Makefile.am: Add HashSet.java and java/lang/ref classes.
* Makefile.am: Add HashSet.java and java/lang/ref classes. Remove BasicMapEntry.java and Bucket.java. * Makefile.in: Rebuilt. * java/util/HashMap.java: Rewritten. * java/util/HashSet.java: Imported from classpath. * java/util/WeakHashMap.java: Imported from classpath. * java/util/Hashtable.java: Rewritten based on new HashMap code. * java/util/Bucket.java: Deleted. * java/util/BasicMapEntry.java: Deleted. * java/util/Collections.java (search): Use a for-loop, not iterator hasNext(). (copy): Use a for-loop. Throw an IndexOutOfBoundsException if run out of elements in source. (max): Use a for-loop. (min): Ditto. (reverse): Keep track of positions instead of using Iterator's nextIndex() and previousIndex(). (shuffle(List)): Initialize defaultRandom if required using double-check thread safety idiom. Call two-argument shuffle method using defaultRandom. (defaultRandom): New field. (shuffle(List, Random)): Use a for-loop. Keep track of pos instead of using previousIndex() and nextIndex(). (singletonMap(iterator)): Use a HashMap.Entry, not BasicMapEntry. * java/util/AbstractCollection.java (toString): Use a StringBuffer. * java/util/AbstractMap.java (toString): Use StringBuffer. * java/lang/ref/PhantomReference.java: Imported from classpath. * java/lang/ref/SoftReference.java: Ditto. * java/lang/ref/Reference.java: Ditto. * java/lang/ref/WeakReference.java: Ditto. * java/lang/ref/ReferenceQueue.java: Ditto. From-SVN: r38183
This commit is contained in:
Bryce McKinlay
Bryce McKinlay
parent
a0932f7d1a
commit
488d42af6f
18 changed files with 2942 additions and 2062 deletions
62
libjava/java/lang/ref/PhantomReference.java
Normal file
62
libjava/java/lang/ref/PhantomReference.java
Normal file
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@ -0,0 +1,62 @@
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/* java.lang.ref.PhantomReference
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Copyright (C) 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
|
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it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation; either version 2, or (at your option)
|
||||
any later version.
|
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|
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GNU Classpath is distributed in the hope that it will be useful, but
|
||||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with GNU Classpath; see the file COPYING. If not, write to the
|
||||
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
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02111-1307 USA.
|
||||
|
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As a special exception, if you link this library with other files to
|
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produce an executable, this library does not by itself cause the
|
||||
resulting executable to be covered by the GNU General Public License.
|
||||
This exception does not however invalidate any other reasons why the
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executable file might be covered by the GNU General Public License. */
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package java.lang.ref;
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/**
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* A phantom reference is useful, to get notified, when an object got
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* finalized. You can't access that object though, since it is
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* finalized. This is the reason, why <code>get()</code> always
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* returns null.
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*
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* @author Jochen Hoenicke
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*/
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public class PhantomReference
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extends Reference
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{
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/**
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* Creates a new phantom reference.
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* @param referent the object that should be watched.
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* @param q the queue that should be notified, if the referent was
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* finalized. This mustn't be <code>null</code>.
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* @exception NullPointerException if q is null.
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*/
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public PhantomReference(Object referent, ReferenceQueue q)
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{
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super(referent, q);
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}
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/**
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* Returns the object, this reference refers to.
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* @return <code>null</code>, since the refered object may be
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* finalized and thus not accessible.
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*/
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public Object get()
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{
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return null;
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}
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}
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166
libjava/java/lang/ref/Reference.java
Normal file
166
libjava/java/lang/ref/Reference.java
Normal file
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@ -0,0 +1,166 @@
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/* java.lang.ref.Reference
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Copyright (C) 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
|
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with GNU Classpath; see the file COPYING. If not, write to the
|
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
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02111-1307 USA.
