Module com.aoapps.persistence

Package com.aoapps.persistence

Class MappedPersistentBuffer

java.lang.Object

com.aoapps.persistence.AbstractPersistentBuffer

com.aoapps.persistence.MappedPersistentBuffer

All Implemented Interfaces:

PersistentBuffer, Closeable, AutoCloseable

public class MappedPersistentBuffer
extends AbstractPersistentBuffer

Uses MappedByteBuffer for persistence. It maps the entire file at once into a single buffer. For this reason, it is limited to a maximum buffer size of 2^31-1. To use memory mapping for larger buffers, at a slight performance cost, use LargeMappedPersistentBuffer.

Author:

AO Industries, Inc.

See Also:

• LargeMappedPersistentBuffer

Field Summary

Fields inherited from class com.aoapps.persistence.AbstractPersistentBuffer

protectionLevel

Constructor Summary

Constructors

Constructor	Description
MappedPersistentBuffer()	Creates a read-write buffer backed by a temporary file.
MappedPersistentBuffer(File file)	Creates a read-write buffer with ProtectionLevel.BARRIER protection level.
MappedPersistentBuffer(File file, ProtectionLevel protectionLevel)	Creates a buffer.
MappedPersistentBuffer(RandomAccessFile raf, ProtectionLevel protectionLevel)	Creates a buffer using the provided RandomAccessFile.
MappedPersistentBuffer(String name)	Creates a read-write buffer with ProtectionLevel.BARRIER protection level.
MappedPersistentBuffer(String name, ProtectionLevel protectionLevel)	Creates a buffer.

Method Summary

Modifier and Type	Method	Description
void	barrier(boolean force)	There is not currently a way to provide a barrier without using force.
long	capacity()	Gets the capacity of this buffer.
void	close()	Closes this buffer.
void	ensureZeros(long position, long len)	Ensures that all values from the position for the provided length are zeros.
byte	get(long position)	Gets a single byte from the buffer.
void	get(long position, byte[] buff, int off, int len)	Implemented as calls to PersistentBuffer.getSome(long, byte[], int, int).
boolean	getBoolean(long position)	Implemented as call to AbstractPersistentBuffer.get(long).
int	getInt(long position)	Implemented as call to AbstractPersistentBuffer.get(long, byte[], int, int).
long	getLong(long position)	Implemented as call to AbstractPersistentBuffer.get(long, byte[], int, int).
int	getSome(long position, byte[] buff, int off, int len)	Reads to the provided byte[], may read fewer than len bytes, but will always read at least one byte.
boolean	isClosed()	Checks if this buffer is closed.
void	put(long position, byte value)	Puts a single byte in the buffer.
void	put(long position, byte[] buff, int off, int len)	Writes the bytes to the provided position.
void	putInt(long position, int value)	Implemented as call to PersistentBuffer.put(long, byte[], int, int).
void	putLong(long position, long value)	Implemented as call to PersistentBuffer.put(long, byte[], int, int).
void	setCapacity(long newLength)	Sets the capacity of this buffer.

Methods inherited from class com.aoapps.persistence.AbstractPersistentBuffer

getInputStream, getOutputStream, getProtectionLevel

Methods inherited from class java.lang.Object

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

Constructor Details

MappedPersistentBuffer

public MappedPersistentBuffer()
                       throws IOException

Creates a read-write buffer backed by a temporary file. The protection level is set to ProtectionLevel.NONE. The temporary file will be deleted when this buffer is closed or on JVM shutdown.

Throws:

IOException

MappedPersistentBuffer

public MappedPersistentBuffer(String name)
                       throws IOException

Creates a read-write buffer with ProtectionLevel.BARRIER protection level.

Throws:

IOException

MappedPersistentBuffer

public MappedPersistentBuffer(String name,
 ProtectionLevel protectionLevel)
                       throws IOException

Creates a buffer.

Throws:

IOException

MappedPersistentBuffer

public MappedPersistentBuffer(File file)
                       throws IOException

Creates a read-write buffer with ProtectionLevel.BARRIER protection level.

Throws:

IOException

MappedPersistentBuffer

public MappedPersistentBuffer(File file,
 ProtectionLevel protectionLevel)
                       throws IOException

Creates a buffer.

Throws:

IOException

MappedPersistentBuffer

public MappedPersistentBuffer(RandomAccessFile raf,
 ProtectionLevel protectionLevel)
                       throws IOException

Creates a buffer using the provided RandomAccessFile.

Throws:

IOException

Method Details

isClosed

public boolean isClosed()

Description copied from interface: PersistentBuffer

Checks if this buffer is closed.

close

public void close()
           throws IOException

Description copied from interface: PersistentBuffer

Closes this buffer. It is OK to close an already closed buffer.

Throws:

IOException

capacity

public long capacity()
              throws IOException

Description copied from interface: PersistentBuffer

Gets the capacity of this buffer.

Throws:

IOException

setCapacity

public void setCapacity(long newLength)
                 throws IOException

Description copied from interface: PersistentBuffer

Sets the capacity of this buffer. If the buffer is increased in size, the new space will be zero-filled. Setting the capacity may impose an automatic barrier(true), depending on implementation. This should be considered an expensive operation.

Throws:

IOException

get

public void get(long position,
 byte[] buff,
 int off,
 int len)
         throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as calls to PersistentBuffer.getSome(long, byte[], int, int).

Specified by:

get in interface PersistentBuffer

Overrides:

get in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• PersistentBuffer.getSome(long, byte[], int, int)

getSome

public int getSome(long position,
 byte[] buff,
 int off,
 int len)
            throws IOException

Description copied from interface: PersistentBuffer

Reads to the provided byte[], may read fewer than len bytes, but will always read at least one byte. Blocks if no data is available.

Throws:

IOException

get

public byte get(long position)
         throws IOException

Gets a single byte from the buffer.

Specified by:

get in interface PersistentBuffer

Overrides:

get in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• AbstractPersistentBuffer.get(long, byte[], int, int)

ensureZeros

public void ensureZeros(long position,
 long len)
                 throws IOException

Description copied from interface: PersistentBuffer

Ensures that all values from the position for the provided length are zeros. This may or may not modify the buffer in the process. The values will all be zero upon return. Some implementations may choose to overwrite zeros and return modified, others may choose to detect zeros and avoid modifications. Thus it is possible for existing zeros to still result in a modification.

Throws:

IOException

put

public void put(long position,
 byte value)
         throws IOException

Puts a single byte in the buffer.

Specified by:

put in interface PersistentBuffer

Overrides:

put in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• PersistentBuffer.put(long, byte[], int, int)

put

public void put(long position,
 byte[] buff,
 int off,
 int len)
         throws IOException

Description copied from interface: PersistentBuffer

Writes the bytes to the provided position. The buffer will not be expanded automatically.

Throws:

IOException

barrier

public void barrier(boolean force)
             throws IOException

There is not currently a way to provide a barrier without using force. This just uses force for both.

Throws:

IOException

See Also:

• PersistentBuffer.getProtectionLevel()

getBoolean

public boolean getBoolean(long position)
                   throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as call to AbstractPersistentBuffer.get(long).

Specified by:

getBoolean in interface PersistentBuffer

Overrides:

getBoolean in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• AbstractPersistentBuffer.get(long)

getInt

public int getInt(long position)
           throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as call to AbstractPersistentBuffer.get(long, byte[], int, int).

Specified by:

getInt in interface PersistentBuffer

Overrides:

getInt in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• AbstractPersistentBuffer.get(long, byte[], int, int)

getLong

public long getLong(long position)
             throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as call to AbstractPersistentBuffer.get(long, byte[], int, int).

Specified by:

getLong in interface PersistentBuffer

Overrides:

getLong in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• AbstractPersistentBuffer.get(long, byte[], int, int)

putInt

public void putInt(long position,
 int value)
            throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as call to PersistentBuffer.put(long, byte[], int, int).

Specified by:

putInt in interface PersistentBuffer

Overrides:

putInt in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• PersistentBuffer.put(long, byte[], int, int)

putLong

public void putLong(long position,
 long value)
             throws IOException

Description copied from class: AbstractPersistentBuffer

Implemented as call to PersistentBuffer.put(long, byte[], int, int).

Specified by:

putLong in interface PersistentBuffer

Overrides:

putLong in class AbstractPersistentBuffer

Throws:

IOException

See Also:

• PersistentBuffer.put(long, byte[], int, int)