org.apache.flink.runtime.state

类 PlaceholderStreamStateHandle

java.lang.Object

org.apache.flink.runtime.state.PlaceholderStreamStateHandle

所有已实现的接口:

Serializable, StateObject, StreamStateHandle

public class PlaceholderStreamStateHandle
extends Object
implements StreamStateHandle

A placeholder state handle for shared state that will replaced by an original that was created in a previous checkpoint. So we don't have to send a state handle twice, e.g. in case of ByteStreamStateHandle. This class is used in the referenced states of IncrementalRemoteKeyedStateHandle.

另请参阅:

序列化表格

构造器概要

构造器

构造器和说明
PlaceholderStreamStateHandle(long stateSize)

方法概要

限定符和类型	方法和说明
Optional<byte[]>	asBytesIfInMemory()
void	discardState() Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage.
long	getStateSize() Returns the size of the state in bytes.
PhysicalStateHandleID	getStreamStateHandleID()
org.apache.flink.core.fs.FSDataInputStream	openInputStream() Returns an FSDataInputStream that can be used to read back the data that was previously written to the stream.

从类继承的方法 java.lang.Object

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

构造器详细资料

PlaceholderStreamStateHandle

public PlaceholderStreamStateHandle(long stateSize)

方法详细资料

openInputStream

public org.apache.flink.core.fs.FSDataInputStream openInputStream()

从接口复制的说明: StreamStateHandle

Returns an FSDataInputStream that can be used to read back the data that was previously written to the stream.

指定者:

openInputStream 在接口中 StreamStateHandle

asBytesIfInMemory

public Optional<byte[]> asBytesIfInMemory()

指定者:

asBytesIfInMemory 在接口中 StreamStateHandle

返回:

Content of this handle as bytes array if it is already in memory.

getStreamStateHandleID

public PhysicalStateHandleID getStreamStateHandleID()

指定者:

getStreamStateHandleID 在接口中 StreamStateHandle

返回:

a unique identifier of this handle.

discardState

public void discardState()
                  throws Exception

从接口复制的说明: StateObject

Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage. This method is called when the state represented by this object will not be used any more.

指定者:

discardState 在接口中 StateObject

抛出:

Exception

getStateSize

public long getStateSize()

从接口复制的说明: StateObject

Returns the size of the state in bytes. If the size is not known, this method should return 0.

The values produced by this method are only used for informational purposes and for metrics/monitoring. If this method returns wrong values, the checkpoints and recovery will still behave correctly. However, efficiency may be impacted (wrong space pre-allocation) and functionality that depends on metrics (like monitoring) will be impacted.

Note for implementors: This method should not perform any I/O operations while obtaining the state size (hence it does not declare throwing an IOException). Instead, the state size should be stored in the state object, or should be computable from the state stored in this object. The reason is that this method is called frequently by several parts of the checkpointing and issuing I/O requests from this method accumulates a heavy I/O load on the storage system at higher scale.

指定者:

getStateSize 在接口中 StateObject

返回:

Size of the state in bytes.