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||||
|
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As a special exception, if you link this library with other files to
|
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produce an executable, this library does not by itself cause the
|
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resulting executable to be covered by the GNU General Public License.
|
||||
This exception does not however invalidate any other reasons why the
|
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executable file might be covered by the GNU General Public License. */
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package java.lang.ref;
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/**
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* This is the base class of all references. A reference allows
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* refering to an object without preventing the garbage collection to
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* collect it. The only way to get the referred object is via the
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* <code>get()</code>-method. This method will return
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* <code>null</code> if the object was collected. <br>
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*
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* A reference may be registered with a queue. When a referred
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* element gets collected the reference will be put on the queue, so
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* that you will be notified. <br>
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*
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* There are currently three types of references: soft reference,
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* weak reference and phantom reference. <br>
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*
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* Soft references will be cleared if the garbage collection is told
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* to free some memory and there are no unreferenced or weakly referenced
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* objects. It is useful for caches. <br>
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*
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* Weak references will be cleared as soon as the garbage collection
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* determines that the refered object is only weakly reachable. They
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* are useful as keys in hashtables (see <code>WeakHashtable</code>) as
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* you get notified when nobody has the key anymore.
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*
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* Phantom references don't prevent finalization. If an object is only
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* phantom reachable, it will be finalized, and the reference will be
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* enqueued, but not cleared. Since you mustn't access an finalized
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* object, the <code>get</code> method of a phantom reference will never
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* work. It is useful to keep track, when an object is finalized.
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*
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* @author Jochen Hoenicke
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* @see java.util.WeakHashtable
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*/
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public abstract class Reference
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{
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/**
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* The underlying object. This field is handled in a special way by
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* the garbage collection.
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*/
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Object referent;
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/**
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* The queue this reference is registered on. This is null, if this
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* wasn't registered to any queue or reference was already enqueued.
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*/
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ReferenceQueue queue;
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/**
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* Link to the next entry on the queue. If this is null, this
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* reference is not enqueued. Otherwise it points to the next
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* reference. The last reference on a queue will point to itself
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* (not to null, that value is used to mark a not enqueued
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* reference).
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*/
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Reference nextOnQueue;
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/**
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* This lock should be taken by the garbage collection, before
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* determining reachability. It will prevent the get()-method to
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* return the reference so that reachability doesn't change.
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*/
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static Object lock = new Object();
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/**
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* Creates a new reference that is not registered to any queue.
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* Since it is package private, it is not possible to overload this
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* class in a different package.
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* @param referent the object we refer to.
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*/
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Reference(Object ref)
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{
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referent = ref;
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}
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/**
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* Creates a reference that is registered to a queue. Since this is
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* package private, it is not possible to overload this class in a
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* different package.
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* @param referent the object we refer to.
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* @param q the reference queue to register on.
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* @exception NullPointerException if q is null.
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*/
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Reference(Object ref, ReferenceQueue q)
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{
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if (q == null)
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throw new NullPointerException();
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referent = ref;
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queue = q;
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}
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/**
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* Returns the object, this reference refers to.
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* @return the object, this reference refers to, or null if the
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* reference was cleared.
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*/
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public Object get()
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{
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synchronized(lock)
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{
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return referent;
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}
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}
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/**
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* Clears the reference, so that it doesn't refer to its object
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* anymore. For soft and weak references this is called by the
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* garbage collection. For phantom references you should call
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* this when enqueuing the reference.
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*/
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public void clear()
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{
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referent = null;
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}
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/**
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* Tells if the object is enqueued on a reference queue.
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* @return true if it is enqueued, false otherwise.
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*/
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public boolean isEnqueued()
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{
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return nextOnQueue != null;
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}
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/**
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* Enqueue an object on a reference queue. This is normally executed
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* by the garbage collection.
