Bug 324873 - [repository] Share IUs for Composite Repositories

4 files changed, 128 insertions, 1 deletions

diff --git a/bundles/org.eclipse.equinox.p2.core/META-INF/MANIFEST.MF b/bundles/org.eclipse.equinox.p2.core/META-INF/MANIFEST.MF
index f2bcbce96..dcc34fa39 100644
--- a/bundles/org.eclipse.equinox.p2.core/META-INF/MANIFEST.MF
+++ b/bundles/org.eclipse.equinox.p2.core/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.equinox.p2.core;singleton:=true
-Bundle-Version: 2.0.100.qualifier
+Bundle-Version: 2.1.0.qualifier
 Bundle-ClassPath: .
 Bundle-Activator: org.eclipse.equinox.internal.p2.core.Activator
 Bundle-Vendor: %providerName
diff --git a/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/IPool.java b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/IPool.java
new file mode 100644
index 000000000..f1b2f0f71
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/IPool.java
@@ -0,0 +1,36 @@
+/*******************************************************************************
+ *  Copyright (c) 2011 IBM Corporation and others.
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ * 
+ *  Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.p2.core;
+
+/**
+ * A Pool allows semantically equivalent objects to be shared.  To be useful, objects added to the pool should implement
+ * a meaningful equals() method.
+ * <p>
+ * Care must be taken by users that object sharing is appropriate for their application.  It is easy
+ * to "over share" objects leading to unexpected and difficult to debug behaviour.
+ * </p><p>
+ * This interface is not intended to be implemented by clients.
+ * </p>
+ * @noimplement This interface is not intended to be implemented by clients. 
+ * @since 2.1
+ */
+public interface IPool<T> {
+
+	/** 
+	 * Returns the first object from this pool which is {@link #equals(Object)} to the given object.  If the pool 
+	 * contains no such object then the object is added to the pool and returned.  If the object is <code>null</code>, 
+	 * <code>null</code> is returned.
+	 * 
+	 * @param newObject the object to add
+	 * @return a shared object that is equal to the given object or <code>null</code>
+	 */
+	public abstract T add(T newObject);
+}
\ No newline at end of file
diff --git a/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/StrongPool.java b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/StrongPool.java
new file mode 100644
index 000000000..d1780388b
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/StrongPool.java
@@ -0,0 +1,44 @@
+/*******************************************************************************
+ * Copyright (c) 2011 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.p2.core;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * An object pool backed by strong references.  Objects stored in this pool
+ * will not be garbage collected as they refer to themselves.  The client is responsible for 
+ * nulling all references to the pool instance when it is no longer needed so that
+ * the contained objects can be garbage collected.  
+ * <p>
+ * If a long lived, memory managed pool is required use {@link org.eclipse.equinox.p2.core.WeakPool}.
+ * </p>
+ * @since 2.1
+ */
+public class StrongPool<T> implements IPool<T> {
+	private Map<T, T> pool = new HashMap<T, T>();
+
+	/* (non-Javadoc)
+	 * @see org.eclipse.equinox.p2.core.IPool#add(T)
+	 */
+	public T add(T newObject) {
+		if (newObject == null) {
+			return null;
+		}
+
+		T reference = pool.get(newObject);
+		if (reference == null) {
+			pool.put(newObject, newObject);
+			return newObject;
+		}
+		return reference;
+	}
+}
diff --git a/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/WeakPool.java b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/WeakPool.java
new file mode 100644
index 000000000..3f389fc75
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/p2/core/WeakPool.java
@@ -0,0 +1,47 @@
+/*******************************************************************************
+ * Copyright (c) 2011 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.p2.core;
+
+import java.lang.ref.WeakReference;
+import java.util.Map;
+import java.util.WeakHashMap;
+
+/**
+ * An object pool backed by weak references.  Objects stored in this pool
+ * will be garbage collected once all strong references to the objects are broken.
+ * <p>
+ * Since {@link WeakReference} are not particularly light-weight, a client could use a {@link StrongPool}
+ * if the pool will be short lived and explicitly nulled by the client.
+ * </p>
+ * @since 2.1
+ */
+public class WeakPool<T> implements IPool<T> {
+	private Map<T, WeakReference<T>> pool = new WeakHashMap<T, WeakReference<T>>();
+
+	/* (non-Javadoc)
+	 * @see org.eclipse.equinox.p2.core.IPool#add(T)
+	 */
+	public T add(T newObject) {
+		if (newObject == null) {
+			return null;
+		}
+
+		WeakReference<T> weakReference = pool.get(newObject);
+		if (weakReference != null) {
+			T reference = weakReference.get();
+			if (reference != null) {
+				return reference;
+			}
+		}
+		pool.put(newObject, new WeakReference<T>(newObject));
+		return newObject;
+	}
+}