org.apache.activemq.artemis.jlibaio

Class LibaioFile<Callback extends SubmitInfo>

java.lang.Object

org.apache.activemq.artemis.jlibaio.LibaioFile<Callback>

public final class LibaioFile<Callback extends SubmitInfo>
extends Object

This is an extension to use libaio.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	open

Method Summary

Modifier and Type	Method and Description
void	close()
void	fallocate(long size) It will use fallocate to initialize a file.
void	fill(long size) It will preallocate the file with a given size.
int	getBlockSize()
long	getSize()
boolean	lock()
ByteBuffer	newBuffer(int size) It will allocate a buffer to be used on libaio operations.
void	read(long position, int size, ByteBuffer buffer, Callback callback) It will submit a read to the queue.
void	write(long position, int size, ByteBuffer buffer, Callback callback) It will submit a write to the queue.

Methods inherited from class java.lang.Object

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

Field Detail

open

protected boolean open

Method Detail

getBlockSize

public int getBlockSize()

lock

public boolean lock()

close

public void close()
           throws IOException

Throws:

IOException

getSize

public long getSize()

Returns:

The size of the file.

write

public void write(long position,
                  int size,
                  ByteBuffer buffer,
                  Callback callback)
           throws IOException

It will submit a write to the queue. The callback sent here will be received on the LibaioContext.poll(SubmitInfo[], int, int) In case of the libaio queue is full (e.g. returning E_AGAIN) this method will return false.
Notice: this won't hold a global reference on buffer, callback should hold a reference towards bufferWrite. And don't free the buffer until the callback was called as this could crash the VM.

Parameters:

position - The position on the file to write. Notice this has to be a multiple of 512.

size - The size of the buffer to use while writing.

buffer - if you are using O_DIRECT the buffer here needs to be allocated by newBuffer(int).

callback - A callback to be returned on the poll method.

Throws:

IOException - in case of error

read

public void read(long position,
                 int size,
                 ByteBuffer buffer,
                 Callback callback)
          throws IOException

It will submit a read to the queue. The callback sent here will be received on the LibaioContext.poll(SubmitInfo[], int, int). In case of the libaio queue is full (e.g. returning E_AGAIN) this method will return false.
Notice: this won't hold a global reference on buffer, callback should hold a reference towards bufferWrite. And don't free the buffer until the callback was called as this could crash the VM. *

Parameters:

position - The position on the file to read. Notice this has to be a multiple of 512.

size - The size of the buffer to use while reading.

buffer - if you are using O_DIRECT the buffer here needs to be allocated by newBuffer(int).

callback - A callback to be returned on the poll method.

Throws:

IOException - in case of error

See Also:

LibaioContext.poll(SubmitInfo[], int, int)

newBuffer

public ByteBuffer newBuffer(int size)

It will allocate a buffer to be used on libaio operations. Buffers here are allocated with posix_memalign.
You need to explicitly free the buffer created from here using the LibaioContext.freeBuffer(java.nio.ByteBuffer).

Parameters:

size - the size of the buffer.

Returns:

the buffer allocated.

fill

public void fill(long size)

It will preallocate the file with a given size.

Parameters:

size - number of bytes to be filled on the file

fallocate

public void fallocate(long size)

It will use fallocate to initialize a file.

Parameters:

size - number of bytes to be filled on the file