feat: lock file

This introduces a lock file for xud that is created in the xud data
directory any time xud starts up. Anytime a lock file already exists,
an error message is logged and xud exits. This prevents multiple
xud processes from trying to use the same node key or directory at the
same time.

The lock files are unique to each network, so running multiple processes
with different networks (e.g. simnet and mainnet) is allowed. They are
deleted when xud shuts down.

Closes #1989.

lib/Xud.ts

@@ -35,9 +35,9 @@ class Xud extends EventEmitter {
   public service!: Service;
   private logger!: Logger;
   private config: Config;
-  private db!: DB;
-  private pool!: Pool;
-  private orderBook!: OrderBook;
+  private db?: DB;
+  private pool?: Pool;
+  private orderBook?: OrderBook;
   private rpcServer?: GrpcServer;
   private httpServer?: HttpServer;
   private grpcAPIProxy?: GrpcWebProxyServer;
@@ -46,6 +46,7 @@ class Xud extends EventEmitter {
   private swapClientManager?: SwapClientManager;
   private unitConverter?: UnitConverter;
   private simnetChannels$?: Subscription;
+  private lockFilePath?: string;
 
   /**
    * Create an Exchange Union daemon.
@@ -88,6 +89,24 @@ class Xud extends EventEmitter {
     }
 
     try {
+      if (this.config.instanceid === 0) {
+        // if we're not running with multiple instances as indicated by an instance id of 0
+        // create a lock file to prevent multiple xud instances from trying to run
+        // with the same node key and/or database
+        const lockFilePath = path.join(this.config.xudir, `${this.config.network}.lock`);
+        try {
+          await (await fs.open(lockFilePath, 'wx')).close();
+          this.lockFilePath = lockFilePath;
+        } catch (err) {
+          if (err.code === 'EEXIST') {
+            this.logger.error(`A lock file exists at ${lockFilePath}. Another xud process is running or a previous process exited ungracefully.`);
+            return;
+          } else {
+            throw err;
+          }
+        }
+      }
+
       if (!this.config.rpc.disable) {
         // start rpc server first, it will respond with UNAVAILABLE error
         // indicating xud is starting until xud finishes initializing
@@ -296,6 +315,10 @@ class Xud extends EventEmitter {
     // TODO: ensure we are not in the middle of executing any trades
     const closePromises: Promise<void>[] = [];
 
+    if (this.lockFilePath) {
+      closePromises.push(fs.unlink(this.lockFilePath).catch(this.logger.error));
+    }
+
     this.simnetChannels$?.unsubscribe();
 
     if (this.swapClientManager) {
@@ -318,7 +341,7 @@ class Xud extends EventEmitter {
     }
     await Promise.all(closePromises);
 
-    await this.db.close();
+    await this.db?.close();
     this.logger.info('XUD shutdown gracefully');
 
     this.emit('shutdown');

lib/service/Service.ts

@@ -5,6 +5,7 @@ import { ProvidePreimageEvent, TransferReceivedEvent } from '../connextclient/ty
 import { OrderSide, Owner, SwapClientType, SwapRole } from '../constants/enums';
 import { OrderAttributes, TradeInstance } from '../db/types';
 import Logger, { Level, LevelPriority } from '../Logger';
+import NodeKey from '../nodekey/NodeKey';
 import OrderBook from '../orderbook/OrderBook';
 import { Currency, isOwnOrder, Order, OrderPortion, OwnLimitOrder, OwnMarketOrder, OwnOrder, PeerOrder, PlaceOrderEvent } from '../orderbook/types';
 import Pool from '../p2p/Pool';
@@ -19,7 +20,6 @@ import { checkDecimalPlaces, sortOrders, toEip55Address } from '../utils/utils';
 import commitHash from '../Version';
 import errors from './errors';
 import { NodeIdentifier, ServiceComponents, ServiceOrder, ServiceOrderSidesArrays, ServicePlaceOrderEvent, ServiceTrade, XudInfo } from './types';
-import NodeKey from 'lib/nodekey/NodeKey';
 
 /** Functions to check argument validity and throw [[INVALID_ARGUMENT]] when invalid. */
 const argChecks = {

test/integration/Service.spec.ts

@@ -111,7 +111,7 @@ describe('API Service', () => {
   });
 
   it('should remove an order', () => {
-    const tp = xud['orderBook'].tradingPairs.get('LTC/BTC')!;
+    const tp = xud['orderBook']!.tradingPairs.get('LTC/BTC')!;
     expect(tp.ownOrders.buyMap.has(orderId!)).to.be.true;
     const args = {
       orderId: '1',

test/p2p/networks.spec.ts

@@ -18,8 +18,8 @@ describe('P2P Networks Tests', () => {
       await Promise.all([srcNode.start(srcNodeConfig), destNode.start(destNodeConfig)]);
 
       const host = 'localhost';
-      const port = destNode['pool']['listenPort']!;
-      const nodePubKey = destNode['pool'].nodePubKey;
+      const port = destNode['pool']!['listenPort']!;
+      const nodePubKey = destNode['pool']!.nodePubKey;
       const nodeTwoUri = toUri({ host, port, nodePubKey });
 
