oracle.toplink.essentials.indirection.IndirectSet Maven / Gradle / Ivy
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package oracle.toplink.essentials.indirection;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.util.*;
import java.io.*;
import java.lang.reflect.Method;
import oracle.toplink.essentials.exceptions.DescriptorException;
import oracle.toplink.essentials.exceptions.QueryException;
import oracle.toplink.essentials.internal.localization.ToStringLocalization;
import oracle.toplink.essentials.internal.indirection.*;
import oracle.toplink.essentials.internal.security.PrivilegedAccessHelper;
import oracle.toplink.essentials.internal.security.PrivilegedGetMethod;
import oracle.toplink.essentials.internal.security.PrivilegedMethodInvoker;
/**
* IndirectSet is an example implementation of the Set protocol that
* allows a domain class to take advantage of TopLink Indirection
* without having to declare its instance variable as a ValueHolderInterface.
* To use an IndirectSet:
* - Declare the appropriate instance variable with type Set (or Collection).
*
- Send the message #useTransparentCollection() to the appropriate
* CollectionMapping.
*
- Send the message #useCollectionClass(IndirectSet.class) to the same
* CollectionMapping. (The order of these two message sends is significant.)
*
* TopLink will place an IndirectSet in the instance variable when the
* containing domain object is read from the datatabase. With the first
* message sent to the IndirectSet, the contents
* are fetched from the database and normal Set behavior is resumed.
*
*
* Implementation notes:
* - The Set interface is implemented by delegating nearly every message
* to the Set held on to by the 'delegate' instance variable. (The 'delegate'
* will be either a HashSet or yet another IndirectSet.)
*
- The IndirectContainer interface is implemented in a straightforward
* fashion:
* - #get- and #setValueHolder() are implemented as simple accessors for the
* 'valueHolder' instance variable. (Note that #setValueHolder() clears out the
* 'delegate' instance variable, since its contents are invalidated by the arrival
* of a new value holder.)
*
- #isInstantiated() is simply delegated to the value holder.
*
* - TopLink requires that the Cloneable interface be implemented. The #clone()
* method must clone the 'delegate'. (The implementation here uses reflection to invoke
* the #clone() method because it is not included in the common interface shared
* by IndirectSet and its base delegate class, HashSet; namely, Set.)
*
- TopLink requires that the Serializable interface be implemented.
*
- The database read is ultimately triggered when one of the "delegated"
* methods makes the first call to #getDelegate(), which in turn calls
* #buildDelegate(), which
* sends the message #getValue() to the value holder.
* The value holder performs the database read.
*
- For debugging purposes, #toString() will not trigger a database
* read. This is not required behavior.
*
*
* @see oracle.toplink.essentials.mappings.CollectionMapping
* @author Big Country
* @since TOPLink/Java 3.0+
*/
public class IndirectSet implements Set, IndirectContainer, Cloneable, Serializable {
/** Reduce type casting */
private volatile Set delegate;
/** Delegate indirection behavior to a value holder */
private ValueHolderInterface valueHolder;
/** The mapping attribute name, used to raise change events. */
private String attributeName;
/** Store initial size for lazy init. */
protected int initialCapacity = 10;
/** Store load factor for lazy init. */
protected float loadFactor = 0.75f;
/**
* Construct an empty IndirectSet.
*/
public IndirectSet() {
this.delegate = null;
this.valueHolder = null;
}
/**
* Construct an empty IndirectSet with the specified initial capacity.
*
* @param initialCapacity the initial capacity of the set
* @exception IllegalArgumentException if the specified initial capacity
* is negative
*/
public IndirectSet(int initialCapacity) {
this.delegate = null;
this.initialCapacity = initialCapacity;
this.valueHolder = null;
}
/**
* Construct an empty IndirectSet with the specified initial capacity and
* load factor.
*
* @param initialCapacity the initial capacity of the set
* @param loadFactor the load factor of the set
* @exception IllegalArgumentException if the specified initial capacity
* is negative
*/
public IndirectSet(int initialCapacity, float loadFactor) {
this.delegate = null;
this.initialCapacity = initialCapacity;
this.loadFactor = loadFactor;
this.valueHolder = null;
}
/**
* Construct an IndirectSet containing the elements of the specified collection.
