com.google.protobuf

Class LazyFieldLite

java.lang.Object

com.google.protobuf.LazyFieldLite

Direct Known Subclasses:

LazyField

public class LazyFieldLite
extends Object

LazyFieldLite encapsulates the logic of lazily parsing message fields. It stores the message in a ByteString initially and then parses it on-demand. LazyFieldLite is thread-compatible: concurrent reads are safe once the proto that this LazyFieldLite is a part of is no longer being mutated by its Builder. However, explicit synchronization is needed under read/write situations. When a LazyFieldLite is used in the context of a MessageLite object, its behavior is considered to be immutable and none of the setter methods in its API are expected to be invoked. All of the getters are expected to be thread-safe. When used in the context of a MessageLite.Builder, setters can be invoked, but there is no guarantee of thread safety. TODO(yatin,dweis): Consider splitting this class's functionality and put the mutable methods into a separate builder class to allow us to give stronger compile-time guarantees. This class is internal implementation detail of the protobuf library, so you don't need to use it directly.

Author:

xiangl@google.com (Xiang Li)

Field Summary

Fields

Modifier and Type	Field and Description
protected MessageLite	value The parsed value.

Constructor Summary

Constructors

Constructor and Description
LazyFieldLite() Constructs a LazyFieldLite with no contents, and no ability to parse extensions.
LazyFieldLite(ExtensionRegistryLite extensionRegistry, ByteString bytes) Constructs a LazyFieldLite with bytes that will be parsed lazily.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the value state of this instance.
boolean	containsDefaultInstance() Determines whether this LazyFieldLite instance represents the default instance of this type.
protected void	ensureInitialized(MessageLite defaultInstance) Might lazily parse the bytes that were previously passed in.
boolean	equals(Object o) Indicates whether some other object is "equal to" this one.
static LazyFieldLite	fromValue(MessageLite value) Constructs a LazyFieldLite instance with a value.
int	getSerializedSize() Due to the optional field can be duplicated at the end of serialized bytes, which will make the serialized size changed after LazyField parsed.
MessageLite	getValue(MessageLite defaultInstance) Returns message instance.
int	hashCode() Returns a hash code value for the object.
void	merge(LazyFieldLite other) Merges another instance's contents.
void	mergeFrom(CodedInputStream input, ExtensionRegistryLite extensionRegistry) Merges another instance's contents from a stream.
void	set(LazyFieldLite other) Overrides the contents of this LazyField.
void	setByteString(ByteString bytes, ExtensionRegistryLite extensionRegistry) Sets this field with bytes to delay-parse.
MessageLite	setValue(MessageLite value) Sets the value of the instance and returns the old value without delay parsing anything.
ByteString	toByteString() Returns a BytesString for this field in a thread-safe way.

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

value

protected volatile MessageLite value

The parsed value. When this is null and a caller needs access to the MessageLite value, then delayedBytes will be parsed lazily at that time.

Constructor Detail

LazyFieldLite

public LazyFieldLite()

Constructs a LazyFieldLite with no contents, and no ability to parse extensions.

LazyFieldLite

public LazyFieldLite(ExtensionRegistryLite extensionRegistry,
                     ByteString bytes)

Constructs a LazyFieldLite with bytes that will be parsed lazily.

Method Detail

clear

public void clear()

Clears the value state of this instance.

LazyField is not thread-safe for write access. Synchronizations are needed under read/write situations.

containsDefaultInstance

public boolean containsDefaultInstance()

Determines whether this LazyFieldLite instance represents the default instance of this type.

ensureInitialized

protected void ensureInitialized(MessageLite defaultInstance)

Might lazily parse the bytes that were previously passed in. Is thread-safe.

equals

public boolean equals(@Nullable
                      Object o)

Description copied from class: Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Overrides:

equals in class Object

Parameters:

o - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), HashMap

fromValue

public static LazyFieldLite fromValue(MessageLite value)

Constructs a LazyFieldLite instance with a value. The LazyFieldLite may not be able to parse the extensions in the value as it has no ExtensionRegistry.

getSerializedSize

public int getSerializedSize()

Due to the optional field can be duplicated at the end of serialized bytes, which will make the serialized size changed after LazyField parsed. Be careful when using this method.

getValue

public MessageLite getValue(MessageLite defaultInstance)

Returns message instance. It may do some thread-safe delayed parsing of bytes.

Parameters:

defaultInstance - its message's default instance. It's also used to get parser for the message type.

hashCode

public int hashCode()

Description copied from class: Object

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

merge

public void merge(LazyFieldLite other)

Merges another instance's contents. In some cases may drop some extensions if both fields contain data. If the other field has an ExtensionRegistry but this does not, then this field will copy over that ExtensionRegistry.

LazyField is not thread-safe for write access. Synchronizations are needed under read/write situations.

mergeFrom

public void mergeFrom(CodedInputStream input,
                      ExtensionRegistryLite extensionRegistry)
               throws IOException

Merges another instance's contents from a stream.

LazyField is not thread-safe for write access. Synchronizations are needed under read/write situations.

Throws:

IOException

set

public void set(LazyFieldLite other)

Overrides the contents of this LazyField.

LazyField is not thread-safe for write access. Synchronizations are needed under read/write situations.

setByteString

public void setByteString(ByteString bytes,
                          ExtensionRegistryLite extensionRegistry)

Sets this field with bytes to delay-parse.

setValue

@Nullable
public MessageLite setValue(MessageLite value)

Sets the value of the instance and returns the old value without delay parsing anything.

LazyField is not thread-safe for write access. Synchronizations are needed under read/write situations.

toByteString

public ByteString toByteString()

Returns a BytesString for this field in a thread-safe way.