Precompute serialization flags; leave @LoadOnly out of the encode order (plan item 3.6)

core/src/main/java/dev/morphia/mapping/codec/MorphiaPropertySerialization.java

@@ -1,8 +1,6 @@
 package dev.morphia.mapping.codec;
 
-import java.lang.annotation.Annotation;
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 
 import com.mongodb.lang.Nullable;
@@ -17,44 +15,31 @@
  * Determines if a property should be serialized or not
  */
 public class MorphiaPropertySerialization implements PropertySerialization<Object> {
-    private final List<Annotation> annotations;
-    private final MorphiaConfig config;
-
-    private final PropertyModel property;
+    // all fixed once the property is mapped, so worked out here rather than on every value
+    private final boolean storeNulls;
+    private final boolean storeEmpties;
+    private final boolean neverSerialized;
 
     /**
      * @param config   the configuration to use
      * @param property the property in question
      */
     public MorphiaPropertySerialization(MorphiaConfig config, PropertyModel property) {
-        this.config = config;
-        annotations = property.getAnnotations();
-        this.property = property;
+        storeNulls = config.storeNulls();
+        storeEmpties = config.storeEmpties();
+        neverSerialized = property.hasAnnotation(LoadOnly.class) || config.ignoreFinals() && property.isFinal();
     }
 
     @Override
     public boolean shouldSerialize(@Nullable Object value) {
-        if (!config.storeNulls() && value == null) {
-            return false;
-        }
-        if (config.ignoreFinals() && property.isFinal()) {
+        if (neverSerialized) {
             return false;
         }
-        if (!config.storeEmpties()) {
-            if (value instanceof Map && ((Map<?, ?>) value).isEmpty()
-                    || value instanceof Collection && ((Collection<?>) value).isEmpty()) {
-                return false;
-            }
-        }
-        return isNotLoadOnly();
-    }
-
-    private boolean isNotLoadOnly() {
-        for (int i = 0; i < annotations.size(); i++) {
-            if (annotations.get(i).annotationType().equals(LoadOnly.class)) {
-                return false;
-            }
+        if (value == null) {
+            return storeNulls;
         }
-        return true;
+        return storeEmpties
+                || !(value instanceof Map && ((Map<?, ?>) value).isEmpty()
+                        || value instanceof Collection && ((Collection<?>) value).isEmpty());
     }
 }

core/src/main/java/dev/morphia/mapping/codec/pojo/CodecPlan.java

@@ -6,6 +6,7 @@
 
 import com.mongodb.lang.Nullable;
 
+import dev.morphia.annotations.LoadOnly;
 import dev.morphia.annotations.internal.MorphiaInternal;
 import dev.morphia.mapping.codec.EnumCodec;
 import dev.morphia.mapping.codec.MorphiaDateCodec;
@@ -84,8 +85,9 @@ public final class CodecPlan {
             directBsonTypes[slot] = codecs[slot] != null ? DIRECT_BSON_TYPES.getOrDefault(codecs[slot].getClass(), 0) : 0;
         }
         PropertyModel idProperty = model.getIdProperty();
+        // the id is written first, separately, and @LoadOnly properties are never written by any encoder
         encodeOrder = Arrays.stream(properties)
-                .filter(property -> property != idProperty)
+                .filter(property -> property != idProperty && !property.hasAnnotation(LoadOnly.class))
                 .toArray(PropertyModel[]::new);
     }
 
@@ -128,7 +130,8 @@ private static int mask(BsonType... types) {
     }
 
     /**
-     * @return the properties to encode after the id, in order. Callers must not modify the array.
+     * @return the properties to encode after the id, in order, without {@code @LoadOnly} properties. Callers must not
+     *         modify the array.
      */
     PropertyModel[] encodeOrder() {
         return encodeOrder;

core/src/main/java/dev/morphia/mapping/codec/pojo/EntityEncoder.java

@@ -15,8 +15,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import static dev.morphia.mapping.codec.CodecHelper.document;
-
 /**
  * @param <T> the entity type
  * @hidden
@@ -42,19 +40,16 @@ public void encode(BsonWriter writer, T value, EncoderContext encoderContext) {
         if (areEquivalentTypes(value.getClass(), model.getType())) {
             LOG.debug("Encoding document using codec for {}", morphiaCodec.getEntityModel().getType().getName());
 
