Separate AbstractSymbolBlock from AbstractBlock

Right now, the AbstractSymbolBlock inherits from AbstractBlock. However, the
AbstractBlock parameters system and getParameters implies that it is always
possible to get the parameters for a block. While this should be true for a
correctly written DJL block, it is not always true to symbol blocks.

So, this change separates them to ensure that trying to get parameters when it
is not possible returns the exception reflecting that the operation is
unsupported. The shared functionality between AbstractSymbolBlock and
AbstractBlock was moved to a common base class, AbstractBaseBlock.

api/src/main/java/ai/djl/nn/AbstractSymbolBlock.java

@@ -15,7 +15,7 @@
 import ai.djl.ndarray.types.Shape;
 
 /** {@code AbstractSymbolBlock} is an abstract implementation of {@link SymbolBlock}. */
-public abstract class AbstractSymbolBlock extends AbstractBlock implements SymbolBlock {
+public abstract class AbstractSymbolBlock extends AbstractBaseBlock implements SymbolBlock {
 
     /** Constructs a new {@code AbstractSymbolBlock} instance. */
     public AbstractSymbolBlock() {}
@@ -34,4 +34,10 @@ public AbstractSymbolBlock(byte version) {
     public Shape[] getOutputShapes(Shape[] inputShapes) {
         throw new UnsupportedOperationException("not implement!");
     }
+
+    /** {@inheritDoc} */
+    @Override
+    public BlockList getChildren() {
+        return new BlockList();
+    }
 }

engines/dlr/dlr-engine/src/main/java/ai/djl/dlr/engine/DlrSymbolBlock.java

@@ -16,6 +16,7 @@
 import ai.djl.dlr.jni.JniUtils;
 import ai.djl.ndarray.NDList;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.training.ParameterStore;
 import ai.djl.util.PairList;
@@ -75,4 +76,10 @@ public void close() {
             JniUtils.deleteDlrModel(pointer);
         }
     }
+
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
 }

engines/ml/xgboost/src/main/java/ai/djl/ml/xgboost/XgbSymbolBlock.java

@@ -17,6 +17,7 @@
 import ai.djl.ndarray.types.DataType;
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.training.ParameterStore;
 import ai.djl.util.PairList;
@@ -105,6 +106,12 @@ void setTreeLimit(int treeLimit) {
         this.treeLimit = treeLimit;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
+
     /** The mode of inference for OptionMask. */
     public enum Mode {
         DEFAULT(0),

engines/mxnet/mxnet-engine/src/main/java/ai/djl/mxnet/engine/MxSymbolBlock.java

@@ -21,6 +21,7 @@
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
 import ai.djl.nn.Parameter;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.training.ParameterStore;
 import ai.djl.util.PairList;
@@ -31,6 +32,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -53,6 +55,7 @@ public class MxSymbolBlock extends AbstractSymbolBlock {
     private CachedOp op;
     private Symbol symbol;
     private List<Parameter> mxNetParams; // includes input data
+    private Map<String, Parameter> parameters;
     private Map<String, Shape> paramShapes;
     private Shape[] outputShapes;
     private PairList<String, Shape> inputDescriptions;
@@ -94,9 +97,10 @@ public void setInputNames(List<String> inputNames) {
         // now that we know which of the parameters are just input placeholders and which
         // are trainable, add them properly so they are correctly handled
         Set<String> nameLookup = new HashSet<>(inputNames);
+        parameters = new LinkedHashMap<>(mxNetParams.size());
         for (Parameter mxNetParameter : mxNetParams) {
             if (!nameLookup.contains(mxNetParameter.getName())) {
-                addParameter(mxNetParameter);
+                parameters.put(mxNetParameter.getName(), mxNetParameter);
             }
         }
     }
@@ -156,6 +160,11 @@ public PairList<String, Shape> describeInput() {
         return inputDescriptions;
     }
 
+    @Override
+    public ParameterList getDirectParameters() {
+        return new ParameterList(parameters);
+    }
+
     /** {@inheritDoc} */
     @Override
     public PairList<String, Shape> describeOutput() {

engines/onnxruntime/onnxruntime-engine/src/main/java/ai/djl/onnxruntime/engine/OrtSymbolBlock.java

@@ -20,6 +20,7 @@
 import ai.djl.ndarray.types.DataType;
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.training.ParameterStore;
 import ai.djl.util.PairList;
@@ -174,4 +175,10 @@ public void close() {
             }
         }
     }
+
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
 }

engines/paddlepaddle/paddlepaddle-engine/src/main/java/ai/djl/paddlepaddle/engine/PpSymbolBlock.java

