Add opt-in Jackson Blackbird optimization to ObjectMappers

conjure-java-jackson-optimizations/build.gradle

@@ -3,4 +3,5 @@ apply plugin: 'com.palantir.revapi'
 
 dependencies {
     api "com.fasterxml.jackson.core:jackson-databind"
+    implementation "com.fasterxml.jackson.module:jackson-module-blackbird"
 }

conjure-java-jackson-optimizations/src/main/java/com/palantir/conjure/java/jackson/optimizations/ObjectMapperOptimizations.java

@@ -16,6 +16,7 @@
 
 package com.palantir.conjure.java.jackson.optimizations;
 
+import com.fasterxml.jackson.module.blackbird.BlackbirdModule;
 import java.util.List;
 
 /**
@@ -25,11 +26,29 @@
  */
 public final class ObjectMapperOptimizations {
 
+    // Blackbird generates classes at runtime via LambdaMetafactory, which native images cannot do.
+    private static final boolean NATIVE_IMAGE = System.getProperty("org.graalvm.nativeimage.imagecode") != null;
+
+    /** Equivalent to {@link #createModules(boolean) createModules(false)}: no optimization modules. */
     public static List<? extends com.fasterxml.jackson.databind.Module> createModules() {
-        // At one point this conditionally returned List.of(new AfterburnerModule), however afterburner is not
-        // supported on any supported LTS Java release anymore, and the Blackbird alternative incurs a memory
-        // leak (https://github.com/FasterXML/jackson-modules-base/issues/147).
-        return List.of();
+        return createModules(false);
+    }
+
+    /**
+     * Optionally registers the Blackbird module, which speeds up (de)serialization by generating accessors at
+     * runtime rather than using reflection. At one point this returned an {@code AfterburnerModule}, however
+     * afterburner is not supported on any supported LTS Java release anymore.
+     *
+     * <p>Blackbird generates a class per accessor via {@code LambdaMetafactory}. This is bounded and safe when a
+     * service reuses a small set of long-lived {@code ObjectMapper}s, but creating mappers per-request leaks
+     * compressed class space (https://github.com/FasterXML/jackson-modules-base/issues/147), so it is opt-in.
+     * Optimizations are always disabled within native images, where runtime class generation is unsupported.
+     */
+    public static List<? extends com.fasterxml.jackson.databind.Module> createModules(boolean useBlackbird) {
+        if (!useBlackbird || NATIVE_IMAGE) {
+            return List.of();
+        }
+        return List.of(new BlackbirdModule());
     }
 
     private ObjectMapperOptimizations() {}

conjure-java-jackson-serialization/src/main/java/com/palantir/conjure/java/serialization/ObjectMappers.java

@@ -50,7 +50,12 @@ private ObjectMappers() {}
      * </ul>
      */
     public static JsonMapper newClientJsonMapper() {
-        return withDefaultModules(JsonMapper.builder(jsonFactory()))
+        return newClientJsonMapper(false);
+    }
+
+    /** Like {@link #newClientJsonMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static JsonMapper newClientJsonMapper(boolean useOptimizations) {
+        return withDefaultModules(JsonMapper.builder(jsonFactory()), useOptimizations)
                 .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -65,7 +70,12 @@ public static JsonMapper newClientJsonMapper() {
      * </ul>
      */
     public static CBORMapper newClientCborMapper() {
-        return withDefaultModules(CBORMapper.builder(cborFactory()))
+        return newClientCborMapper(false);
+    }
+
+    /** Like {@link #newClientCborMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static CBORMapper newClientCborMapper(boolean useOptimizations) {
+        return withDefaultModules(CBORMapper.builder(cborFactory()), useOptimizations)
                 .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -81,7 +91,12 @@ public static CBORMapper newClientCborMapper() {
      * </ul>
      */
     public static SmileMapper newClientSmileMapper() {
-        return withDefaultModules(SmileMapper.builder(smileFactory()))
+        return newClientSmileMapper(false);
+    }
+
+    /** Like {@link #newClientSmileMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static SmileMapper newClientSmileMapper(boolean useOptimizations) {
+        return withDefaultModules(SmileMapper.builder(smileFactory()), useOptimizations)
                 .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -96,7 +111,12 @@ public static SmileMapper newClientSmileMapper() {
      * </ul>
      */
     public static JsonMapper newServerJsonMapper() {
-        return withDefaultModules(JsonMapper.builder(jsonFactory()))
+        return newServerJsonMapper(false);
+    }
+
+    /** Like {@link #newServerJsonMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static JsonMapper newServerJsonMapper(boolean useOptimizations) {
+        return withDefaultModules(JsonMapper.builder(jsonFactory()), useOptimizations)
                 .enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -111,7 +131,12 @@ public static JsonMapper newServerJsonMapper() {
      * </ul>
      */
     public static CBORMapper newServerCborMapper() {
-        return withDefaultModules(CBORMapper.builder(cborFactory()))
+        return newServerCborMapper(false);
+    }
+
+    /** Like {@link #newServerCborMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static CBORMapper newServerCborMapper(boolean useOptimizations) {
+        return withDefaultModules(CBORMapper.builder(cborFactory()), useOptimizations)
                 .enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -127,7 +152,12 @@ public static CBORMapper newServerCborMapper() {
      * </ul>
      */
     public static SmileMapper newServerSmileMapper() {
-        return withDefaultModules(SmileMapper.builder(smileFactory()))
+        return newServerSmileMapper(false);
+    }
+
+    /** Like {@link #newServerSmileMapper()}, optionally enabling Jackson optimization modules (Blackbird). */
+    public static SmileMapper newServerSmileMapper(boolean useOptimizations) {
+        return withDefaultModules(SmileMapper.builder(smileFactory()), useOptimizations)
                 .enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
                 .build();
     }
@@ -170,13 +200,22 @@ public static ObjectMapper newSmileServerObjectMapper() {
      *   <li>Deserializing a null for a primitive field will throw an exception.
      * </ul>
      */
-    @SuppressWarnings("for-rollout:deprecation")
     public static <M extends ObjectMapper, B extends MapperBuilder<M, B>> B withDefaultModules(B builder) {
+        return withDefaultModules(builder, false);
+    }
+
+    /**
+     * Like {@link #withDefaultModules(MapperBuilder)}, optionally enabling Jackson optimization modules (Blackbird).
+     * See {@link ObjectMapperOptimizations#createModules(boolean)} for the tradeoffs of enabling optimizations.
+     */
+    @SuppressWarnings("for-rollout:deprecation")
+    public static <M extends ObjectMapper, B extends MapperBuilder<M, B>> B withDefaultModules(
+            B builder, boolean useOptimizations) {
         return builder.typeFactory(NonCachingTypeFactory.from(builder.build().getTypeFactory()))
                 .addModule(new GuavaModule())
                 .addModule(new ShimJdk7Module())
                 .addModule(new Jdk8Module().configureAbsentsAsNulls(true))
-                .addModules(ObjectMapperOptimizations.createModules())
+                .addModules(ObjectMapperOptimizations.createModules(useOptimizations))
                 .addModule(new JavaTimeModule())
                 .addModule(new LenientLongModule())
                 // we strongly recommend using built-in java.time classes instead of joda ones. Joda deserialization