-            document(writer, () -> {
-
-                PropertyModel idModel = model.getIdProperty();
-                encodeIdProperty(writer, value, encoderContext, idModel);
-
-                if (model.useDiscriminator()) {
-                    encodeDiscriminator(writer, model);
-                }
-
-                for (PropertyModel propertyModel : morphiaCodec.getPlan().encodeOrder()) {
-                    encodeProperty(writer, propertyModel, value, encoderContext);
-                }
-            });
+            // written out rather than through CodecHelper.document, whose lambda would capture these locals per encode
+            writer.writeStartDocument();
+            encodeIdProperty(writer, value, encoderContext, model.getIdProperty());
+            if (model.useDiscriminator()) {
+                encodeDiscriminator(writer, model);
+            }
+            for (PropertyModel propertyModel : morphiaCodec.getPlan().encodeOrder()) {
+                encodeProperty(writer, propertyModel, value, encoderContext);
+            }
+            writer.writeEndDocument();
         } else {
             morphiaCodec.codecForSubtype((Class) value.getClass())
                     .encode(writer, value, encoderContext);

core/src/test/java/dev/morphia/mapping/codec/pojo/TestCodecPlanEncodeOrder.java

@@ -0,0 +1,50 @@
+package dev.morphia.mapping.codec.pojo;
+
+import java.util.Arrays;
+import java.util.List;
+
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+
+import dev.morphia.MorphiaDatastore;
+import dev.morphia.annotations.LoadOnly;
+import dev.morphia.config.ManualMorphiaConfig;
+import dev.morphia.mapping.DiscriminatorFunction;
+import dev.morphia.mapping.MapperType;
+import dev.morphia.test.mapping.codec.harness.models.HarnessRenames;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+/**
+ * The plan's encode order holds every property an encoder may write, in model order: everything but the id, which is
+ * written first on its own, and {@code @LoadOnly} properties, which no encoder writes.
+ */
+public class TestCodecPlanEncodeOrder {
+    @ParameterizedTest
+    @EnumSource(MapperType.class)
+    void leavesOutTheIdAndLoadOnlyProperties(MapperType mapper) {
+        // nothing here talks to a server
+        try (MongoClient client = MongoClients.create("mongodb://localhost:1")) {
+            MorphiaDatastore datastore = new MorphiaDatastore(client, ManualMorphiaConfig.configure()
+                    .database("codec_plan_encode_order")
+                    .mapper(mapper)
+                    .packages(List.of(HarnessRenames.class.getPackageName()))
+                    .discriminator(DiscriminatorFunction.className())
+                    .applyIndexes(false)
+                    .applyCaps(false)
+                    .applyDocumentValidations(false));
+            CodecPlan plan = ((MorphiaCodec<?>) datastore.getCodecRegistry().get(HarnessRenames.class)).getPlan();
+            EntityModel model = plan.model();
+
+            List<PropertyModel> expected = model.getProperties().stream()
+                    .filter(property -> property != model.getIdProperty() && !property.hasAnnotation(LoadOnly.class))
+                    .toList();
+            Assertions.assertEquals(expected, Arrays.asList(plan.encodeOrder()));
+            Assertions.assertTrue(Arrays.stream(plan.encodeOrder()).noneMatch(property -> property.getName().equals("legacy")),
+                    mapper + ": the @LoadOnly property is left out");
+            Assertions.assertEquals(model.getProperties().size() - 2, plan.encodeOrder().length, mapper.toString());
+        }
+    }
+}

design/mapping-game-plan.md

@@ -234,7 +234,7 @@ JMH numbers on both mappers.
 - Cache `ArrayCodec`'s component codec.
 - Add a per-codec subtype-codec cache for encode.
 
-### 3.6 Precompute serialization flags and the encode order (#6, B11/A7)
+### ~~3.6 Precompute serialization flags and the encode order (#6, B11/A7)~~
 - Give `MorphiaPropertySerialization` final booleans.
 - Put `encodeOrder` in the plan, without the id property and without properties that are always skipped.
 - Use `==` instead of `equals(idModel)`. The deep `equals` is already gone after 2.7.