       const rejectionMsg = `Peer ${nodePubKey}@${host}:${port} closed due to WireProtocolErr framer: incompatible msg origin network (expected: ${srcNodeNetwork}, found: ${destNodeNetwork})`;
@@ -39,11 +39,11 @@ describe('P2P Networks Tests', () => {
       const srcNode = new Xud();
       const destNode = new Xud();
       await Promise.all([srcNode.start(srcNodeConfig), destNode.start(destNodeConfig)]);
-      const srcNodePubKey = srcNode['pool'].nodePubKey;
-      const destNodePubKey = destNode['pool'].nodePubKey;
+      const srcNodePubKey = srcNode['pool']!.nodePubKey;
+      const destNodePubKey = destNode['pool']!.nodePubKey;
 
       const host = 'localhost';
-      const port = destNode['pool']['listenPort']!;
+      const port = destNode['pool']!['listenPort']!;
       const nodeTwoUri = toUri({ host, port, nodePubKey: destNodePubKey });
 
       await expect(srcNode.service.connect({ nodeUri: nodeTwoUri, retryConnecting: false })).to.be.fulfilled;

test/p2p/sanity.spec.ts

@@ -61,11 +61,11 @@ describe('P2P Sanity Tests', () => {
 
     await Promise.all([nodeOne.start(nodeOneConfig), nodeTwo.start(nodeTwoConfig)]);
 
-    nodeOnePubKey = nodeOne['pool'].nodePubKey;
-    nodeTwoPubKey = nodeTwo['pool'].nodePubKey;
+    nodeOnePubKey = nodeOne['pool']!.nodePubKey;
+    nodeTwoPubKey = nodeTwo['pool']!.nodePubKey;
 
-    nodeTwoPort = nodeTwo['pool']['listenPort']!;
-    nodeOneUri = toUri({ nodePubKey: nodeOnePubKey, host: 'localhost', port: nodeOne['pool']['listenPort']! });
+    nodeTwoPort = nodeTwo['pool']!['listenPort']!;
+    nodeOneUri = toUri({ nodePubKey: nodeOnePubKey, host: 'localhost', port: nodeOne['pool']!['listenPort']! });
     nodeTwoUri = toUri({ nodePubKey: nodeTwoPubKey, host: 'localhost', port: nodeTwoPort });
 
     unusedPort = await getUnusedPort();
@@ -82,13 +82,13 @@ describe('P2P Sanity Tests', () => {
 
   it('should update the node state', (done) => {
     const btcPubKey = '0395033b252c6f40e3756984162d68174e2bd8060a129c0d3462a9370471c6d28f';
-    const nodeTwoPeer = nodeOne['pool'].getPeer(nodeTwoPubKey);
+    const nodeTwoPeer = nodeOne['pool']!.getPeer(nodeTwoPubKey);
     nodeTwoPeer.on('nodeStateUpdate', () => {
       expect(nodeTwoPeer['nodeState']!.lndPubKeys['BTC']).to.equal(btcPubKey);
       done();
     });
 
-    nodeTwo['pool'].updateLndState({
+    nodeTwo['pool']!.updateLndState({
       currency: 'BTC',
       pubKey: btcPubKey,
     });
@@ -100,7 +100,7 @@ describe('P2P Sanity Tests', () => {
   });
 
   it('should disconnect successfully', async () => {
-    await nodeOne['pool']['closePeer'](nodeTwoPubKey, DisconnectionReason.NotAcceptingConnections);
+    await nodeOne['pool']!['closePeer'](nodeTwoPubKey, DisconnectionReason.NotAcceptingConnections);
 
     const listPeersResult = nodeOne.service.listPeers();
     expect(listPeersResult).to.be.empty;

test/simulation/custom-xud.patch

@@ -1,8 +1,8 @@
 diff --git a/lib/Xud.ts b/lib/Xud.ts
-index 489a50a4..f9391527 100644
+index d83880e0..1b95a77a 100644
 --- a/lib/Xud.ts
 +++ b/lib/Xud.ts
-@@ -87,6 +87,11 @@ class Xud extends EventEmitter {
+@@ -88,6 +88,11 @@ class Xud extends EventEmitter {
        this.logger.info('config file loaded');
      }
 
