1 files changed, 66 insertions, 0 deletions
diff --git a/config-model/src/main/java/com/yahoo/schema/expressiontransforms/TensorFlowFeatureConverter.java b/config-model/src/main/java/com/yahoo/schema/expressiontransforms/TensorFlowFeatureConverter.java
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+++ b/config-model/src/main/java/com/yahoo/schema/expressiontransforms/TensorFlowFeatureConverter.java
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+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.schema.expressiontransforms;
+
+import com.yahoo.path.Path;
+import com.yahoo.searchlib.rankingexpression.rule.Arguments;
+import com.yahoo.searchlib.rankingexpression.rule.CompositeNode;
+import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
+import com.yahoo.searchlib.rankingexpression.rule.ReferenceNode;
+import com.yahoo.searchlib.rankingexpression.transform.ExpressionTransformer;
+import com.yahoo.vespa.model.ml.ConvertedModel;
+import com.yahoo.vespa.model.ml.FeatureArguments;
+
+import java.io.UncheckedIOException;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Replaces instances of the tensorflow(model-path, signature, output)
+ * pseudofeature with the native Vespa ranking expression implementing
+ * the same computation.
+ *
+ * @author bratseth
+ */
+public class TensorFlowFeatureConverter extends ExpressionTransformer<RankProfileTransformContext>  {
+
+    /** A cache of imported models indexed by model path. This avoids importing the same model multiple times. */
+    private final Map<Path, ConvertedModel> convertedTensorFlowModels = new HashMap<>();
+
+    public TensorFlowFeatureConverter() {}
+
+    @Override
+    public ExpressionNode transform(ExpressionNode node, RankProfileTransformContext context) {
+        if (node instanceof ReferenceNode)
+            return transformFeature((ReferenceNode) node, context);
+        else if (node instanceof CompositeNode)
+            return super.transformChildren((CompositeNode) node, context);
+        else
+            return node;
+    }
+
+    private ExpressionNode transformFeature(ReferenceNode feature, RankProfileTransformContext context) {
+        if ( ! feature.getName().equals("tensorflow")) return feature;
+
+        try {
+            FeatureArguments arguments = asFeatureArguments(feature.getArguments());
+            ConvertedModel convertedModel =
+                    convertedTensorFlowModels.computeIfAbsent(arguments.path(),
+                                                              path -> ConvertedModel.fromSourceOrStore(path, false, context));
+            return convertedModel.expression(arguments, context);
+        }
+        catch (IllegalArgumentException | UncheckedIOException e) {
+            throw new IllegalArgumentException("Could not use tensorflow model from " + feature, e);
+        }
+    }
+
+    private FeatureArguments asFeatureArguments(Arguments arguments) {
+        if (arguments.isEmpty())
+            throw new IllegalArgumentException("A tensorflow node must take an argument pointing to " +
+                                               "the tensorflow model directory under [application]/models");
+        if (arguments.expressions().size() > 3)
+            throw new IllegalArgumentException("A tensorflow feature can have at most 3 arguments");
+
+        return new FeatureArguments(arguments);
+    }
+
+}