*
* @param c the initial elements of the set
*/
public IndirectSet(Collection c) {
this.delegate = null;
this.valueHolder = new ValueHolder(new HashSet(c));
}
/**
* @see java.util.Set#add(java.lang.Object)
*/
public synchronized boolean add(Object o) {
this.getDelegate().add(o);
this.raiseAddChangeEvent(o);
return true;
}
/**
* @see java.util.Set#addAll(java.util.Collection)
*/
public synchronized boolean addAll(Collection c) {
// Must trigger add events if tracked or uow.
if (hasBeenRegistered()) {
Iterator objects = c.iterator();
while (objects.hasNext()) {
this.add(objects.next());
}
return true;
}
return getDelegate().addAll(c);
}
/**
* Return the freshly-built delegate.
*/
protected Set buildDelegate() {
return (Set)getValueHolder().getValue();
}
/**
* @see java.util.Set#clear()
*/
public void clear() {
if (hasBeenRegistered()) {
Iterator objects = this.iterator();
while (objects.hasNext()) {
Object o = objects.next();
objects.remove();
this.raiseRemoveChangeEvent(o);
}
} else {
this.getDelegate().clear();
}
}
/**
* @see java.lang.Object#clone()
* This will result in a database query if necessary.
*/
/*
There are 3 situations when #clone() is called:
1. The developer actually wants to clone the collection (typically to modify one
of the 2 resulting collections). In which case the contents must be read from
the database.
2. A UnitOfWork needs a clone (or backup clone) of the collection. But the
UnitOfWork checks "instantiation" before cloning collections (i.e. "un-instantiated"
collections are not cloned).
3. A MergeManager needs an extra copy of the collection (because the "backup"
and "target" are the same object?). But the MergeManager also checks "instantiation"
before merging collections (again, "un-instantiated" collections are not merged).
*/
public Object clone() {
try {
IndirectSet result = (IndirectSet)super.clone();
result.delegate = this.cloneDelegate();
result.attributeName = null;
return result;
} catch (CloneNotSupportedException e) {
throw new InternalError("clone not supported");
}
}
/**
* Clone the delegate.
*/
protected Set cloneDelegate() {
java.lang.reflect.Method cloneMethod;
try {
if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
try {
cloneMethod = (Method)AccessController.doPrivileged(new PrivilegedGetMethod(this.getDelegate().getClass(), "clone", (Class[])null, false));
} catch (PrivilegedActionException exception) {
throw QueryException.cloneMethodRequired();
}
} else {
cloneMethod = PrivilegedAccessHelper.getMethod(this.getDelegate().getClass(), "clone", (Class[])null, false);
}
} catch (NoSuchMethodException ex) {
throw QueryException.cloneMethodRequired();
}
try {
if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
try {
return (Set)AccessController.doPrivileged(new PrivilegedMethodInvoker(cloneMethod, this.getDelegate(), (Object[])null));
} catch (PrivilegedActionException exception) {
Exception throwableException = exception.getException();
if (throwableException instanceof IllegalAccessException) {
throw QueryException.cloneMethodInaccessible();
} else {
throw QueryException.cloneMethodThrowException(((java.lang.reflect.InvocationTargetException)throwableException).getTargetException());
}
}
} else {
return (Set)PrivilegedAccessHelper.invokeMethod(cloneMethod, this.getDelegate(), (Object[])null);
}
} catch (IllegalAccessException ex1) {
throw QueryException.cloneMethodInaccessible();
} catch (java.lang.reflect.InvocationTargetException ex2) {
throw QueryException.cloneMethodThrowException(ex2.getTargetException());
}
}
/**
* @see java.util.Set#contains(java.lang.Object)
*/
public boolean contains(Object o) {
return this.getDelegate().contains(o);
}
/**
* @see java.util.Set#containsAll(java.util.Collection)
*/
public boolean containsAll(Collection c) {
return this.getDelegate().containsAll(c);
}
/**
* @see java.util.Set#equals(java.lang.Object)
*/
public boolean equals(Object o) {
return this.getDelegate().equals(o);
}
/**
* Check whether the contents have been read from the database.
* If they have not, read them and set the delegate.
*/
protected Set getDelegate() {
if (delegate == null) {
synchronized(this){
if (delegate == null) {
delegate = this.buildDelegate();
}
}
}
return delegate;
}
/**
* Return the valueHolder.
