modules/jdbc-pool/src/main/java/org/apache/tomcat/jdbc/pool/MultiLockFairBlockingQueue.java [282:517]:
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    @Override
    public boolean add(E e) {
        return offer(e);
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public int drainTo(Collection<? super E> c, int maxElements) {
        throw new UnsupportedOperationException("int drainTo(Collection<? super E> c, int maxElements)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public int drainTo(Collection<? super E> c) {
        return drainTo(c,Integer.MAX_VALUE);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void put(E e) throws InterruptedException {
        offer(e);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int remainingCapacity() {
        return Integer.MAX_VALUE - size();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public E take() throws InterruptedException {
        return this.poll(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean addAll(Collection<? extends E> c) {
        Iterator<? extends E> i = c.iterator();
        while (i.hasNext()) {
            E e = i.next();
            offer(e);
        }
        return true;
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public void clear() {
        throw new UnsupportedOperationException("void clear()");

    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean containsAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean containsAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isEmpty() {
        return size() == 0;
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean removeAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean removeAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean retainAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean retainAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public Object[] toArray() {
        throw new UnsupportedOperationException("Object[] toArray()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public <T> T[] toArray(T[] a) {
        throw new UnsupportedOperationException("<T> T[] toArray(T[] a)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E element() {
        throw new UnsupportedOperationException("E element()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E peek() {
        throw new UnsupportedOperationException("E peek()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E remove() {
        throw new UnsupportedOperationException("E remove()");
    }



    //------------------------------------------------------------------
    // Non cancellable Future used to check and see if a connection has been made available
    //------------------------------------------------------------------
    protected class ItemFuture<T> implements Future<T> {
        protected volatile T item = null;
        protected volatile ExchangeCountDownLatch<T> latch = null;
        protected volatile boolean canceled = false;

        public ItemFuture(T item) {
            this.item = item;
        }

        public ItemFuture(ExchangeCountDownLatch<T> latch) {
            this.latch = latch;
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return false; //don't allow cancel for now
        }

        @Override
        public T get() throws InterruptedException, ExecutionException {
            if (item!=null) {
                return item;
            } else if (latch!=null) {
                latch.await();
                return latch.getItem();
            } else {
                throw new ExecutionException("ItemFuture incorrectly instantiated. Bug in the code?", new Exception());
            }
        }

        @Override
        public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
            if (item!=null) {
                return item;
            } else if (latch!=null) {
                boolean timedout = !latch.await(timeout, unit);
                if (timedout) throw new TimeoutException();
                else return latch.getItem();
            } else {
                throw new ExecutionException("ItemFuture incorrectly instantiated. Bug in the code?", new Exception());
            }
        }

        @Override
        public boolean isCancelled() {
            return false;
        }

        @Override
        public boolean isDone() {
            return (item!=null || latch.getItem()!=null);
        }

    }

    //------------------------------------------------------------------
    // Count down latch that can be used to exchange information
    //------------------------------------------------------------------
    protected class ExchangeCountDownLatch<T> extends CountDownLatch {
        protected volatile T item;
        public ExchangeCountDownLatch(int i) {
            super(i);
        }
        public T getItem() {
            return item;
        }
        public void setItem(T item) {
            this.item = item;
        }
    }

    //------------------------------------------------------------------
    // Iterator safe from concurrent modification exceptions
    //------------------------------------------------------------------
    protected class FairIterator implements Iterator<E> {
        E[] elements = null;
        int index;
        E element = null;

        @SuppressWarnings("unchecked") // Can't create arrays of generic types
        public FairIterator() {
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modules/jdbc-pool/src/main/java/org/apache/tomcat/jdbc/pool/FairBlockingQueue.java [284:520]:
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    @Override
    public boolean add(E e) {
        return offer(e);
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public int drainTo(Collection<? super E> c, int maxElements) {
        throw new UnsupportedOperationException("int drainTo(Collection<? super E> c, int maxElements)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */

    @Override
    public int drainTo(Collection<? super E> c) {
        return drainTo(c,Integer.MAX_VALUE);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void put(E e) throws InterruptedException {
        offer(e);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int remainingCapacity() {
        return Integer.MAX_VALUE - size();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public E take() throws InterruptedException {
        return this.poll(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean addAll(Collection<? extends E> c) {
        Iterator<? extends E> i = c.iterator();
        while (i.hasNext()) {
            E e = i.next();
            offer(e);
        }
        return true;
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public void clear() {
        throw new UnsupportedOperationException("void clear()");

    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean containsAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean containsAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isEmpty() {
        return size() == 0;
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean removeAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean removeAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public boolean retainAll(Collection<?> c) {
        throw new UnsupportedOperationException("boolean retainAll(Collection<?> c)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public Object[] toArray() {
        throw new UnsupportedOperationException("Object[] toArray()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public <T> T[] toArray(T[] a) {
        throw new UnsupportedOperationException("<T> T[] toArray(T[] a)");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E element() {
        throw new UnsupportedOperationException("E element()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E peek() {
        throw new UnsupportedOperationException("E peek()");
    }

    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException - this operation is not supported
     */
    @Override
    public E remove() {
        throw new UnsupportedOperationException("E remove()");
    }



    //------------------------------------------------------------------
    // Non cancellable Future used to check and see if a connection has been made available
    //------------------------------------------------------------------
    protected class ItemFuture<T> implements Future<T> {
        protected volatile T item = null;
        protected volatile ExchangeCountDownLatch<T> latch = null;
        protected volatile boolean canceled = false;

        public ItemFuture(T item) {
            this.item = item;
        }

        public ItemFuture(ExchangeCountDownLatch<T> latch) {
            this.latch = latch;
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return false; //don't allow cancel for now
        }

        @Override
        public T get() throws InterruptedException, ExecutionException {
            if (item!=null) {
                return item;
            } else if (latch!=null) {
                latch.await();
                return latch.getItem();
            } else {
                throw new ExecutionException("ItemFuture incorrectly instantiated. Bug in the code?", new Exception());
            }
        }

        @Override
        public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
            if (item!=null) {
                return item;
            } else if (latch!=null) {
                boolean timedout = !latch.await(timeout, unit);
                if (timedout) throw new TimeoutException();
                else return latch.getItem();
            } else {
                throw new ExecutionException("ItemFuture incorrectly instantiated. Bug in the code?", new Exception());
            }
        }

        @Override
        public boolean isCancelled() {
            return false;
        }

        @Override
        public boolean isDone() {
            return (item!=null || latch.getItem()!=null);
        }

    }

    //------------------------------------------------------------------
    // Count down latch that can be used to exchange information
    //------------------------------------------------------------------
    protected class ExchangeCountDownLatch<T> extends CountDownLatch {
        protected volatile T item;
        public ExchangeCountDownLatch(int i) {
            super(i);
        }
        public T getItem() {
            return item;
        }
        public void setItem(T item) {
            this.item = item;
        }
    }

    //------------------------------------------------------------------
    // Iterator safe from concurrent modification exceptions
    //------------------------------------------------------------------
    protected class FairIterator implements Iterator<E> {
        E[] elements = null;
        int index;
        E element = null;

        @SuppressWarnings("unchecked") // Can't create arrays of generic types
        public FairIterator() {
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