@ -25,4 +25,26 @@ export class Common {
     arr.push(transactions[lastindex].feePerVsize);
     return arr;
   }
+
+  static findRbfTransactions(added: TransactionExtended[], deleted: TransactionExtended[]): { [txid: string]: TransactionExtended } {
+    const matches: { [txid: string]: TransactionExtended } = {};
+    deleted
+      // The replaced tx must have at least one input with nSequence < maxint-1 (That’s the opt-in)
+      .filter((tx) => tx.vin.some((vin) => vin.sequence < 0xfffffffe))
+      .forEach((deletedTx) => {
+        const foundMatches = added.find((addedTx) => {
+          // The new tx must, absolutely speaking, pay at least as much fee as the replaced tx.
+          return addedTx.fee > deletedTx.fee
+            // The new transaction must pay more fee per kB than the replaced tx.
+            && addedTx.feePerVsize > deletedTx.feePerVsize
+            // Spends one or more of the same inputs
+            && deletedTx.vin.some((deletedVin) =>
+              addedTx.vin.some((vin) => vin.txid === deletedVin.txid));
+            });
+        if (foundMatches) {
+          matches[deletedTx.txid] = foundMatches;
+        }
+      });
+    return matches;
+  }
 }

backend/src/api/mempool-blocks.ts

@@ -49,9 +49,9 @@ class MempoolBlocks {
         transactions.push(tx);
       } else {
         mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockVSize, mempoolBlocks.length));
-        blockVSize = 0;
-        blockSize = 0;
-        transactions = [];
+        blockVSize = tx.vsize;
+        blockSize = tx.size;
+        transactions = [tx];
       }
     });
     if (transactions.length) {

backend/src/api/mempool.ts

@@ -123,31 +123,30 @@ class Mempool {
         }
       }
 
-      // Replace mempool to clear already confirmed transactions
+      // Replace mempool to clear deleted transactions
       const newMempool = {};
-      transactions.forEach((tx) => {
-        if (this.mempoolCache[tx]) {
+      const deletedTransactions: Transaction[] = [];
+      for (const tx in this.mempoolCache) {
+        if (transactions.indexOf(tx) > -1) {
           newMempool[tx] = this.mempoolCache[tx];
         } else {
-          hasChange = true;
+          deletedTransactions.push(this.mempoolCache[tx]);
         }
-      });
+      }
 
       if (!this.inSync && transactions.length === Object.keys(newMempool).length) {
         this.inSync = true;
         console.log('The mempool is now in sync!');
       }
 
-      console.log(`New mempool size: ${Object.keys(newMempool).length} Change: ${diff}`);
-
-      this.mempoolCache = newMempool;
-
-      if (hasChange && this.mempoolChangedCallback) {
-        this.mempoolChangedCallback(this.mempoolCache, newTransactions);
+      if (this.mempoolChangedCallback && (hasChange || deletedTransactions.length)) {
+        this.mempoolCache = newMempool;
+        this.mempoolChangedCallback(this.mempoolCache, newTransactions, deletedTransactions);
       }
 
       const end = new Date().getTime();
       const time = end - start;
+      console.log(`New mempool size: ${Object.keys(newMempool).length} Change: ${diff}`);
       console.log('Mempool updated in ' + time / 1000 + ' seconds');
     } catch (err) {
       console.log('getRawMempool error.', err);

backend/src/api/websocket-handler.ts

@@ -8,6 +8,7 @@ import backendInfo from './backend-info';
 import mempoolBlocks from './mempool-blocks';
 import fiatConversion from './fiat-conversion';
 import * as os from 'os';
+import { Common } from './common';
 
 class WebsocketHandler {
   private wss: WebSocket.Server | undefined;
@@ -121,7 +122,8 @@ class WebsocketHandler {
     });
   }
 
-  handleMempoolChange(newMempool: { [txid: string]: TransactionExtended }, newTransactions: TransactionExtended[]) {
+  handleMempoolChange(newMempool: { [txid: string]: TransactionExtended },
+    newTransactions: TransactionExtended[], deletedTransactions: TransactionExtended[]) {
     if (!this.wss) {
       throw new Error('WebSocket.Server is not set');
     }
@@ -130,6 +132,7 @@ class WebsocketHandler {
     const mBlocks = mempoolBlocks.getMempoolBlocks();
     const mempoolInfo = memPool.getMempoolInfo();
     const vBytesPerSecond = memPool.getVBytesPerSecond();
+    const rbfTransactions = Common.findRbfTransactions(newTransactions, deletedTransactions);
 
     this.wss.clients.forEach((client: WebSocket) => {
       if (client.readyState !== WebSocket.OPEN) {
@@ -204,6 +207,15 @@ class WebsocketHandler {
         }
       }
 
+      if (client['track-tx'] && rbfTransactions[client['track-tx']]) {
+        for (const rbfTransaction in rbfTransactions) {
+          if (client['track-tx'] === rbfTransaction) {
+            response['rbfTransaction'] = rbfTransactions[rbfTransaction];
+            break;
+          }
+        }
+      }
+
       if (Object.keys(response).length) {
         client.send(JSON.stringify(response));
       }
@@ -228,7 +240,7 @@ class WebsocketHandler {
         }
       }
 
-      matchRate = Math.ceil((matches.length / txIds.length) * 100);
+      matchRate = Math.round((matches.length / (txIds.length - 1)) * 100);
       if (matchRate > 0) {
         const currentMemPool = memPool.getMempool();
         for (const txId of matches) {