Package com.mckoi.store

Class JournalledSystem.Resource

java.lang.Object

com.mckoi.store.JournalledSystem.AbstractResource

com.mckoi.store.JournalledSystem.Resource

All Implemented Interfaces:

JournalledResource

Enclosing class:

JournalledSystem

private final class JournalledSystem.Resource
extends JournalledSystem.AbstractResource

Represents a resource in this system. A resource is backed by a StoreDataAccessor and may have one or more modifications to it in the journal.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	data_deleted	True if the data resource was deleted.
private boolean	data_exists	True if the data store exists.
private boolean	data_open	True if the data resource is open.
private JournalledSystem.JournalEntry[]	journal_map	The hash of all journal entries on this resource (JournalEntry).
private byte[]	page_buffer	A temporary buffer the size of a page.
private boolean	really_open	True if the underlying resource is really open.
private long	size	The size of the resource.
private boolean	there_is_backing_data	True if there is actually data to be read in the above object.

Fields inherited from class com.mckoi.store.JournalledSystem.AbstractResource

data, id, name, read_only

Constructor Summary

Constructors

Constructor	Description
Resource(java.lang.String name, long id, StoreDataAccessor data)	Constructs the resource.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the resource.
void	delete()	Deletes the resource.
boolean	exists()	Returns true if the resource currently exists.
long	getSize()	Returns the size of this resource.
void	notifyPostRecover()
void	open(boolean read_only)	Opens the resource.
(package private) void	persistClose()
void	persistDelete()
private void	persistOpen(boolean read_only)
void	persistPageChange(long page, int off, int len, java.io.DataInputStream din)
void	persistSetSize(long new_size)
void	read(long page_number, byte[] buf, int off)	Reads a page from the resource.
void	setSize(long size)	Sets the size of the resource.
void	synch()
void	write(long page_number, byte[] buf, int off, int len)	Writes a page of some previously specified size to the top log.

Methods inherited from class com.mckoi.store.JournalledSystem.AbstractResource

getID, getPageSize, toString

Methods inherited from class java.lang.Object

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

Field Detail

size

private long size

The size of the resource.

there_is_backing_data

private boolean there_is_backing_data

True if there is actually data to be read in the above object.

really_open

private boolean really_open

True if the underlying resource is really open.

data_exists

private boolean data_exists

True if the data store exists.

data_open

private boolean data_open

True if the data resource is open.

data_deleted

private boolean data_deleted

True if the data resource was deleted.

journal_map

private final JournalledSystem.JournalEntry[] journal_map

The hash of all journal entries on this resource (JournalEntry).

page_buffer

private final byte[] page_buffer

A temporary buffer the size of a page.

Constructor Detail

Resource

Resource(java.lang.String name,
         long id,
         StoreDataAccessor data)

Constructs the resource.

Method Detail

persistOpen

private void persistOpen(boolean read_only)
                  throws java.io.IOException

Throws:

java.io.IOException

persistClose

void persistClose()
           throws java.io.IOException

Specified by:

persistClose in class JournalledSystem.AbstractResource

Throws:

java.io.IOException

persistDelete

public void persistDelete()
                   throws java.io.IOException

Specified by:

persistDelete in class JournalledSystem.AbstractResource

Throws:

java.io.IOException

persistSetSize

public void persistSetSize(long new_size)
                    throws java.io.IOException

Specified by:

persistSetSize in class JournalledSystem.AbstractResource

Throws:

java.io.IOException

persistPageChange

public void persistPageChange(long page,
                              int off,
                              int len,
                              java.io.DataInputStream din)
                       throws java.io.IOException

Specified by:

persistPageChange in class JournalledSystem.AbstractResource

Throws:

java.io.IOException

synch

public void synch()
           throws java.io.IOException

Specified by:

synch in class JournalledSystem.AbstractResource

Throws:

java.io.IOException

notifyPostRecover

public void notifyPostRecover()

Specified by:

notifyPostRecover in class JournalledSystem.AbstractResource

open

public void open(boolean read_only)
          throws java.io.IOException

Opens the resource. This method will check if the resource exists. If it doesn't exist the 'read' method will return just the journal modifications of a page. If it does exist it opens the resource and uses that as the backing to any 'read' operations.

Throws:

java.io.IOException

read

public void read(long page_number,
                 byte[] buf,
                 int off)
          throws java.io.IOException

Reads a page from the resource. This method reconstructs the page from the underlying data, and from any journal entries. This should read the data to be put into a buffer in memory.

Throws:

java.io.IOException

write

public void write(long page_number,
                  byte[] buf,
                  int off,
                  int len)
           throws java.io.IOException

Writes a page of some previously specified size to the top log. This will add a single entry to the log and any 'read' operations after will contain the written data.

Throws:

java.io.IOException

setSize

public void setSize(long size)
             throws java.io.IOException

Sets the size of the resource.

Throws:

java.io.IOException

getSize

public long getSize()
             throws java.io.IOException

Returns the size of this resource.

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Closes the resource. This will actually simply log that the resource has been closed.

Throws:

java.io.IOException

delete

public void delete()
            throws java.io.IOException

Deletes the resource. This will actually simply log that the resource has been deleted.

Throws:

java.io.IOException

exists

public boolean exists()

Returns true if the resource currently exists.