org.apache.flink.state.api.functions

类 KeyedStateReaderFunction<K,OUT>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.state.api.functions.KeyedStateReaderFunction<K,OUT>

类型参数:

K - Type of the keys

OUT - Type of the output elements.

所有已实现的接口:

Serializable, org.apache.flink.api.common.functions.Function, org.apache.flink.api.common.functions.RichFunction

@PublicEvolving
public abstract class KeyedStateReaderFunction<K,OUT>
extends org.apache.flink.api.common.functions.AbstractRichFunction

A function that processes keys from a restored operator

For every key readKey(Object, Context, Collector) is invoked. This can produce zero or more elements as output.

NOTE: State descriptors must be eagerly registered in open(Configuration). Any attempt to dynamically register states inside of readKey will result in a RuntimeException.

NOTE: A KeyedStateReaderFunction is always a RichFunction. Therefore, access to the RuntimeContext is always available and setup and teardown methods can be implemented. See RichFunction.open(Configuration) and RichFunction.close().

另请参阅:

序列化表格

嵌套类概要

嵌套类

限定符和类型	类和说明
static interface	KeyedStateReaderFunction.Context Context that KeyedStateReaderFunction's can use for getting additional data about an input record.

构造器概要

构造器

构造器和说明
KeyedStateReaderFunction()

方法概要

限定符和类型	方法和说明
abstract void	open(org.apache.flink.configuration.Configuration parameters) Initialization method for the function.
abstract void	readKey(K key, KeyedStateReaderFunction.Context ctx, org.apache.flink.util.Collector<OUT> out) Process one key from the restored state backend.

从类继承的方法 org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

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

KeyedStateReaderFunction

public KeyedStateReaderFunction()

方法详细资料

open

public abstract void open(org.apache.flink.configuration.Configuration parameters)
                   throws Exception

Initialization method for the function. It is called before readKey(Object, Context, Collector) and thus suitable for one time setup work.

This is the only method that my register state descriptors within a KeyedStateReaderFunction.

指定者:

open 在接口中 org.apache.flink.api.common.functions.RichFunction

覆盖:

open 在类中 org.apache.flink.api.common.functions.AbstractRichFunction

抛出:

Exception

readKey

public abstract void readKey(K key,
                             KeyedStateReaderFunction.Context ctx,
                             org.apache.flink.util.Collector<OUT> out)
                      throws Exception

Process one key from the restored state backend.

This function can read partitioned state from the restored state backend and output zero or more elements using the Collector parameter.

参数:

key - The input value.

out - The collector for returning result values.

抛出:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.