org.apache.openjpa.kernel
Interface FetchConfiguration

All Superinterfaces:

Cloneable, LockLevels, QueryFlushModes, Serializable

All Known Subinterfaces:

JDBCFetchConfiguration

All Known Implementing Classes:

DelegatingFetchConfiguration, DelegatingJDBCFetchConfiguration, FetchConfigurationImpl, JDBCFetchConfigurationImpl

public interface FetchConfiguration
extends Serializable, Cloneable, LockLevels, QueryFlushModes

Allows configuration and optimization of how objects are loaded from the data store.

Since:

0.3.0

Author:

Abe White, Pinaki Poddar

Field Summary

static int	DEFAULT Constant to revert any setting back to its default value.
static int	FETCH_LOAD Constant indicating that a field requires a fetch and load of fetched data.
static int	FETCH_NONE Constant indicating that a field does not require fetching.
static int	FETCH_REF Constant indicating that a reference to the field's value must be fetched, but loading data is not necessary.

Fields inherited from interface org.apache.openjpa.kernel.LockLevels

LOCK_NONE, LOCK_READ, LOCK_WRITE

Fields inherited from interface org.apache.openjpa.kernel.QueryFlushModes

FLUSH_FALSE, FLUSH_TRUE, FLUSH_WITH_CONNECTION

Method Summary

FetchConfiguration	addFetchGroup(String group) Adds group to the set of fetch group names to use when loading objects.
FetchConfiguration	addFetchGroups(Collection groups) Adds groups to the set of fetch group names to use when loading objects.
FetchConfiguration	addField(String field) Adds field to the set of fully-qualified field names to use when loading objects.
FetchConfiguration	addFields(Collection fields) Adds fields to the set of fully-qualified field names to use when loading objects.
FetchConfiguration	clearFetchGroups() Clears the set of fetch group names to use when loading data.
FetchConfiguration	clearFields() Clears the set of field names to use when loading data.
Object	clone() Clone this instance.
void	copy(FetchConfiguration fetch) Copy the state from the given fetch configuration to this one.
StoreContext	getContext() Return the context assiciated with this configuration; may be null if it has not been set or this object has been serialized.
int	getFetchBatchSize() Return the fetch batch size for large result set support.
Set	getFetchGroups() Returns immutable set of names of the fetch groups that this component will use when loading objects.
Set	getFields() Returns the set of fully-qualified field names that this component will use when loading objects.
int	getFlushBeforeQueries() The query automatic flush configuration.
Object	getHint(String name) Returns the hint for the specific key, or null if the hint is not specified.
int	getLockTimeout() The number of milliseconds to wait for an object lock, or -1 for no limit.
int	getMaxFetchDepth() Return the maximum depth of fetched instance graph.
boolean	getQueryCache() Return whether or not query caching is enabled.
int	getReadLockLevel() The lock level to use for locking loaded objects.
Set	getRootClasses() Root classes for recursive operations.
Set	getRootInstances() Root instances for recursive operations.
int	getWriteLockLevel() The lock level to use for locking dirtied objects.
boolean	hasFetchGroup(String group) Return true if the given fetch group has been added.
boolean	hasField(String field) Return true if the given fully-qualified field has been added.
void	lock() Synchronize on internal lock if multithreaded is true.
ResultList	newResultList(ResultObjectProvider rop) Return a new result list for the current fetch configuration.
FetchConfiguration	removeFetchGroup(String group) Remove the given fetch group.
FetchConfiguration	removeFetchGroups(Collection groups) Removes groups from the set of fetch group names to use when loading objects.
FetchConfiguration	removeField(String field) Remove the given fully-qualified field.
FetchConfiguration	removeFields(Collection fields) Removes fields from the set of fully-qualified field names to use when loading objects.
int	requiresFetch(FieldMetaData fm) Affirms if the given field requires to be fetched in the context of current fetch operation.
boolean	requiresLoad() Return false if we know that the object being fetched with this configuration does not require a load, because this configuration came from a traversal of a FETCH_REF field.
FetchConfiguration	resetFetchGroups() Resets the set of fetch groups to the list in the global configuration.
void	setContext(StoreContext ctx) Called automatically by the system to associate the fetch configuration with a context before use.
FetchConfiguration	setFetchBatchSize(int fetchBatchSize) Set the fetch batch size for large result set support.
FetchConfiguration	setFlushBeforeQueries(int flush) The query automatic flush configuration.
void	setHint(String name, Object value) Sets an arbitrary query hint that may be utilized during execution.
FetchConfiguration	setLockTimeout(int timeout) The number of milliseconds to wait for an object lock, or -1 for no limit.
FetchConfiguration	setMaxFetchDepth(int max) Set the maximum depth of the fetched instance graph.
FetchConfiguration	setQueryCache(boolean cache) Control whether or not query caching is enabled.
FetchConfiguration	setReadLockLevel(int level) The lock level to use for locking loaded objects.
FetchConfiguration	setRootClasses(Collection classes) Root classes for recursive operations.
FetchConfiguration	setRootInstances(Collection roots) Root instances for recursive operations.
FetchConfiguration	setWriteLockLevel(int level) The lock level to use for locking dirtied objects.
FetchConfiguration	traverse(FieldMetaData fm) Traverse the given field to generate (possibly) a new configuration state.
void	unlock() Release internal lock if multithreaded is true.

Field Detail

DEFAULT

static final int DEFAULT

Constant to revert any setting back to its default value.

See Also:

Constant Field Values

FETCH_NONE

static final int FETCH_NONE

Constant indicating that a field does not require fetching.

See Also:

requiresFetch(org.apache.openjpa.meta.FieldMetaData), Constant Field Values

FETCH_LOAD

static final int FETCH_LOAD

Constant indicating that a field requires a fetch and load of fetched data.

See Also:

requiresFetch(org.apache.openjpa.meta.FieldMetaData), Constant Field Values

FETCH_REF

static final int FETCH_REF

Constant indicating that a reference to the field's value must be fetched, but loading data is not necessary. Used when we know the data will be loaded anyway, such as when traversing the back-ptr of a bidirectional relation where the other side is also being fetched.

See Also:

requiresFetch(org.apache.openjpa.meta.FieldMetaData), Constant Field Values

Method Detail

getContext

StoreContext getContext()

Return the context assiciated with this configuration; may be null if it has not been set or this object has been serialized.

setContext

void setContext(StoreContext ctx)

Called automatically by the system to associate the fetch configuration with a context before use. The fetch configuration properties should be synchronized with the context's configuration object. Subclasses for specific back ends cannot rely on the context's configuration implementing their back end's configuration sub-interface.

clone

Object clone()

Clone this instance.

copy

void copy(FetchConfiguration fetch)

Copy the state from the given fetch configuration to this one.

getFetchBatchSize

int getFetchBatchSize()

Return the fetch batch size for large result set support. Defaults to the openjpa.FetchBatchSize setting. Note that this property will be ignored under some data stores.

setFetchBatchSize

FetchConfiguration setFetchBatchSize(int fetchBatchSize)

Set the fetch batch size for large result set support. Defaults to the openjpa.FetchBatchSize setting. Note that this property will be ignored under some data stores.

getMaxFetchDepth

int getMaxFetchDepth()

Return the maximum depth of fetched instance graph. Defaults to 1

setMaxFetchDepth

FetchConfiguration setMaxFetchDepth(int max)

Set the maximum depth of the fetched instance graph.

Parameters:

max - denotes limiting length of traversal path from a root instance. -1 implies no limit. 0 is not permissible.

getQueryCache

boolean getQueryCache()

Return whether or not query caching is enabled. If this returns true but the datacache plugin is not installed, caching will not be enabled. If this returns false, query caching will not be used even if the datacache plugin is installed.

setQueryCache

FetchConfiguration setQueryCache(boolean cache)

Control whether or not query caching is enabled. This has no effect if the datacache plugin is not installed, or if the query cache size is set to zero.

getFlushBeforeQueries

int getFlushBeforeQueries()

The query automatic flush configuration.

setFlushBeforeQueries

FetchConfiguration setFlushBeforeQueries(int flush)

The query automatic flush configuration.

getFetchGroups

Set getFetchGroups()

Returns immutable set of names of the fetch groups that this component will use when loading objects. Defaults to the openjpa.FetchGroups setting. This set is not thread safe.

