Remove dead JSON serialization from Signature and FunctionMetadata

Neither type is ever serialized at runtime: there is no JsonCodec or
deserializer binding for either, no server/REST DTO carries a raw
Signature, and the plan wire form uses BoundSignature (resolved, with
concrete types). The @JsonProperty getters and @JsonCreator fromJson
factories were dead code — the only exercise was a single round-trip
test. Remove them, and trim that test to the structural assertions it
still covers, so the upcoming change to how a Signature represents its
argument and return types need not carry a serialization format that
nothing uses.

Author: martint

core/trino-main/src/test/java/io/trino/metadata/TestSignature.java

@@ -13,72 +13,29 @@
  */
 package io.trino.metadata;
 
-import com.google.common.collect.ImmutableMap;
-import io.airlift.json.JsonCodec;
-import io.airlift.json.JsonCodecFactory;
-import io.airlift.json.JsonMapperProvider;
 import io.trino.spi.function.Signature;
 import io.trino.spi.function.Signature.Argument;
-import io.trino.spi.type.Type;
-import io.trino.spi.type.TypeSignature;
-import io.trino.type.TypeDeserializer;
-import io.trino.type.TypeSignatureDeserializer;
 import org.junit.jupiter.api.Test;
 
 import java.util.Optional;
 
 import static io.trino.spi.type.BigintType.BIGINT;
-import static io.trino.spi.type.BooleanType.BOOLEAN;
-import static io.trino.spi.type.DoubleType.DOUBLE;
 import static io.trino.spi.type.VarcharType.VARCHAR;
-import static io.trino.type.InternalTypeManager.TESTING_TYPE_MANAGER;
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class TestSignature
 {
-    private static final JsonCodec<Signature> CODEC = new JsonCodecFactory(
-            new JsonMapperProvider()
-                    .withJsonDeserializers(ImmutableMap.of(
-                            Type.class, new TypeDeserializer(TESTING_TYPE_MANAGER),
-                            TypeSignature.class, new TypeSignatureDeserializer()))
-                    .get())
-            .prettyPrint()
-            .jsonCodec(Signature.class);
-
-    @Test
-    public void testSerializationRoundTrip()
-    {
-        Signature expected = Signature.builder()
-                .returnType(BIGINT)
-                .argumentType(BOOLEAN)
-                .argumentType(DOUBLE)
-                .argumentType(VARCHAR)
-                .build();
-
-        String json = CODEC.toJson(expected);
-        Signature actual = CODEC.fromJson(json);
-
-        assertThat(actual).isEqualTo(expected);
-        assertThat(actual.getArguments()).allSatisfy(argument -> assertThat(argument.name()).isEmpty());
-    }
-
     @Test
-    public void testArgumentNamesRoundTrip()
+    public void testArgumentNames()
     {
-        Signature expected = Signature.builder()
+        Signature signature = Signature.builder()
                 .returnType(VARCHAR.getTypeSignature())
                 .argumentType(VARCHAR.getTypeSignature(), "string")
                 .argumentType(BIGINT.getTypeSignature(), "from")
                 .argumentType(BIGINT.getTypeSignature())
                 .build();
 
-        assertThat(expected.getArguments())
-                .extracting(Argument::name)
-                .containsExactly(Optional.of("string"), Optional.of("from"), Optional.empty());
-
-        Signature actual = CODEC.fromJson(CODEC.toJson(expected));
-        assertThat(actual).isEqualTo(expected);
-        assertThat(actual.getArguments())
+        assertThat(signature.getArguments())
                 .extracting(Argument::name)
                 .containsExactly(Optional.of("string"), Optional.of("from"), Optional.empty());
     }

core/trino-spi/pom.xml

@@ -346,6 +346,20 @@
                                     <annotationType>com.fasterxml.jackson.annotation.JsonProperty</annotationType>
                                     <justification>getArgumentTypes() is now a derived view; JsonProperty moved to getArguments()</justification>
                                 </item>
+                                <!-- Remove dead JSON serialization from Signature and FunctionMetadata (never serialized at runtime). -->
+                                <item>
+                                    <regex>true</regex>
+                                    <code>java.annotation.removed</code>
+                                    <old>method .* io\.trino\.spi\.function\.(Signature|FunctionMetadata)::.*</old>
+                                    <annotationType>com\.fasterxml\.jackson\.annotation\.Json.*</annotationType>
+                                    <justification>Signature and FunctionMetadata are never JSON-serialized at runtime; removing the dead serialization.</justification>
+                                </item>
+                                <item>
+                                    <regex>true</regex>
+                                    <code>java.method.removed</code>
+                                    <old>method .* io\.trino\.spi\.function\.(Signature|FunctionMetadata)::fromJson\(.*</old>
+                                    <justification>Remove the dead @JsonCreator; Signature/FunctionMetadata are never deserialized.</justification>
+                                </item>
                             </differences>
                         </revapi.differences>
                     </analysisConfiguration>

core/trino-spi/src/main/java/io/trino/spi/function/FunctionMetadata.java

@@ -13,9 +13,6 @@
  */
 package io.trino.spi.function;
 
