From a3ae613d7e2cde43096dcd80f8a1e04a7fb2512f Mon Sep 17 00:00:00 2001
From: Adam Soltys <asoltys@gmail.com>
Date: Mon, 14 Oct 2019 23:41:20 -0700
Subject: use database transaction when updating balance on block receipt

---
 bitcoinPayments.js | 44 +++++++++++++++++++++++++++++---------------
 sendCoins.js       | 13 ++++++-------
 stripe.js          |  3 ++-
 3 files changed, 37 insertions(+), 23 deletions(-)

diff --git a/bitcoinPayments.js b/bitcoinPayments.js
index 479298b8..b3d54a21 100644
--- a/bitcoinPayments.js
+++ b/bitcoinPayments.js
@@ -103,26 +103,40 @@ module.exports = (app, bc, db, addresses, payments, emit) => {
         let block = bitcoin.Block.fromHex(message);
         l("block", block.getHash().toString("hex"));
 
-        const processPayment = async p => {
-          if ((await bc.getRawTransaction(p.hash, true)).confirmations > 0) {
-            let user = await db.User.findByPk(p.user_id);
-            l(user.pending);
-            p.confirmed = true;
-            user.balance += p.amount;
-            user.pending -= p.amount;
-            await user.save();
-            await p.save();
+        const processPayment = async (payment, transaction) => {
+          if (
+            (await bc.getRawTransaction(payment.hash, true)).confirmations > 0
+          ) {
+            let user = await db.User.findByPk(payment.user_id, { transaction });
+            payment.confirmed = true;
+            user.balance += payment.amount;
+            user.pending -= payment.amount;
+            await user.save({ transaction });
+            await payment.save({ transaction });
             emit(user.username, "user", user);
             emit(user.username, "block", message);
           }
         };
 
-        await db.Payment.findAll({
-          where: { confirmed: false }
-        }).reduce(async (prev, payment) => {
-          const result = await prev;
-          return [...result, await processPayment(payment)];
-        }, Promise.resolve([]));
+        const transaction = await db.transaction();
+        try {
+          const payments = await db.Payment.findAll({
+            where: { confirmed: false },
+            lock: transaction.LOCK.UPDATE,
+            transaction
+          });
+
+          await Promise.all(
+            payments.map(async payment => {
+              await processPayment(payment, transaction);
+              return;
+            })
+          );
+        } catch (e) {
+          transaction.rollback();
+        }
+
+        await transaction.commit();
 
         break;
       }
diff --git a/sendCoins.js b/sendCoins.js
index 7eebdc8a..997af0dd 100644
--- a/sendCoins.js
+++ b/sendCoins.js
@@ -24,14 +24,13 @@ module.exports = (app, bc, db, emit) => async (req, res) => {
 
   try {
     await db.transaction(async transaction => {
-      let { balance } = await db.User.findOne(
-        {
-          where: {
-            username: req.user.username
-          }
+      let { balance } = await db.User.findOne({
+        where: {
+          username: req.user.username
         },
-        { transaction }
-      );
+        lock: transaction.LOCK.UPDATE,
+        transaction
+      });
 
       if (amount !== balance && amount + fee > balance) {
         l("amount exceeds balance", amount, fee, balance);
diff --git a/stripe.js b/stripe.js
index ba1f68f7..090def4b 100644
--- a/stripe.js
+++ b/stripe.js
@@ -1,4 +1,5 @@
 const config = require("./config");
+const l = console.log;
 
 module.exports = (auth, app, db, emit) => {
   app.post("/buy", auth, async (req, res) => {
@@ -33,7 +34,7 @@ module.exports = (auth, app, db, emit) => {
 
       res.send(`Bought ${amount}`);
     } catch (e) {
-      console.log(e);
+      l(e);
       res.status(500).send(e);
     }
   });
-- 
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