Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.store.raw.data.CachedPage

Modifier and Type	Field and Description
protected boolean	alreadyReadPage
protected CacheManager	containerCache The container cache my container lives in. MT - Immutable
private long	containerRowCount
protected BaseDataFileFactory	dataFactory My factory class.
protected int	initialRowCount
protected boolean	isDirty
protected static final int	PAGE_FORMAT_ID_SIZE
protected CacheManager	pageCache The page cache I live in. MT - Immutable
protected byte[]	pageData
protected boolean	preDirty
public static final int	WRITE_NO_SYNC
public static final int	WRITE_SYNC

Access	Constructor and Description
public	CachedPage()

Method Summary

Modifier and Type	Method and Description
private CachedPage	Returns: The new object created with the input fid and transfered info. changeInstanceTo(int The format id of the new page. fid, PageKey The key of the new page. newIdentity) Convert this page to requested type, as defined by input format id. The current cache entry is a different format id than the requested type, change it.
public void	clean(boolean True if the object will be removed remove) Implements org.apache.derby.iapi.services.cache.Cacheable.clean. Write the page to disk.
public void	clearIdentity() Overrides org.apache.derby.impl.store.raw.data.BasePage.clearIdentity. Implements org.apache.derby.iapi.services.cache.Cacheable.clearIdentity. Put the object into the No Identity state.
public Cacheable	Returns: new page, higher levels have already checked the page number is valid for an open. createIdentity(Object Which page is this? key, Object details needed to create page like size, format id, ... createParameter) Implements org.apache.derby.iapi.services.cache.Cacheable.createIdentity. Find the container and then create the page in that container.
protected abstract void	createPage(PageKey id, PageCreationArgs args)
protected byte[]	Returns: The array of bytes that is the on disk version of page. getPageArray() Implements abstract org.apache.derby.impl.store.raw.data.BasePage.getPageArray. Returns the page data array used to write on disk version.
protected abstract void	initFromData(FileContainer container, PageKey id)
protected void	initialize() Overrides org.apache.derby.impl.store.raw.data.BasePage.initialize. Initialize a CachedPage.
public boolean	Returns: true if changes have actually been made to the page in memory. isActuallyDirty() Has the page or its header been modified.
public boolean	Returns: true if the page is dirty. isDirty() Implements org.apache.derby.iapi.services.cache.Cacheable.isDirty. Is the page dirty?
public void	preDirty() Implements abstract org.apache.derby.impl.store.raw.data.BasePage.preDirty. Set state to indicate the page or its header is about to be modified.
private void	readPage(FileContainer the container to read the page from. myContainer, PageKey indentity (ie. page number) of the page to read newIdentity) read the page from disk into this CachedPage object.
protected void	releaseExclusive() Overrides org.apache.derby.impl.store.raw.data.BasePage.releaseExclusive. exclusive latch on page is being released.
public void	setContainerRowCount(long rowCount) Implements abstract org.apache.derby.impl.store.raw.data.BasePage.setContainerRowCount. Set the number of rows in the container - the page uses this to decide whether it needs to aggressive set the container's row count when it changes.
protected void	setDirty() Set state to indicate the page or its header has been modified.
public final void	setFactory(BaseDataFileFactory factory)
public Cacheable	Returns: always true, higher levels have already checked the page number is valid for an open. setIdentity(Object The handle on the cacheable key) Implements org.apache.derby.iapi.services.cache.Cacheable.setIdentity. Find the container and then read the page from that container.
protected void	setPageArray(int pageSize) if the page size is different from the page buffer, then make a new page buffer and make subclass use the new page buffer
protected abstract void	usePageBuffer(byte[] buffer)
protected abstract void	writeFormatId(PageKey identity)
private void	writePage(PageKey indentity (ie. page number) of the page to read identity, boolean does the write of this single page have to be sync'd? syncMe) write the page from this CachedPage object to disk.
protected abstract void	writePage(PageKey id)

