feat(cli): improved streamorders (#780)

This commit changes the behavior of the `streamorders` cli call:

1. Allow it to start before xud. `streamorders` will wait for xud to
start and not issue an error.
2. Print a line upon connection.
3. Upon termination of xud or any other RPC error - reconnect to xud
and wait if xud is not available.
4. Upon connection to xud - print existing orders.

Closes #687.

lib/cli/commands/subscribeorders.ts

@@ -1,6 +1,7 @@
 import { loadXudClient } from '../command';
 import { Arguments } from 'yargs';
 import * as xudrpc from '../../proto/xudrpc_pb';
+import { XudClient } from '../../proto/xudrpc_grpc_pb';
 
 export const command = 'streamorders [existing]';
 
@@ -15,20 +16,58 @@ export const builder = {
 };
 
 export const handler = (argv: Arguments) => {
+  ensureConnection(argv, true);
+};
+
+let xud: XudClient;
+
+const ensureConnection = (argv: Arguments, printError?: boolean) => {
+  if (!xud) xud = loadXudClient(argv);
+  xud.waitForReady(Number.POSITIVE_INFINITY, (error: Error | null) => {
+    if (error) {
+      if (printError) console.error(`${error.name}: ${error.message}`);
+      setTimeout(ensureConnection.bind(undefined, argv), 3000);
+    } else {
+      console.log('Successfully connected, subscribing for orders');
+      subscribeOrders(argv);
+    }
+  });
+};
+
+const subscribeOrders = (argv: Arguments) =>  {
   const addedOrdersRequest = new xudrpc.SubscribeAddedOrdersRequest();
   addedOrdersRequest.setExisting(argv.existing);
   const addedOrdersSubscription = loadXudClient(argv).subscribeAddedOrders(addedOrdersRequest);
   addedOrdersSubscription.on('data', (order: xudrpc.Order) => {
     console.log(`Order added: ${JSON.stringify(order.toObject())}`);
   });
 
+  // adding end, close, error events only once,
+  // since they'll be thrown for three of subscriptions in the corresponding cases, catching once is enough.
+  addedOrdersSubscription.on('end', reconnect.bind(undefined, argv));
+  addedOrdersSubscription.on('error', (err: Error) => {
+    console.log(`Unexpected error occured: ${JSON.stringify(err)}, trying to reconnect`);
+    ensureConnection(argv);
+  });
+
   const removedOrdersSubscription = loadXudClient(argv).subscribeRemovedOrders(new xudrpc.SubscribeRemovedOrdersRequest());
   removedOrdersSubscription.on('data', (orderRemoval: xudrpc.OrderRemoval) => {
     console.log(`Order removed: ${JSON.stringify(orderRemoval.toObject())}`);
   });
 
+  // prevent exiting and do nothing, it's already caught above.
+  removedOrdersSubscription.on('error', () => {});
+
   const swapsSubscription = loadXudClient(argv).subscribeSwaps(new xudrpc.SubscribeSwapsRequest());
   swapsSubscription.on('data', (swapResult: xudrpc.SwapResult) => {
     console.log(`Order swapped: ${JSON.stringify(swapResult.toObject())}`);
   });
+
+  // prevent exiting and do nothing, it's already caught above.
+  swapsSubscription.on('error', () => {});
+};
+
+const reconnect = (argv: Arguments) => {
+  console.log('Stream has closed, trying to reconnect');
+  ensureConnection(argv, false);
 };