org.apache.flink.runtime.memory

类 AbstractPagedInputView

java.lang.Object

org.apache.flink.runtime.memory.AbstractPagedInputView

所有已实现的接口:

DataInput, org.apache.flink.core.memory.DataInputView

直接已知子类:

AbstractChannelReaderInputView, FileChannelInputView, HashPartition, RandomAccessInputView, SeekableFileChannelInputView

public abstract class AbstractPagedInputView
extends Object
implements org.apache.flink.core.memory.DataInputView

The base class for all input views that are backed by multiple memory pages. This base class contains all decoding methods to read data from a page and detect page boundary crossing. The concrete sub classes must implement the methods to provide the next memory page once the boundary is crossed.

字段概要

字段

限定符和类型	字段和说明
protected int	headerLength

构造器概要

构造器

限定符	构造器和说明
protected	AbstractPagedInputView(int headerLength) Creates a new view that is initially not bound to a memory segment.
protected	AbstractPagedInputView(org.apache.flink.core.memory.MemorySegment initialSegment, int initialLimit, int headerLength) Creates a new view that starts with the given segment.

方法概要

限定符和类型	方法和说明
void	advance() Advances the view to the next memory segment.
protected void	clear() Clears the internal state of the view.
protected void	doAdvance()
int	getCurrentPositionInSegment() Gets the position from which the next byte will be read.
org.apache.flink.core.memory.MemorySegment	getCurrentSegment() Gets the memory segment that will be used to read the next bytes from.
int	getCurrentSegmentLimit() Gets the current limit in the memory segment.
int	getHeaderLength()
protected abstract int	getLimitForSegment(org.apache.flink.core.memory.MemorySegment segment) Gets the limit for reading bytes from the given memory segment.
protected abstract org.apache.flink.core.memory.MemorySegment	nextSegment(org.apache.flink.core.memory.MemorySegment current) The method by which concrete subclasses realize page crossing.
int	read(byte[] b)
int	read(byte[] b, int off, int len)
boolean	readBoolean()
byte	readByte()
char	readChar()
double	readDouble()
float	readFloat()
void	readFully(byte[] b)
void	readFully(byte[] b, int off, int len)
int	readInt()
String	readLine()
long	readLong()
short	readShort()
int	readUnsignedByte()
int	readUnsignedShort()
String	readUTF()
protected void	seekInput(org.apache.flink.core.memory.MemorySegment segment, int positionInSegment, int limitInSegment) Sets the internal state of the view such that the next bytes will be read from the given memory segment, starting at the given position.
int	skipBytes(int n)
void	skipBytesToRead(int numBytes)

从类继承的方法 java.lang.Object

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

字段详细资料

headerLength

protected final int headerLength

构造器详细资料

AbstractPagedInputView

protected AbstractPagedInputView(org.apache.flink.core.memory.MemorySegment initialSegment,
                                 int initialLimit,
                                 int headerLength)

Creates a new view that starts with the given segment. The input starts directly after the header of the given page. If the header size is zero, it starts at the beginning. The specified initial limit describes up to which position data may be read from the current segment, before the view must advance to the next segment.

参数:

initialSegment - The memory segment to start reading from.

initialLimit - The position one after the last valid byte in the initial segment.

headerLength - The number of bytes to skip at the beginning of each segment for the header. This length must be the same for all memory segments.

AbstractPagedInputView

protected AbstractPagedInputView(int headerLength)

Creates a new view that is initially not bound to a memory segment. This constructor is typically for views that always seek first.

WARNING: The view is not readable until the first call to either advance(), or to seekInput(MemorySegment, int, int).

参数:

headerLength - The number of bytes to skip at the beginning of each segment for the header.

方法详细资料

getCurrentSegment

public org.apache.flink.core.memory.MemorySegment getCurrentSegment()

Gets the memory segment that will be used to read the next bytes from. If the segment is exactly exhausted, meaning that the last byte read was the last byte available in the segment, then this segment will not serve the next bytes. The segment to serve the next bytes will be obtained through the nextSegment(MemorySegment) method.

返回:

The current memory segment.

getCurrentPositionInSegment

public int getCurrentPositionInSegment()

Gets the position from which the next byte will be read. If that position is equal to the current limit, then the next byte will be read from next segment.

返回:

The position from which the next byte will be read.

另请参阅:

getCurrentSegmentLimit()

getCurrentSegmentLimit

public int getCurrentSegmentLimit()

Gets the current limit in the memory segment. This value points to the byte one after the last valid byte in the memory segment.

返回:

The current limit in the memory segment.

