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fil/packages/java/dev/kreuzberg/ValidatorBridge.java

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2026-06-01 23:40:55 +02:00
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 IValidator implementation,
* assembles the C vtable in native memory, and provides static
* registerValidator/unregisterValidator helpers.
*/
public final class ValidatorBridge 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, ValidatorBridge>
VALIDATOR_BRIDGES = new ConcurrentHashMap<>();
// C vtable: 9 fields (4 plugin methods + 3 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, ValueLayout.ADDRESS, ValueLayout.ADDRESS);
private static final long VTABLE_SIZE = VTABLE_LAYOUT.byteSize();
private final Arena arena;
private final MemorySegment vtable;
private final IValidator impl;
ValidatorBridge(final IValidator 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 stubValidate = LINKER.upcallStub(LOOKUP.bind(this, "handleValidate",
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, stubValidate);
offset += ValueLayout.ADDRESS.byteSize();
var stubShouldValidate = LINKER.upcallStub(LOOKUP.bind(this, "handleShouldValidate",
MethodType.methodType(
int.class,
MemorySegment.class,
MemorySegment.class,
MemorySegment.class,
MemorySegment.class,
MemorySegment.class
)),
FunctionDescriptor.of(
ValueLayout.JAVA_INT,
ValueLayout.ADDRESS,
ValueLayout.ADDRESS,
ValueLayout.ADDRESS,
ValueLayout.ADDRESS,
ValueLayout.ADDRESS
),
arena);
vtable.set(ValueLayout.ADDRESS, offset, stubShouldValidate);
offset += ValueLayout.ADDRESS.byteSize();
var stubPriority = LINKER.upcallStub(LOOKUP.bind(this, "handlePriority",
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, stubPriority);
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 handleValidate(MemorySegment userData, MemorySegment result_in, MemorySegment config_in, MemorySegment outError) {
try {
String result_json = result_in.reinterpret(Long.MAX_VALUE).getString(0);
ExtractionResult result = JSON.readValue(result_json, ExtractionResult.class);
String config_json = config_in.reinterpret(Long.MAX_VALUE).getString(0);
ExtractionConfig config = JSON.readValue(config_json, ExtractionConfig.class);
impl.validate(result, config);
return 0;
} catch (Throwable e) {
writeError(outError, e);
return 1;
}
}
private int handleShouldValidate(
MemorySegment userData,
MemorySegment _result_in,
MemorySegment _config_in,
MemorySegment outResult,
MemorySegment outError
) {
try {
String _result_json = _result_in.reinterpret(Long.MAX_VALUE).getString(0);
ExtractionResult _result = JSON.readValue(_result_json, ExtractionResult.class);
String _config_json = _config_in.reinterpret(Long.MAX_VALUE).getString(0);
ExtractionConfig _config = JSON.readValue(_config_json, ExtractionConfig.class);
boolean result = impl.should_validate(_result, _config);
String json = JSON.writeValueAsString(result);
MemorySegment jsonCs = arena.allocateFrom(json);
outResult.set(ValueLayout.ADDRESS, 0, jsonCs);
return 0;
} catch (Throwable e) {
writeError(outError, e);
return 1;
}
}
private int handlePriority(MemorySegment userData, MemorySegment outResult, MemorySegment outError) {
try {
int result = impl.priority();
String json = JSON.writeValueAsString(result);
MemorySegment jsonCs = arena.allocateFrom(json);
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 Validator implementation via Panama FFM upcall stubs. */
public static void registerValidator(final IValidator impl) throws Exception {
var bridge = new ValidatorBridge(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_VALIDATOR.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("registerValidator: " + msg);
}
}
} catch (Throwable t) {
bridge.close();
if (t instanceof Exception e) {
throw e;
} else {
throw new RuntimeException("Unexpected error during registration", t);
}
}
VALIDATOR_BRIDGES.put(impl.name(), bridge);
}
/** Unregister a Validator implementation by name. */
public static void unregisterValidator(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_VALIDATOR.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("unregisterValidator: " + msg);
}
}
} catch (Throwable t) {
if (t instanceof Exception e) {
throw e;
} else {
throw new RuntimeException("Unexpected error during unregistration", t);
}
}
ValidatorBridge old = VALIDATOR_BRIDGES.remove(name);
if (old != null) { old.close(); }
}
/** Clear all registered Validator implementations. */
public static void clearValidators() throws Exception {
try {
try (var arena = Arena.ofShared()) {
MemorySegment outErr = arena.allocate(ValueLayout.ADDRESS);
int rc = (int) NativeLib.KREUZBERG_CLEAR_VALIDATOR.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("clearValidators: " + msg);
}
}
} catch (Throwable t) {
if (t instanceof Exception e) {
throw e;
} else {
throw new RuntimeException("Unexpected error during clear", t);
}
}
VALIDATOR_BRIDGES.values().forEach(ValidatorBridge::close);
VALIDATOR_BRIDGES.clear();
}
}