Introduce SessionSynchronization.NEVER, reduce allocations

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>3.3.0-SNAPSHOT</version>
+	<version>3.3.0-3760-SNAPSHOT</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data MongoDB</name>

spring-data-mongodb-benchmarks/pom.xml

@@ -7,7 +7,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.3.0-SNAPSHOT</version>
+		<version>3.3.0-3760-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb-distribution/pom.xml

@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.3.0-SNAPSHOT</version>
+		<version>3.3.0-3760-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb/pom.xml

@@ -11,7 +11,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.3.0-SNAPSHOT</version>
+		<version>3.3.0-3760-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoDatabaseUtils.java

@@ -104,7 +104,8 @@ private static MongoDatabase doGetMongoDatabase(@Nullable String dbName, MongoDa
 
 		Assert.notNull(factory, "Factory must not be null!");
 
-		if (!TransactionSynchronizationManager.isSynchronizationActive()) {
+		if (sessionSynchronization == SessionSynchronization.NEVER
+				|| !TransactionSynchronizationManager.isSynchronizationActive()) {
 			return StringUtils.hasText(dbName) ? factory.getMongoDatabase(dbName) : factory.getMongoDatabase();
 		}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/ReactiveMongoDatabaseUtils.java

@@ -138,6 +138,10 @@ private static Mono<MongoDatabase> doGetMongoDatabase(@Nullable String dbName, R
 
 		Assert.notNull(factory, "DatabaseFactory must not be null!");
 
+		if (sessionSynchronization == SessionSynchronization.NEVER) {
+			return getMongoDatabaseOrDefault(dbName, factory);
+		}
+
 		return TransactionSynchronizationManager.forCurrentTransaction()
 				.filter(TransactionSynchronizationManager::isSynchronizationActive) //
 				.flatMap(synchronizationManager -> {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/SessionSynchronization.java

@@ -15,13 +15,20 @@
  */
 package org.springframework.data.mongodb;
 
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+
 /**
- * {@link SessionSynchronization} is used along with {@link org.springframework.data.mongodb.core.MongoTemplate} to
- * define in which type of transactions to participate if any.
+ * {@link SessionSynchronization} is used along with {@code MongoTemplate} to define in which type of transactions to
+ * participate if any.
  *
  * @author Christoph Strobl
  * @author Mark Paluch
  * @since 2.1
+ * @see MongoTemplate#setSessionSynchronization(SessionSynchronization)
+ * @see MongoDatabaseUtils#getDatabase(MongoDatabaseFactory, SessionSynchronization)
+ * @see ReactiveMongoTemplate#setSessionSynchronization(SessionSynchronization)
+ * @see ReactiveMongoDatabaseUtils#getDatabase(ReactiveMongoDatabaseFactory, SessionSynchronization)
  */
 public enum SessionSynchronization {
 
@@ -34,5 +41,12 @@ public enum SessionSynchronization {
 	/**
 	 * Synchronize with native MongoDB transactions initiated via {@link MongoTransactionManager}.
 	 */
-	ON_ACTUAL_TRANSACTION;
+	ON_ACTUAL_TRANSACTION,
+
+	/**
+	 * Do not participate in ongoing transactions.
+	 *
+	 * @since 3.2.5
+	 */
+	NEVER;
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MappedDocument.java

@@ -156,5 +156,14 @@ public Boolean isIsolated() {
 		public List<ArrayFilter> getArrayFilters() {
 			return delegate.getArrayFilters();
 		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.query.UpdateDefinition#hasArrayFilters()
+		 */
+		@Override
+		public boolean hasArrayFilters() {
+			return delegate.hasArrayFilters();
+		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/QueryOperations.java

@@ -613,7 +613,7 @@ class UpdateContext extends QueryContext {
 
 		UpdateContext(MappedDocument update, boolean upsert) {
 
-			super(new BasicQuery(new Document(BsonUtils.asMap(update.getIdFilter()))));
+			super(new BasicQuery(BsonUtils.asDocument(update.getIdFilter())));
 			this.multi = false;
 			this.upsert = upsert;
 			this.mappedDocument = update;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/DocumentAccessor.java

@@ -135,7 +135,7 @@ public Object get(MongoPersistentProperty property) {
 	 */
 	@Nullable
 	public Object getRawId(MongoPersistentEntity<?> entity) {
-		return entity.hasIdProperty() ? get(entity.getRequiredIdProperty()) : BsonUtils.asMap(document).get("_id");
+		return entity.hasIdProperty() ? get(entity.getRequiredIdProperty()) : BsonUtils.get(document, "_id");
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java

@@ -25,7 +25,6 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -1316,21 +1315,22 @@ protected Map<Object, Object> readMap(ConversionContext context, Bson bson, Type
 			return map;
 		}
 
-		for (Entry<String, Object> entry : sourceMap.entrySet()) {
+		sourceMap.forEach((k, v) -> {
 
-			if (typeMapper.isTypeKey(entry.getKey())) {
-				continue;
+			if (typeMapper.isTypeKey(k)) {
+				return;
 			}
 
-			Object key = potentiallyUnescapeMapKey(entry.getKey());
+			Object key = potentiallyUnescapeMapKey(k);
 
 			if (!rawKeyType.isAssignableFrom(key.getClass())) {
 				key = doConvert(key, rawKeyType);
 			}
 
-			Object value = entry.getValue();
+			Object value = v;
 			map.put(key, value == null ? value : context.convert(value, valueType));
-		}
+
+		});
 
 		return map;
 	}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MongoConverter.java

@@ -140,6 +140,9 @@ default Object convertId(@Nullable Object id, Class<?> targetType) {
 				if (ObjectId.isValid(id.toString())) {
 					return new ObjectId(id.toString());
 				}
+
+				// avoid ConversionException as convertToMongoType will return String anyways.
+				return id;
 			}
 		}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/QueryMapper.java

@@ -193,12 +193,11 @@ public Document getMappedSort(Document sortObject, @Nullable MongoPersistentEnti
 		Assert.notNull(sortObject, "SortObject must not be null!");
 
 		if (sortObject.isEmpty()) {
-			return new Document();
+			return BsonUtils.EMPTY_DOCUMENT;
 		}
 
 		Document mappedSort = mapFieldsToPropertyNames(sortObject, entity);
-		mapMetaAttributes(mappedSort, entity, MetaMapping.WHEN_PRESENT);
-		return mappedSort;
+		return mapMetaAttributes(mappedSort, entity, MetaMapping.WHEN_PRESENT);
 	}
 
 	/**
@@ -215,42 +214,51 @@ public Document getMappedFields(Document fieldsObject, @Nullable MongoPersistent
 		Assert.notNull(fieldsObject, "FieldsObject must not be null!");
 
 		Document mappedFields = mapFieldsToPropertyNames(fieldsObject, entity);
-		mapMetaAttributes(mappedFields, entity, MetaMapping.FORCE);
-		return mappedFields;
+		return mapMetaAttributes(mappedFields, entity, MetaMapping.FORCE);
 	}
 
 	private Document mapFieldsToPropertyNames(Document fields, @Nullable MongoPersistentEntity<?> entity) {
 
 		if (fields.isEmpty()) {
-			return new Document();
+			return BsonUtils.EMPTY_DOCUMENT;
 
 		}
 		Document target = new Document();
-		for (Map.Entry<String, Object> entry : BsonUtils.asMap(filterUnwrappedObjects(fields, entity)).entrySet()) {
 
-			Field field = createPropertyField(entity, entry.getKey(), mappingContext);
+		BsonUtils.asMap(filterUnwrappedObjects(fields, entity)).forEach((k, v) -> {
+
+			Field field = createPropertyField(entity, k, mappingContext);
 			if (field.getProperty() != null && field.getProperty().isUnwrapped()) {
-				continue;
+				return;
 			}
 
-			target.put(field.getMappedKey(), entry.getValue());
-		}
+			target.put(field.getMappedKey(), v);
+		});
+
 		return target;
 	}
 
-	private void mapMetaAttributes(Document source, @Nullable MongoPersistentEntity<?> entity, MetaMapping metaMapping) {
+	private Document mapMetaAttributes(Document source, @Nullable MongoPersistentEntity<?> entity,
+			MetaMapping metaMapping) {
 
 		if (entity == null) {
-			return;
+			return source;
 		}
 
 		if (entity.hasTextScoreProperty() && !MetaMapping.IGNORE.equals(metaMapping)) {
+
+			if (source == BsonUtils.EMPTY_DOCUMENT) {
+				source = new Document();
+			}
+
 			MongoPersistentProperty textScoreProperty = entity.getTextScoreProperty();
 			if (MetaMapping.FORCE.equals(metaMapping)
 					|| (MetaMapping.WHEN_PRESENT.equals(metaMapping) && source.containsKey(textScoreProperty.getFieldName()))) {
 				source.putAll(getMappedTextScoreField(textScoreProperty));
 			}
 		}
+
+		return source;
 	}
 
 	private Document filterUnwrappedObjects(Document fieldsObject, @Nullable MongoPersistentEntity<?> entity) {
@@ -679,7 +687,7 @@ protected final Entry<String, Object> createMapEntry(Field field, @Nullable Obje
 	private Entry<String, Object> createMapEntry(String key, @Nullable Object value) {
 
 		Assert.hasText(key, "Key must not be null or empty!");
-		return Collections.singletonMap(key, value).entrySet().iterator().next();
+		return new AbstractMap.SimpleEntry<>(key, value);
 	}
 
 	private Object createReferenceFor(Object source, MongoPersistentProperty property) {
@@ -733,13 +741,13 @@ protected boolean isNestedKeyword(@Nullable Object candidate) {
 			return false;
 		}
 
-		Set<String> keys = BsonUtils.asMap((Bson) candidate).keySet();
+		Map<String, Object> map = BsonUtils.asMap((Bson) candidate);
 
-		if (keys.size() != 1) {
+		if (map.size() != 1) {
 			return false;
 		}
 
-		return isKeyword(keys.iterator().next());
+		return isKeyword(map.entrySet().iterator().next().getKey());
 	}
 
 	/**
@@ -823,11 +831,14 @@ public Keyword(Bson source, String key) {
 
 		public Keyword(Bson bson) {
 
-			Set<String> keys = BsonUtils.asMap(bson).keySet();
-			Assert.isTrue(keys.size() == 1, "Can only use a single value Document!");
+			Map<String, Object> map = BsonUtils.asMap(bson);
+			Assert.isTrue(map.size() == 1, "Can only use a single value Document!");
+
+			Set<Entry<String, Object>> entries = map.entrySet();
+			Entry<String, Object> entry = entries.iterator().next();
 
-			this.key = keys.iterator().next();
-			this.value = BsonUtils.get(bson, key);
+			this.key = entry.getKey();
+			this.value = entry.getValue();
 		}
 
 		/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Meta.java

@@ -49,8 +49,8 @@ private enum MetaKey {
 		}
 	}
 
-	private final Map<String, Object> values = new LinkedHashMap<>(2);
-	private final Set<CursorOption> flags = new LinkedHashSet<>();
+	private Map<String, Object> values = Collections.emptyMap();
+	private Set<CursorOption> flags = Collections.emptySet();
 	private Integer cursorBatchSize;
 	private Boolean allowDiskUse;
 
@@ -63,8 +63,9 @@ public Meta() {}
 	 * @param source
 	 */
 	Meta(Meta source) {
-		this.values.putAll(source.values);
-		this.flags.addAll(source.flags);
+
+		this.values = new LinkedHashMap<>(source.values);
+		this.flags = new LinkedHashSet<>(source.flags);
 		this.cursorBatchSize = source.cursorBatchSize;
 		this.allowDiskUse = source.allowDiskUse;
 	}
@@ -158,6 +159,11 @@ public void setCursorBatchSize(int cursorBatchSize) {
 	public boolean addFlag(CursorOption option) {
 
 		Assert.notNull(option, "CursorOption must not be null!");
+
+		if (this.flags == Collections.EMPTY_SET) {
+			this.flags = new LinkedHashSet<>(2);
+		}
+
 		return this.flags.add(option);
 	}
 
@@ -220,6 +226,10 @@ void setValue(String key, @Nullable Object value) {
 
 		Assert.hasText(key, "Meta key must not be 'null' or blank.");
 
+		if (values == Collections.EMPTY_MAP) {
+			values = new LinkedHashMap<>(2);
+		}
+
 		if (value == null || (value instanceof String && !StringUtils.hasText((String) value))) {
 			this.values.remove(key);
 		}