@@ -17,6 +17,7 @@
 import ai.djl.ndarray.NDManager;
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.paddlepaddle.jni.JniUtils;
 import ai.djl.training.ParameterStore;
@@ -73,6 +74,12 @@ private PpNDArray[] getInputs(PpNDManager sub, NDList inputs) {
         return inputArray;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
+
     /** {@inheritDoc} */
     @Override
     public Shape[] getOutputShapes(Shape[] inputShapes) {

engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtSymbolBlock.java

@@ -18,6 +18,8 @@
 import ai.djl.ndarray.NDManager;
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.Parameter;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.pytorch.jni.IValue;
 import ai.djl.pytorch.jni.IValueUtils;
@@ -27,6 +29,8 @@
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
+import java.util.LinkedHashMap;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -49,6 +53,7 @@ public class PtSymbolBlock extends AbstractSymbolBlock implements AutoCloseable
     private PairList<String, Shape> inputDescriptions;
     private PairList<String, Shape> outputDescriptions;
     private boolean first;
+    private Map<String, Parameter> parameters;
 
     /**
      * Constructs a {@code PtSymbolBlock}.
@@ -146,6 +151,42 @@ public PairList<String, Shape> describeInput() {
         return inputDescriptions;
     }
 
+    @Override
+    public ParameterList getDirectParameters() {
+        if (parameters == null) {
+            NDList params = JniUtils.moduleGetParams(this, manager);
+            parameters = new LinkedHashMap<>(params.size());
+            for (NDArray param : params) {
+                parameters.put(
+                        param.getName(),
+                        Parameter.builder()
+                                .setName(param.getName())
+                                .setType(inferType(param.getName()))
+                                .optArray(param)
+                                .build());
+            }
+        }
+        // Defensive copy
+        return new ParameterList(parameters);
+    }
+
+    private static Parameter.Type inferType(String name) {
+        if (name.contains("bias")) {
+            return Parameter.Type.BIAS;
+        } else if (name.contains("gamma")) {
+            return Parameter.Type.GAMMA;
+        } else if (name.contains("beta")) {
+            return Parameter.Type.BETA;
+        } else if (name.contains("moving_mean") || name.contains("running_mean")) {
+            return Parameter.Type.RUNNING_MEAN;
+        } else if (name.contains("moving_var") || name.contains("running_var")) {
+            return Parameter.Type.RUNNING_VAR;
+        } else if (name.contains("weight")) {
+            return Parameter.Type.WEIGHT;
+        }
+        return Parameter.Type.OTHER;
+    }
+
     /** {@inheritDoc} */
     @Override
     public PairList<String, Shape> describeOutput() {

engines/tensorflow/tensorflow-engine/src/main/java/ai/djl/tensorflow/engine/TfSymbolBlock.java

@@ -19,6 +19,7 @@
 import ai.djl.ndarray.types.DataType;
 import ai.djl.ndarray.types.Shape;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.tensorflow.engine.javacpp.JavacppUtils;
 import ai.djl.training.ParameterStore;
@@ -192,6 +193,12 @@ public final PairList<String, Shape> describeInput() {
         return inputDescriptions;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
+
     /** {@inheritDoc} */
     @Override
     public final PairList<String, Shape> describeOutput() {

engines/tensorrt/src/main/java/ai/djl/tensorrt/engine/TrtSymbolBlock.java

@@ -15,6 +15,7 @@
 
 import ai.djl.ndarray.NDList;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.tensorrt.jni.JniUtils;
 import ai.djl.training.ParameterStore;
@@ -66,4 +67,10 @@ TrtSession createSession(TrtNDManager manager) {
         long session = JniUtils.createSession(handle.get());
         return new TrtSession(manager, handle.get(), session);
     }
+
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
 }

engines/tflite/tflite-engine/src/main/java/ai/djl/tflite/engine/TfLiteSymbolBlock.java

@@ -16,6 +16,7 @@
 import ai.djl.ndarray.NDArray;
 import ai.djl.ndarray.NDList;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import ai.djl.nn.SymbolBlock;
 import ai.djl.training.ParameterStore;
 import ai.djl.util.PairList;
@@ -65,4 +66,10 @@ protected NDList forwardInternal(
     public void close() {
         interpreter.close();
     }
+
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
 }

extensions/fasttext/src/main/java/ai/djl/fasttext/FtAbstractBlock.java

@@ -14,6 +14,7 @@
 
 import ai.djl.fasttext.jni.FtWrapper;
 import ai.djl.nn.AbstractSymbolBlock;
+import ai.djl.nn.ParameterList;
 import java.nio.file.Path;
 
 /**
@@ -55,6 +56,12 @@ public float[] embedWord(String word) {
         return fta.getWordVector(word);
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public ParameterList getDirectParameters() {
+        throw new UnsupportedOperationException("Not yet supported");
+    }
+
     @Override
     public void close() {
         fta.unloadModel();