Fix emulator boot reliability: AVD detection order, offline skip, early exit

src/Xamarin.Android.Tools.AndroidSdk/Runners/AdbRunner.cs

@@ -48,7 +48,8 @@ public AdbRunner (string adbPath, IDictionary<string, string>? environmentVariab
 
 	/// <summary>
 	/// Lists connected devices using 'adb devices -l'.
-	/// For emulators, queries the AVD name using 'adb -s &lt;serial&gt; emu avd name'.
+	/// For online emulators, queries the AVD name via <c>getprop</c> / <c>emu avd name</c>.
+	/// Offline emulators are included but without AVD names (querying them would fail).
 	/// </summary>
 	public virtual async Task<IReadOnlyList<AdbDeviceInfo>> ListDevicesAsync (CancellationToken cancellationToken = default)
 	{
@@ -61,9 +62,11 @@ public virtual async Task<IReadOnlyList<AdbDeviceInfo>> ListDevicesAsync (Cancel
 
 		var devices = ParseAdbDevicesOutput (stdout.ToString ().Split ('\n'));
 
-		// For each emulator, try to get the AVD name
+		// For each online emulator, try to get the AVD name.
+		// Skip offline emulators — neither getprop nor 'emu avd name' work on them
+		// and attempting these commands causes unnecessary delays during boot polling.
 		foreach (var device in devices) {
-			if (device.Type == AdbDeviceType.Emulator) {
+			if (device.Type == AdbDeviceType.Emulator && device.Status == AdbDeviceStatus.Online) {
 				device.AvdName = await GetEmulatorAvdNameAsync (device.Serial, cancellationToken).ConfigureAwait (false);
 				device.Description = BuildDeviceDescription (device);
 			}
@@ -74,15 +77,26 @@ public virtual async Task<IReadOnlyList<AdbDeviceInfo>> ListDevicesAsync (Cancel
 
 	/// <summary>
 	/// Queries the emulator for its AVD name.
-	/// Tries <c>adb -s &lt;serial&gt; emu avd name</c> first (emulator console protocol),
-	/// then falls back to <c>adb shell getprop ro.boot.qemu.avd_name</c> which reads the
-	/// boot property set by the emulator kernel. The fallback is needed because
-	/// <c>emu avd name</c> can return empty output on some adb/emulator version
-	/// combinations (observed with adb v36).
+	/// Tries <c>adb shell getprop ro.boot.qemu.avd_name</c> first (reliable on all modern
+	/// emulators), then falls back to <c>adb -s &lt;serial&gt; emu avd name</c> (emulator
+	/// console protocol) for older emulator versions. The <c>emu avd name</c> command returns
+	/// empty output on emulator 36.4.10+ (observed with adb v36), so <c>getprop</c> is the
+	/// preferred method.
 	/// </summary>
 	internal async Task<string?> GetEmulatorAvdNameAsync (string serial, CancellationToken cancellationToken = default)
 	{
-		// Try 1: Console command (fast, works on most emulator versions)
+		// Try 1: Shell property (reliable on modern emulators, always set by the emulator kernel)
+		try {
+			var avdName = await GetShellPropertyAsync (serial, "ro.boot.qemu.avd_name", cancellationToken).ConfigureAwait (false);
+			if (avdName is { Length: > 0 } name && !string.IsNullOrWhiteSpace (name))
+				return name.Trim ();
+		} catch (OperationCanceledException) {
+			throw;
+		} catch {
+			// Fall through to console command fallback
+		}
+
+		// Try 2: Console command (fallback for older emulators where getprop may not be available)
 		try {
 			using var stdout = new StringWriter ();
 			var psi = ProcessUtils.CreateProcessStartInfo (adbPath, "-s", serial, "emu", "avd", "name");
@@ -97,17 +111,6 @@ public virtual async Task<IReadOnlyList<AdbDeviceInfo>> ListDevicesAsync (Cancel
 			}
 		} catch (OperationCanceledException) {
 			throw;
-		} catch {
-			// Fall through to getprop fallback
-		}
-
-		// Try 2: Shell property (fallback when 'adb emu avd name' returns empty on some adb/emulator versions)
-		try {
-			var avdName = await GetShellPropertyAsync (serial, "ro.boot.qemu.avd_name", cancellationToken).ConfigureAwait (false);
-			if (avdName is { Length: > 0 } name && !string.IsNullOrWhiteSpace (name))
-				return name.Trim ();
-		} catch (OperationCanceledException) {
-			throw;
 		} catch {
 			// Both methods failed
 		}

src/Xamarin.Android.Tools.AndroidSdk/Runners/EmulatorRunner.cs

@@ -204,10 +204,33 @@ public async Task<EmulatorBootResult> BootEmulatorAsync (
 		// Poll for the new emulator serial to appear.
 		// If the boot times out or is cancelled, terminate the process we spawned
 		// to avoid leaving orphan emulator processes.
+		//
+		// On macOS, the emulator binary may fork the real QEMU process and exit with
+		// code 0 immediately. The real emulator continues as a separate process and
+		// will eventually appear in 'adb devices'. We only treat non-zero exit codes
+		// as immediate failures; exit code 0 means we continue polling.
 		try {
 			string? newSerial = null;
+			bool processExitedWithZero = false;
 			while (newSerial == null) {
 				timeoutCts.Token.ThrowIfCancellationRequested ();
+
+				// Detect early process exit for fast failure
+				if (emulatorProcess.HasExited && !processExitedWithZero) {
+					if (emulatorProcess.ExitCode != 0) {
+						emulatorProcess.Dispose ();
+						return new EmulatorBootResult {
+							Success = false,
+							ErrorKind = EmulatorBootErrorKind.LaunchFailed,
+							ErrorMessage = $"Emulator process for '{deviceOrAvdName}' exited with code {emulatorProcess.ExitCode} before becoming available.",
+						};
+					}
+					// Exit code 0: emulator likely forked (common on macOS).
+					// The real emulator runs as a separate process — keep polling.
+					logger.Invoke (TraceLevel.Verbose, $"Emulator launcher process exited with code 0 (likely forked). Continuing to poll adb devices.");
+					processExitedWithZero = true;
+				}
+
 				await Task.Delay (options.PollInterval, timeoutCts.Token).ConfigureAwait (false);
 
 				devices = await adbRunner.ListDevicesAsync (timeoutCts.Token).ConfigureAwait (false);