com.aspc.DBObj.Internal

Class DBData

java.lang.Object

com.aspc.DBObj.Internal.DBData

All Implemented Interfaces:

DBDataInterface

public final class DBData
extends java.lang.Object
implements DBDataInterface

DBData is the main storage for all data objects. The system relies on the fact that there is only ever ONE copy of DBData per database object. The system may have many versions of the related DBObjects which can be modifiable or read only. When the underlying DBData is changed all related DBObjects will be notified.
PERFORMANCE: 56 bytes per DBData object in 32 bit mode THREAD MODE: MULTI-THREADED MEMORY USAGE: 568 bytes average per DBData excluding LayerData memory

Since:

January 26, 2000

Author:

Nigel Leck

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DBData.SLOW_LOAD_LOCATION where should we run slowly

Field Summary

Fields

Modifier and Type	Field and Description
static int	CACHE_COMPRESS_SIZE The size of the field data before we should compress it ?
static int	CACHE_LOAD_SEGMENTS The maximum number of segments to load into the cache without a direct request
static java.lang.String	ENV_DATA_CLASSES_HIGH Classes that will be put into med-high cost cache
static java.lang.String	ENV_DATA_CLASSES_LOW Classes that will be put into med-low cost cache
static java.util.concurrent.atomic.AtomicLong	LINKAGE_FUSE the linkage fuse
static java.util.concurrent.ConcurrentHashMap<java.lang.String,java.util.concurrent.FutureTask<LayerData>>	LOADING_MAP
static int	MAX_READ_AHEAD The maximum number of additional rows to read ahead
static java.lang.String	NOTIFY_CREATED Notify when a new create is created.
static java.lang.String	NOTIFY_DELETED Notify when a record is deleted
static java.lang.String	NOTIFY_MODIFIED Notify when a record is modified
long	rowId the actual row id
static boolean	SLOW_LOAD_ALLOWED DEBUG ONLY Allow an artificially slow load time at selected spots of the code.
static java.lang.String	SLOW_LOAD_LOCATION1 Location 1 for debug.
static VersionENV	VERSION the version to use

Method Summary

Modifier and Type	Method and Description
void	addDependanceListener(DependanceListener dl) Add a dependence listener
boolean	checkDirty(VirtualDB layer, LayerData layerData, long transId) Check if this layer data needs to be reloaded
boolean	checkDirty(VirtualDB layer, long transId) Check if this layer data needs to be reloaded
DBObject	createDBObject(DataSource ds, Hint hint) Create a DBObject for this row
void	dispose(DBObject theObject) dispose of the object
static boolean	doesClassListen(GlobalId classId) Does this class Id listen ? If we don't know anything about the class yet ie.
boolean	existedAt(java.util.Date date) Did this row exists at this date.
static DBData	fetchKey(GlobalKey gk) Find the raw data based on a Global Key
LayerData	fetchLayerData(VirtualDB layer) fetch the layer data for this record
static DBData	find(long rowId, DBClass requestedClass) The only method of finding/creating a DBData THREAD SAFE: This method must ensure that only one DBData per database record ever exists.
static DBData	find(long rowId, DBClass requestedClass, boolean create) The only method of finding/creating a DBData THREAD SAFE: This method must ensure that only one DBData per database record ever exists.
static DBData	find(long rowId, GlobalKeyId rootClassId) find
static DBData	find(long rowId, GlobalKeyId rootClassId, boolean create) find
int	getBaseLayerId() The base layer
static MemoryHandler.Cost	getCost(DBClass dbClass) the cost of the class
GlobalKey	getGlobalKey(Hint hint) The globalKey for this DBData.
GlobalKey	getGlobalKey(VirtualDB layer, DBField field, Hint hint) retrieve the global key for this field.
LayerData	getLayerData(VirtualDB layer, Hint hint) Return the layer data for this record
long	getLinkedRowId(VirtualDB layer, DBField field, Hint hint) Get the linked row id if known.
java.lang.Object	getRawValue(VirtualDB layer, DBField field, Hint hint) Retrieves the raw data for the specified field the supplied virtual db indicates how the object views the data for this field We will scroll down the virtual db tree until we find a value for the field.
DBClass	getRealDBClass(VirtualDB layer, Hint hint) Return the REAL DBClass if known else null.
GlobalKeyId	getRootDBClassId() The root class for this record
long	getRowId() The row id for this database object.
long	getTransId(VirtualDB layer, Hint hint) The current transaction id for this database object.
static int	getVersion() The version being used.
boolean	hasLayerDataLoaded(VirtualDB layer) Have we loaded this layer
boolean	hasRawFieldInLayer(VirtualDB layer, DBField field, Hint hint) Does raw data for a field exist in this layer ? This ignores the final flag as it is used for deleting data.
boolean	hasRawRowInLayer(VirtualDB layer, Hint hint) Does raw data for a field exist in this layer ? This ignores the final flag as it is used for deleting data.
static boolean	isClassWatched(DBClass rootClass) is this class watched ?
boolean	isDeleted(VirtualDB layer, Hint hint) Is the database object deleted.
boolean	isFinal(VirtualDB layer, Hint hint) Is this layer's data marked as final ? No changes may be recorded for a record that is final from below.
boolean	isLoaded(int layerID) is loaded ?
boolean	isLocked() is this data locked in memory ?
static long[]	listRowsInMemory(GlobalKeyId rootClassId) list in memory rows for this class
static DBData	load(DBObject obj, long transId) Load the DBData from an object just saved INTERNAL ONLY
void	lock() lock the record into memory
static boolean	recordsLoaded(GlobalId classId) Are any records for this class loaded ?
void	register(DBObject theObject) registers any objects that contain this data object this allows us to notify these objects of any changes made to the data Now that we have a initiated DBObject we can test to see if this class type is a dependenceListener.
void	reloadLayer(VirtualDB vDB) Reloads this layer's data from the raw database.
static void	reloadLayer(VirtualDB layer, DBClass theClass, long[] rowsToReload, long transNr) Reload the data for the layer that relates to the virtual database
static void	removeSaveLock(MutableDataSource ds) Remove all locks held by mutable data source.
static void	simulateSlowLoad(int milliSecondsPerLoad, DBData.SLOW_LOAD_LOCATION slowLocation) simulate slow load
static void	stats(StatsCollector collector) The statistics
static void	takeSaveLock(MutableDataSource ds, DBObject[] list) Prevent multiple saves of the same record within the one application.
void	unlock() remove the hard link on this record.
static void	unlockAll(GlobalKeyId rootClassId) unlock

