Code improvements and more logging on connection handling

Summary:
In an attempt to trace Android issues:

1. added more logging to the process (opted for info level for now since this is pretty critical for support requests, yet not super repetitive overall. We could maybe turn it into usage tracking at some point to have central stats?).
2. rewrote promise chains to async/await since they are easier to follow and harder to do accidentally wrong
3. fixed some minor potential problems, will highlights those in code.

Changelog: Improved handling of edge cases in certificate exchange, which should address cases where a Flipper connection wouldn't come up when connection to Android / IOS. Added explicit logging around connection negation.

Reviewed By: lblasa

Differential Revision: D30838947

fbshipit-source-id: a898c6d3be6edc22bd24f9d2bad76e81871360da

desktop/app/src/server/comms/ServerController.tsx

@@ -151,6 +151,9 @@ class ServerController extends EventEmitter implements ServerEventsListener {
     const {app, os, device, device_id, sdk_version, csr, csr_path, medium} =
       clientQuery;
     const transformedMedium = transformCertificateExchangeMediumToType(medium);
+    console.log(
+      `[conn] Connection established: ${app} on ${device_id}. Medium ${medium}. CSR: ${csr_path}`,
+    );
     return this.addConnection(
       clientConnection,
       {
@@ -293,6 +296,9 @@ class ServerController extends EventEmitter implements ServerEventsListener {
         csr_path,
         csr,
       );
+      console.log(
+        `[conn] Detected ${app_name} on ${query.device_id} in certificate`,
+      );
     }
 
     query.app = appNameWithUpdateHint(query);
@@ -303,8 +309,9 @@ class ServerController extends EventEmitter implements ServerEventsListener {
       device: query.device,
       device_id: query.device_id,
     });
-    console.debug(`Device connected: ${id}`, 'server');
-
+    console.log(
+      `[conn] Matching device for ${query.app} on ${query.device_id}...`,
+    );
     const device =
       getDeviceBySerial(this.store.getState(), query.device_id) ??
       (await findDeviceForConnection(this.store, query.app, query.device_id));
@@ -324,6 +331,10 @@ class ServerController extends EventEmitter implements ServerEventsListener {
       connection: connection,
     };
 
+    console.log(
+      `[conn] Initializing client ${query.app} on ${query.device_id}...`,
+    );
+
     await client.init();
 
     connection.subscribeToEvents((status: ConnectionStatus) => {
@@ -336,7 +347,7 @@ class ServerController extends EventEmitter implements ServerEventsListener {
     });
 
     console.debug(
-      `Device client initialized: ${id}. Supported plugins: ${Array.from(
+      `[conn] Device client initialized: ${id}. Supported plugins: ${Array.from(
         client.plugins,
       ).join(', ')}`,
       'server',
@@ -382,6 +393,9 @@ class ServerController extends EventEmitter implements ServerEventsListener {
   removeConnection(id: string) {
     const info = this.connections.get(id);
     if (info) {
+      console.log(
+        `[conn] Disconnected: ${info.client.query.app} on ${info.client.query.device_id}.`,
+      );
       info.client.disconnect();
       this.connections.delete(id);
       this.emit('clients-change');
@@ -412,7 +426,7 @@ class ConnectionTracker {
     this.connectionAttempts.set(key, entry);
     if (entry.length >= this.connectionProblemThreshold) {
       console.error(
-        `Connection loop detected with ${key}. Connected ${
+        `[conn] Connection loop detected with ${key}. Connected ${
           this.connectionProblemThreshold
         } times within ${this.timeWindowMillis / 1000}s.`,
         'server',
@@ -444,7 +458,10 @@ async function findDeviceForConnection(
       const timeout = setTimeout(() => {
         unsubscribe();
         const error = `Timed out waiting for device ${serial} for client ${clientId}`;
-        console.error('Unable to find device for connection. Error:', error);
+        console.error(
+          '[conn] Unable to find device for connection. Error:',
+          error,
+        );
         reject(error);
       }, 15000);
       unsubscribe = sideEffect(
@@ -460,6 +477,7 @@ async function findDeviceForConnection(
             (device) => device.serial === serial,
           );
           if (matchingDevice) {
+            console.log(`[conn] Found device for: ${clientId} on ${serial}.`);
             clearTimeout(timeout);
             resolve(matchingDevice);
             unsubscribe();