*/
public ValueHolderInterface getValueHolder() {
// PERF: lazy initialize value holder and vector as are normally set after creation.
if (valueHolder == null) {
synchronized(this){
if (valueHolder == null) {
valueHolder = new ValueHolder(new HashSet(initialCapacity, loadFactor));
}
}
}
return valueHolder;
}
/**
* INTERNAL:
* Return whether this IndirectSet has been registered in a UnitOfWork
*/
public boolean hasBeenRegistered() {
return getValueHolder() instanceof oracle.toplink.essentials.internal.indirection.UnitOfWorkQueryValueHolder;
}
/**
* @see java.util.Set#hashCode()
*/
public int hashCode() {
return this.getDelegate().hashCode();
}
/**
* @see java.util.Set#isEmpty()
*/
public boolean isEmpty() {
return this.getDelegate().isEmpty();
}
/**
* Return whether the contents have been read from the database.
*/
public boolean isInstantiated() {
return this.getValueHolder().isInstantiated();
}
/**
* @see java.util.Set#iterator()
*/
public Iterator iterator() {
// Must wrap the interator to raise the remove event.
return new Iterator() {
Iterator delegateIterator = IndirectSet.this.getDelegate().iterator();
Object currentObject;
public boolean hasNext() {
return this.delegateIterator.hasNext();
}
public Object next() {
this.currentObject = this.delegateIterator.next();
return this.currentObject;
}
public void remove() {
this.delegateIterator.remove();
IndirectSet.this.raiseRemoveChangeEvent(this.currentObject);
}
};
}
/**
* @see java.util.Set#remove(java.lang.Object)
*/
public synchronized boolean remove(Object o) {
if (this.getDelegate().remove(o)) {
this.raiseRemoveChangeEvent(o);
return true;
}
return false;
}
/**
* @see java.util.Set#removeAll(java.util.Collection)
*/
public synchronized boolean removeAll(Collection c) {
// Must trigger remove events if tracked or uow.
if (hasBeenRegistered()) {
Iterator objects = c.iterator();
while (objects.hasNext()) {
this.remove(objects.next());
}
return true;
}
return this.getDelegate().removeAll(c);
}
/**
* @see java.util.Set#retainAll(java.util.Collection)
*/
public synchronized boolean retainAll(Collection c) {
// Must trigger remove events if tracked or uow.
if (hasBeenRegistered()) {
Iterator objects = getDelegate().iterator();
while (objects.hasNext()) {
Object object = objects.next();
if (!c.contains(object)) {
objects.remove();
this.raiseRemoveChangeEvent(object);
}
}
return true;
}
return this.getDelegate().retainAll(c);
}
/**
* Set the value holder.
* Note that the delegate must be cleared out.
*/
public void setValueHolder(ValueHolderInterface valueHolder) {
this.delegate = null;
this.valueHolder = valueHolder;
}
/**
* @see java.util.Set#size()
*/
public int size() {
return this.getDelegate().size();
}
/**
* @see java.util.Set#toArray()
*/
public Object[] toArray() {
return this.getDelegate().toArray();
}
/**
* @see java.util.Set#toArray(java.lang.Object[])
*/
public Object[] toArray(Object[] a) {
return this.getDelegate().toArray(a);
}
/**
* Use the delegate's #toString(); but wrap it with braces to indicate
* there is a bit of indirection.
* Don't allow this method to trigger a database read.
* @see java.util.HashSet#toString()
*/
public String toString() {
if (ValueHolderInterface.shouldToStringInstantiate) {
return this.getDelegate().toString();
}
if (this.isInstantiated()) {
return "{" + this.getDelegate().toString() + "}";
} else {
return "{" + oracle.toplink.essentials.internal.helper.Helper.getShortClassName(this.getClass()) + ": " + ToStringLocalization.buildMessage("not_instantiated", (Object[])null) + "}";
}
}
/**
* Raise the add change event and relationship maintainence.
*/
protected void raiseAddChangeEvent(Object element) {
if (hasBeenRegistered()) {
((UnitOfWorkQueryValueHolder)getValueHolder()).updateForeignReferenceSet(element, null);
}
}
/**
* Raise the remove change event.
*/
protected void raiseRemoveChangeEvent(Object element) {
if (hasBeenRegistered()) {
((UnitOfWorkQueryValueHolder)getValueHolder()).updateForeignReferenceRemove(element);
}
}
/**
* Return the mapping attribute name, used to raise change events.
*/
public String getTopLinkAttributeName() {
return attributeName;
}
/**
* Set the mapping attribute name, used to raise change events.
* This is required if the change listener is set.
*/
public void setTopLinkAttributeName(String attributeName) {
this.attributeName = attributeName;
}
}