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ModelCache.cs

//
// ModelCache.cs
//
// Author:
//   Gabriel Burt <gburt@novell.com>
//
// Copyright (C) 2007 Novell, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Collections.Generic;

namespace Hyena.Data
{
    public abstract class ModelCache<T> where T : ICacheableItem, new ()
    {
        protected ICacheableModel model;

        public ModelCache (ICacheableModel model)
        {
            this.model = model;
        }

        public virtual T GetValue (long index)
        {
            lock (this) {
                if (ContainsKey (index))
                    return this[index];

                FetchSet (index, model.FetchCount);

                if (ContainsKey (index))
                    return this[index];

                return default (T);
            }
        }

        // Responsible for fetching a set of items and placing them in the cache
        protected abstract void FetchSet (long offset, long limit);

        // Regenerate the cache
        public abstract void Reload ();

        public abstract bool ContainsKey (long i);
        public abstract void Add (long i, T item);
        public abstract T this[long i] { get; }
        public abstract void Clear ();
    }
}

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