Package panamagl.platform.macos

Class AppKitMainThread

java.lang.Object

panamagl.platform.macos.AppKitMainThread

public class AppKitMainThread
extends Object

Provides main thread detection and dispatch on macOS using only the Panama FFI — no JNI and no native companion library required.

This is functionally equivalent to JOGL's OSXUtil.IsMainThread() and OSXUtil.RunOnMainThread(), with the following advantages:

• No dependency on any external native library.
• Implemented entirely with the standard java.lang.foreign API (Panama FFI).
• Consistent with the rest of PanamaGL's approach of calling native APIs directly from Java.

Uses two macOS system APIs from libSystem:

• pthread_main_np() — returns 1 if the calling thread is the main POSIX thread.
• dispatch_sync_f(queue, context, work) — synchronously dispatches a C function pointer to a GCD queue and blocks until it completes.

Important limitation

runOnMainThread(Runnable) uses dispatch_sync_f on the main dispatch queue. This requires the main thread to be running a CFRunLoop or pumping its dispatch queue. If the main thread is idle (e.g., main() has returned without entering a run loop), the call will deadlock.

Calling runOnMainThread while already on the main thread is safe — the task is executed directly to avoid deadlock.

Author:

Martin Pernollet

Method Summary

Modifier and Type	Method	Description
static boolean	isMainThread()	Returns true if the calling thread is the macOS main (AppKit) thread.
static void	runOnMainThread(Runnable task)	Executes the given task on the macOS main thread and blocks until it completes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

isMainThread

public static boolean isMainThread()

Returns true if the calling thread is the macOS main (AppKit) thread.

runOnMainThread

public static void runOnMainThread(Runnable task)

Executes the given task on the macOS main thread and blocks until it completes.

If the calling thread is already the main thread, the task is executed directly to avoid a deadlock (dispatching synchronously to the main queue from the main thread would block forever).

Parameters:

task - the task to run on the main thread

Throws:

RuntimeException - if the native dispatch call fails or the task throws