package com.ibm.awb.weakref; /* * @(#)WeakRef.java * * IBM Confidential-Restricted * * OCO Source Materials * * 03L7246 (c) Copyright IBM Corp. 1996, 1998 * * The source code for this program is not published or otherwise * divested of its trade secrets, irrespective of what has been * deposited with the U.S. Copyright Office. */ import java.io.*; public abstract class WeakRef implements Ref { /* package */ long _ref_count = 0; protected WeakRefTable _table = null; protected WeakRef(WeakRefTable table) { _table = table; } /* * Find new reference if any */ abstract protected Ref findRef(); /* * Find a reference in a table. */ abstract protected Ref findRef(ObjectInputStream s) throws IOException, ClassNotFoundException; /* package */ /* synchronized */ public final Ref getRef(VirtualRef vref) { Ref found = findRef(); // this reference must be updated. if (found != null) { vref.setRef(found); return found; } return this; } /* * Get Reference ID */ abstract protected Object getRefID(); /* * Called when referenced */ /* package */ synchronized public final void referenced() { // System.out.println("-- referenced --"); // Thread.dumpStack(); _ref_count++; } /* * Get reference and increment refernce count */ /* package */ public final void setRef(VirtualRef vref, ObjectInputStream s) throws IOException, ClassNotFoundException { // this reference must be already updated. Ref ref = findRef(s); if (ref != null) { vref.setRef(ref); } } public String toString() { return "WeakRef[count=" + _ref_count + "]"; } /* * Called when the proxy unreferenced the ref. */ /* package */ public /* synchronized */ final void unreferenced() { _table.unreference(this); } protected boolean updateRef(VirtualRef vref) { return vref.getRef() == this; } }