Methods inherited from class java.lang.Object

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

Field Detail

VERSION

public static final VersionENV VERSION

the version to use

MAX_READ_AHEAD

public static final int MAX_READ_AHEAD

The maximum number of additional rows to read ahead

See Also:

Constant Field Values

NOTIFY_CREATED

public static final java.lang.String NOTIFY_CREATED

Notify when a new create is created.

See Also:

Constant Field Values

NOTIFY_MODIFIED

public static final java.lang.String NOTIFY_MODIFIED

Notify when a record is modified

See Also:

Constant Field Values

NOTIFY_DELETED

public static final java.lang.String NOTIFY_DELETED

Notify when a record is deleted

See Also:

Constant Field Values

CACHE_LOAD_SEGMENTS

public static final int CACHE_LOAD_SEGMENTS

The maximum number of segments to load into the cache without a direct request

CACHE_COMPRESS_SIZE

public static final int CACHE_COMPRESS_SIZE

The size of the field data before we should compress it ?

ENV_DATA_CLASSES_HIGH

public static final java.lang.String ENV_DATA_CLASSES_HIGH

Classes that will be put into med-high cost cache

See Also:

Constant Field Values

ENV_DATA_CLASSES_LOW

public static final java.lang.String ENV_DATA_CLASSES_LOW

Classes that will be put into med-low cost cache

See Also:

Constant Field Values

LINKAGE_FUSE

public static final java.util.concurrent.atomic.AtomicLong LINKAGE_FUSE

the linkage fuse

rowId

public final long rowId

the actual row id

SLOW_LOAD_LOCATION1

public static final java.lang.String SLOW_LOAD_LOCATION1

Location 1 for debug.

See Also:

Constant Field Values

SLOW_LOAD_ALLOWED

public static final boolean SLOW_LOAD_ALLOWED

DEBUG ONLY Allow an artificially slow load time at selected spots of the code.

LOADING_MAP

public static final java.util.concurrent.ConcurrentHashMap<java.lang.String,java.util.concurrent.FutureTask<LayerData>> LOADING_MAP

Method Detail

getRootDBClassId

@CheckReturnValue
 @Nonnull
public GlobalKeyId getRootDBClassId()

The root class for this record

Specified by:

getRootDBClassId in interface DBDataInterface

Returns:

The root class

simulateSlowLoad

public static void simulateSlowLoad(@Nonnegative
                                    int milliSecondsPerLoad,
                                    @Nullable
                                    DBData.SLOW_LOAD_LOCATION slowLocation)

simulate slow load

Parameters:

milliSecondsPerLoad - number of milliseconds

slowLocation - The place to cause the slowness

checkDirty

@CheckReturnValue
public boolean checkDirty(@Nonnull
                                            VirtualDB layer,
                                            @Nonnull
                                            LayerData layerData,
                                            @Nonnegative
                                            long transId)

