Timeline of replacements for RBF-d transactions

backend/src/api/bitcoin/bitcoin.routes.ts

@@ -32,7 +32,7 @@ class BitcoinRoutes {
       .get(config.MEMPOOL.API_URL_PREFIX + 'backend-info', this.getBackendInfo)
       .get(config.MEMPOOL.API_URL_PREFIX + 'init-data', this.getInitData)
       .get(config.MEMPOOL.API_URL_PREFIX + 'validate-address/:address', this.validateAddress)
-      .get(config.MEMPOOL.API_URL_PREFIX + 'tx/:txId/replaces', this.getRbfHistory)
+      .get(config.MEMPOOL.API_URL_PREFIX + 'tx/:txId/rbf', this.getRbfHistory)
       .get(config.MEMPOOL.API_URL_PREFIX + 'tx/:txId/cached', this.getCachedTx)
       .post(config.MEMPOOL.API_URL_PREFIX + 'tx/push', this.$postTransactionForm)
       .get(config.MEMPOOL.API_URL_PREFIX + 'donations', async (req, res) => {
@@ -642,8 +642,12 @@ class BitcoinRoutes {
 
   private async getRbfHistory(req: Request, res: Response) {
     try {
-      const result = rbfCache.getReplaces(req.params.txId);
-      res.json(result || []);
+      const replacements = rbfCache.getRbfChain(req.params.txId) || [];
+      const replaces = rbfCache.getReplaces(req.params.txId) || null;
+      res.json({
+        replacements,
+        replaces
+      });
     } catch (e) {
       res.status(500).send(e instanceof Error ? e.message : e);
     }

backend/src/api/mempool.ts

@@ -269,7 +269,7 @@ class Mempool {
     for (const rbfTransaction in rbfTransactions) {
       if (this.mempoolCache[rbfTransaction]) {
         // Store replaced transactions
-        rbfCache.add(this.mempoolCache[rbfTransaction], rbfTransactions[rbfTransaction].txid);
+        rbfCache.add(this.mempoolCache[rbfTransaction], rbfTransactions[rbfTransaction]);
         // Erase the replaced transactions from the local mempool
         delete this.mempoolCache[rbfTransaction];
       }

backend/src/api/rbf-cache.ts

@@ -1,8 +1,15 @@
-import { TransactionExtended } from "../mempool.interfaces";
+import { TransactionExtended, TransactionStripped } from "../mempool.interfaces";
+import { Common } from "./common";
+
+interface RbfTransaction extends TransactionStripped {
+  rbf?: boolean;
+}
 
 class RbfCache {
   private replacedBy: { [txid: string]: string; } = {};
   private replaces: { [txid: string]: string[] } = {};
+  private rbfChains: { [root: string]: { tx: TransactionStripped, time: number, mined?: boolean }[] } = {}; // sequences of consecutive replacements
+  private chainMap: { [txid: string]: string } = {}; // map of txids to sequence ids
   private txs: { [txid: string]: TransactionExtended } = {};
   private expiring: { [txid: string]: Date } = {};
 
@@ -10,13 +17,34 @@ class RbfCache {
     setInterval(this.cleanup.bind(this), 1000 * 60 * 60);
   }
 
-  public add(replacedTx: TransactionExtended, newTxId: string): void {
-    this.replacedBy[replacedTx.txid] = newTxId;
-    this.txs[replacedTx.txid] = replacedTx;
-    if (!this.replaces[newTxId]) {
-      this.replaces[newTxId] = [];
+  public add(replacedTxExtended: TransactionExtended, newTxExtended: TransactionExtended): void {
+    const replacedTx = Common.stripTransaction(replacedTxExtended) as RbfTransaction;
+    replacedTx.rbf = replacedTxExtended.vin.some((v) => v.sequence < 0xfffffffe);
+    const newTx = Common.stripTransaction(newTxExtended) as RbfTransaction;
+    newTx.rbf = newTxExtended.vin.some((v) => v.sequence < 0xfffffffe);
+
+    this.replacedBy[replacedTx.txid] = newTx.txid;
+    this.txs[replacedTx.txid] = replacedTxExtended;
+    if (!this.replaces[newTx.txid]) {
+      this.replaces[newTx.txid] = [];
+    }
+    this.replaces[newTx.txid].push(replacedTx.txid);
+
+    // maintain rbf chains
+    if (this.chainMap[replacedTx.txid]) {
+      // add to an existing chain
+      const chainRoot = this.chainMap[replacedTx.txid];
+      this.rbfChains[chainRoot].push({ tx: newTx, time: newTxExtended.firstSeen || Date.now() });
+      this.chainMap[newTx.txid] = chainRoot;
+    } else {
+      // start a new chain
+      this.rbfChains[replacedTx.txid] = [
+        { tx: replacedTx, time: replacedTxExtended.firstSeen || Date.now() },
+        { tx: newTx, time: newTxExtended.firstSeen || Date.now() },
+      ];
+      this.chainMap[replacedTx.txid] = replacedTx.txid;
+      this.chainMap[newTx.txid] = replacedTx.txid;
     }
-    this.replaces[newTxId].push(replacedTx.txid);
   }
 
   public getReplacedBy(txId: string): string | undefined {
@@ -31,6 +59,10 @@ class RbfCache {
     return this.txs[txId];
   }
 
+  public getRbfChain(txId: string): { tx: TransactionStripped, time: number }[] {
+    return this.rbfChains[this.chainMap[txId]] || [];
+  }
+
   // flag a transaction as removed from the mempool
   public evict(txid): void {
     this.expiring[txid] = new Date(Date.now() + 1000 * 86400); // 24 hours
@@ -48,14 +80,20 @@ class RbfCache {
 
   // remove a transaction & all previous versions from the cache
   private remove(txid): void {
-    // don't remove a transaction while a newer version remains in the mempool
-    if (this.replaces[txid] && !this.replacedBy[txid]) {
+    // don't remove a transaction if a newer version remains in the mempool
+    if (!this.replacedBy[txid]) {
       const replaces = this.replaces[txid];
       delete this.replaces[txid];
+      delete this.chainMap[txid];
+      delete this.txs[txid];
+      delete this.expiring[txid];
       for (const tx of replaces) {
         // recursively remove prior versions from the cache
         delete this.replacedBy[tx];
-        delete this.txs[tx];
+        // if this is the root of a chain, remove that too
+        if (this.chainMap[tx] === tx) {
+          delete this.rbfChains[tx];
+        }
         this.remove(tx);
       }
     }