staticbucketmap.java

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     * @return the key set
     */
    public Set keySet() {
        return new KeySet();
    }

    /**
     * Gets the values.
     * 
     * @return the values
     */
    public Collection values() {
        return new Values();
    }

    /**
     * Gets the entry set.
     * 
     * @return the entry set
     */
    public Set entrySet() {
        return new EntrySet();
    }

    //-----------------------------------------------------------------------
    /**
     * Puts all the entries from the specified map into this map.
     * This operation is <b>not atomic</b> and may have undesired effects.
     * 
     * @param map  the map of entries to add
     */
    public void putAll(Map map) {
        Iterator i = map.keySet().iterator();

        while (i.hasNext()) {
            Object key = i.next();
            put(key, map.get(key));
        }
    }

    /**
     * Clears the map of all entries.
     */
    public void clear() {
        for (int i = 0; i < buckets.length; i++) {
            Lock lock = locks[i];
            synchronized (lock) {
                buckets[i] = null;
                lock.size = 0;
            }
        }
    }

    /**
     * Compares this map to another, as per the Map specification.
     * 
     * @param obj  the object to compare to
     * @return true if equal
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj instanceof Map == false) {
            return false;
        }
        Map other = (Map) obj;
        return entrySet().equals(other.entrySet());
    }

    /**
     * Gets the hash code, as per the Map specification.
     * 
     * @return the hash code
     */
    public int hashCode() {
        int hashCode = 0;

        for (int i = 0; i < buckets.length; i++) {
            synchronized (locks[i]) {
                Node n = buckets[i];

                while (n != null) {
                    hashCode += n.hashCode();
                    n = n.next;
                }
            }
        }
        return hashCode;
    }

    //-----------------------------------------------------------------------
    /**
     * The Map.Entry for the StaticBucketMap.
     */
    private static final class Node implements Map.Entry, KeyValue {
        protected Object key;
        protected Object value;
        protected Node next;

        public Object getKey() {
            return key;
        }

        public Object getValue() {
            return value;
        }

        public int hashCode() {
            return ((key == null ? 0 : key.hashCode()) ^
                    (value == null ? 0 : value.hashCode()));
        }

        public boolean equals(Object obj) {
            if (obj == this) {
                return true;
            }
            if (obj instanceof Map.Entry == false) {
                return false;
            }

            Map.Entry e2 = (Map.Entry) obj;
            return (
                (key == null ? e2.getKey() == null : key.equals(e2.getKey())) &&
                (value == null ? e2.getValue() == null : value.equals(e2.getValue())));
        }

        public Object setValue(Object obj) {
            Object retVal = value;
            value = obj;
            return retVal;
        }
    }


    /**
     * The lock object, which also includes a count of the nodes in this lock.
     */
    private final static class Lock {
        public int size;
    }


    //-----------------------------------------------------------------------
    private class EntryIterator implements Iterator {

        private ArrayList current = new ArrayList();
        private int bucket;
        private Map.Entry last;


        public boolean hasNext() {
            if (current.size() > 0) return true;
            while (bucket < buckets.length) {
                synchronized (locks[bucket]) {
                    Node n = buckets[bucket];
                    while (n != null) {
                        current.add(n);
                        n = n.next;
                    }
                    bucket++;
                    if (current.size() > 0) return true;
                }
            }
            return false;
        }

        protected Map.Entry nextEntry() {
            if (!hasNext()) throw new NoSuchElementException();
            last = (Map.Entry)current.remove(current.size() - 1);
            return last;
        }

        public Object next() {
            return nextEntry();
        }

        public void remove() {
            if (last == null) throw new IllegalStateException();
            StaticBucketMap.this.remove(last.getKey());
            last = null;
        }

    }

    private class ValueIterator extends EntryIterator {

        public Object next() {
            return nextEntry().getValue();
        }

    }

    private class KeyIterator extends EntryIterator {

        public Object next() {
            return nextEntry().getKey();
        }

    }

    private class EntrySet extends AbstractSet {

        public int size() {
            return StaticBucketMap.this.size();
        }

        public void clear() {
            StaticBucketMap.this.clear();
        }

        public Iterator iterator() {
            return new EntryIterator();
        }

        public boolean contains(Object obj) {
            Map.Entry entry = (Map.Entry) obj;
            int hash = getHash(entry.getKey());
            synchronized (locks[hash]) {
                for (Node n = buckets[hash]; n != null; n = n.next) {
                    if (n.equals(entry)) return true;
                }
            }
            return false;
        }

        public boolean remove(Object obj) {
            if (obj instanceof Map.Entry == false) {
                return false;
            }
            Map.Entry entry = (Map.Entry) obj;
            int hash = getHash(entry.getKey());
            synchronized (locks[hash]) {
                for (Node n = buckets[hash]; n != null; n = n.next) {
                    if (n.equals(entry)) {
                        StaticBucketMap.this.remove(n.getKey());
                        return true;
                    }
                }
            }
            return false;
        }

    }


    private class KeySet extends AbstractSet {

        public int size() {
            return StaticBucketMap.this.size();
        }

        public void clear() {
            StaticBucketMap.this.clear();
        }

        public Iterator iterator() {
            return new KeyIterator();
        }

        public boolean contains(Object obj) {
            return StaticBucketMap.this.containsKey(obj);
        }

        public boolean remove(Object obj) {
            int hash = getHash(obj);
            synchronized (locks[hash]) {
                for (Node n = buckets[hash]; n != null; n = n.next) {
                    Object k = n.getKey();
                    if ((k == obj) || ((k != null) && k.equals(obj))) {
                        StaticBucketMap.this.remove(k);
                        return true;
                    }
                }
            }
            return false;

        }

    }


    private class Values extends AbstractCollection {

        public int size() {
            return StaticBucketMap.this.size();
        }

        public void clear() {
            StaticBucketMap.this.clear();
        }

        public Iterator iterator() {
            return new ValueIterator();
        }

    }


    /**
     *  Prevents any operations from occurring on this map while the
     *  given {@link Runnable} executes.  This method can be used, for
     *  instance, to execute a bulk operation atomically: 
     *
     *  <pre>
     *    staticBucketMapInstance.atomic(new Runnable() {
     *        public void run() {
     *            staticBucketMapInstance.putAll(map);
     *        }
     *    });
     *  </pre>
     *
     *  It can also be used if you need a reliable iterator:
     *
     *  <pre>
     *    staticBucketMapInstance.atomic(new Runnable() {
     *        public void run() {
     *            Iterator iterator = staticBucketMapInstance.iterator();
     *            while (iterator.hasNext()) {
     *                foo(iterator.next();
     *            }
     *        }
     *    });
     *  </pre>
     *
     *  <b>Implementation note:</b> This method requires a lot of time
     *  and a ton of stack space.  Essentially a recursive algorithm is used
     *  to enter each bucket's monitor.  If you have twenty thousand buckets
     *  in your map, then the recursive method will be invoked twenty thousand
     *  times.  You have been warned.
     *
     *  @param r  the code to execute atomically
     */
    public void atomic(Runnable r) {
        if (r == null) throw new NullPointerException();
        atomic(r, 0);
    }

    private void atomic(Runnable r, int bucket) {
        if (bucket >= buckets.length) {
            r.run();
            return;
        }
        synchronized (locks[bucket]) {
            atomic(r, bucket + 1);
        }
    }

}