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*/
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public boolean enqueue()
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{
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if (queue != null)
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{
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queue.enqueue(this);
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queue = null;
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return true;
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}
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return false;
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}
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}
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134
libjava/java/lang/ref/ReferenceQueue.java
Normal file
134
libjava/java/lang/ref/ReferenceQueue.java
Normal file
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@ -0,0 +1,134 @@
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/* java.lang.ref.ReferenceQueue
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Copyright (C) 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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|
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GNU Classpath is free software; you can redistribute it and/or modify
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||||
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
|
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any later version.
|
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|
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GNU Classpath is distributed in the hope that it will be useful, but
|
||||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with GNU Classpath; see the file COPYING. If not, write to the
|
||||
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
||||
02111-1307 USA.
|
||||
|
||||
As a special exception, if you link this library with other files to
|
||||
produce an executable, this library does not by itself cause the
|
||||
resulting executable to be covered by the GNU General Public License.
|
||||
This exception does not however invalidate any other reasons why the
|
||||
executable file might be covered by the GNU General Public License. */
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package java.lang.ref;
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/**
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* This is the queue, where references can enqueue themselve on. Each
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* reference may be registered to a queue at initialization time and
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* will be appended to the queue, when the enqueue method is called.
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*
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* The enqueue method may be automatically called by the garbage
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* collector if it detects, that the object is only reachable through
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* the Reference objects.
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*
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* @author Jochen Hoenicke
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* @see Reference#enqueue()
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*/
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public class ReferenceQueue
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{
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/**
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* This is a linked list of references. If this is null, the list is
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* empty. Otherwise this points to the first reference on the queue.
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* The first reference will point to the next reference via the
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* <code>nextOnQueue</code> field. The last reference will point to
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* itself (not to null, since <code>nextOnQueue</code> is used to
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* determine if a reference is enqueued).
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*/
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private Reference first;
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/**
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* Creates a new empty reference queue.
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*/
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public ReferenceQueue()
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{
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}
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/**
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* Checks if there is a reference on the queue, returning it
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* immediately. The reference will be dequeued.
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*
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* @return a reference on the queue, if there is one,
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* <code>null</code> otherwise.
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*/
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public synchronized Reference poll()
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{
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return dequeue();
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}
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/**
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* This is called by reference to enqueue itself on this queue.
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* @param ref the reference that should be enqueued.
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*/
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synchronized void enqueue(Reference ref)
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{
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/* last reference will point to itself */
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ref.nextOnQueue = first == null ? ref : first;
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first = ref;
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/* this wakes only one remove thread. */
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notify();
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}
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/**
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* Remove a reference from the queue, if there is one.
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* @return the first element of the queue, or null if there isn't any.
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*/
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private Reference dequeue()
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{
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if (first == null)
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return null;
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Reference result = first;
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first = (first == first.nextOnQueue) ? null : first.nextOnQueue;
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result.nextOnQueue = null;
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return result;
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}
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/**
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* Removes a reference from the queue, blocking for <code>timeout</code>
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* until a reference is enqueued.
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* @param timeout the timeout period in milliseconds, <code>0</code> means
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* wait forever.
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* @return the reference removed from the queue, or
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* <code>null</code> if timeout period expired.
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* @exception InterruptedException if the wait was interrupted.
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*/
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public synchronized Reference remove(long timeout)
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throws InterruptedException
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{
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if (first == null)
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{
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wait(timeout);
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}
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return dequeue();
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}
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/**
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* Removes a reference from the queue, blocking until a reference is
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* enqueued.
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*
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* @return the reference removed from the queue.
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* @exception InterruptedException if the wait was interrupted.
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*/
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public Reference remove()
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throws InterruptedException
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||||
{
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return remove(0L);
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||||
}
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||||
}
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73
libjava/java/lang/ref/SoftReference.java
Normal file
73
libjava/java/lang/ref/SoftReference.java
Normal file
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@ -0,0 +1,73 @@
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/* java.lang.ref.SoftReference
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Copyright (C) 1999 Free Software Foundation, Inc.
|
||||
|
||||
This file is part of GNU Classpath.
|
||||
|
||||
GNU Classpath is free software; you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation; either version 2, or (at your option)
|
||||
any later version.
|
||||
|
||||
GNU Classpath is distributed in the hope that it will be useful, but
|
||||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with GNU Classpath; see the file COPYING. If not, write to the
|
||||
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
||||
02111-1307 USA.
|
||||
|
||||
As a special exception, if you link this library with other files to
|
||||
produce an executable, this library does not by itself cause the
|
||||
resulting executable to be covered by the GNU General Public License.