Check if this layer data needs to be reloaded

Parameters:

layer -

layerData - the current data.

transId - the transaction number to check

Returns:

true if dirty

checkDirty

@CheckReturnValue
public boolean checkDirty(@Nonnull
                                            VirtualDB layer,
                                            @Nonnegative
                                            long transId)

Check if this layer data needs to be reloaded

Parameters:

layer - the layer.

transId - the transaction number to check

Returns:

true if dirty

lock

public void lock()

lock the record into memory

isLocked

@CheckReturnValue
public boolean isLocked()

is this data locked in memory ?

Returns:

TRUE if locked

unlockAll

public static void unlockAll(@Nonnull
                             GlobalKeyId rootClassId)

unlock

Parameters:

rootClassId - the class

listRowsInMemory

@CheckReturnValue
 @Nonnull
public static long[] listRowsInMemory(@Nonnull
                                                                  GlobalKeyId rootClassId)

list in memory rows for this class

Parameters:

rootClassId - the class

Returns:

list of row IDs in memory

unlock

public void unlock()

remove the hard link on this record.

getRealDBClass

@CheckReturnValue
public DBClass getRealDBClass(@Nonnull
                                                VirtualDB layer,
                                                @Nullable
                                                Hint hint)

Return the REAL DBClass if known else null.

Specified by:

getRealDBClass in interface DBDataInterface

Parameters:

layer - The layer

hint - What other rows will be loaded.

Returns:

The REAL class

createDBObject

@CheckReturnValue
 @Nonnull
public DBObject createDBObject(@Nonnull
                                                           DataSource ds,
                                                           @Nullable
                                                           Hint hint)
                                                    throws NotFoundException

Create a DBObject for this row

Parameters:

ds - The DataSource that the object will be created for

hint - The rows that will be loaded.

Returns:

The newly created object

Throws:

NotFoundException - The row was not found

getGlobalKey

@CheckReturnValue
public GlobalKey getGlobalKey(@Nullable
                                                Hint hint)

The globalKey for this DBData. PERFORMANCE: Cache the globalKey for future use. By design the key may not
be changed once the record has been created. Don't cache the global key if it doesn't have a row Id yet. As this may change and wont know.

Specified by:

getGlobalKey in interface DBDataInterface

Parameters:

hint - If we need to hit the database, then also get these rows

Returns:

The global key

getRawValue

@CheckReturnValue
 @Nullable
public java.lang.Object getRawValue(@Nonnull
                                                                 VirtualDB layer,
                                                                 @Nonnull
                                                                 DBField field,
                                                                 @Nullable
                                                                 Hint hint)

Retrieves the raw data for the specified field the supplied virtual db indicates how the object views the data for this field We will scroll down the virtual db tree until we find a value for the field.

Specified by:

getRawValue in interface DBDataInterface

Parameters:

layer - Which layer.

field - The field to get

hint - Which other rows will we be asking for.

Returns:

The value of the field in this layer.

getGlobalKey

@CheckReturnValue
 @Nullable
public GlobalKey getGlobalKey(@Nonnull
                                                           VirtualDB layer,
                                                           @Nonnull
                                                           DBField field,
                                                           @Nullable
                                                           Hint hint)

retrieve the global key for this field. We'll scroll down the virtual db tree until we find a value for this field.

Specified by:

getGlobalKey in interface DBDataInterface

Parameters:

layer - Which layer.

field - The field to get

hint - Which other rows will we be asking for.

Returns:

The global key for this field in this layer.

getLinkedRowId

@CheckReturnValue
public long getLinkedRowId(@Nonnull
                                             VirtualDB layer,
                                             @Nonnull
                                             DBField field,
                                             @Nullable
                                             Hint hint)

Get the linked row id if known.

Specified by:

getLinkedRowId in interface DBDataInterface

Parameters:

layer - Which layer.

field - The field to get

hint - Which other rows will we be asking for.

Returns:

The global key for this field in this layer.

reloadLayer

public static void reloadLayer(@Nonnull
                               VirtualDB layer,
                               @Nonnull
                               DBClass theClass,
                               @Nonnull
                               long[] rowsToReload,
                               @Nonnegative
                               long transNr)
                        throws java.lang.Exception

Reload the data for the layer that relates to the virtual database

Parameters:

rowsToReload - The list of rows to load

transNr - The transaction that we need to load

layer - Which layer

theClass - The class of the records.

