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feat(): Controller Performance Changes (WinHandler) #1455

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feat(): Controller Performance Changes (WinHandler) #1455

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b2dd5b6
feat(): Pre-allocate the SDL byte array rather than initializing it o…
phobos665 May 18, 2026
39bb8a3
feat(): Adjust sendVirtualGamepadState to also use the instance's sdl…
phobos665 May 18, 2026
9f32503
feat(): fix an issue with potentially a duplicate polling thread for …
phobos665 May 18, 2026
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47 changes: 27 additions & 20 deletions app/src/main/java/com/winlator/winhandler/WinHandler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ public class WinHandler {
private final ArrayList<Integer> xinputProcesses;
private final XServer xServer;
private final XServerView xServerView;
private byte[] sdlButtons = new byte[15];

private InputControlsView inputControlsView;
private Thread rumblePollerThread;
Expand Down Expand Up @@ -546,8 +547,12 @@ public void start() {
} catch (UnknownHostException e2) {
}
}
this.running = true;
startSendThread();

if(!this.running) {
this.running = true;
startSendThread();
}
Comment on lines +551 to +554
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@coderabbitai coderabbitai Bot May 19, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Make send-thread startup guard atomic and single-sourced.

Line 551 and Line 575 both do unsynchronized check-then-set on running, so concurrent start() calls can still pass the guard and invoke startSendThread() twice. Consolidate to one guarded block and make visibility/thread-safety explicit.

Suggested fix 
@@
-    private boolean running;
+    private volatile boolean running;
+    private final Object lifecycleLock = new Object();
@@
-        if(!this.running) {
-            this.running = true;
-            startSendThread();
-        }
+        synchronized (lifecycleLock) {
+            if (this.running) return;
+            this.running = true;
+            startSendThread();
+        }
@@
-        if(!running) {
-            running = true;
-            startSendThread();
-        }
+        // send thread already started in the lifecycle guard above

Also applies to: 575-578

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@app/src/main/java/com/winlator/winhandler/WinHandler.java` around lines 551 -
554, The two unsynchronized check-then-set guards around the field running
permit concurrent start() calls to invoke startSendThread() twice; replace both
guards with a single thread-safe startup guard: change running to an
AtomicBoolean (or make it volatile and protect with a synchronized block) and
use compareAndSet(false, true) in start() to atomically flip the flag and call
startSendThread() exactly once; remove the duplicate check at the other site so
startSendThread() is only invoked from the single guarded path (referencing the
running field, start() method, and startSendThread()).


Executors.newSingleThreadExecutor().execute(() -> {
try {
DatagramSocket datagramSocket = new DatagramSocket((SocketAddress) null);
Expand All @@ -567,8 +572,10 @@ public void start() {
});

startRumblePoller();
running = true;
startSendThread();
if(!running) {
running = true;
startSendThread();
}
}

private void startRumblePoller() {
Expand Down Expand Up @@ -811,7 +818,7 @@ private void sendMemoryFileState(ExternalController controller, MappedByteBuffer
buffer.putShort((short)lAxis);
buffer.putShort((short)rAxis);
// --- Buttons and D-Pad are perfect. No changes here. ---
byte[] sdlButtons = new byte[15];

sdlButtons[0] = state.isPressed(0) ? (byte)1 : (byte)0; // A
sdlButtons[1] = state.isPressed(1) ? (byte)1 : (byte)0; // B
sdlButtons[2] = state.isPressed(2) ? (byte)1 : (byte)0; // X
Expand Down Expand Up @@ -851,21 +858,21 @@ public void sendVirtualGamepadState(GamepadState state) {
gamepadBuffer.putShort((short)rAxis);

// Buttons & D-Pad
byte[] sdlButtons = new byte[15];
sdlButtons[0] = state.isPressed(0) ? (byte)1 : (byte)0; // A
sdlButtons[1] = state.isPressed(1) ? (byte)1 : (byte)0; // B
sdlButtons[2] = state.isPressed(2) ? (byte)1 : (byte)0; // X
sdlButtons[3] = state.isPressed(3) ? (byte)1 : (byte)0; // Y
sdlButtons[9] = state.isPressed(4) ? (byte)1 : (byte)0; // Left Bumper
sdlButtons[10] = state.isPressed(5) ? (byte)1 : (byte)0; // Right Bumper
sdlButtons[4] = state.isPressed(6) ? (byte)1 : (byte)0; // Select/Back
sdlButtons[6] = state.isPressed(7) ? (byte)1 : (byte)0; // Start
sdlButtons[7] = state.isPressed(8) ? (byte)1 : (byte)0; // Left Stick
sdlButtons[8] = state.isPressed(9) ? (byte)1 : (byte)0; // Right Stick
sdlButtons[11] = state.dpad[0] ? (byte)1 : (byte)0; // DPAD_UP
sdlButtons[12] = state.dpad[2] ? (byte)1 : (byte)0; // DPAD_DOWN
sdlButtons[13] = state.dpad[3] ? (byte)1 : (byte)0; // DPAD_LEFT
sdlButtons[14] = state.dpad[1] ? (byte)1 : (byte)0; // DPAD_RIGHT

this.sdlButtons[0] = state.isPressed(0) ? (byte)1 : (byte)0; // A
this.sdlButtons[1] = state.isPressed(1) ? (byte)1 : (byte)0; // B
this.sdlButtons[2] = state.isPressed(2) ? (byte)1 : (byte)0; // X
this.sdlButtons[3] = state.isPressed(3) ? (byte)1 : (byte)0; // Y
this.sdlButtons[9] = state.isPressed(4) ? (byte)1 : (byte)0; // Left Bumper
this.sdlButtons[10] = state.isPressed(5) ? (byte)1 : (byte)0; // Right Bumper
this.sdlButtons[4] = state.isPressed(6) ? (byte)1 : (byte)0; // Select/Back
this.sdlButtons[6] = state.isPressed(7) ? (byte)1 : (byte)0; // Start
this.sdlButtons[7] = state.isPressed(8) ? (byte)1 : (byte)0; // Left Stick
this.sdlButtons[8] = state.isPressed(9) ? (byte)1 : (byte)0; // Right Stick
this.sdlButtons[11] = state.dpad[0] ? (byte)1 : (byte)0; // DPAD_UP
this.sdlButtons[12] = state.dpad[2] ? (byte)1 : (byte)0; // DPAD_DOWN
this.sdlButtons[13] = state.dpad[3] ? (byte)1 : (byte)0; // DPAD_LEFT
this.sdlButtons[14] = state.dpad[1] ? (byte)1 : (byte)0; // DPAD_RIGHT
gamepadBuffer.put(sdlButtons);
gamepadBuffer.put((byte)0); // Ignored HAT value
}
Expand Down
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