Inherited from org.apache.derby.impl.store.raw.data.BasePage:: allowInsert appendOverflowFieldHeader bumpPageVersion bumpRecordCount cleanPageForReuse clearLastLogInstant compactRecord compactRecord copyAndPurge deallocatePage deleteAtSlot doUpdateAtSlot entireRecordOnPage fetchFieldFromSlot fetchFromSlot fetchNumFields fetchNumFieldsAtSlot fillInIdentity findRecordById getAuxObject getHeaderAtSlot getIdentity getInvalidRecordHandle getLastLogInstant getNewOverflowPage getNextSlotNumber getOverflowPageForInsert getPageId getPageKey getPageNumber getPageStatus getPageVersion getRecordHandle getRecordHandleAtSlot getRecordLength getReservedCount getSlotNumber getTotalSpace initializeHeaders initPage initPage insert insertAllowOverflow insertAtSlot insertLongColumn insertNoOverflow internalDeletedRecordCount internalNonDeletedRecordCount isDeletedAtSlot isDeletedOnPage isLatched isOverflowPage isRepositionNeeded logColumn logField logLongColumn logRecord logRow MakeRecordHandle makeRecordHandle newRecordId newRecordId newRecordIdAndBump nonDeletedRecordCount purgeAtSlot purgeRecord purgeRowPieces recordCount recordExists recordHeaderOnDemand removeAndShiftDown reserveSpaceForSlot restorePortionLongColumn restoreRecordFromSlot restoreRecordFromStream setAuxObject setDeleteStatus setDeleteStatus setExclusive setExclusiveNoWait setHeaderAtSlot setPageStatus setPageStatus setPageVersion setRepositionNeeded setReservedSpace shiftUp shouldReclaimSpace skipField skipRecord slotTableToString spaceForCopy storeField storeRecord unfilled unlatch update updateAtSlot updateFieldAtSlot updateFieldOverflowDetails updateLastLogInstant updateOverflowDetails

alreadyReadPage	back to summary
protected boolean alreadyReadPage

containerCache	back to summary
protected CacheManager containerCache The container cache my container lives in. MT - Immutable

containerRowCount	back to summary
private long containerRowCount

dataFactory	back to summary
protected BaseDataFileFactory dataFactory My factory class. MT - Immutable -

initialRowCount	back to summary
protected int initialRowCount

isDirty	back to summary
protected boolean isDirty

PAGE_FORMAT_ID_SIZE	back to summary
protected static final int PAGE_FORMAT_ID_SIZE

pageCache	back to summary
protected CacheManager pageCache The page cache I live in. MT - Immutable

pageData	back to summary
protected byte[] pageData

preDirty	back to summary
protected boolean preDirty

WRITE_NO_SYNC	back to summary
public static final int WRITE_NO_SYNC

WRITE_SYNC	back to summary
public static final int WRITE_SYNC

CachedPage	back to summary
public CachedPage()

Method Detail

changeInstanceTo	back to summary
private CachedPage changeInstanceTo(int fid, PageKey newIdentity) throws StandardException Convert this page to requested type, as defined by input format id. The current cache entry is a different format id than the requested type, change it. This object is instantiated to the wrong subtype of cachedPage, this routine will create an object with the correct subtype, and transfer all pertinent information from this to the new correct object. Parameters fid:int The format id of the new page. newIdentity:PageKey The key of the new page. Returns:CachedPage The new object created with the input fid and transfered info. Exceptions StandardException: Standard exception policy.

changeInstanceTo

back to summary

private CachedPage changeInstanceTo(int fid, PageKey newIdentity) throws StandardException

Convert this page to requested type, as defined by input format id.

The current cache entry is a different format id than the requested type, change it. This object is instantiated to the wrong subtype of cachedPage, this routine will create an object with the correct subtype, and transfer all pertinent information from this to the new correct object.

Parameters

fid:int: The format id of the new page.
newIdentity:PageKey: The key of the new page.

