org.apache.derby.impl.store.raw.data
Class CachedPage

java.lang.Object
  extended by org.apache.derby.impl.store.raw.data.BasePage
      extended by org.apache.derby.impl.store.raw.data.CachedPage
All Implemented Interfaces:
java.util.Observer, Cacheable, TypedFormat, Page
Direct Known Subclasses:
StoredPage

public abstract class CachedPage
extends BasePage
implements Cacheable

A base page that is cached. Since there are multiple page formats, use this abstract class to implement cacheable interface.


Field Summary
protected  boolean alreadyReadPage
           
protected  CacheManager containerCache
          The container cache my container lives in.
private  long containerRowCount
           
protected  BaseDataFileFactory dataFactory
          My factory class.
protected  int initialRowCount
           
protected  boolean isDirty
           
protected static int PAGE_FORMAT_ID_SIZE
           
protected  CacheManager pageCache
          The page cache I live in.
protected  byte[] pageData
           
protected  boolean preDirty
           
static int WRITE_NO_SYNC
           
static int WRITE_SYNC
           
 
Fields inherited from class org.apache.derby.impl.store.raw.data.BasePage
identity, inClean, INIT_PAGE_OVERFLOW, INIT_PAGE_REUSE, INIT_PAGE_REUSE_RECORDID, INVALID_PAGE, LOG_RECORD_DEFAULT, LOG_RECORD_FOR_PURGE, LOG_RECORD_FOR_UPDATE, owner, preLatch, VALID_PAGE
 
Fields inherited from interface org.apache.derby.iapi.store.raw.Page
DIAG_BYTES_FREE, DIAG_BYTES_RESERVED, DIAG_MAXROWSIZE, DIAG_MINIMUM_REC_SIZE, DIAG_MINROWSIZE, DIAG_NUMOVERFLOWED, DIAG_PAGE_SIZE, DIAG_PAGEOVERHEAD, DIAG_RESERVED_SPACE, DIAG_ROWSIZE, DIAG_SLOTTABLE_SIZE, FIRST_SLOT_NUMBER, INSERT_CONDITIONAL, INSERT_DEFAULT, INSERT_FOR_SPLIT, INSERT_INITIAL, INSERT_OVERFLOW, INSERT_UNDO_WITH_PURGE, INVALID_SLOT_NUMBER
 
Constructor Summary
CachedPage()
           
 
Method Summary
private  CachedPage changeInstanceTo(int fid, PageKey newIdentity)
          Convert this page to requested type, as defined by input format id.
 void clean(boolean remove)
          Write the page to disk.
 void clearIdentity()
          Put the object into the No Identity state.
 Cacheable createIdentity(java.lang.Object key, java.lang.Object createParameter)
          Find the container and then create the page in that container.
protected abstract  void createPage(PageKey id, PageCreationArgs args)
           
protected  byte[] getPageArray()
          Returns the page data array used to write on disk version.
protected abstract  void initFromData(FileContainer container, PageKey id)
           
protected  void initialize()
          Initialize a CachedPage.
 boolean isActuallyDirty()
          Has the page or its header been modified.
 boolean isDirty()
          Is the page dirty?
 void preDirty()
          Set state to indicate the page or its header is about to be modified.
private  void readPage(FileContainer myContainer, PageKey newIdentity)
          read the page from disk into this CachedPage object.
protected  void releaseExclusive()
          exclusive latch on page is being released.
 void setContainerRowCount(long rowCount)
          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.
 void setFactory(BaseDataFileFactory factory)
           
 Cacheable setIdentity(java.lang.Object key)
          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)
           
protected abstract  void writePage(PageKey id)
           
private  void writePage(PageKey identity, boolean syncMe)
          write the page from this CachedPage object to disk.
 