@@ -12,8 +12,8 @@ index 489a50a4..f9391527 100644
 +    }
 +
      try {
-       if (!this.config.rpc.disable) {
-         // start rpc server first, it will respond with UNAVAILABLE error
+       if (this.config.instanceid === 0) {
+         // if we're not running with multiple instances as indicated by an instance id of 0
 diff --git a/lib/swaps/SwapRecovery.ts b/lib/swaps/SwapRecovery.ts
 index 3759f6a3..4089dc94 100644
 --- a/lib/swaps/SwapRecovery.ts
@@ -39,10 +39,10 @@ index 3759f6a3..4089dc94 100644
    }
 
 diff --git a/lib/swaps/Swaps.ts b/lib/swaps/Swaps.ts
-index 9648e02b..0e850119 100644
+index c6946347..730cf781 100644
 --- a/lib/swaps/Swaps.ts
 +++ b/lib/swaps/Swaps.ts
-@@ -730,6 +730,24 @@ class Swaps extends EventEmitter {
+@@ -699,6 +699,24 @@ class Swaps extends EventEmitter {
      } else if (deal.state === SwapState.Active) {
        // we check that the deal is still active before we try to settle the invoice
        try {
@@ -67,7 +67,7 @@ index 9648e02b..0e850119 100644
          await swapClient.settleInvoice(rHash, rPreimage, currency);
        } catch (err) {
          this.logger.error(`could not settle invoice for deal ${rHash}`, err);
-@@ -750,7 +768,9 @@ class Swaps extends EventEmitter {
+@@ -719,7 +737,9 @@ class Swaps extends EventEmitter {
                } catch (err) {
                  this.logger.error(`could not settle invoice for deal ${rHash}`, err);
                }
@@ -78,7 +78,7 @@ index 9648e02b..0e850119 100644
            });
            await settleRetryPromise;
          } else {
-@@ -774,6 +794,16 @@ class Swaps extends EventEmitter {
+@@ -743,6 +763,16 @@ class Swaps extends EventEmitter {
     * accepted, initiates the swap.
     */
    private handleSwapAccepted = async (responsePacket: packets.SwapAcceptedPacket, peer: Peer) => {
@@ -95,7 +95,7 @@ index 9648e02b..0e850119 100644
      assert(responsePacket.body, 'SwapAcceptedPacket does not contain a body');
      const { quantity, rHash, makerCltvDelta } = responsePacket.body;
      const deal = this.getDeal(rHash);
-@@ -861,6 +891,11 @@ class Swaps extends EventEmitter {
+@@ -830,6 +860,11 @@ class Swaps extends EventEmitter {
 
      try {
        await makerSwapClient.sendPayment(deal);
@@ -107,7 +107,7 @@ index 9648e02b..0e850119 100644
      } catch (err) {
        // first we must handle the edge case where the maker has paid us but failed to claim our payment
        // in this case, we've already marked the swap as having been paid and completed
-@@ -1042,6 +1077,18 @@ class Swaps extends EventEmitter {
+@@ -1011,6 +1046,18 @@ class Swaps extends EventEmitter {
 
        this.logger.debug('Executing maker code to resolve hash');
 
@@ -126,7 +126,7 @@ index 9648e02b..0e850119 100644
        const swapClient = this.swapClientManager.get(deal.takerCurrency)!;
 
        // we update the phase persist the deal to the database before we attempt to send payment
-@@ -1052,6 +1099,13 @@ class Swaps extends EventEmitter {
+@@ -1021,6 +1068,13 @@ class Swaps extends EventEmitter {
        assert(deal.state !== SwapState.Error, `cannot send payment for failed swap ${deal.rHash}`);
 
        try {
@@ -140,7 +140,7 @@ index 9648e02b..0e850119 100644
          deal.rPreimage = await swapClient.sendPayment(deal);
        } catch (err) {
          this.logger.debug(`sendPayment in resolveHash for swap ${deal.rHash} failed due to ${err.message}`);
-@@ -1129,10 +1183,22 @@ class Swaps extends EventEmitter {
+@@ -1098,10 +1152,22 @@ class Swaps extends EventEmitter {
          }
        }
 
@@ -164,7 +164,7 @@ index 9648e02b..0e850119 100644
        return deal.rPreimage;
      } else {
        // If we are here we are the taker
-@@ -1140,6 +1206,16 @@ class Swaps extends EventEmitter {
+@@ -1109,6 +1175,16 @@ class Swaps extends EventEmitter {
        assert(htlcCurrency === undefined || htlcCurrency === deal.takerCurrency, 'incoming htlc does not match expected deal currency');
        this.logger.debug('Executing taker code to resolve hash');
 
@@ -181,7 +181,7 @@ index 9648e02b..0e850119 100644
        return deal.rPreimage;
      }
    }
-@@ -1308,8 +1384,11 @@ class Swaps extends EventEmitter {
+@@ -1277,8 +1353,11 @@ class Swaps extends EventEmitter {
          swapClient.removeInvoice(deal.rHash).catch(this.logger.error); // we don't need to await the remove invoice call
        }
      } else if (deal.phase === SwapPhase.SendingPayment) {
@@ -195,7 +195,7 @@ index 9648e02b..0e850119 100644
      }
 
      this.logger.trace(`emitting swap.failed event for ${deal.rHash}`);
-@@ -1373,9 +1452,14 @@ class Swaps extends EventEmitter {
+@@ -1343,9 +1422,14 @@ class Swaps extends EventEmitter {
 
          if (deal.role === SwapRole.Maker) {
            // the maker begins execution of the swap upon accepting the deal