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonProperty;
-import com.google.errorprone.annotations.DoNotCall;
 import io.trino.spi.type.TypeSignature;
 
 import java.util.ArrayList;
@@ -93,7 +90,6 @@ private FunctionMetadata(
     /**
      * Unique id of this function.
      */
-    @JsonProperty
     public FunctionId getFunctionId()
     {
         return functionId;
@@ -102,7 +98,6 @@ public FunctionId getFunctionId()
     /**
      * Signature of a matching call site.
      */
-    @JsonProperty
     public Signature getSignature()
     {
         return signature;
@@ -111,7 +106,6 @@ public Signature getSignature()
     /**
      * The canonical name of the function.
      */
-    @JsonProperty
     public String getCanonicalName()
     {
         return canonicalName;
@@ -120,25 +114,21 @@ public String getCanonicalName()
     /**
      * Canonical name and any aliases.
      */
-    @JsonProperty
     public Set<String> getNames()
     {
         return names;
     }
 
-    @JsonProperty
     public FunctionNullability getFunctionNullability()
     {
         return functionNullability;
     }
 
-    @JsonProperty
     public boolean isHidden()
     {
         return hidden;
     }
 
-    @JsonProperty
     public boolean isDeterministic()
     {
         return deterministic;
@@ -147,25 +137,21 @@ public boolean isDeterministic()
     /**
      * Whether function never fails for any possible combination of input parameters.
      */
-    @JsonProperty
     public boolean isNeverFails()
     {
         return neverFails;
     }
 
-    @JsonProperty
     public String getDescription()
     {
         return description;
     }
 
-    @JsonProperty
     public FunctionKind getKind()
     {
         return kind;
     }
 
-    @JsonProperty
     public boolean isDeprecated()
     {
         return deprecated;
@@ -178,7 +164,6 @@ public boolean isDeprecated()
      * the type of the {@code self} parameter (the first declared argument).
      * Empty for regular functions.
      */
-    @JsonProperty
     public Optional<TypeSignature> getReceiverType()
     {
         return receiverType;
@@ -189,45 +174,11 @@ public Optional<TypeSignature> getReceiverType()
      * argument) rather than a static method. Only meaningful when
      * {@link #getReceiverType()} is present.
      */
-    @JsonProperty
     public boolean isInstanceMethod()
     {
         return instanceMethod;
     }
 
-    @JsonCreator
-    @DoNotCall // For JSON deserialization only
-    public static FunctionMetadata fromJson(
-            @JsonProperty FunctionId functionId,
-            @JsonProperty Signature signature,
-            @JsonProperty String canonicalName,
-            @JsonProperty Set<String> names,
-            @JsonProperty FunctionNullability functionNullability,
-            @JsonProperty boolean hidden,
-            @JsonProperty boolean deterministic,
-            @JsonProperty boolean neverFails,
-            @JsonProperty String description,
-            @JsonProperty FunctionKind kind,
-            @JsonProperty boolean deprecated,
-            @JsonProperty Optional<TypeSignature> receiverType,
-            @JsonProperty boolean instanceMethod)
-    {
-        return new FunctionMetadata(
-                functionId,
-                signature,
-                canonicalName,
-                names,
-                functionNullability,
-                hidden,
-                deterministic,
-                neverFails,
-                description,
-                kind,
-                deprecated,
-                receiverType == null ? Optional.empty() : receiverType,
-                instanceMethod);
-    }
-
     @Override
     public String toString()
     {

core/trino-spi/src/main/java/io/trino/spi/function/Signature.java

@@ -13,9 +13,6 @@
  */
 package io.trino.spi.function;
 
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonProperty;
-import com.google.errorprone.annotations.DoNotCall;
 import io.trino.spi.type.Type;
 import io.trino.spi.type.TypeSignature;
 
@@ -32,7 +29,7 @@
 
 public class Signature
 {
-    public record Argument(@JsonProperty("type") TypeSignature type, @JsonProperty("name") Optional<String> name)
+    public record Argument(TypeSignature type, Optional<String> name)
     {
         public static Argument of(TypeSignature type)
         {
@@ -65,13 +62,11 @@ private Signature(
         this.variableArity = variableArity;
     }
 
-    @JsonProperty
     public TypeSignature getReturnType()
     {
         return returnType;
     }
 
-    @JsonProperty
     public List<Argument> getArguments()
     {
         return arguments;
@@ -84,7 +79,6 @@ public List<TypeSignature> getArgumentTypes()
                 .collect(toUnmodifiableList());
     }
 
-    @JsonProperty
     public boolean isVariableArity()
     {
         return variableArity;
@@ -98,13 +92,11 @@ public boolean isGeneric()
         return !typeVariableConstraints.isEmpty();
     }
 
-    @JsonProperty
     public List<TypeVariableConstraint> getTypeVariableConstraints()
     {
         return typeVariableConstraints;
     }
 
-    @JsonProperty
     public List<LongVariableConstraint> getLongVariableConstraints()
     {
         return longVariableConstraints;
@@ -308,17 +300,4 @@ public Signature build()
             return new Signature(typeVariableConstraints, longVariableConstraints, returnType, arguments, variableArity);
         }
     }
-
-    @JsonCreator
-    @DoNotCall // For JSON deserialization only
-    @Deprecated // Discourage usages in SPI consumers
-    public static Signature fromJson(
-            @JsonProperty("typeVariableConstraints") List<TypeVariableConstraint> typeVariableConstraints,
-            @JsonProperty("longVariableConstraints") List<LongVariableConstraint> longVariableConstraints,
-            @JsonProperty("returnType") TypeSignature returnType,
-            @JsonProperty("arguments") List<Argument> arguments,
-            @JsonProperty("variableArity") boolean variableArity)
-    {
-        return new Signature(typeVariableConstraints, longVariableConstraints, returnType, arguments, variableArity);
-    }
 }