Methods inherited from class 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, 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
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.apache.derby.iapi.services.cache.Cacheable
getIdentity
 
Methods inherited from interface org.apache.derby.iapi.store.raw.Page
currentTimeStamp, equalTimeStamp, moveRecordForCompressAtSlot, setTimeStamp, spaceForInsert, spaceForInsert
 
Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat
getTypeFormatId
 

Field Detail

alreadyReadPage

protected boolean alreadyReadPage

pageData

protected byte[] pageData

isDirty

protected boolean isDirty

preDirty

protected boolean preDirty

initialRowCount

protected int initialRowCount

containerRowCount

private long containerRowCount

pageCache

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


containerCache

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


dataFactory

protected BaseDataFileFactory dataFactory
My factory class.
MT - Immutable -


PAGE_FORMAT_ID_SIZE

protected static final int PAGE_FORMAT_ID_SIZE
See Also:
Constant Field Values

WRITE_SYNC

public static final int WRITE_SYNC
See Also:
Constant Field Values

WRITE_NO_SYNC

public static final int WRITE_NO_SYNC
See Also:
Constant Field Values
Constructor Detail

CachedPage

public CachedPage()
Method Detail

setFactory

public final void setFactory(BaseDataFileFactory factory)

initialize

protected void initialize()
Initialize a CachedPage.

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

Overrides:
initialize in class BasePage

setIdentity

public Cacheable setIdentity(java.lang.Object key)
                      throws StandardException
Find the container and then read the page from that container.

This is the way new pages enter the page cache.

Specified by:
setIdentity in interface Cacheable
Returns:
always true, higher levels have already checked the page number is valid for an open.
Throws:
StandardException - Standard Derby policy.
See Also:
Cacheable.setIdentity(java.lang.Object)

createIdentity

public Cacheable createIdentity(java.lang.Object key,
                                java.lang.Object createParameter)
                         throws StandardException
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.

Specified by:
createIdentity in interface Cacheable
Parameters:
key - Which page is this?
createParameter - details needed to create page like size, format id, ...
Returns:
new page, higher levels have already checked the page number is valid for an open.
Throws:
StandardException - Standard exception policy.
See Also:
Cacheable.createIdentity(java.lang.Object, java.lang.Object)

changeInstanceTo

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 - The format id of the new page.
newIdentity - The key of the new page.
Returns:
The new object created with the input fid and transfered info.
Throws:
StandardException - Standard exception policy.

isDirty

public boolean 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.

Specified by:
isDirty in interface Cacheable
Returns:
true if the page is dirty.
See Also:
Cacheable.isDirty()

isActuallyDirty

public boolean isActuallyDirty()
Has the page or its header been modified.

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

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

preDirty

public void 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.

Specified by:
preDirty in class BasePage

setDirty

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.


releaseExclusive

protected void 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.

Overrides:
releaseExclusive in class BasePage

clean

public void clean(boolean remove)
           throws StandardException
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.

Specified by:
clean in interface Cacheable
Throws:
StandardException - Error writing the page.
See Also:
Cacheable.clean(boolean)

clearIdentity

public void clearIdentity()
Description copied from interface: Cacheable
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.

Specified by:
clearIdentity in interface Cacheable
Overrides:
clearIdentity in class BasePage

readPage

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 - the container to read the page from.
newIdentity - indentity (ie. page number) of the page to read
Throws:
StandardException - Standard exception policy.

writePage

private void writePage(PageKey identity,
                       boolean syncMe)
                throws StandardException
write the page from this CachedPage object to disk.

Parameters:
identity - indentity (ie. page number) of the page to read
syncMe - does the write of this single page have to be sync'd?
Throws:
StandardException - Standard exception policy.

setContainerRowCount

public void setContainerRowCount(long rowCount)
Description copied from class: BasePage
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.

Specified by:
setContainerRowCount in class BasePage

setPageArray

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


getPageArray

protected byte[] getPageArray()
                       throws StandardException
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).

Specified by:
getPageArray in class BasePage
Returns:
The array of bytes that is the on disk version of page.
Throws:
StandardException - Standard exception policy.

usePageBuffer

protected abstract void usePageBuffer(byte[] buffer)

initFromData

protected abstract void initFromData(FileContainer container,
                                     PageKey id)
                              throws StandardException
Throws:
StandardException

createPage

protected abstract void createPage(PageKey id,
                                   PageCreationArgs args)
                            throws StandardException
Throws:
StandardException

writePage

protected abstract void writePage(PageKey id)
                           throws StandardException
Throws:
StandardException

writeFormatId

protected abstract void writeFormatId(PageKey identity)
                               throws StandardException
Throws:
StandardException

Built on Thu 2011-03-10 11:54:14+0000, from revision ???

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