com.yahoo.memory

Class WritableMapHandle

java.lang.Object

com.yahoo.memory.MapHandle

com.yahoo.memory.WritableMapHandle

All Implemented Interfaces:

Handle, WritableHandle, AutoCloseable

public final class WritableMapHandle
extends MapHandle
implements WritableHandle

Gets a WritableMemory for a writable memory-mapped file resource. It is highly recommended that this be created inside a try-with-resources statement.

Author:

Roman Leventov, Lee Rhodes

Method Summary

Modifier and Type	Method and Description
void	force() Forces any changes made to this content to be written to the storage device containing the mapped file.
WritableMemory	get() Gets a Memory
boolean	isLoaded() Tells whether or not the content is resident in physical memory.
void	load() Loads content into physical memory.

Methods inherited from class com.yahoo.memory.MapHandle

close, isLoaded, load

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.yahoo.memory.Handle

close

Method Detail

get

public WritableMemory get()

Description copied from interface: Handle

Gets a Memory

Specified by:

get in interface Handle

Specified by:

get in interface WritableHandle

Overrides:

get in class MapHandle

Returns:

a Memory

force

public void force()

Forces any changes made to this content to be written to the storage device containing the mapped file.

If the file mapped into this buffer resides on a local storage device then when this method returns, it is guaranteed that all changes made to the buffer since it was created, or since this method was last invoked, will have been written to that device.

If the file does not reside on a local device then no such guarantee can be made.

If this buffer was not mapped in read/write mode (java.nio.channels.FileChannel.MapMode.READ_WRITE) then invoking this method has no effect.

See Also:

java/nio/MappedByteBuffer.force

load

public void load()

Loads content into physical memory. This method makes a best effort to ensure that, when it returns, this buffer's content is resident in physical memory. Invoking this method may cause some number of page faults and I/O operations to occur.

See Also:

java/nio/MappedByteBuffer.load

isLoaded

public boolean isLoaded()

Tells whether or not the content is resident in physical memory. A return value of true implies that it is highly likely that all of the data in this buffer is resident in physical memory and may therefore be accessed without incurring any virtual-memory page faults or I/O operations. A return value of false does not necessarily imply that the content is not resident in physical memory. The returned value is a hint, rather than a guarantee, because the underlying operating system may have paged out some of the buffer's data by the time that an invocation of this method returns.

Returns:

true if loaded

See Also:

java /nio/MappedByteBuffer.isLoaded