Returns:CachedPage

The new object created with the input fid and transfered info.

Exceptions

StandardException:: Standard exception policy.

clean back to summary

clean	back to summary
public void clean(boolean remove) throws StandardException Implements org.apache.derby.iapi.services.cache.Cacheable.clean. Write the page to disk. MP - In a simple world we would just not allow clean until it held the latch on the page. But in order to fit into the cache system, we don't have enough state around to just make clean() latch the page while doing the I/O - but we still need someway to insure that no changes happen to the page while the I/O is taking place. Also someday it would be fine to allow reads of this page while the I/O was taking place. Parameters remove:boolean Doc from org.apache.derby.iapi.services.cache.Cacheable.clean. True if the object will be removed Exceptions StandardException: Error writing the page. See Also `Cacheable#clean`

public void clean(boolean remove) throws StandardException

Implements org.apache.derby.iapi.services.cache.Cacheable.clean.

Write the page to disk.

MP - In a simple world we would just not allow clean until it held the latch on the page. But in order to fit into the cache system, we don't have enough state around to just make clean() latch the page while doing the I/O - but we still need someway to insure that no changes happen to the page while the I/O is taking place. Also someday it would be fine to allow reads of this page while the I/O was taking place.

Parameters

remove:boolean

Doc from org.apache.derby.iapi.services.cache.Cacheable.clean.

True if the object will be removed

Exceptions

StandardException:: Error writing the page.

See Also

Cacheable#clean

clearIdentity	back to summary
public void clearIdentity() Overrides org.apache.derby.impl.store.raw.data.BasePage.clearIdentity. Implements org.apache.derby.iapi.services.cache.Cacheable.clearIdentity. Doc from org.apache.derby.iapi.services.cache.Cacheable.clearIdentity. Put the object into the No Identity state. MT - single thread required - Method must only be called be cache manager and the cache manager will guarantee only one thread can be calling it.

clearIdentity

back to summary

public void clearIdentity()

Overrides org.apache.derby.impl.store.raw.data.BasePage.clearIdentity.

Implements org.apache.derby.iapi.services.cache.Cacheable.clearIdentity.

Doc from org.apache.derby.iapi.services.cache.Cacheable.clearIdentity.

Put the object into the No Identity state.
MT - single thread required - Method must only be called be cache manager and the cache manager will guarantee only one thread can be calling it.

createIdentity back to summary

createIdentity	back to summary
public Cacheable createIdentity(Object key, Object createParameter) throws StandardException Implements org.apache.derby.iapi.services.cache.Cacheable.createIdentity. Find the container and then create the page in that container. This is the process of creating a new page in a container, in that case no need to read the page from disk - just need to initialize it in the cache. Parameters key:Object Which page is this? createParameter:Object details needed to create page like size, format id, ... Returns:Cacheable new page, higher levels have already checked the page number is valid for an open. Exceptions StandardException: Standard exception policy. See Also `Cacheable#createIdentity`

public Cacheable createIdentity(Object key, Object createParameter) throws StandardException

Implements org.apache.derby.iapi.services.cache.Cacheable.createIdentity.

Find the container and then create the page in that container.

This is the process of creating a new page in a container, in that case no need to read the page from disk - just need to initialize it in the cache.

Parameters

key:Object: Which page is this?
createParameter:Object: details needed to create page like size, format id, ...

Returns:Cacheable

new page, higher levels have already checked the page number is valid for an open.

Exceptions

StandardException:: Standard exception policy.

See Also

Cacheable#createIdentity

createPage	back to summary
protected abstract void createPage(PageKey id, PageCreationArgs args) throws StandardException

getPageArray	back to summary
protected byte[] getPageArray() throws StandardException Implements abstract org.apache.derby.impl.store.raw.data.BasePage.getPageArray. Returns the page data array used to write on disk version. returns the page data array, that is actually written to the disk, when the page is cleaned from the page cache. Takes care of flushing in-memory information to the array (like page header and format id info). Returns:byte[] The array of bytes that is the on disk version of page. Exceptions StandardException: Standard exception policy.

getPageArray

back to summary

protected byte[] getPageArray() throws StandardException

Implements abstract org.apache.derby.impl.store.raw.data.BasePage.getPageArray.

