7200507: Refactor Introspector internals

Reviewed-by: ahgross, art

src/share/classes/java/beans/ThreadGroupContext.java

 /*
- * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,7 +29,6 @@ import com.sun.beans.finder.BeanInfoFinder;
 import com.sun.beans.finder.PropertyEditorFinder;
 
 import java.awt.GraphicsEnvironment;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.WeakHashMap;
 
@@ -42,7 +41,7 @@ import java.util.WeakHashMap;
  */
 final class ThreadGroupContext {
 
-    private static final Map<ThreadGroup, ThreadGroupContext> contexts = new WeakHashMap<>();
+    private static final WeakIdentityMap<ThreadGroupContext> contexts = new WeakIdentityMap<>();
 
     /**
      * Returns the appropriate {@code AppContext} for the caller,
@@ -69,6 +68,8 @@ final class ThreadGroupContext {
     private BeanInfoFinder beanInfoFinder;
     private PropertyEditorFinder propertyEditorFinder;
 
+    private ThreadGroupContext() {
+    }
 
     boolean isDesignTime() {
         return this.isDesignTime;

src/share/classes/java/beans/WeakIdentityMap.java

+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.beans;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+
+/**
+ * Hash table based mapping, which uses weak references to store keys
+ * and reference-equality in place of object-equality to compare them.
+ * An entry will automatically be removed when its key is no longer
+ * in ordinary use.  Both null values and the null key are supported.
+ *
+ * @see java.util.IdentityHashMap
+ * @see java.util.WeakHashMap
+ */
+final class WeakIdentityMap<T> {
+
+    private static final int MAXIMUM_CAPACITY = 1 << 30; // it MUST be a power of two
+    private static final Object NULL = new Object(); // special object for null key
+
+    private final ReferenceQueue<Object> queue = new ReferenceQueue<Object>();
+
+    private Entry<T>[] table = newTable(1<<3); // table's length MUST be a power of two
+    private int threshold = 6; // the next size value at which to resize
+    private int size = 0; // the number of key-value mappings
+
+    public T get(Object key) {
+        removeStaleEntries();
+        if (key == null) {
+            key = NULL;
+        }
+        int hash = key.hashCode();
+        int index = getIndex(this.table, hash);
+        for (Entry<T> entry = this.table[index]; entry != null; entry = entry.next) {
+            if (entry.isMatched(key, hash)) {
+                return entry.value;
+            }
+        }
+        return null;
+    }
+
+    public T put(Object key, T value) {
+        removeStaleEntries();
+        if (key == null) {
+            key = NULL;
+        }
+        int hash = key.hashCode();
+        int index = getIndex(this.table, hash);
+        for (Entry<T> entry = this.table[index]; entry != null; entry = entry.next) {
+            if (entry.isMatched(key, hash)) {
+                T oldValue = entry.value;
+                entry.value = value;
+                return oldValue;
+            }
+        }
+        this.table[index] = new Entry<T>(key, hash, value, this.queue, this.table[index]);
+        if (++this.size >= this.threshold) {
+            if (this.table.length == MAXIMUM_CAPACITY) {
+                this.threshold = Integer.MAX_VALUE;
+            }
+            else {
+                removeStaleEntries();
+                Entry<T>[] table = newTable(this.table.length * 2);
+                transfer(this.table, table);
+
+                // If ignoring null elements and processing ref queue caused massive
+                // shrinkage, then restore old table.  This should be rare, but avoids
+                // unbounded expansion of garbage-filled tables.
+                if (this.size >= this.threshold / 2) {
+                    this.table = table;
+                    this.threshold *= 2;
+                }
+                else {
+                    transfer(table, this.table);
+                }
+            }
+        }
+        return null;
+    }
+
+    private void removeStaleEntries() {
+        for (Object ref = this.queue.poll(); ref != null; ref = this.queue.poll()) {
+            @SuppressWarnings("unchecked")
+            Entry<T> entry = (Entry<T>) ref;
+            int index = getIndex(this.table, entry.hash);
+
+            Entry<T> prev = this.table[index];
+            Entry<T> current = prev;
+            while (current != null) {
+                Entry<T> next = current.next;
+                if (current == entry) {
+                    if (prev == entry) {
+                        this.table[index] = next;
+                    }
+                    else {
+                        prev.next = next;
+                    }
+                    entry.value = null; // Help GC
+                    entry.next = null; // Help GC
+                    this.size--;
+                    break;
+                }
+                prev = current;
+                current = next;
+            }
+        }
+    }
+
+    private void transfer(Entry<T>[] oldTable, Entry<T>[] newTable) {
+        for (int i = 0; i < oldTable.length; i++) {
+            Entry<T> entry = oldTable[i];
+            oldTable[i] = null;
+            while (entry != null) {
+                Entry<T> next = entry.next;
+                Object key = entry.get();
+                if (key == null) {
+                    entry.value = null; // Help GC
+                    entry.next = null; // Help GC
+                    this.size--;
+                }
+                else {
+                    int index = getIndex(newTable, entry.hash);
+                    entry.next = newTable[index];
+                    newTable[index] = entry;
+                }
+                entry = next;
+            }
+        }
+    }
+
+
+    @SuppressWarnings("unchecked")
+    private Entry<T>[] newTable(int length) {
+        return (Entry<T>[]) new Entry<?>[length];
+    }
+
+    private static int getIndex(Entry<?>[] table, int hash) {
+        return hash & (table.length - 1);
+    }
+
+    private static class Entry<T> extends WeakReference<Object> {
+        private final int hash;
+        private T value;
+        private Entry<T> next;
+
+        Entry(Object key, int hash, T value, ReferenceQueue<Object> queue, Entry<T> next) {
+            super(key, queue);
+            this.hash = hash;
+            this.value = value;
+            this.next  = next;
+        }
+
+        boolean isMatched(Object key, int hash) {
+            return (this.hash == hash) && (key == get());
+        }
+    }
+}