fix(Blockchain, Node, Wallet): prevent race conditions when closing a component while initializing

Errors could occur when a component was closed while still handling its initialization.

Author: mappum

lib/blockchain.js

@@ -87,9 +87,18 @@ Blockchain.prototype._initStore = function (cb) {
   async.parallel(tasks, cb)
 }
 
+Blockchain.prototype.waitForReady = function (cb) {
+  if (this.initialized) return cb()
+  this.on('ready', cb)
+}
+
 Blockchain.prototype.close = function (cb) {
-  this.closed = true
-  this.store.close(cb)
+  var self = this
+  this.waitForReady(function () {
+    self.closed = true
+    self.syncing = false
+    self.store.close(cb)
+  })
 }
 
 Blockchain.prototype.sync = function (opts, cb) {
@@ -322,7 +331,7 @@ Blockchain.prototype._setDownloadPeer = function (peer) {
 Blockchain.prototype._getHeaders = function (opts) {
   var self = this
 
-  if (!this.syncing || this.closed) return
+  if (!this.syncing) return
   if (!this.downloadPeer) {
     this._findDownloadPeer(function (err, peer) {
       if (err) return self._error(err)

lib/node.js

@@ -38,6 +38,9 @@ var Node = module.exports = function (opts, cb) {
 
   this.wallets = {}
 
+  this.closing = false
+  this.closed = false
+
   if (cb) this.start(cb)
 }
 util.inherits(Node, EventEmitter)
@@ -57,6 +60,7 @@ Node.prototype.close = function (cb) {
   if (!cb) cb = function () {}
   var self = this
 
+  this.closing = true
   this.peers.disconnect()
 
   var wallets = []
@@ -66,6 +70,7 @@ Node.prototype.close = function (cb) {
 
     self.chain.close(function (err) {
       if (err) return cb(err)
+      this.closed = true
       self.emit('end')
       cb(null)
     })
@@ -137,7 +142,9 @@ Node.prototype._sendHeaders = function (peer, message) {
       }
     })
   }, function (err) {
-    if (err !== true) return self._error(err)
+    if (err !== true && !(err.message === 'Database is not open' && self.closing)) {
+      return self._error(err)
+    }
     if (!start || !start.next) return
     self.chain.store.get(start.next, next)
   })

lib/wallet.js

@@ -51,13 +51,17 @@ var Wallet = module.exports = function (opts, cb) {
   this.feePerKb = opts.feePerKb || 10000
 
   this._error = this._error.bind(this)
+  this.initialized = false
   this._initialize(cb)
 }
 util.inherits(Wallet, EventEmitter)
 
 Wallet.prototype.close = function (cb) {
-  this.closed = true
-  this.store.close(cb)
+  var self = this
+  this.waitForReady(function () {
+    self.closed = true
+    self.store.close(cb)
+  })
 }
 
 Wallet.prototype.getKey = function () {
@@ -159,11 +163,17 @@ Wallet.prototype._initialize = function (cb) {
   ], function (err, res) {
     if (err) return (cb || self._error)(err)
     self._listenToChain()
+    self.initialized = true
     self.emit('ready')
     if (cb) cb(null)
   })
 }
 
+Wallet.prototype.waitForReady = function (cb) {
+  if (this.initialized) return cb()
+  this.on('ready', cb)
+}
+
 Wallet.prototype._listenToChain = function () {
   var self = this
   if (this.peers.numberConnected() === 0) {
@@ -243,6 +253,9 @@ Wallet.prototype._scanChain = function (opts) {
           self.emit('synced')
         })
       })
+      txs.blocks.on('data', function (block) {
+        self.emit('sync', block)
+      })
     }
   })
 }