Nomad changes

packages/java/dev/kreuzberg/RendererBridge.java

@@ -0,0 +1,245 @@
+package dev.kreuzberg;
+
+import java.lang.foreign.Arena;
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.Linker;
+import java.lang.foreign.MemoryLayout;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.ValueLayout;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.util.concurrent.ConcurrentHashMap;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * Allocates Panama FFM upcall stubs for an IRenderer implementation,
+ * assembles the C vtable in native memory, and provides static
+ * registerRenderer/unregisterRenderer helpers.
+ */
+public final class RendererBridge implements AutoCloseable {
+
+    private static final Linker LINKER = Linker.nativeLinker();
+    private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
+    private static final ObjectMapper JSON = new ObjectMapper();
+
+    /** Live registry — keeps Arenas and upcall stubs alive past the register call. */
+    private static final ConcurrentHashMap<String, RendererBridge>
+            RENDERER_BRIDGES = new ConcurrentHashMap<>();
+
+    // C vtable: 7 fields (4 plugin methods + 1 trait methods + free_string + free_user_data)
+    private static final MemoryLayout VTABLE_LAYOUT = MemoryLayout.structLayout(ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS);
+    private static final long VTABLE_SIZE = VTABLE_LAYOUT.byteSize();
+
+    private final Arena arena;
+    private final MemorySegment vtable;
+    private final IRenderer impl;
+
+    RendererBridge(final IRenderer impl) {
+        this.impl = impl;
+        this.arena = Arena.ofShared();
+        this.vtable = arena.allocate(VTABLE_SIZE);
+
+        try {
+            long offset = 0L;
+
+            var stubName = LINKER.upcallStub(LOOKUP.bind(this, "handleName",
+                MethodType.methodType(int.class, MemorySegment.class, MemorySegment.class, MemorySegment.class)),
+                FunctionDescriptor.of(ValueLayout.JAVA_INT, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubName);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubVersion = LINKER.upcallStub(LOOKUP.bind(this, "handleVersion",
+                MethodType.methodType(int.class, MemorySegment.class, MemorySegment.class, MemorySegment.class)),
+                FunctionDescriptor.of(ValueLayout.JAVA_INT, ValueLayout.ADDRESS, ValueLayout.ADDRESS, ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubVersion);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubInitialize = LINKER.upcallStub(LOOKUP.bind(this, "handleInitialize",
+                MethodType.methodType(int.class, MemorySegment.class, MemorySegment.class)),
+                FunctionDescriptor.of(ValueLayout.JAVA_INT, ValueLayout.ADDRESS, ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubInitialize);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubShutdown = LINKER.upcallStub(LOOKUP.bind(this, "handleShutdown",
+                MethodType.methodType(int.class, MemorySegment.class, MemorySegment.class)),
+                FunctionDescriptor.of(ValueLayout.JAVA_INT, ValueLayout.ADDRESS, ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubShutdown);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubRender = LINKER.upcallStub(LOOKUP.bind(this, "handleRender",
+                MethodType.methodType(int.class, MemorySegment.class, MemorySegment.class, MemorySegment.class, MemorySegment.class)),
+                FunctionDescriptor.of(
+                    ValueLayout.JAVA_INT,
+                    ValueLayout.ADDRESS,
+                    ValueLayout.ADDRESS,
+                    ValueLayout.ADDRESS,
+                    ValueLayout.ADDRESS
+                ),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubRender);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubFreeString = LINKER.upcallStub(LOOKUP.bind(this, "freeString",
+                MethodType.methodType(void.class, MemorySegment.class)),
+                FunctionDescriptor.ofVoid(ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubFreeString);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+            var stubFreeUserData = LINKER.upcallStub(LOOKUP.bind(this, "freeUserData",
+                MethodType.methodType(void.class, MemorySegment.class)),
+                FunctionDescriptor.ofVoid(ValueLayout.ADDRESS),
+                arena);
+            vtable.set(ValueLayout.ADDRESS, offset, stubFreeUserData);
+            offset += ValueLayout.ADDRESS.byteSize();
+
+
+        } catch (ReflectiveOperationException e) {
+            arena.close();
+            throw new RuntimeException("Failed to create trait bridge stubs", e);
+        }
+    }
+
+    MemorySegment vtableSegment() { return vtable; }
+
+    private int handleName(MemorySegment userData, MemorySegment outName, MemorySegment outError) {
+        try {
+            outName.set(ValueLayout.ADDRESS, 0, arena.allocateFrom(impl.name()));
+            return 0;
+        } catch (Throwable e) { return 1; }
+    }
+
+    private int handleVersion(MemorySegment userData, MemorySegment outVersion, MemorySegment outError) {
+        try {
+            outVersion.set(ValueLayout.ADDRESS, 0, arena.allocateFrom(impl.version()));
+            return 0;
+        } catch (Throwable e) { return 1; }
+    }
+
+    private int handleInitialize(MemorySegment userData, MemorySegment outError) {
+        try {
+            impl.initialize();
+            return 0;
+        } catch (Throwable e) { return 1; }
+    }
+
+    private int handleShutdown(MemorySegment userData, MemorySegment outError) {
+        try {
+            impl.shutdown();
+            return 0;
+        } catch (Throwable e) { return 1; }
+    }
+
+    private int handleRender(MemorySegment userData, MemorySegment doc_in, MemorySegment outResult, MemorySegment outError) {
+        try {
+            String doc = doc_in.reinterpret(Long.MAX_VALUE).getString(0);
+            String result = impl.render(doc);
+            MemorySegment jsonCs = arena.allocateFrom(result);
+            outResult.set(ValueLayout.ADDRESS, 0, jsonCs);
+            return 0;
+        } catch (Throwable e) {
+            writeError(outError, e);
+            return 1;
+        }
+    }
+
+    private void writeError(MemorySegment outError, Throwable e) {
+        try { outError.set(ValueLayout.ADDRESS, 0, arena.allocateFrom(e.getClass().getSimpleName() + ": " + e.getMessage())); }
+        catch (Throwable ignored) { /* swallow */ }
+    }
+
+    private void freeString(MemorySegment ptr) {
+        // Strings returned by Java callbacks are arena-owned and released when this bridge closes.
