Improve LNC realiability by being nicer (#1658)

* be nicer to lnc

* decrease timeout to 4 seconds

wallets/lnc/client.js

@@ -3,18 +3,47 @@ import { bolt11Tags } from '@/lib/bolt11'
 import { Mutex } from 'async-mutex'
 export * from '@/wallets/lnc'
 
-async function disconnect (lnc, logger) {
-  if (lnc) {
+const mutex = new Mutex()
+const serverHost = 'mailbox.terminal.lightning.today:443'
+
+export async function testSendPayment (credentials, { logger }) {
+  const lnc = await getLNC(credentials, { logger })
+  logger?.info('validating permissions ...')
+  await validateNarrowPerms(lnc)
+  logger?.info('permissions ok')
+  return lnc.credentials.credentials
+}
+
+export async function sendPayment (bolt11, credentials, { logger }) {
+  const hash = bolt11Tags(bolt11).payment_hash
+  return await mutex.runExclusive(async () => {
     try {
+      const lnc = await getLNC(credentials, { logger })
+      const { paymentError, paymentPreimage: preimage } = await lnc.lnd.lightning.sendPaymentSync({ payment_request: bolt11 })
+      if (paymentError) throw new Error(paymentError)
+      if (!preimage) throw new Error('No preimage in response')
+      return preimage
+    } catch (err) {
+      const msg = err.message || err.toString?.()
+      if (msg.includes('invoice expired')) throw new InvoiceExpiredError(hash)
+      if (msg.includes('canceled')) throw new InvoiceCanceledError(hash)
+      throw err
+    }
+  })
+}
+
+async function disconnectLNC (lnc, { logger } = {}) {
+  try {
+    if (!lnc?.isConnected) return
     lnc.disconnect()
-      logger.info('disconnecting...')
-      // wait for lnc to disconnect before releasing the mutex
+    logger?.info('disconnecting...')
+    // wait for lnc to disconnect
     await new Promise((resolve, reject) => {
       let counter = 0
       const interval = setInterval(() => {
         if (lnc?.isConnected) {
           if (counter++ > 100) {
-              logger.error('failed to disconnect from lnc')
+            logger?.error('failed to disconnect from lnc')
             clearInterval(interval)
             reject(new Error('failed to disconnect from lnc'))
           }
@@ -24,85 +53,59 @@ async function disconnect (lnc, logger) {
         resolve()
       })
     }, 50)
-      logger.info('disconnected')
+    logger?.info('disconnected')
   } catch (err) {
-      logger.error('failed to disconnect from lnc: ' + err)
-    }
-  }
-}
-
-export async function testSendPayment (credentials, { logger }) {
-  let lnc
-  try {
-    lnc = await getLNC(credentials)
-
-    logger.info('connecting ...')
-    await lnc.connect()
-    logger.info('connected')
-
-    logger.info('validating permissions ...')
-    await validateNarrowPerms(lnc)
-    logger.info('permissions ok')
-
-    return lnc.credentials.credentials
-  } finally {
-    await disconnect(lnc, logger)
+    logger?.error('failed to disconnect from lnc: ' + err)
   }
 }
 
-const mutex = new Mutex()
+async function getLNC (credentials = {}, { logger } = {}) {
+  if (window.snLncKillerTimeout) clearTimeout(window.snLncKillerTimeout)
 
-export async function sendPayment (bolt11, credentials, { logger }) {
-  const hash = bolt11Tags(bolt11).payment_hash
-
-  return await mutex.runExclusive(async () => {
-    let lnc
-    try {
-      lnc = await getLNC(credentials)
-
-      await lnc.connect()
-      const { paymentError, paymentPreimage: preimage } =
-          await lnc.lnd.lightning.sendPaymentSync({ payment_request: bolt11 })
-
-      if (paymentError) throw new Error(paymentError)
-      if (!preimage) throw new Error('No preimage in response')
-
-      return preimage
-    } catch (err) {
-      const msg = err.message || err.toString?.()
-      if (msg.includes('invoice expired')) {
-        throw new InvoiceExpiredError(hash)
-      }
-      if (msg.includes('canceled')) {
-        throw new InvoiceCanceledError(hash)
-      }
-      throw err
-    } finally {
-      await disconnect(lnc, logger)
-    }
-  })
-}
-
-async function getLNC (credentials = {}) {
-  const serverHost = 'mailbox.terminal.lightning.today:443'
-  // XXX we MUST reuse the same instance of LNC because it references a global Go object
-  // that holds closures to the first LNC instance it's created with
-  if (window.lnc) {
-    window.lnc.credentials.credentials = {
-      ...window.lnc.credentials.credentials,
-      ...credentials,
-      serverHost
-    }
-    return window.lnc
-  }
+  if (!window.snLnc) { // create new instance
     const { default: LNC } = await import('@lightninglabs/lnc-web')
-  window.lnc = new LNC({
+    window.snLnc = new LNC({
       credentialStore: new LncCredentialStore({
         ...credentials,
         serverHost
       })
     })
-  return window.lnc
+
+    window.addEventListener('beforeunload', () => {
+      // try to disconnect gracefully when the page is closed
+      disconnectLNC(window.snLnc, { logger })
+    })
+  } else if (JSON.stringify(window.snLncCredentials ?? {}) !== JSON.stringify(credentials)) {
+    console.log('LNC instance has new credentials')
+    // disconnect and update credentials if they've changed
+    await disconnectLNC(window.snLnc, { logger })
+    // XXX we MUST reuse the same instance of LNC because it references a global Go object
+    // that holds closures to the first LNC instance it's created with
+    window.snLnc.credentials.credentials = {
+      ...window.snLnc.credentials.credentials,
+      ...credentials,
+      serverHost
+    }
+  }
+
+  if (!window.snLnc.isConnected) {
+    logger?.info('connecting ...')
+    await window.snLnc.connect()
+    logger?.info('connected')
+  }
+
+  window.snLncCredentials = {
+    ...credentials
+  }
+
+  window.snLncKillerTimeout = setTimeout(() => {
+    logger?.info('disconnecting from lnc due to inactivity ...')
+    mutex.runExclusive(async () => {
+      await disconnectLNC(window.snLnc, { logger })
+    })
+  }, 4000)
+
+  return window.snLnc
 }
 
 function validateNarrowPerms (lnc) {