Throws:

java.lang.Exception - A serious problem occurred.

reloadLayer

public void reloadLayer(@Nonnull
                        VirtualDB vDB)
                 throws java.lang.Exception

Reloads this layer's data from the raw database.

Specified by:

reloadLayer in interface DBDataInterface

Parameters:

vDB - For which layer

Throws:

java.lang.Exception - A serious problem.

getRowId

@CheckReturnValue
public long getRowId()

The row id for this database object.

Specified by:

getRowId in interface DBDataInterface

Returns:

The row id

getTransId

@CheckReturnValue
public long getTransId(@Nonnull
                                         VirtualDB layer,
                                         @Nullable
                                         Hint hint)

The current transaction id for this database object.

Specified by:

getTransId in interface DBDataInterface

Parameters:

layer - Which layer

hint - What other rows.

Returns:

The current transaction id for this database object/layer

isDeleted

@CheckReturnValue
public boolean isDeleted(@Nonnull
                                           VirtualDB layer,
                                           @Nullable
                                           Hint hint)

Is the database object deleted. An object may be active in a layer below but deleted in a layer above.

Specified by:

isDeleted in interface DBDataInterface

Parameters:

layer - In which layer ?

hint - What other rows will you be asking about

Returns:

Is the record deleted in this layer

isLoaded

@CheckReturnValue
public boolean isLoaded(@Nonnegative
                                          int layerID)

is loaded ?

Parameters:

layerID - the layer

Returns:

true if loaded

takeSaveLock

public static void takeSaveLock(@Nonnull
                                MutableDataSource ds,
                                @Nonnull
                                DBObject[] list)
                         throws TimeoutException

Prevent multiple saves of the same record within the one application. We need to handle dirty cache situations but no need to cause them ourselves.
We'll wait until we can get a lock on all items to be saved.

Parameters:

ds - The saving data source

list - The universe of objects to be saved.

Throws:

TimeoutException

removeSaveLock

public static void removeSaveLock(@Nonnull
                                  MutableDataSource ds)

Remove all locks held by mutable data source.

Parameters:

ds - The datasource to remove all locks for.

dispose

public void dispose(@Nonnull
                    DBObject theObject)

dispose of the object

Parameters:

theObject - to dispose

register

public void register(@Nonnull
                     DBObject theObject)

registers any objects that contain this data object this allows us to notify these objects of any changes made to the data Now that we have a initiated DBObject we can test to see if this class type is a dependenceListener. If it is not record that fact to reduce the event notification when creating large number of objects.

Specified by:

register in interface DBDataInterface

Parameters:

theObject - to notify

load

@Nonnull
public static DBData load(@Nonnull
                                   DBObject obj,
                                   @Nonnegative
                                   long transId)
                            throws java.lang.Exception

Load the DBData from an object just saved INTERNAL ONLY

Parameters:

obj - The object just saved.

transId - The transaction id for which it was saved.

Returns:

The DBData for this DBObject

Throws:

java.lang.Exception - A serious problem

hasLayerDataLoaded

@CheckReturnValue
public boolean hasLayerDataLoaded(@Nonnull
                                                    VirtualDB layer)

Have we loaded this layer

Parameters:

layer - The layer

Returns:

TRUE if loaded

fetchLayerData

@CheckReturnValue
 @Nullable
public LayerData fetchLayerData(@Nonnull
                                                             VirtualDB layer)

fetch the layer data for this record

Parameters:

layer - From which layer

Returns:

The layer data for this record.

getLayerData

@CheckReturnValue
 @Nonnull
public LayerData getLayerData(@Nonnull
                                                          VirtualDB layer,
                                                          @Nullable
                                                          Hint hint)

Return the layer data for this record

Specified by:

getLayerData in interface DBDataInterface

Parameters:

layer - From which layer

hint - What other records will you be asking

Returns:

The layer data for this record.

addDependanceListener

public void addDependanceListener(@Nonnull
                                  DependanceListener dl)

Add a dependence listener

Specified by:

addDependanceListener in interface DBDataInterface

Parameters:

dl - The listener

doesClassListen

@CheckReturnValue
public static boolean doesClassListen(@Nullable
                                                        GlobalId classId)

Does this class Id listen ? If we don't know anything about the class yet ie. no rows loaded then return true. It's safer and works around a bug when generating a search screen when no screens have been loaded yet.

Parameters:

classId - Does this class listen ?

Returns:

TRUE if it listens

isClassWatched

@CheckReturnValue
public static boolean isClassWatched(@Nonnull
                                                       DBClass rootClass)

is this class watched ?

