com.sleepycat.db
Class DbMpoolFile

java.lang.Object
  |
  +--com.sleepycat.db.DbMpoolFile

public class DbMpoolFile

extends Object

The memory pool interfaces for the Berkeley DB database environment are methods of the DbEnv handle. The DbEnv memory pool methods and the DbMpoolFile class provide general-purpose, page-oriented buffer management of files. Although designed to work with the other Db classes, they are also useful for more general purposes. The memory pools are referred to in this document as simply pools.

In the Berkeley DB Java API, the DbMpoolFile class provides a very limited set of operations. It is only intended to modify settings for a Db object using the Db.get_mpf method.

Method Summary

int	get_flags() Deprecated. As of Berkeley DB 4.2, replaced by getFlags()
long	get_maxsize() Deprecated. As of Berkeley DB 4.2, replaced by getMaxsize()
int	get_priority() Deprecated. As of Berkeley DB 4.2, replaced by getPriority()
int	getFlags() The DbMpoolFile.getFlags method returns the flags.
long	getMaxsize() The DbMpoolFile.getMaxsize method returns the size of the cache in bytes.
int	getPriority() The DbMpoolFile.getPriority method returns the cache priority.
void	set_flags(int flags, boolean onoff) Deprecated. As of Berkeley DB 4.2, replaced by setFlags(int,boolean)
void	set_maxsize(long bytes) Deprecated. As of Berkeley DB 4.2, replaced by setMaxsize(long)
void	set_priority(int priority) Deprecated. As of Berkeley DB 4.2, replaced by setPriority(int)
void	setFlags(int flags, boolean onoff) Configure a file in the cache.
void	setMaxsize(long bytes) Set the maximum size for the file to be bytes bytes.
void	setPriority(int priority) Set the cache priority for pages from the specified file.

Methods inherited from class java.lang.Object

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

Method Detail

get_priority

public int get_priority()
                 throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by getPriority()

DbException

getPriority

public int getPriority()
                throws DbException

The DbMpoolFile.getPriority method returns the cache priority.

The DbMpoolFile.getPriority method may be called at any time during the life of the application.

Returns:

The DbMpoolFile.getPriority method returns the cache priority.

Throws:

DbException - Signals that an exception of some sort has occurred.

set_priority

public void set_priority(int priority)
                  throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by setPriority(int)

DbException

setPriority

public void setPriority(int priority)
                 throws DbException

Set the cache priority for pages from the specified file. The priority of a page biases the replacement algorithm to be more or less likely to discard a page when space is needed in the buffer pool. The bias is temporary, and pages will eventually be discarded if they are not referenced again. The DbMpoolFile.setPriority method is only advisory, and does not guarantee pages will be treated in a specific way.

To set the priority for the pages belonging to a particular database, call the DbMpoolFile.setPriority method using the DbMpoolFile handle returned by calling the Db.get_mpf method.

The DbMpoolFile.setPriority method may be called at any time during the life of the application.

Parameters:

priority - must be set to one of the following values:

• Db.DB_PRIORITY_VERY_LOW

  The lowest priority: pages are the most likely to be discarded.

• Db.DB_PRIORITY_LOW

  The next lowest priority.

• Db.DB_PRIORITY_DEFAULT

  The default priority.

• Db.DB_PRIORITY_HIGH

  The next highest priority.

• Db.DB_PRIORITY_VERY_HIGH

  The highest priority: pages are the least likely to be discarded.

Throws:

DbException - Signals that an exception of some sort has occurred.

get_flags

public int get_flags()
              throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by getFlags()

DbException

getFlags

public int getFlags()
             throws DbException

The DbMpoolFile.getFlags method returns the flags.

The DbMpoolFile.getFlags method may be called at any time during the life of the application.

Returns:

The DbMpoolFile.getFlags method returns the flags.

Throws:

DbException - Signals that an exception of some sort has occurred.

set_flags

public void set_flags(int flags,
                      boolean onoff)
               throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by setFlags(int,boolean)

DbException

setFlags

public void setFlags(int flags,
                     boolean onoff)
              throws DbException

Configure a file in the cache.

To set the flags for a particular database, call the DbMpoolFile.setFlags method using the DbMpoolFile handle stored in the mpf field of the Db handle.

Parameters:

flags - must be set by bitwise inclusively OR'ing together one or more of the following values:

• Db.DB_MPOOL_NOFILE

  If set, no backing temporary file will be opened for in-memory databases, even if they expand to fill the entire cache. Attempts to create new file pages after the cache has been filled will fail.

  The Db.DB_MPOOL_NOFILE flag may be used to configure Berkeley DB at any time during the life of the application.

onoff - If onoff is false, the specified flags are cleared; otherwise they are set.

Throws:

DbException - Signals that an exception of some sort has occurred.

get_maxsize

public long get_maxsize()
                 throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by getMaxsize()

DbException

getMaxsize

public long getMaxsize()
                throws DbException

The DbMpoolFile.getMaxsize method returns the size of the cache in bytes.

The DbMpoolFile.getMaxsize method may be called at any time during the life of the application.

Returns:

The DbMpoolFile.getMaxsize method returns the size of the cache in bytes.

Throws:

DbException - Signals that an exception of some sort has occurred.

set_maxsize

public void set_maxsize(long bytes)
                 throws DbException

Deprecated. As of Berkeley DB 4.2, replaced by setMaxsize(long)

DbException

setMaxsize

public void setMaxsize(long bytes)
                throws DbException

Set the maximum size for the file to be bytes bytes. Attempts to allocate new pages in the file after the limit has been reached will fail.

To set the maximum file size for a particular database, call the DbMpoolFile.setMaxsize method using the DbMpoolFile handle stored in the mpf field of the Db handle. Attempts to insert new items into the database after the limit has been reached may fail.

The DbMpoolFile.setMaxsize method may be called at any time during the life of the application.

Parameters:

bytes - The maximum size of the files in bytes.

Throws:

DbException - Signals that an exception of some sort has occurred.