fix(grpc): ensure full disconnect on window close

Do not try to send incoming data from GRPC streams to the main window
after the window has been closed.

Fix LN-Zap#677

app/lib/lnd/lightning.js

@@ -89,22 +89,23 @@ class Lightning {
    */
   subscribe(mainWindow) {
     this.mainWindow = mainWindow
-    this.subscriptions.channelGraph = subscribeToChannelGraph(this.mainWindow, this.lnd, mainLog)
-    this.subscriptions.invoices = subscribeToInvoices(this.mainWindow, this.lnd, mainLog)
-    this.subscriptions.transactions = subscribeToTransactions(this.mainWindow, this.lnd, mainLog)
+
+    this.subscriptions.channelGraph = subscribeToChannelGraph.call(this)
+    this.subscriptions.invoices = subscribeToInvoices.call(this)
+    this.subscriptions.transactions = subscribeToTransactions.call(this)
   }
 
   /**
    * Unsubscribe from all bi-directional streams.
    */
   unsubscribe() {
+    this.mainWindow = null
     Object.keys(this.subscriptions).forEach(subscription => {
       if (this.subscriptions[subscription]) {
         this.subscriptions[subscription].cancel()
         this.subscriptions[subscription] = null
       }
     })
-    this.mainWindow = null
   }
 }
 

app/lib/lnd/subscribe/channelgraph.js

@@ -1,14 +1,21 @@
 import { status } from 'grpc'
+import { mainLog } from '../../utils/log'
 
-export default function subscribeToChannelGraph(mainWindow, lnd, log) {
-  const call = lnd.subscribeChannelGraph({})
+export default function subscribeToChannelGraph() {
+  const call = this.lnd.subscribeChannelGraph({})
 
-  call.on('data', channelGraphData => mainWindow.send('channelGraphData', { channelGraphData }))
-  call.on('end', () => log.info('end'))
-  call.on('error', error => error.code !== status.CANCELLED && log.error(error))
-  call.on('status', channelGraphStatus =>
-    mainWindow.send('channelGraphStatus', { channelGraphStatus })
-  )
+  call.on('data', channelGraphData => {
+    if (this.mainWindow) {
+      this.mainWindow.send('channelGraphData', { channelGraphData })
+    }
+  })
+  call.on('end', () => mainLog.info('end'))
+  call.on('error', error => error.code !== status.CANCELLED && mainLog.error(error))
+  call.on('status', channelGraphStatus => {
+    if (this.mainWindow) {
+      this.mainWindow.send('channelGraphStatus', { channelGraphStatus })
+    }
+  })
 
   return call
 }

app/lib/lnd/subscribe/invoices.js

@@ -1,15 +1,18 @@
 import { status } from 'grpc'
+import { mainLog } from '../../utils/log'
 
-export default function subscribeToInvoices(mainWindow, lnd, log) {
-  const call = lnd.subscribeInvoices({})
+export default function subscribeToInvoices() {
+  const call = this.lnd.subscribeInvoices({})
 
   call.on('data', invoice => {
-    log.info('INVOICE:', invoice)
-    mainWindow.send('invoiceUpdate', { invoice })
+    mainLog.info('INVOICE:', invoice)
+    if (this.mainWindow) {
+      this.mainWindow.send('invoiceUpdate', { invoice })
+    }
   })
-  call.on('end', () => log.info('end'))
-  call.on('error', error => error.code !== status.CANCELLED && log.error(error))
-  call.on('status', status => log.info('INVOICE STATUS:', status))
+  call.on('end', () => mainLog.info('end'))
+  call.on('error', error => error.code !== status.CANCELLED && mainLog.error(error))
+  call.on('status', status => mainLog.info('INVOICE STATUS:', status))
 
   return call
 }

app/lib/lnd/subscribe/transactions.js

@@ -1,15 +1,18 @@
 import { status } from 'grpc'
+import { mainLog } from '../../utils/log'
 
-export default function subscribeToTransactions(mainWindow, lnd, log) {
-  const call = lnd.subscribeTransactions({})
+export default function subscribeToTransactions() {
+  const call = this.lnd.subscribeTransactions({})
 
   call.on('data', transaction => {
-    log.info('TRANSACTION:', transaction)
-    mainWindow.send('newTransaction', { transaction })
+    mainLog.info('TRANSACTION:', transaction)
+    if (this.mainWindow) {
+      this.mainWindow.send('newTransaction', { transaction })
+    }
   })
-  call.on('end', () => log.info('end'))
-  call.on('error', error => error.code !== status.CANCELLED && log.error(error))
-  call.on('status', status => log.info('TRANSACTION STATUS: ', status))
+  call.on('end', () => mainLog.info('end'))
+  call.on('error', error => error.code !== status.CANCELLED && mainLog.error(error))
+  call.on('status', status => mainLog.info('TRANSACTION STATUS: ', status))
 
   return call
 }