conjure-java-jackson-serialization/src/test/java/com/palantir/conjure/java/serialization/ObjectMappersTest.java

@@ -33,6 +33,7 @@
 import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.fasterxml.jackson.dataformat.smile.SmileFactory;
 import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
+import com.palantir.conjure.java.jackson.optimizations.ObjectMapperOptimizations;
 import com.palantir.logsafe.Preconditions;
 import com.palantir.tritium.metrics.registry.SharedTaggedMetricRegistries;
 import com.palantir.tritium.metrics.registry.TaggedMetricRegistry;
@@ -50,6 +51,7 @@
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -511,6 +513,40 @@ public void testExtraordinarilyLargeStrings() throws IOException {
         assertThat(parsed).hasSize(size);
     }
 
+    @Test
+    public void optimizationsDisabledByDefault() {
+        assertThat(ObjectMapperOptimizations.createModules()).isEmpty();
+        assertThat(ObjectMapperOptimizations.createModules(false)).isEmpty();
+        assertThat(hasBlackbird(ObjectMappers.newServerJsonMapper()))
+                .as("Blackbird should not be registered by default")
+                .isFalse();
+    }
+
+    @Test
+    public void blackbirdOptimizationRegistersModuleAndPreservesOutput() throws IOException {
+        assertThat(ObjectMapperOptimizations.createModules(true)).hasSize(1);
+
+        JsonMapper optimized = ObjectMappers.newServerJsonMapper(true);
+        assertThat(hasBlackbird(optimized))
+                .as("Blackbird should be registered when optimizations are enabled")
+                .isTrue();
+        assertThat(hasBlackbird(ObjectMappers.newClientJsonMapper(true)))
+                .as("Blackbird should be registered on client mappers too")
+                .isTrue();
+
+        // Blackbird only changes how (de)serialization is performed, not the wire output.
+        Map<String, Object> value = Map.of("name", "witchcraft", "count", 42);
+        String optimizedJson = optimized.writeValueAsString(value);
+        assertThat(optimizedJson).isEqualTo(ObjectMappers.newServerJsonMapper().writeValueAsString(value));
+        assertThat(optimized.readValue(optimizedJson, new TypeReference<Map<String, Object>>() {}))
+                .isEqualTo(value);
+    }
+
+    private static boolean hasBlackbird(ObjectMapper mapper) {
+        return mapper.getRegisteredModuleIds().stream()
+                .anyMatch(id -> id.toString().toLowerCase(Locale.ROOT).contains("blackbird"));
+    }
+
     private static String ser(Object object) throws IOException {
         return MAPPER.writeValueAsString(object);
     }

versions.lock

@@ -4,9 +4,9 @@ com.fasterxml:classmate:1.5.1 (1 constraints: 9a122a13)
 
 com.fasterxml.jackson.core:jackson-annotations:2.21 (12 constraints: 03de1b79)
 
-com.fasterxml.jackson.core:jackson-core:2.21.4 (14 constraints: d1231840)
+com.fasterxml.jackson.core:jackson-core:2.21.4 (15 constraints: 503a606a)
 
-com.fasterxml.jackson.core:jackson-databind:2.21.4 (18 constraints: c86371a8)
+com.fasterxml.jackson.core:jackson-databind:2.21.4 (19 constraints: 477ad144)
 
 com.fasterxml.jackson.dataformat:jackson-dataformat-cbor:2.21.4 (2 constraints: 2f204c06)
 
@@ -24,6 +24,8 @@ com.fasterxml.jackson.jakarta.rs:jackson-jakarta-rs-base:2.21.4 (1 constraints:
 
 com.fasterxml.jackson.jakarta.rs:jackson-jakarta-rs-cbor-provider:2.21.4 (1 constraints: 3b053a3b)
 
+com.fasterxml.jackson.module:jackson-module-blackbird:2.21.4 (1 constraints: 3b053a3b)
+
 com.fasterxml.jackson.module:jackson-module-jakarta-xmlbind-annotations:2.21.4 (2 constraints: e53097b3)
 
 com.fasterxml.jackson.module:jackson-module-scala_2.12:2.21.4 (1 constraints: 3b053a3b)