hasFetchGroup

boolean hasFetchGroup(String group)

Return true if the given fetch group has been added.

addFetchGroup

FetchConfiguration addFetchGroup(String group)

Adds group to the set of fetch group names to use when loading objects.

addFetchGroups

FetchConfiguration addFetchGroups(Collection groups)

Adds groups to the set of fetch group names to use when loading objects.

removeFetchGroup

FetchConfiguration removeFetchGroup(String group)

Remove the given fetch group.

removeFetchGroups

FetchConfiguration removeFetchGroups(Collection groups)

Removes groups from the set of fetch group names to use when loading objects.

clearFetchGroups

FetchConfiguration clearFetchGroups()

Clears the set of fetch group names to use when loading data. After this operation is invoked, only those fields in the default fetch group (and any requested field) will be loaded when loading an object.

resetFetchGroups

FetchConfiguration resetFetchGroups()

Resets the set of fetch groups to the list in the global configuration.

getFields

Set getFields()

Returns the set of fully-qualified field names that this component will use when loading objects. Defaults to the empty set. This set is not thread safe.

hasField

boolean hasField(String field)

Return true if the given fully-qualified field has been added.

addField

FetchConfiguration addField(String field)

Adds field to the set of fully-qualified field names to use when loading objects.

addFields

FetchConfiguration addFields(Collection fields)

Adds fields to the set of fully-qualified field names to use when loading objects.

removeField

FetchConfiguration removeField(String field)

Remove the given fully-qualified field.

removeFields

FetchConfiguration removeFields(Collection fields)

Removes fields from the set of fully-qualified field names to use when loading objects.

clearFields

FetchConfiguration clearFields()

Clears the set of field names to use when loading data. After this operation is invoked, only those fields in the configured fetch groups will be loaded when loading an object.

getLockTimeout

int getLockTimeout()

The number of milliseconds to wait for an object lock, or -1 for no limit.

Since:

0.3.1

setLockTimeout

FetchConfiguration setLockTimeout(int timeout)

The number of milliseconds to wait for an object lock, or -1 for no limit.

Since:

0.3.1

getReadLockLevel

int getReadLockLevel()

The lock level to use for locking loaded objects.

Since:

0.3.1

setReadLockLevel

FetchConfiguration setReadLockLevel(int level)

The lock level to use for locking loaded objects.

Since:

0.3.1

getWriteLockLevel

int getWriteLockLevel()

The lock level to use for locking dirtied objects.

Since:

0.3.1

setWriteLockLevel

FetchConfiguration setWriteLockLevel(int level)

The lock level to use for locking dirtied objects.

Since:

0.3.1

newResultList

ResultList newResultList(ResultObjectProvider rop)

Return a new result list for the current fetch configuration.

setHint

void setHint(String name,
             Object value)

Sets an arbitrary query hint that may be utilized during execution. The hint may be datastore-specific.

Parameters:

name - the name of the hint

value - the value of the hint

Since:

0.4.0

getHint

Object getHint(String name)

Returns the hint for the specific key, or null if the hint is not specified.

Parameters:

name - the hint name

Since:

0.4.0

getRootClasses

Set getRootClasses()

Root classes for recursive operations. This set is not thread safe.

setRootClasses

FetchConfiguration setRootClasses(Collection classes)

Root classes for recursive operations.

getRootInstances

Set getRootInstances()

Root instances for recursive operations. This set is not thread safe.

setRootInstances

FetchConfiguration setRootInstances(Collection roots)

Root instances for recursive operations.

lock

void lock()

Synchronize on internal lock if multithreaded is true.

unlock

void unlock()

Release internal lock if multithreaded is true.

requiresFetch

int requiresFetch(FieldMetaData fm)

Affirms if the given field requires to be fetched in the context of current fetch operation. Returns one of FETCH_NONE, FETCH_LOAD, FETCH_REF.

Since:

0.4.1

requiresLoad

boolean requiresLoad()

Return false if we know that the object being fetched with this configuration does not require a load, because this configuration came from a traversal of a FETCH_REF field.

traverse

FetchConfiguration traverse(FieldMetaData fm)

Traverse the given field to generate (possibly) a new configuration state.

Returns:

a new configuration state resulting out of traversal

Since:

0.4.1