Refactor ml extension support

api/src/main/java/ai/djl/util/passthrough/PassthroughNDArray.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.util.passthrough;
+
+import ai.djl.ndarray.NDArray;
+import ai.djl.ndarray.NDArrayAdapter;
+import java.nio.ByteBuffer;
+
+/**
+ * An {@link NDArray} that stores an arbitrary Java object.
+ *
+ * <p>This class is mainly for use in extensions and hybrid engines. Despite it's name, it will
+ * often not contain actual {@link NDArray}s but just any object necessary to conform to the DJL
+ * predictor API.
+ */
+public class PassthroughNDArray extends NDArrayAdapter {
+
+    private Object object;
+
+    /**
+     * Constructs a {@link PassthroughNDArray} storing an object.
+     *
+     * @param object the object to store
+     */
+    public PassthroughNDArray(Object object) {
+        super(null, null, null, null, null);
+        this.object = object;
+    }
+
+    /**
+     * Returns the object stored.
+     *
+     * @return the object stored
+     */
+    public Object getObject() {
+        return object;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public ByteBuffer toByteBuffer() {
+        throw new UnsupportedOperationException("Operation not supported for FastText");
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void intern(NDArray replaced) {
+        throw new UnsupportedOperationException("Operation not supported for FastText");
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void detach() {}
+}

api/src/main/java/ai/djl/util/passthrough/PassthroughNDManager.java

@@ -0,0 +1,209 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.util.passthrough;
+
+import ai.djl.Device;
+import ai.djl.engine.Engine;
+import ai.djl.ndarray.NDArray;
+import ai.djl.ndarray.NDList;
+import ai.djl.ndarray.NDManager;
+import ai.djl.ndarray.NDResource;
+import ai.djl.ndarray.types.DataType;
+import ai.djl.ndarray.types.Shape;
+import ai.djl.util.PairList;
+import java.nio.Buffer;
+import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
+import java.nio.file.Path;
+
+/** An {@link NDManager} that does nothing, for use in extensions and hybrid engines. */
+public final class PassthroughNDManager implements NDManager {
+
+    private static final String UNSUPPORTED = "Not supported by PassthroughNDManager";
+    public static final PassthroughNDManager INSTANCE = new PassthroughNDManager();
+
+    private PassthroughNDManager() {}
+
+    @Override
+    public Device defaultDevice() {
+        return Device.cpu();
+    }
+
+    @Override
+    public ByteBuffer allocateDirect(int capacity) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray from(NDArray array) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray create(String[] data, Charset charset, Shape shape) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray create(Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray createCSR(Buffer data, long[] indptr, long[] indices, Shape shape) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray createRowSparse(Buffer data, Shape dataShape, long[] indices, Shape shape) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray createCoo(Buffer data, long[][] indices, Shape shape) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDList load(Path path) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public void setName(String name) {}
+
+    @Override
+    public String getName() {
+        return "PassthroughNDManager";
+    }
+
+    @Override
+    public NDArray zeros(Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray ones(Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray full(Shape shape, float value, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray arange(float start, float stop, float step, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray eye(int rows, int cols, int k, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray linspace(float start, float stop, int num, boolean endpoint) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray randomInteger(long low, long high, Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray randomUniform(float low, float high, Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray randomNormal(float loc, float scale, Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray truncatedNormal(float loc, float scale, Shape shape, DataType dataType) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray randomMultinomial(int n, NDArray pValues) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDArray randomMultinomial(int n, NDArray pValues, Shape shape) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public boolean isOpen() {
+        return true;
+    }
+
+    @Override
+    public NDManager getParentManager() {
+        return this;
+    }
+
+    @Override
+    public NDManager newSubManager() {
+        return this;
+    }
+
+    @Override
+    public NDManager newSubManager(Device device) {
+        return this;
+    }
+
+    @Override
+    public Device getDevice() {
+        return Device.cpu();
+    }
+
+    @Override
+    public void attachInternal(String resourceId, AutoCloseable resource) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public void tempAttachInternal(
+            NDManager originalManager, String resourceId, NDResource resource) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public void detachInternal(String resourceId) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public void invoke(
+            String operation, NDArray[] src, NDArray[] dest, PairList<String, ?> params) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public NDList invoke(String operation, NDList src, PairList<String, ?> params) {
+        throw new UnsupportedOperationException(UNSUPPORTED);
+    }
+
+    @Override
+    public Engine getEngine() {
+        return null;
+    }
+
+    @Override
+    public void close() {}
+}

api/src/main/java/ai/djl/util/passthrough/PassthroughTranslator.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.util.passthrough;
+
+import ai.djl.ndarray.NDList;
+import ai.djl.translate.NoBatchifyTranslator;
+import ai.djl.translate.TranslatorContext;
+
+/**
+ * A translator that stores and removes data from a {@link PassthroughNDArray}.
+ *
+ * @param <I> translator input type
+ * @param <O> translator output type
+ */
+public class PassthroughTranslator<I, O> implements NoBatchifyTranslator<I, O> {
+
+    @Override
+    public NDList processInput(TranslatorContext ctx, I input) throws Exception {
+        return new NDList(new PassthroughNDArray(input));
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public O processOutput(TranslatorContext ctx, NDList list) {
+        PassthroughNDArray wrapper = (PassthroughNDArray) list.singletonOrThrow();
+        return (O) wrapper.getObject();
+    }
+}

api/src/main/java/ai/djl/util/passthrough/package-info.java

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+
+/** Contains passthrough DJL classes for use in extensions and hybrid engines. */
+package ai.djl.util.passthrough;

extensions/fasttext/README.md

@@ -5,8 +5,10 @@
 This module contains the NLP support with fastText implementation.
 
 fastText module's implementation in DJL is not considered as an Engine, it doesn't support Trainer and Predictor.
-The training and inference functionality is directly provided through [FtModel](https://javadoc.io/doc/ai.djl.fasttext/fasttext-engine/latest/ai/djl/fasttext/FtModel.html)
-class. You can find examples [here](https://github.com/deepjavalibrary/djl/blob/master/extensions/fasttext/src/test/java/ai/djl/fasttext/CookingStackExchangeTest.java).
+Training is only supported by using [TrainFastText](https://javadoc.io/doc/ai.djl.fasttext/fasttext-engine/latest/ai/djl/fasttext/TrainFastText.html).
+This produces a special block which can perform inference on its own or by using a model and predictor.
+Pre-trained FastText models can also be loaded by using the standard DJL criteria.
+You can find examples [here](https://github.com/deepjavalibrary/djl/blob/master/extensions/fasttext/src/test/java/ai/djl/fasttext/CookingStackExchangeTest.java).
 
 Current implementation has the following limitations: