Package org.apache.cassandra.io.util

Class BufferManagingRebufferer

java.lang.Object

org.apache.cassandra.io.util.BufferManagingRebufferer

All Implemented Interfaces:

java.lang.AutoCloseable, ReaderFileProxy, Rebufferer, Rebufferer.BufferHolder

Direct Known Subclasses:

BufferManagingRebufferer.Aligned, BufferManagingRebufferer.Unaligned

public abstract class BufferManagingRebufferer
extends java.lang.Object
implements Rebufferer, Rebufferer.BufferHolder

Buffer manager used for reading from a ChunkReader when cache is not in use. Instances of this class are reader-specific and thus do not need to be thread-safe since the reader itself isn't. The instances reuse themselves as the BufferHolder to avoid having to return a new object for each rebuffer call.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BufferManagingRebufferer.Aligned
static class	BufferManagingRebufferer.Unaligned

Nested classes/interfaces inherited from interface org.apache.cassandra.io.util.Rebufferer

Rebufferer.BufferHolder

Field Summary

Fields

Modifier and Type	Field	Description
protected java.nio.ByteBuffer	buffer
protected long	offset
protected ChunkReader	source

Fields inherited from interface org.apache.cassandra.io.util.Rebufferer

EMPTY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	BufferManagingRebufferer(ChunkReader wrapped)

Method Summary

Modifier and Type	Method	Description
java.nio.ByteBuffer	buffer()	Returns a useable buffer (i.e.
ChannelProxy	channel()
void	close()
void	closeReader()	Called when a reader is closed.
long	fileLength()
double	getCrcCheckChance()	Needed for tests.
long	offset()	Position in the file of the start of the buffer.
Rebufferer.BufferHolder	rebuffer(long position)	Rebuffer (move on or seek to) a given position, and return a buffer that can be used there.
void	release()	To be called when this buffer is no longer in use.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.cassandra.io.util.Rebufferer.BufferHolder

floatBuffer, intBuffer

Field Detail

source

protected final ChunkReader source

buffer

protected final java.nio.ByteBuffer buffer

offset

protected long offset

Constructor Detail

BufferManagingRebufferer

protected BufferManagingRebufferer(ChunkReader wrapped)

Method Detail

closeReader

public void closeReader()

Description copied from interface: Rebufferer

Called when a reader is closed. Should clean up reader-specific data.

Specified by:

closeReader in interface Rebufferer

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface ReaderFileProxy

channel

public ChannelProxy channel()

Specified by:

channel in interface ReaderFileProxy

fileLength

public long fileLength()

Specified by:

fileLength in interface ReaderFileProxy

rebuffer

public Rebufferer.BufferHolder rebuffer(long position)

Description copied from interface: Rebufferer

Rebuffer (move on or seek to) a given position, and return a buffer that can be used there. The only guarantee about the size of the returned data is that unless rebuffering at the end of the file, the buffer will not be empty and will contain the requested position, i.e. offset <= position < offset + bh.buffer().limit(), but the buffer will not be positioned there.

Specified by:

rebuffer in interface Rebufferer

getCrcCheckChance

public double getCrcCheckChance()

Description copied from interface: ReaderFileProxy

Needed for tests. Returns the table's CRC check chance, which is only set for compressed tables.

Specified by:

getCrcCheckChance in interface ReaderFileProxy

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

buffer

public java.nio.ByteBuffer buffer()

Description copied from interface: Rebufferer.BufferHolder

Returns a useable buffer (i.e. one whose position and limit can be freely modified). Its limit will be set to the size of the available data in the buffer. The buffer must be treated as read-only.

Specified by:

buffer in interface Rebufferer.BufferHolder

offset

public long offset()

Description copied from interface: Rebufferer.BufferHolder

Position in the file of the start of the buffer.

Specified by:

offset in interface Rebufferer.BufferHolder

release

public void release()

Description copied from interface: Rebufferer.BufferHolder

To be called when this buffer is no longer in use. Must be called for all BufferHolders, or ChunkCache will not be able to free blocks.

Specified by:

release in interface Rebufferer.BufferHolder