Package db.buffers

Interface ManagedBufferFile

All Superinterfaces:

BufferFile

All Known Implementing Classes:

LocalManagedBufferFile, ManagedBufferFileAdapter

public interface ManagedBufferFile
extends BufferFile

BufferFile facilitates read/write access to buffer oriented file. Access to related resources, such as parameters and change data, is also facilitated.

Method Summary

Modifier and Type	Method	Description
boolean	canSave()	Returns true if a save file is provided for creating a new version of this buffer file.
long	getCheckinID()	Returns the checkin ID corresponding to this buffer file.
byte[]	getForwardModMapData(int oldVersion)	Returns a bit map corresponding to all buffers modified since oldVersion.
BufferFile	getNextChangeDataFile(boolean getFirst)	Get the next change data file which corresponds to this buffer file.
BufferFile	getSaveChangeDataFile()	Returns a temporary change data buffer file which should be used to store a application-level ChangeSet associated with this new buffer file version.
ManagedBufferFile	getSaveFile()	Returns a Save file if available.
void	saveCompleted(boolean commit)	After getting the save file, this method must be invoked to terminate the save.
void	setVersionComment(java.lang.String comment)	Set the comment which will be associated with this buffer file if saved.

Methods inherited from interface db.buffers.BufferFile

clearParameters, close, delete, dispose, get, getBufferSize, getFreeIndexes, getIndexCount, getParameter, getParameterNames, isReadOnly, put, setFreeIndexes, setParameter, setReadOnly

Method Detail

getNextChangeDataFile

BufferFile getNextChangeDataFile(boolean getFirst)
                          throws java.io.IOException

Get the next change data file which corresponds to this buffer file. This method acts like an iterator which each successive invocation returning the next available file. Null is returned when no more files are available. The invoker is responsible for closing each file returned. It is highly recommended that each file be closed prior to requesting the next file.

Parameters:

getFirst - causes the iterator to reset and return the first available file.

Throws:

java.io.IOException - if an I/O error occurs

getSaveChangeDataFile

BufferFile getSaveChangeDataFile()
                          throws java.io.IOException

Returns a temporary change data buffer file which should be used to store a application-level ChangeSet associated with this new buffer file version. The getSaveFile method must be successfully invoked prior to invoking this method.

Returns:

change data file or null if one is not available.

Throws:

java.io.IOException - if an I/O error occurs

getForwardModMapData

byte[] getForwardModMapData(int oldVersion)
                     throws java.io.IOException

Returns a bit map corresponding to all buffers modified since oldVersion. This identifies all buffers contained within the oldVersion which have been modified during any revision up until this file version. Buffers added since oldVersion are not identified NOTE: The bit mask may identify empty/free buffers within this file version.

Parameters:

oldVersion - indicates the older version of this file for which a change map will be returned. This method may only be invoked if this file is at version 2 or higher, has an associated BufferFileManager and the oldVersion related files still exist.

Returns:

ModMap buffer change map data

Throws:

java.io.IOException - if an I/O error occurs

getSaveFile

ManagedBufferFile getSaveFile()
                       throws java.io.IOException

Returns a Save file if available. Returns null if a save can not be performed. This method may block for an extended period of time if the pre-save process has not already completed. This method does not accept a monitor since a remote TaskMonitor does not yet exist.

Throws:

java.io.IOException - if an I/O error occurs

saveCompleted

void saveCompleted(boolean commit)
            throws java.io.IOException

After getting the save file, this method must be invoked to terminate the save.

Parameters:

commit - if true the save file will be reopened as read-only for update. If false, the save file will be deleted and the object will become invalid.

Throws:

java.io.IOException

canSave

boolean canSave()
         throws java.io.IOException

Returns true if a save file is provided for creating a new version of this buffer file.

Throws:

java.io.IOException - if an I/O error occurs

See Also:

getSaveFile()

setVersionComment

void setVersionComment(java.lang.String comment)
                throws java.io.IOException

Set the comment which will be associated with this buffer file if saved. The comment must be set prior to invoking close or setReadOnly.

Parameters:

comment - comment text

Throws:

java.io.IOException - if an I/O error occurs

getCheckinID

long getCheckinID()
           throws java.io.IOException

Returns the checkin ID corresponding to this buffer file. The returned value is only valid if this buffer file has an associated buffer file manager and is either being created (see isReadOnly) or is intended for update (see canSave).

Throws:

java.io.IOException - if an I/O error occurs