Parameters:

rootClass - the root class

Returns:

true if watched.

recordsLoaded

@CheckReturnValue
public static boolean recordsLoaded(@Nullable
                                                      GlobalId classId)

Are any records for this class loaded ?

Parameters:

classId - Are records for this class loaded ?

Returns:

TRUE if loaded

hasRawFieldInLayer

@CheckReturnValue
public boolean hasRawFieldInLayer(@Nonnull
                                                    VirtualDB layer,
                                                    @Nonnull
                                                    DBField field,
                                                    @Nullable
                                                    Hint hint)

Does raw data for a field exist in this layer ? This ignores the final flag as it is used for deleting data.

Specified by:

hasRawFieldInLayer in interface DBDataInterface

Parameters:

layer - From which layer.

field - The field

hint - Which other rows.

Returns:

True if has a raw field record

fetchKey

@CheckReturnValue
 @Nullable
public static DBData fetchKey(@Nonnull
                                                           GlobalKey gk)

Find the raw data based on a Global Key

Parameters:

gk - The key to search for.

Returns:

The data

hasRawRowInLayer

@CheckReturnValue
public boolean hasRawRowInLayer(@Nonnull
                                                  VirtualDB layer,
                                                  @Nullable
                                                  Hint hint)

Does raw data for a field exist in this layer ? This ignores the final flag as it is used for deleting data.

Specified by:

hasRawRowInLayer in interface DBDataInterface

Parameters:

layer - From which layer

hint - Which other rows.

Returns:

True if it has a raw record row the in database.

isFinal

@CheckReturnValue
public boolean isFinal(@Nonnull
                                         VirtualDB layer,
                                         @Nullable
                                         Hint hint)

Is this layer's data marked as final ? No changes may be recorded for a record that is final from below.

Specified by:

isFinal in interface DBDataInterface

Parameters:

layer - From which layer.

hint - What other rows.

Returns:

Is it final in this layer? ( can I make changes)

find

@CheckReturnValue
 @Nullable
public static DBData find(long rowId,
                                                       @Nonnull
                                                       DBClass requestedClass,
                                                       boolean create)
                                                throws NotFoundException

The only method of finding/creating a DBData THREAD SAFE: This method must ensure that only one DBData per database record ever exists.

Parameters:

requestedClass - The class of the DBData.

create - Should we create the DBData if not found.

rowId - The row id of the record.

Returns:

The DBData for the record

Throws:

NotFoundException - If the row id for this DBClass is not found.

find

@CheckReturnValue
 @Nonnull
public static DBData find(long rowId,
                                                      @Nonnull
                                                      DBClass requestedClass)
                                               throws NotFoundException

The only method of finding/creating a DBData THREAD SAFE: This method must ensure that only one DBData per database record ever exists.

Parameters:

requestedClass - The class of the DBData.

rowId - The row id of the record.

Returns:

The DBData for the record

Throws:

NotFoundException - If the row id for this DBClass is not found.

getCost

@CheckReturnValue
 @Nonnull
public static MemoryHandler.Cost getCost(@Nonnull
                                                                     DBClass dbClass)

the cost of the class

Parameters:

dbClass - the class

Returns:

the cost

find

@Nonnull
 @CheckReturnValue
public static DBData find(long rowId,
                                                      @Nonnull
                                                      GlobalKeyId rootClassId)
                                               throws NotFoundException

find

Parameters:

rowId - the row

rootClassId - the class

Returns:

the DBData

Throws:

NotFoundException - not found

find

@Nullable
 @CheckReturnValue
public static DBData find(long rowId,
                                                       @Nonnull
                                                       GlobalKeyId rootClassId,
                                                       boolean create)
                                                throws NotFoundException

find

Parameters:

rowId - the row

rootClassId - the class

create - create if not found

Returns:

the DBData

Throws:

NotFoundException - not found

existedAt

@CheckReturnValue
public boolean existedAt(@Nonnull
                                           java.util.Date date)

Did this row exists at this date. Without getting into religious arguments if no creation transaction exists then the record is said to have always existed which is clearly impossible.

Parameters:

date - The as of date

Returns:

True if the row existed.

stats

public static void stats(@Nonnull
                         StatsCollector collector)

The statistics

Parameters:

collector - the collector

getVersion

@CheckReturnValue
public static int getVersion()

The version being used.

Returns:

the data version.

getBaseLayerId

@CheckReturnValue
public int getBaseLayerId()

The base layer

Specified by:

getBaseLayerId in interface DBDataInterface

Returns:

The layer id.