Returns the page data array used to write on disk version.

returns the page data array, that is actually written to the disk, when the page is cleaned from the page cache. Takes care of flushing in-memory information to the array (like page header and format id info).

Returns:byte[]

The array of bytes that is the on disk version of page.

Exceptions

StandardException:: Standard exception policy.

initFromData	back to summary
protected abstract void initFromData(FileContainer container, PageKey id) throws StandardException

initialize	back to summary
protected void initialize() Overrides org.apache.derby.impl.store.raw.data.BasePage.initialize. Initialize a CachedPage. Initialize the object, ie. perform work normally perfomed in constructor. Called by setIdentity() and createIdentity().

initialize

back to summary

protected void initialize()

Overrides org.apache.derby.impl.store.raw.data.BasePage.initialize.

Initialize a CachedPage.

Initialize the object, ie. perform work normally perfomed in constructor. Called by setIdentity() and createIdentity().

isActuallyDirty	back to summary
public boolean isActuallyDirty() Has the page or its header been modified. See comment on class header on meaning of isDirty and preDirty bits. Returns:boolean true if changes have actually been made to the page in memory.

isActuallyDirty

back to summary

public boolean isActuallyDirty()

Has the page or its header been modified.

See comment on class header on meaning of isDirty and preDirty bits.

Returns:boolean: true if changes have actually been made to the page in memory.

isDirty back to summary

isDirty	back to summary
public boolean isDirty() Implements org.apache.derby.iapi.services.cache.Cacheable.isDirty. Is the page dirty? The isDirty flag indicates if the pageData or pageHeader has been modified. The preDirty flag indicates that the pageData or the pageHeader is about to be modified. The reason for these 2 flags instead of just one is to accomodate checkpoint. After a clean (latched) page sends a log record to the log stream but before that page is dirtied by the log operation, a checkpoint could be taken. If so, then the redoLWM will be after the log record but, without preDirty, the cache cleaning will not have waited for the change. So the preDirty bit is to stop the cache cleaning from skipping over this (latched) page even though it has not really been modified yet. Returns:boolean true if the page is dirty. See Also `Cacheable#isDirty`

public boolean isDirty()

Implements org.apache.derby.iapi.services.cache.Cacheable.isDirty.

Is the page dirty?

The isDirty flag indicates if the pageData or pageHeader has been modified. The preDirty flag indicates that the pageData or the pageHeader is about to be modified. The reason for these 2 flags instead of just one is to accomodate checkpoint. After a clean (latched) page sends a log record to the log stream but before that page is dirtied by the log operation, a checkpoint could be taken. If so, then the redoLWM will be after the log record but, without preDirty, the cache cleaning will not have waited for the change. So the preDirty bit is to stop the cache cleaning from skipping over this (latched) page even though it has not really been modified yet.

Returns:boolean: true if the page is dirty.
See Also: Cacheable#isDirty

preDirty	back to summary
public void preDirty() Implements abstract org.apache.derby.impl.store.raw.data.BasePage.preDirty. Set state to indicate the page or its header is about to be modified. See comment on class header on meaning of isDirty and preDirty bits.

preDirty

back to summary

public void preDirty()

Implements abstract org.apache.derby.impl.store.raw.data.BasePage.preDirty.

Set state to indicate the page or its header is about to be modified.

