Module tools.jackson.databind

Package tools.jackson.databind.deser

Class DeserializerCache

java.lang.Object

tools.jackson.databind.deser.DeserializerCache

All Implemented Interfaces:

Serializable

public final class DeserializerCache
extends Object
implements Serializable

Class that defines caching layer between callers (like ObjectMapper, DeserializationContext) and classes that construct deserializers (DeserializerFactory).

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private final LookupCache<JavaType,ValueDeserializer<Object>>	_cachedDeserializers	We will also cache some dynamically constructed deserializers; specifically, ones that are expensive to construct.
private final HashMap<JavaType,ValueDeserializer<Object>>	_incompleteDeserializers	During deserializer construction process we may need to keep track of partially completed deserializers, to resolve cyclic dependencies.
private final ReentrantLock	_incompleteDeserializersLock	We hold an explicit lock while creating deserializers to avoid creating duplicates.
static final int	DEFAULT_MAX_CACHE_SIZE	Default size of the underlying cache to use.
private static final long	serialVersionUID

Constructor Summary

Constructors

Constructor	Description
DeserializerCache()
DeserializerCache(LookupCache<JavaType,ValueDeserializer<Object>> cache)

Method Summary

Modifier and Type	Method	Description
protected ValueDeserializer<Object>	_createAndCache2(DeserializationContext ctxt, DeserializerFactory factory, JavaType type, boolean isCustom)	Method that handles actual construction (via factory) and caching (both intermediate and eventual)
protected ValueDeserializer<Object>	_createAndCacheValueDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)	Method that will try to create a deserializer for given type, and resolve and cache it if necessary
protected ValueDeserializer<Object>	_createDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)	Method that does the heavy lifting of checking for per-type annotations, find out full type, and figure out which actual factory method to call.
protected ValueDeserializer<?>	_createDeserializer2(DeserializationContext ctxt, DeserializerFactory factory, JavaType type, BeanDescription.Supplier beanDescRef)
protected ValueDeserializer<Object>	_findCachedDeserializer(JavaType type)
protected KeyDeserializer	_handleUnknownKeyDeserializer(DeserializationContext ctxt, JavaType type)
protected ValueDeserializer<Object>	_handleUnknownValueDeserializer(DeserializationContext ctxt, JavaType type)
private boolean	_hasCustomHandlers(JavaType t)	Helper method used to prevent both caching and cache lookups for structured types that have custom value handlers
private Class<?>	_verifyAsClass(Object src, String methodName, Class<?> noneClass)
int	cachedDeserializersCount()	Method that can be used to determine how many deserializers this provider is caching currently (if it does caching: default implementation does) Exact count depends on what kind of deserializers get cached; default implementation caches only dynamically constructed deserializers, but not eagerly constructed standard deserializers (which is different from how serializer provider works).
DeserializerCache	emptyCopy()
protected Converter<Object,Object>	findConverter(DeserializationContext ctxt, Annotated a)
protected ValueDeserializer<Object>	findConvertingDeserializer(DeserializationContext ctxt, Annotated a, ValueDeserializer<Object> deser)	Helper method that will check whether given annotated entity (usually class, but may also be a property accessor) indicates that a Converter is to be used; and if so, to construct and return suitable serializer for it.
protected ValueDeserializer<Object>	findDeserializerFromAnnotation(DeserializationContext ctxt, Annotated ann)	Helper method called to check if a class or method has annotation that tells which class to use for deserialization.
KeyDeserializer	findKeyDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)	Method called to get hold of a deserializer to use for deserializing keys for Map.
ValueDeserializer<Object>	findValueDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType propertyType)	Method called to get hold of a deserializer for a value of given type; or if no such deserializer can be found, a default handler (which may do a best-effort generic serialization or just simply throw an exception when invoked).
void	flushCachedDeserializers()	Method that will drop all dynamically constructed deserializers (ones that are counted as result value for cachedDeserializersCount()).
private JavaType	modifyTypeByAnnotation(DeserializationContext ctxt, Annotated a, JavaType type)	Method called to see if given method has annotations that indicate a more specific type than what the argument specifies.
protected Object	readResolve()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

serialVersionUID

private static final long serialVersionUID

See Also:

• Constant Field Values

DEFAULT_MAX_CACHE_SIZE

public static final int DEFAULT_MAX_CACHE_SIZE

Default size of the underlying cache to use.

NOTE: reduced from 2.x default.

See Also:

• Constant Field Values

_cachedDeserializers

private final LookupCache<JavaType,ValueDeserializer<Object>> _cachedDeserializers

We will also cache some dynamically constructed deserializers; specifically, ones that are expensive to construct. This currently (3.0) means POJO, Enum and Container (collection, map) deserializers.

_incompleteDeserializers

private final transient HashMap<JavaType,ValueDeserializer<Object>> _incompleteDeserializers

During deserializer construction process we may need to keep track of partially completed deserializers, to resolve cyclic dependencies. This is the map used for storing deserializers before they are fully complete.

_incompleteDeserializersLock

private final ReentrantLock _incompleteDeserializersLock

We hold an explicit lock while creating deserializers to avoid creating duplicates. Guards _incompleteDeserializers.

Constructor Details

DeserializerCache

public DeserializerCache()

DeserializerCache

public DeserializerCache(LookupCache<JavaType,ValueDeserializer<Object>> cache)

Method Details

emptyCopy

public DeserializerCache emptyCopy()

readResolve

protected Object readResolve()

cachedDeserializersCount

public int cachedDeserializersCount()

Method that can be used to determine how many deserializers this provider is caching currently (if it does caching: default implementation does) Exact count depends on what kind of deserializers get cached; default implementation caches only dynamically constructed deserializers, but not eagerly constructed standard deserializers (which is different from how serializer provider works).

The main use case for this method is to allow conditional flushing of deserializer cache, if certain number of entries is reached.

flushCachedDeserializers

public void flushCachedDeserializers()

Method that will drop all dynamically constructed deserializers (ones that are counted as result value for cachedDeserializersCount()). This can be used to remove memory usage (in case some deserializers are only used once or so), or to force re-construction of deserializers after configuration changes for mapper than owns the provider.

findValueDeserializer

public ValueDeserializer<Object> findValueDeserializer(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType propertyType)

Method called to get hold of a deserializer for a value of given type; or if no such deserializer can be found, a default handler (which may do a best-effort generic serialization or just simply throw an exception when invoked).

Note: this method is only called for value types; not for keys. Key deserializers can be accessed using findKeyDeserializer(tools.jackson.databind.DeserializationContext, tools.jackson.databind.deser.DeserializerFactory, tools.jackson.databind.JavaType).

Note also that deserializer returned is guaranteed to be resolved (see ValueDeserializer.resolve(tools.jackson.databind.DeserializationContext)), but not contextualized (wrt ValueDeserializer.createContextual(tools.jackson.databind.DeserializationContext, tools.jackson.databind.BeanProperty)): caller has to handle latter if necessary.

Parameters:

ctxt - Deserialization context

propertyType - Declared type of the value to deserializer (obtained using 'setter' method signature and/or type annotations

findKeyDeserializer

public KeyDeserializer findKeyDeserializer(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType type)

Method called to get hold of a deserializer to use for deserializing keys for Map.

Throws:

DatabindException - if there are fatal problems with accessing suitable key deserializer; including that of not finding any serializer

_findCachedDeserializer

protected ValueDeserializer<Object> _findCachedDeserializer(JavaType type)

_createAndCacheValueDeserializer

protected ValueDeserializer<Object> _createAndCacheValueDeserializer(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType type)

Method that will try to create a deserializer for given type, and resolve and cache it if necessary

Parameters:

ctxt - Currently active deserialization context

type - Type of property to deserialize (never null, callers verify)

_createAndCache2

protected ValueDeserializer<Object> _createAndCache2(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType type,
 boolean isCustom)

Method that handles actual construction (via factory) and caching (both intermediate and eventual)

_createDeserializer

protected ValueDeserializer<Object> _createDeserializer(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType type)

Method that does the heavy lifting of checking for per-type annotations, find out full type, and figure out which actual factory method to call.

_createDeserializer2

protected ValueDeserializer<?> _createDeserializer2(DeserializationContext ctxt,
 DeserializerFactory factory,
 JavaType type,
 BeanDescription.Supplier beanDescRef)

findDeserializerFromAnnotation

protected ValueDeserializer<Object> findDeserializerFromAnnotation(DeserializationContext ctxt,
 Annotated ann)

Helper method called to check if a class or method has annotation that tells which class to use for deserialization. Returns null if no such annotation found.

findConvertingDeserializer

protected ValueDeserializer<Object> findConvertingDeserializer(DeserializationContext ctxt,
 Annotated a,
 ValueDeserializer<Object> deser)

Helper method that will check whether given annotated entity (usually class, but may also be a property accessor) indicates that a Converter is to be used; and if so, to construct and return suitable serializer for it. If not, will simply return given serializer as is.

findConverter

protected Converter<Object,Object> findConverter(DeserializationContext ctxt,
 Annotated a)

modifyTypeByAnnotation

private JavaType modifyTypeByAnnotation(DeserializationContext ctxt,
 Annotated a,
 JavaType type)

Method called to see if given method has annotations that indicate a more specific type than what the argument specifies. If annotations are present, they must specify compatible Class; instance of which can be assigned using the method. This means that the Class has to be raw class of type, or its sub-class (or, implementing class if original Class instance is an interface).

Parameters:

a - Method or field that the type is associated with

type - Type derived from the setter argument

Returns:

Original type if no annotations are present; or a more specific type derived from it if type annotation(s) was found

_hasCustomHandlers

private boolean _hasCustomHandlers(JavaType t)

Helper method used to prevent both caching and cache lookups for structured types that have custom value handlers

_verifyAsClass

private Class<?> _verifyAsClass(Object src,
 String methodName,
 Class<?> noneClass)

_handleUnknownValueDeserializer

protected ValueDeserializer<Object> _handleUnknownValueDeserializer(DeserializationContext ctxt,
 JavaType type)

_handleUnknownKeyDeserializer

protected KeyDeserializer _handleUnknownKeyDeserializer(DeserializationContext ctxt,
 JavaType type)