f native image, just build a jar

src/main/java/com/gregor/jprototerm/LinuxPty.java

@@ -16,19 +16,16 @@ import java.util.Map;
 /**
  * A Linux PTY backed by libc via the Foreign Function & Memory API.
  *
- * <p>This replaces pty4j (which loads a JNA JNI shim that does not initialise under a
- * GraalVM native image). It uses {@code posix_openpt}/{@code posix_spawnp} rather than
- * {@code fork}/{@code forkpty}: doing work between {@code fork} and {@code exec} inside a
- * multithreaded JVM is unsafe (only async-signal-safe calls are permitted), whereas
- * {@code posix_spawn} performs the dangerous part in libc with no Java on the stack.
+ * <p>This replaces pty4j (which loads a JNA JNI shim). It uses
+ * {@code posix_openpt}/{@code posix_spawnp} rather than {@code fork}/{@code forkpty}:
+ * doing work between {@code fork} and {@code exec} inside a multithreaded JVM is unsafe
+ * (only async-signal-safe calls are permitted), whereas {@code posix_spawn} performs the
+ * dangerous part in libc with no Java on the stack.
  *
  * <p>The child gets a fresh session via {@code POSIX_SPAWN_SETSID}; it then opens the slave
  * PTY itself (as fd 0, without {@code O_NOCTTY}) so the slave becomes its controlling
  * terminal. glibc applies attribute flags (the setsid) before file actions, so the open
  * happens in the new session.
- *
- * <p>FFM downcall descriptors are registered for native image by
- * {@link PtyForeignRegistrationFeature}; keep the two in sync.
  */
 public final class LinuxPty implements AutoCloseable {
     static final Linker LINKER = Linker.nativeLinker();
@@ -40,7 +37,7 @@ public final class LinuxPty implements AutoCloseable {
     static final ValueLayout.OfLong C_LONG = (ValueLayout.OfLong) LINKER.canonicalLayouts().get("long");
     static final ValueLayout.OfLong C_SIZE_T = (ValueLayout.OfLong) LINKER.canonicalLayouts().get("size_t");
 
-    // Function descriptors. Mirrored in PtyForeignRegistrationFeature.
+    // Function descriptors.
     static final FunctionDescriptor FD_INT_INT = FunctionDescriptor.of(C_INT, C_INT);
     static final FunctionDescriptor FD_PTSNAME_R = FunctionDescriptor.of(C_INT, C_INT, C_POINTER, C_SIZE_T);
     static final FunctionDescriptor FD_RW = FunctionDescriptor.of(C_LONG, C_INT, C_POINTER, C_SIZE_T);

src/main/java/com/gregor/jprototerm/PtyForeignRegistrationFeature.java

@@ -1,39 +0,0 @@
-package com.gregor.jprototerm;
-
-import org.graalvm.nativeimage.hosted.Feature;
-import org.graalvm.nativeimage.hosted.RuntimeForeignAccess;
-
-import java.lang.foreign.Linker;
-
-/**
- * Registers the FFM downcall descriptors used by {@link LinuxPty} for GraalVM releases that
- * do not consume {@code foreign.downcalls} from reachability-metadata.json. Mirrors
- * jlibghostty's {@code GhosttyForeignRegistrationFeature}.
- *
- * <p>Wired in via {@code --features=com.gregor.jprototerm.PtyForeignRegistrationFeature}
- * in the gluonfx compiler args.
- */
-public final class PtyForeignRegistrationFeature implements Feature {
-    @Override
-    public void duringSetup(DuringSetupAccess access) {
-        downcall(LinuxPty.FD_INT_INT);          // posix_openpt / grantpt / unlockpt / close
-        downcall(LinuxPty.FD_PTSNAME_R);        // ptsname_r
-        downcall(LinuxPty.FD_RW);               // read / write
-        downcall(LinuxPty.FD_KILL);             // kill
-        downcall(LinuxPty.FD_WAITPID);          // waitpid
-        downcall(LinuxPty.FD_SPAWN);            // posix_spawnp
-        downcall(LinuxPty.FD_FA_INIT);          // *_init / *_destroy
-        downcall(LinuxPty.FD_FA_ADDCLOSE);      // posix_spawn_file_actions_addclose
-        downcall(LinuxPty.FD_FA_ADDDUP2);       // posix_spawn_file_actions_adddup2
-        downcall(LinuxPty.FD_FA_ADDOPEN);       // posix_spawn_file_actions_addopen
-        downcall(LinuxPty.FD_FA_ADDCHDIR);      // posix_spawn_file_actions_addchdir_np
-        downcall(LinuxPty.FD_ATTR_SETFLAGS);    // posix_spawnattr_setflags
-
-        // ioctl(int, unsigned long, ...) is variadic; register with the same linker option.
-        RuntimeForeignAccess.registerForDowncall(LinuxPty.FD_IOCTL, Linker.Option.firstVariadicArg(2));
-    }
-
-    private static void downcall(java.lang.foreign.FunctionDescriptor descriptor) {
-        RuntimeForeignAccess.registerForDowncall(descriptor);
-    }
-}

src/main/java/com/gregor/jprototerm/TerminalCanvasView.java

@@ -121,13 +121,24 @@ public final class TerminalCanvasView {
         String cacheKey = paneCacheKey(pane, metrics);
         int imageWidth = Math.max(1, (int) Math.ceil(pane.width()));
         int imageHeight = Math.max(1, (int) Math.ceil(pane.height()));
-        if (cache.image == null || cache.canvas == null || cache.imageWidth != imageWidth || cache.imageHeight != imageHeight || !cacheKey.equals(cache.key)) {
+
+        // Allocate the offscreen buffers only when the pane size changes. Reallocating a
+        // full-pane Canvas + WritableImage on every content change churns ~20 MB per frame,
+        // which the native image's serial GC turns into Full-GC frame drops.
+        if (cache.canvas == null || cache.image == null || cache.imageWidth != imageWidth || cache.imageHeight != imageHeight) {
             cache.canvas = new Canvas(imageWidth, imageHeight);
-            drawPaneContent(cache.canvas.getGraphicsContext2D(), pane, font, metrics, 0.0, 0.0, imageWidth, imageHeight, true);
             cache.image = new WritableImage(imageWidth, imageHeight);
-            cache.canvas.snapshot(null, cache.image);
             cache.imageWidth = imageWidth;
             cache.imageHeight = imageHeight;
+            cache.key = null;
+        }
+
+        // Redraw and re-snapshot into the existing buffers only when content changed.
+        if (!cacheKey.equals(cache.key)) {
+            GraphicsContext cacheGc = cache.canvas.getGraphicsContext2D();
+            cacheGc.clearRect(0, 0, imageWidth, imageHeight);
+            drawPaneContent(cacheGc, pane, font, metrics, 0.0, 0.0, imageWidth, imageHeight, true);
+            cache.canvas.snapshot(null, cache.image);
             cache.key = cacheKey;
         }
 

src/main/resources/META-INF/native-image/com.gregor/jprototerm/reachability-metadata.json

@@ -1,3 +0,0 @@
-{
-  "resources": []
-}

src/main/resources/META-INF/native-image/com.gregor/jprototerm/resource-config.json

@@ -1,5 +0,0 @@
-{
-  "resources": {
-    "includes": []
-  }
-}