另请参阅:

getCurrentPositionInSegment()

nextSegment

protected abstract org.apache.flink.core.memory.MemorySegment nextSegment(org.apache.flink.core.memory.MemorySegment current)
                                                                   throws EOFException,
                                                                          IOException

The method by which concrete subclasses realize page crossing. This method is invoked when the current page is exhausted and a new page is required to continue the reading. If no further page is available, this method must throw an EOFException.

参数:

current - The current page that was read to its limit. May be null, if this method is invoked for the first time.

返回:

The next page from which the reading should continue. May not be null. If the input is exhausted, an EOFException must be thrown instead.

抛出:

EOFException - Thrown, if no further segment is available.

IOException - Thrown, if the method cannot provide the next page due to an I/O related problem.

getLimitForSegment

protected abstract int getLimitForSegment(org.apache.flink.core.memory.MemorySegment segment)

Gets the limit for reading bytes from the given memory segment. This method must return the position of the byte after the last valid byte in the given memory segment. When the position returned by this method is reached, the view will attempt to switch to the next memory segment.

参数:

segment - The segment to determine the limit for.

返回:

The limit for the given memory segment.

advance

public void advance()
             throws IOException

Advances the view to the next memory segment. The reading will continue after the header of the next segment. This method uses nextSegment(MemorySegment) and getLimitForSegment(MemorySegment) to get the next segment and set its limit.

抛出:

IOException - Thrown, if the next segment could not be obtained.

另请参阅:

nextSegment(MemorySegment), getLimitForSegment(MemorySegment)

doAdvance

protected void doAdvance()
                  throws IOException

抛出:

IOException

getHeaderLength

public int getHeaderLength()

返回:

header length.

seekInput

protected void seekInput(org.apache.flink.core.memory.MemorySegment segment,
                         int positionInSegment,
                         int limitInSegment)

Sets the internal state of the view such that the next bytes will be read from the given memory segment, starting at the given position. The memory segment will provide bytes up to the given limit position.

参数:

segment - The segment to read the next bytes from.

positionInSegment - The position in the segment to start reading from.

limitInSegment - The limit in the segment. When reached, the view will attempt to switch to the next segment.

clear

protected void clear()

Clears the internal state of the view. After this call, all read attempts will fail, until the advance() or seekInput(MemorySegment, int, int) method have been invoked.

read

public int read(byte[] b)
         throws IOException

指定者:

read 在接口中 org.apache.flink.core.memory.DataInputView

抛出:

IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

指定者:

read 在接口中 org.apache.flink.core.memory.DataInputView

抛出:

IOException

readFully

public void readFully(byte[] b)
               throws IOException

指定者:

readFully 在接口中 DataInput

抛出:

IOException

readFully

public void readFully(byte[] b,
                      int off,
                      int len)
               throws IOException

指定者:

readFully 在接口中 DataInput

抛出:

IOException

readBoolean

public boolean readBoolean()
                    throws IOException

指定者:

readBoolean 在接口中 DataInput

抛出:

IOException

readByte

public byte readByte()
              throws IOException

指定者:

readByte 在接口中 DataInput

抛出:

IOException

readUnsignedByte

public int readUnsignedByte()
                     throws IOException

指定者:

readUnsignedByte 在接口中 DataInput

抛出:

IOException

readShort

public short readShort()
                throws IOException

指定者:

readShort 在接口中 DataInput

抛出:

IOException

readUnsignedShort

public int readUnsignedShort()
                      throws IOException

指定者:

readUnsignedShort 在接口中 DataInput

抛出:

IOException

readChar

public char readChar()
              throws IOException

指定者:

readChar 在接口中 DataInput

抛出:

IOException

readInt

public int readInt()
            throws IOException

指定者:

readInt 在接口中 DataInput

抛出:

IOException

readLong

public long readLong()
              throws IOException

指定者:

readLong 在接口中 DataInput

抛出:

IOException

readFloat

public float readFloat()
                throws IOException

指定者:

readFloat 在接口中 DataInput

抛出:

IOException

readDouble

public double readDouble()
                  throws IOException

指定者:

readDouble 在接口中 DataInput

抛出:

IOException

readLine

public String readLine()
                throws IOException

指定者:

readLine 在接口中 DataInput

抛出:

IOException

readUTF

public String readUTF()
               throws IOException

指定者:

readUTF 在接口中 DataInput

抛出:

IOException

skipBytes

public int skipBytes(int n)
              throws IOException

指定者:

skipBytes 在接口中 DataInput

抛出:

IOException

skipBytesToRead

public void skipBytesToRead(int numBytes)
                     throws IOException

指定者:

skipBytesToRead 在接口中 org.apache.flink.core.memory.DataInputView

抛出:

IOException