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diff --git a/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/cache/SoftTimedCache.java b/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/cache/SoftTimedCache.java
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+++ b/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/cache/SoftTimedCache.java
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+/*******************************************************************************
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management
+ * in Industry THTH ry.
+ * 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:
+ *     VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+package org.simantics.utils.datastructures.cache;
+
+import java.lang.ref.SoftReference;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Timer;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+import org.simantics.utils.threads.ThreadUtils;
+
+/**
+ * A timed (Key, Value) cache which disposes the cached entry after the
+ * specified amount of time if it is not removed from the cache. The hold time
+ * is given to the {@link #put(Object, Object, long)} method, separately for
+ * each value.
+ * 
+ * <p>
+ * The cached values are held as soft references, which makes them collectible
+ * under memory pressure, even before their hold time has ran out.
+ * 
+ * @author Tuukka Lehtonen
+ * 
+ * @param <K> key type, held by strong references
+ * @param <V> value type, held by soft references to allow collection of the
+ *        cached elements when under memory pressure
+ */
+public class SoftTimedCache<K, V> implements ITimedCache<K, V> {
+
+    protected class Entry {
+        final K key;
+        final SoftReference<V> ref;
+        long holdTime;
+        TimeUnit unit;
+
+        ScheduledFuture<?> future;
+
+        Entry(K k, V v, long holdTime, TimeUnit unit) {
+            assert k != null;
+            assert v != null;
+
+            this.key = k;
+            this.ref = new SoftReference<V>(v);
+            this.holdTime = holdTime;
+            this.unit = unit;
+        }
+    }
+
+    private final Map<K, Entry> cache = Collections.synchronizedMap(new HashMap<K, Entry>());
+
+    @SuppressWarnings("unused")
+    private String name;
+
+    private Timer timer;
+
+    public SoftTimedCache() {
+        this("Cache Timer");
+    }
+
+    public SoftTimedCache(String name) {
+        this.name = name;
+    }
+
+    public int size() {
+        return cache.size();
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        if (timer != null) {
+            timer.cancel();
+        }
+        clear();
+        super.finalize();
+    }
+
+    public synchronized void clear() {
+        Object[] entries;
+        synchronized (this) {
+            entries = cache.values().toArray();
+            cache.clear();
+        }
+        for (Object o : entries) {
+            @SuppressWarnings("unchecked")
+            Entry e = (Entry) o;
+            V v = e.ref.get();
+            e.ref.clear();
+            cleanup(e);
+            disposeValue(v);
+        }
+    }
+
+    @Override
+    public void put(final K k, V v, long holdTime, TimeUnit unit) {
+        Entry e = new Entry(k, v, holdTime, unit);
+        synchronized (this) {
+            // First dispose of a previous entry.
+            dispose(k);
+            // Then cache the new one.
+            cache.put(k, e);
+
+            if (unit != null && holdTime > 0) {
+                schedule(e);
+            }
+        }
+    }
+
+    @Override
+    public V release(K k) {
+        Entry e;
+        synchronized (this) {
+            e = cache.remove(k);
+        }
+        if (e == null)
+            return null;
+        return cleanup(e);
+    }
+
+    private V cleanup(Entry e) {
+        if (e.future != null) {
+            if (!e.future.isCancelled()) {
+                boolean ret = e.future.cancel(false);
+                if (ret == false)
+                    // Already disposing of this cached entry, let it be.
+                    return null;
+            }
+        }
+        return e.ref.get();
+    }
+
+    private void dispose(K k) {
+        Entry e;
+        synchronized (this) {
+            e = cache.remove(k);
+        }
+        if (e == null)
+            // Has been released.
+            return;
+
+        V v = e.ref.get();
+        if (v != null) {
+            if (e.future != null)
+                e.future.cancel(false);
+            e.ref.clear();
+            disposeValue(v);
+        }
+    }
+
+    void schedule(final Entry e) {
+        e.future = ThreadUtils.getNonBlockingWorkExecutor().schedule(new Runnable() {
+            @Override
+            public void run() {
+                // Disposal may block, must transfer to blocking work executor.
+                ThreadUtils.getBlockingWorkExecutor().execute(new Runnable() {
+                    @Override
+                    public void run() {
+                        dispose(e.key);
+                    }
+                });
+            }
+        }, e.holdTime, e.unit);
+    }
+
+
+    /**
+     * Override to customize disposal of values when their timer elapses.
+     * 
+     * @param v the value to dispose of
+     */
+    protected void disposeValue(V v) {
+        // Do nothing by default.
+    }
+
+    public class CacheEntry {
+        private final Entry e;
+        private final V value;
+        public CacheEntry(Entry e) {
+            this.e = e;
+            this.value = e.ref.get();
+        }
+        public K getKey() {
+            return e.key;
+        }
+        public V getValue() {
+            return value;
+        }
+        public boolean disposeScheduled() {
+            return e.future != null;
+        }
+        public void schedule(long holdTime, TimeUnit unit) {
+            if (e.future == null) {
+                e.holdTime = holdTime;
+                e.unit = unit;
+                SoftTimedCache.this.schedule(e);
+            }
+        }
+    }
+
+    public Collection<CacheEntry> getEntries() {
+        ArrayList<CacheEntry> result = new ArrayList<CacheEntry>();
+        synchronized (this) {
+            for (Entry e : cache.values()) {
+                result.add(new CacheEntry(e));
+            }
+        }
+        return result;
+    }
+
+}