|
||||
This exception does not however invalidate any other reasons why the
|
||||
executable file might be covered by the GNU General Public License. */
|
||||
|
||||
|
||||
package java.lang.ref;
|
||||
|
||||
/**
|
||||
* A soft reference will be cleared, if the object is only softly
|
||||
* reachable and the garbage collection needs more memory. The garbage
|
||||
* collection will use an intelligent strategy to determine which soft
|
||||
* references it should clear. This makes a soft reference ideal for
|
||||
* caches.<br>
|
||||
*
|
||||
* @author Jochen Hoenicke
|
||||
*/
|
||||
public class SoftReference
|
||||
extends Reference
|
||||
{
|
||||
/**
|
||||
* Create a new soft reference, that is not registered to any queue.
|
||||
* @param referent the object we refer to.
|
||||
*/
|
||||
public SoftReference(Object referent)
|
||||
{
|
||||
super(referent);
|
||||
}
|
||||
|
||||
/**
|
||||
* Create a new soft reference.
|
||||
* @param referent the object we refer to.
|
||||
* @param q the reference queue to register on.
|
||||
* @exception NullPointerException if q is null.
|
||||
*/
|
||||
public SoftReference(Object referent, ReferenceQueue q)
|
||||
{
|
||||
super(referent, q);
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the object, this reference refers to.
|
||||
* @return the object, this reference refers to, or null if the
|
||||
* reference was cleared.
|
||||
*/
|
||||
public Object get()
|
||||
{
|
||||
/* Why is this overloaded???
|
||||
* Maybe for a kind of LRU strategy. */
|
||||
return super.get();
|
||||
}
|
||||
}
|
||||
68
libjava/java/lang/ref/WeakReference.java
Normal file
68
libjava/java/lang/ref/WeakReference.java
Normal file
|
|
@ -0,0 +1,68 @@
|
|||
/* java.lang.ref.WeakReference
|
||||
Copyright (C) 1999 Free Software Foundation, Inc.
|
||||
|
||||
This file is part of GNU Classpath.
|
||||
|
||||
GNU Classpath is free software; you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation; either version 2, or (at your option)
|
||||
any later version.
|
||||
|
||||
GNU Classpath is distributed in the hope that it will be useful, but
|
||||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with GNU Classpath; see the file COPYING. If not, write to the
|
||||
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
||||
02111-1307 USA.
|
||||
|
||||
As a special exception, if you link this library with other files to
|
||||
produce an executable, this library does not by itself cause the
|
||||
resulting executable to be covered by the GNU General Public License.
|
||||
This exception does not however invalidate any other reasons why the
|
||||
executable file might be covered by the GNU General Public License. */
|
||||
|
||||
|
||||
package java.lang.ref;
|
||||
|
||||
/**
|
||||
* A weak reference will be cleared, if the object is only weakly
|
||||
* reachable. It is useful for lookup tables, where you aren't
|
||||
* interested in an entry, if the key isn't reachable anymore.
|
||||
* <code>WeakHashtable</code> is a complete implementation of such a
|
||||
* table. <br>
|
||||
*
|
||||
* It is also useful to make objects unique: You create a set of weak
|
||||
* references to those objects, and when you create a new object you
|
||||
* look in this set, if the object already exists and return it. If
|
||||
* an object is not referenced anymore, the reference will
|
||||
* automatically cleared, and you may remove it from the set. <br>
|
||||
*
|
||||
* @author Jochen Hoenicke
|
||||
* @see java.util.WeakHashtable
|
||||
*/
|
||||
public class WeakReference
|
||||
extends Reference
|
||||
{
|
||||
/**
|
||||
* Create a new weak reference, that is not registered to any queue.
|
||||
* @param referent the object we refer to.
|
||||
*/
|
||||
public WeakReference(Object referent)
|
||||
{
|
||||
super(referent);
|
||||
}
|
||||
|
||||
/**
|
||||
* Create a new weak reference.
|
||||
* @param referent the object we refer to.
|
||||
* @param q the reference queue to register on.
|
||||
* @exception NullPointerException if q is null.
|
||||
*/
|
||||
public WeakReference(Object referent, ReferenceQueue q)
|
||||
{
|
||||
super(referent, q);
|
||||
}
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue