From 3a75b3823290a36ec47135594c4713be3dfd4994 Mon Sep 17 00:00:00 2001
From: Matias Alejo Garcia <ematiu@gmail.com>
Date: Tue, 31 Oct 2017 20:13:37 -0300
Subject: [PATCH] add lock

---
 lib/server.js | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/lib/server.js b/lib/server.js
index a9f5fee..d821384 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -1277,21 +1277,24 @@ WalletService.prototype._getBalanceFromAddresses = function(opts, cb) {
 WalletService.prototype._getBalanceOneStep = function(opts, cb) {
   var self = this;
 
-  self.storage.fetchAddresses(self.walletId, function(err, addresses) {
-    if (err) return cb(err);
-    self._getBalanceFromAddresses({
-      coin: opts.coin,
-      addresses: addresses
-    }, function(err, balance) {
+  // This lock is to prevent server starvation on big wallets
+  self._runLocked(cb, function(cb) {
+    self.storage.fetchAddresses(self.walletId, function(err, addresses) {
       if (err) return cb(err);
+      self._getBalanceFromAddresses({
+        coin: opts.coin,
+        addresses: addresses
+      }, function(err, balance) {
+        if (err) return cb(err);
 
-      // Update cache
-      var withBalance = _.map(balance.byAddress, 'address')
-      self.storage.storeAddressesWithBalance(self.walletId, withBalance, function(err) {
-        if (err) {
-          log.warn('Could not update wallet cache', err);
-        }
-        return cb(null, balance);
+        // Update cache
+        var withBalance = _.map(balance.byAddress, 'address')
+        self.storage.storeAddressesWithBalance(self.walletId, withBalance, function(err) {
+          if (err) {
+            log.warn('Could not update wallet cache', err);
+          }
+          return cb(null, balance);
+        });
       });
     });
   });