java.lang.Object
- org.apache.flink.api.connector.source.lib.util.IteratorSourceReaderBase<E,O,IterT,SplitT>

Type Parameters:

E - The type of events returned by the reader.

IterT - The type of the iterator that produces the events. This type exists to make the conversion between iterator and IteratorSourceSplit type safe.

SplitT - The concrete type of the IteratorSourceSplit that creates and converts the iterator that produces this reader's elements.

All Implemented Interfaces:

AutoCloseable, CheckpointListener, SourceReader<O,SplitT>

Direct Known Subclasses:

DoubleEmittingSourceReaderWithCheckpointsInBetween, GeneratingIteratorSourceReader, IteratorSourceReader
```
@Public
public abstract class IteratorSourceReaderBase<E,O,IterT extends Iterator<E>,SplitT extends IteratorSourceSplit<E,IterT>>
extends Object
implements SourceReader<O,SplitT>
```
A SourceReader that returns the values of an iterator, supplied via an IteratorSourceSplit.
The IteratorSourceSplit is also responsible for taking the current iterator and turning it back into a split for checkpointing.

Field Summary

Fields
Modifier and Type	Field	Description
`protected CompletableFuture<Void>`	`availability`	The availability future.
`protected SplitT`	`currentSplit`	The split whose data we return.
`protected IterT`	`iterator`	The iterator producing data.

Constructor Summary

Constructors
Constructor Description

IteratorSourceReaderBase(SourceReaderContext context)

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addSplits(List<SplitT> splits)`	Adds a list of splits for this reader to read.
`void`	`close()`
`protected abstract O`	`convert(E value)`
`protected void`	`finishSplit()`
`CompletableFuture<Void>`	`isAvailable()`	Returns a future that signals that data is available from the reader.
`void`	`notifyNoMoreSplits()`	This method is called when the reader is notified that it will not receive any further splits.
`InputStatus`	`pollNext(ReaderOutput<O> output)`	Poll the next available record into the `ReaderOutput`.
`List<SplitT>`	`snapshotState(long checkpointId)`	Checkpoint on the state of the source.
`void`	`start()`	Start the reader.
`protected void`	`start(SourceReaderContext context)`
`protected InputStatus`	`tryMoveToNextSplit()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.flink.api.common.state.CheckpointListener
notifyCheckpointAborted

Methods inherited from interface org.apache.flink.api.connector.source.SourceReader
handleSourceEvents, notifyCheckpointComplete, pauseOrResumeSplits

- Field Detail
  - availability
```
protected CompletableFuture<Void> availability
```
    The availability future. This reader is available as soon as a split is assigned.
  - iterator
```
@Nullable
protected IterT extends Iterator<E> iterator
```
    The iterator producing data. Non-null after a split has been assigned. This field is null or non-null always together with the currentSplit field.
  - currentSplit
```
@Nullable
protected SplitT extends IteratorSourceSplit<E,IterT> currentSplit
```
    The split whose data we return. Non-null after a split has been assigned. This field is null or non-null always together with the iterator field.
- Constructor Detail
  - IteratorSourceReaderBase
```
public IteratorSourceReaderBase(SourceReaderContext context)
```
- Method Detail
  - start
```
public void start()
```
    Description copied from interface: SourceReader
    
    Start the reader.
    
    Specified by:
    
    start in interface SourceReader<E,O>
  - start
```
protected void start(SourceReaderContext context)
```
  - pollNext
```
public InputStatus pollNext(ReaderOutput<O> output)
```
    Description copied from interface: SourceReader
    
    Poll the next available record into the ReaderOutput.
    The implementation must make sure this method is non-blocking.
    Although the implementation can emit multiple records into the given ReaderOutput, it is recommended not doing so. Instead, emit one record into the ReaderOutput and return a InputStatus.MORE_AVAILABLE to let the caller thread know there are more records available.
    
    Specified by:
    
    pollNext in interface SourceReader<E,O>
    
    Returns:
    
    The InputStatus of the SourceReader after the method invocation.
  - convert
```
protected abstract O convert(E value)
```
  - finishSplit
```
protected void finishSplit()
```
  - tryMoveToNextSplit
```
protected InputStatus tryMoveToNextSplit()
```
  - isAvailable
```
public CompletableFuture<Void> isAvailable()
```
    Description copied from interface: SourceReader
    
    Returns a future that signals that data is available from the reader.
    Once the future completes, the runtime will keep calling the SourceReader.pollNext(ReaderOutput) method until that method returns a status other than InputStatus.MORE_AVAILABLE. After that, the runtime will again call this method to obtain the next future. Once that completes, it will again call SourceReader.pollNext(ReaderOutput) and so on.
    The contract is the following: If the reader has data available, then all futures previously returned by this method must eventually complete. Otherwise the source might stall indefinitely.
    It is not a problem to have occasional "false positives", meaning to complete a future even if no data is available. However, one should not use an "always complete" future in cases no data is available, because that will result in busy waiting loops calling pollNext(...) even though no data is available.
    
    Specified by:
    
    isAvailable in interface SourceReader<E,O>
    
    Returns:
    
    a future that will be completed once there is a record available to poll.
  - addSplits
```
public void addSplits(List<SplitT> splits)
```
    Description copied from interface: SourceReader
    
    Adds a list of splits for this reader to read. This method is called when the enumerator assigns a split via SplitEnumeratorContext.assignSplit(SourceSplit, int) or SplitEnumeratorContext.assignSplits(SplitsAssignment).
    
    Specified by:
    
    addSplits in interface SourceReader<E,O>
    
    Parameters:
    
    splits - The splits assigned by the split enumerator.
  - notifyNoMoreSplits
```
public void notifyNoMoreSplits()
```
    Description copied from interface: SourceReader
    
    This method is called when the reader is notified that it will not receive any further splits.
    It is triggered when the enumerator calls SplitEnumeratorContext.signalNoMoreSplits(int) with the reader's parallel subtask.
    
    Specified by:
    
    notifyNoMoreSplits in interface SourceReader<E,O>
  - snapshotState
```
public List<SplitT> snapshotState(long checkpointId)
```
    Description copied from interface: SourceReader
    
    Checkpoint on the state of the source.
    
    Specified by:
    
    snapshotState in interface SourceReader<E,O>
    
    Returns:
    
    the state of the source.
  - close
```
public void close()
           throws Exception
```
    Specified by:
    
    close in interface AutoCloseable
    
    Throws:
    
    Exception

Class IteratorSourceReaderBase<E,​O,​IterT extends Iterator<E>,​SplitT extends IteratorSourceSplit<E,​IterT>>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.flink.api.common.state.CheckpointListener

Methods inherited from interface org.apache.flink.api.connector.source.SourceReader

Field Detail

availability

iterator

currentSplit

Constructor Detail

IteratorSourceReaderBase

Method Detail

start

start

pollNext

convert

finishSplit

tryMoveToNextSplit

isAvailable

addSplits

notifyNoMoreSplits

snapshotState

close

Class IteratorSourceReaderBase<E,O,IterT extends Iterator<E>,SplitT extends IteratorSourceSplit<E,IterT>>