+    }
+
+    private void freeUserData(MemorySegment userData) {
+        // User data is Java-side state (the impl object), not freed by Rust on drop.
+    }
+
+    /** Read a NUL-terminated native C string safely without unbounded reinterpret. */
+    private static String readNativeString(MemorySegment ptr) {
+        return ptr.reinterpret(4096).getString(0);
+    }
+
+    @Override
+    public void close() { arena.close(); }
+
+    /** Register a Renderer implementation via Panama FFM upcall stubs. */
+    public static void registerRenderer(final IRenderer impl) throws Exception {
+        var bridge = new RendererBridge(impl);
+        try {
+            try (var nameArena = Arena.ofShared()) {
+                var nameCs = nameArena.allocateFrom(impl.name());
+                MemorySegment outErr = nameArena.allocate(ValueLayout.ADDRESS);
+                int rc = (int) NativeLib.KREUZBERG_REGISTER_RENDERER.invoke(nameCs, bridge.vtableSegment(), MemorySegment.NULL, outErr);
+                if (rc != 0) {
+                    MemorySegment errPtr = outErr.get(ValueLayout.ADDRESS, 0);
+                    String msg = errPtr.equals(MemorySegment.NULL) ? "registration failed (rc=" + rc + ")" : readNativeString(errPtr);
+                    throw new RuntimeException("registerRenderer: " + msg);
+                }
+            }
+        } catch (Throwable t) {
+            bridge.close();
+            if (t instanceof Exception e) {
+                throw e;
+            } else {
+                throw new RuntimeException("Unexpected error during registration", t);
+            }
+        }
+        RENDERER_BRIDGES.put(impl.name(), bridge);
+    }
+
+    /** Unregister a Renderer implementation by name. */
+    public static void unregisterRenderer(String name) throws Exception {
+        try {
+            try (var nameArena = Arena.ofShared()) {
+                var nameCs = nameArena.allocateFrom(name);
+                MemorySegment outErr = nameArena.allocate(ValueLayout.ADDRESS);
+                int rc = (int) NativeLib.KREUZBERG_UNREGISTER_RENDERER.invoke(nameCs, outErr);
+                if (rc != 0) {
+                    MemorySegment errPtr = outErr.get(ValueLayout.ADDRESS, 0);
+                    String msg = errPtr.equals(MemorySegment.NULL)
+                        ? "unregistration failed (rc=" + rc + ")"
+                        : errPtr.reinterpret(Long.MAX_VALUE).getString(0);
+                    throw new RuntimeException("unregisterRenderer: " + msg);
+                }
+            }
+        } catch (Throwable t) {
+            if (t instanceof Exception e) {
+                throw e;
+            } else {
+                throw new RuntimeException("Unexpected error during unregistration", t);
+            }
+        }
+        RendererBridge old = RENDERER_BRIDGES.remove(name);
+        if (old != null) { old.close(); }
+    }
+    /** Clear all registered Renderer implementations. */
+    public static void clearRenderers() throws Exception {
+        try {
+            try (var arena = Arena.ofShared()) {
+                MemorySegment outErr = arena.allocate(ValueLayout.ADDRESS);
+                int rc = (int) NativeLib.KREUZBERG_CLEAR_RENDERER.invoke(outErr);
+                if (rc != 0) {
+                    MemorySegment errPtr = outErr.get(ValueLayout.ADDRESS, 0);
+                    String msg = errPtr.equals(MemorySegment.NULL)
+                        ? "clear failed (rc=" + rc + ")"
+                        : errPtr.reinterpret(Long.MAX_VALUE).getString(0);
+                    throw new RuntimeException("clearRenderers: " + msg);
+                }
+            }
+        } catch (Throwable t) {
+            if (t instanceof Exception e) {
+                throw e;
+            } else {
+                throw new RuntimeException("Unexpected error during clear", t);
+            }
+        }
+        RENDERER_BRIDGES.values().forEach(RendererBridge::close);
+        RENDERER_BRIDGES.clear();
+    }
+}