refactor: Optimize startup time with adaptive server pinging (pgadmin-org#9782)

* Fix exponential backoff logic and ping race condition in desktop startup
* Adaptive polling mechanism in startDesktopMode().
   -  Fix exponential backoff to cap at 1000ms instead of cycling back to 100ms
   - Move pingInProgress flag before the async pingServer() call to prevent race conditions
* Update showErrorDialog to use clearTimeout consistent with setTimeout-based scheduling

Author: dev-hari-prasad

runtime/src/js/pgadmin.js

@@ -159,11 +159,11 @@ function openConfigure() {
   }
 }
 
-function showErrorDialog(intervalID) {
+function showErrorDialog(timeoutID) {
   if(!splashWindow.isVisible()) {
     return;
   }
-  clearInterval(intervalID);
+  clearTimeout(timeoutID);
   splashWindow.close();
 
   new BrowserWindow({
@@ -222,7 +222,7 @@ function startDesktopMode() {
   if (pgadminServerProcess != null)
     return;
 
-  let pingIntervalID;
+  let pingTimeoutID;
   // Set the environment variables so that pgAdmin 4 server
   // starts listening on the appropriate port.
   process.env.PGADMIN_INT_PORT = serverPort;
@@ -271,7 +271,7 @@ function startDesktopMode() {
     // Log the error into the log file if process failed to launch
     misc.writeServerLog('Failed to launch pgAdmin4. Error:');
     misc.writeServerLog(err);
-    showErrorDialog(pingIntervalID);
+    showErrorDialog(pingTimeoutID);
   });
 
   let spawnEndTime = (new Date).getTime();
@@ -299,22 +299,27 @@ function startDesktopMode() {
   let midTime1 = currentTime + (connectionTimeout / 2);
   let midTime2 = currentTime + (connectionTimeout * 2 / 3);
   let pingInProgress = false;
+  let currentPingInterval = 100;
 
-  // ping pgAdmin server every 1 second.
+  // ping pgAdmin server with adaptive polling.
   let pingStartTime = (new Date).getTime();
-  pingIntervalID = setInterval(function () {
+  
+  function performPing() {
     // If ping request is already send and response is not
     // received no need to send another request.
-    if (pingInProgress)
+    if (pingInProgress) {
+      pingTimeoutID = setTimeout(performPing, currentPingInterval);
       return;
+    }
 
+    pingInProgress = true;
     pingServer().then(() => {
       pingInProgress = false;
       splashWindow.webContents.executeJavaScript('document.getElementById(\'loader-text-status\').innerHTML = \'pgAdmin 4 started\';', true);
       // Set the pgAdmin process object to misc
       misc.setProcessObject(pgadminServerProcess);
 
-      clearInterval(pingIntervalID);
+      clearTimeout(pingTimeoutID);
       let appEndTime = (new Date).getTime();
       misc.writeServerLog('------------------------------------------');
       misc.writeServerLog('Total time taken to ping pgAdmin4 server: ' + (appEndTime - pingStartTime) / 1000 + ' Sec');
@@ -328,7 +333,8 @@ function startDesktopMode() {
       // if the connection timeout has lapsed then throw an error
       // and stop pinging the server.
       if (curTime >= endTime) {
-        showErrorDialog(pingIntervalID);
+        showErrorDialog(pingTimeoutID);
+        return;
       }
 
       if (curTime > midTime1) {
@@ -338,10 +344,15 @@ function startDesktopMode() {
           splashWindow.webContents.executeJavaScript('document.getElementById(\'loader-text-status\').innerHTML = \'Almost there...\';', true);
         }
       }
-    });
 
-    pingInProgress = true;
-  }, 1000);
+      pingTimeoutID = setTimeout(performPing, currentPingInterval);
+      if (currentPingInterval < 1000) {
+        currentPingInterval = Math.min(currentPingInterval * 2, 1000);
+      }
+    });
+  }
+  
+  performPing();
 }
 
 // This function is used to hide the splash screen and create/launch