See comment on class header on meaning of isDirty and preDirty bits.

readPage	back to summary
private void readPage(FileContainer myContainer, PageKey newIdentity) throws StandardException read the page from disk into this CachedPage object. A page is read in from disk into the pageData array of this object, and then put in the cache. Parameters myContainer:FileContainer the container to read the page from. newIdentity:PageKey indentity (ie. page number) of the page to read Exceptions StandardException: Standard exception policy.

releaseExclusive	back to summary
protected void releaseExclusive() Overrides org.apache.derby.impl.store.raw.data.BasePage.releaseExclusive. exclusive latch on page is being released. The only work done in CachedPage is to update the row count on the container if it is too out of sync.

releaseExclusive

back to summary

protected void releaseExclusive()

Overrides org.apache.derby.impl.store.raw.data.BasePage.releaseExclusive.

exclusive latch on page is being released.

The only work done in CachedPage is to update the row count on the container if it is too out of sync.

setContainerRowCount	back to summary
public void setContainerRowCount(long rowCount) Implements abstract org.apache.derby.impl.store.raw.data.BasePage.setContainerRowCount. Doc from org.apache.derby.impl.store.raw.data.BasePage.setContainerRowCount. Set the number of rows in the container - the page uses this to decide whether it needs to aggressive set the container's row count when it changes.

setContainerRowCount

back to summary

public void setContainerRowCount(long rowCount)

Implements abstract org.apache.derby.impl.store.raw.data.BasePage.setContainerRowCount.

Doc from org.apache.derby.impl.store.raw.data.BasePage.setContainerRowCount.

Set the number of rows in the container - the page uses this to decide whether it needs to aggressive set the container's row count when it changes.

setDirty	back to summary
protected void setDirty() Set state to indicate the page or its header has been modified. See comment on class header on meaning of isDirty and preDirty bits.

setDirty

back to summary

protected void setDirty()

Set state to indicate the page or its header has been modified.

See comment on class header on meaning of isDirty and preDirty bits.

setFactory	back to summary
public final void setFactory(BaseDataFileFactory factory)

setIdentity back to summary

setIdentity	back to summary
public Cacheable setIdentity(Object key) throws StandardException Implements org.apache.derby.iapi.services.cache.Cacheable.setIdentity. Find the container and then read the page from that container. This is the way new pages enter the page cache. Parameters key:Object Doc from org.apache.derby.iapi.services.cache.Cacheable.setIdentity. The handle on the cacheable Returns:Cacheable always true, higher levels have already checked the page number is valid for an open. Exceptions StandardException: Standard Derby policy. See Also `Cacheable#setIdentity`

public Cacheable setIdentity(Object key) throws StandardException

Implements org.apache.derby.iapi.services.cache.Cacheable.setIdentity.

Find the container and then read the page from that container.

This is the way new pages enter the page cache.

Parameters

key:Object

Doc from org.apache.derby.iapi.services.cache.Cacheable.setIdentity.

The handle on the cacheable

Returns:Cacheable

always true, higher levels have already checked the page number is valid for an open.

Exceptions

StandardException:: Standard Derby policy.

See Also

Cacheable#setIdentity

setPageArray	back to summary
protected void setPageArray(int pageSize) if the page size is different from the page buffer, then make a new page buffer and make subclass use the new page buffer

usePageBuffer	back to summary
protected abstract void usePageBuffer(byte[] buffer)

writeFormatId	back to summary
protected abstract void writeFormatId(PageKey identity) throws StandardException

writePage	back to summary
private void writePage(PageKey identity, boolean syncMe) throws StandardException write the page from this CachedPage object to disk. Parameters identity:PageKey indentity (ie. page number) of the page to read syncMe:boolean does the write of this single page have to be sync'd? Exceptions StandardException: Standard exception policy.

writePage

back to summary

private void writePage(PageKey identity, boolean syncMe) throws StandardException

write the page from this CachedPage object to disk.

Parameters

identity:PageKey: indentity (ie. page number) of the page to read
syncMe:boolean: does the write of this single page have to be sync'd?

Exceptions

StandardException:: Standard exception policy.

writePage	back to summary
protected abstract void writePage(PageKey id) throws StandardException

public abstract Class CachedPage

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail