From 59cf85ab5504c24d953097ed9c270499a79ea1cc Mon Sep 17 00:00:00 2001
From: Jamie Ford <Jamie@chainflip.io>
Date: Mon, 25 Nov 2024 13:47:53 +1100
Subject: [PATCH] refactor: use mutex instead of locking

---
 bouncer/shared/send_btc.ts      | 67 ++++++++++++++++++++++++---------
 bouncer/tests/btc_vault_swap.ts | 35 ++++-------------
 2 files changed, 56 insertions(+), 46 deletions(-)

diff --git a/bouncer/shared/send_btc.ts b/bouncer/shared/send_btc.ts
index 95aad18f5f..57da971383 100644
--- a/bouncer/shared/send_btc.ts
+++ b/bouncer/shared/send_btc.ts
@@ -12,32 +12,63 @@ export const btcClient = new Client({
 });
 
 export async function selectInputs(amount: number) {
-  return btcClientMutex.runExclusive(async () => {
-    // List unspent UTXOs
-    const utxos = await btcClient.listUnspent();
+  // List unspent UTXOs
+  const utxos = await btcClient.listUnspent();
+
+  // Find a UTXO with enough funds
+  const utxo = utxos.find((u) => u.amount >= amount);
+  if (!utxo) throw new Error('Insufficient funds');
+  // TODO: be able to select more than one UTXO
+
+  const change = utxo.amount - amount;
 
-    // Find a UTXO with enough funds
-    const utxo = utxos.find((u) => u.amount >= amount);
-    if (!utxo) throw new Error('Insufficient funds');
-    // TODO: be able to select more than one UTXO
+  // Prepare the transaction inputs
+  const inputs = [
+    {
+      txid: utxo.txid,
+      vout: utxo.vout,
+    },
+  ];
 
-    // Lock the selected UTXO to prevent it from being used in another transaction
-    await btcClient.lockUnspent(false, [{ txid: utxo.txid, vout: utxo.vout }]);
+  return {
+    inputs,
+    change,
+  };
+}
+
+export async function sendVaultTransaction(
+  nulldataUtxo: string,
+  amountBtc: number,
+  depositAddress: string,
+  refundAddress: string,
+) {
+  return btcClientMutex.runExclusive(async () => {
+    const feeBtc = 0.00001;
+    const { inputs, change } = await selectInputs(Number(amountBtc) + feeBtc);
 
-    const change = utxo.amount - amount;
+    // The `createRawTransaction` function will add the op codes, so we have to remove them here.
+    const nullDataWithoutOpCodes = nulldataUtxo.replace('0x', '').substring(4);
 
-    // Prepare the transaction inputs
-    const inputs = [
+    const outputs = [
       {
-        txid: utxo.txid,
-        vout: utxo.vout,
+        [depositAddress]: amountBtc,
+      },
+      {
+        data: nullDataWithoutOpCodes,
+      },
+      {
+        [refundAddress]: change,
       },
     ];
 
-    return {
-      inputs,
-      change,
-    };
+    const rawTx = await btcClient.createRawTransaction(inputs, outputs, 0, false);
+    const signedTx = await btcClient.signRawTransactionWithWallet(rawTx);
+    const txid = await btcClient.sendRawTransaction(signedTx.hex);
+
+    if (!txid) {
+      throw new Error('Broadcast failed');
+    }
+    return txid as string;
   });
 }
 
diff --git a/bouncer/tests/btc_vault_swap.ts b/bouncer/tests/btc_vault_swap.ts
index d3d72dfd5a..b93ceb18da 100644
--- a/bouncer/tests/btc_vault_swap.ts
+++ b/bouncer/tests/btc_vault_swap.ts
@@ -1,11 +1,10 @@
 import assert from 'assert';
 import { ExecutableTest } from '../shared/executable_test';
-import { BTC_ENDPOINT, selectInputs, waitForBtcTransaction, btcClient } from '../shared/send_btc';
+import { BTC_ENDPOINT, waitForBtcTransaction, sendVaultTransaction } from '../shared/send_btc';
 import {
   amountToFineAmount,
   Asset,
   assetDecimals,
-  btcClientMutex,
   createStateChainKeypair,
   newAddress,
   observeBalanceIncrease,
@@ -51,9 +50,6 @@ async function buildAndSendBtcVaultSwap(
     affiliates.push({ account: affiliateAddress, bps: commissionBps });
   }
 
-  const feeBtc = 0.00001;
-  const { inputs, change } = await selectInputs(Number(depositAmountBtc) + feeBtc);
-
   const vaultSwapDetails = (await chainflip.rpc(
     `cf_get_vault_swap_details`,
     broker.address,
@@ -71,32 +67,15 @@ async function buildAndSendBtcVaultSwap(
   testBtcVaultSwap.debugLog('nulldata_utxo:', vaultSwapDetails.nulldata_utxo);
   testBtcVaultSwap.debugLog('deposit_address:', vaultSwapDetails.deposit_address);
 
-  // The `createRawTransaction` function will add the op codes, so we have to remove them here.
-  const nullDataWithoutOpCodes = vaultSwapDetails.nulldata_utxo.replace('0x', '').substring(4);
-
-  const outputs = [
-    {
-      [vaultSwapDetails.deposit_address]: depositAmountBtc,
-    },
-    {
-      data: nullDataWithoutOpCodes,
-    },
-    {
-      [refundAddress]: change,
-    },
-  ];
-
-  const rawTx = await btcClient.createRawTransaction(inputs, outputs, 0, false);
-  const signedTx = await btcClient.signRawTransactionWithWallet(rawTx);
-  const txid = await btcClientMutex.runExclusive(async () =>
-    btcClient.sendRawTransaction(signedTx.hex),
+  const txid = await sendVaultTransaction(
+    vaultSwapDetails.nulldata_utxo,
+    depositAmountBtc,
+    vaultSwapDetails.deposit_address,
+    refundAddress,
   );
-  if (!txid) {
-    throw new Error('Broadcast failed');
-  }
   testBtcVaultSwap.log('Broadcast successful, txid:', txid);
 
-  await waitForBtcTransaction(txid as string);
+  await waitForBtcTransaction(txid);
   testBtcVaultSwap.debugLog('Transaction confirmed');
 }