CachePointNode.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;

using Deveel.Data;
using Deveel.Data.Serialization;
using Deveel.Data.Sql.Tables;

namespace Deveel.Data.Sql.Query {
    [Serializable]
    sealed class CachePointNode : SingleQueryPlanNode {
        private readonly static Object GlobLock = new Object();
        private static int GlobId;

        public CachePointNode(IQueryPlanNode child)
            : this(child,NewId()) {
        }

        public CachePointNode(IQueryPlanNode child, long id)
            : base(child) {
            Id = id;
        }

        private CachePointNode(ObjectData data)
            : base(data) {
            Id = data.GetInt32("Id");
        }

        private static long NewId() {
            long id;
            lock (GlobLock) {
                id = ((int)DateTime.Now.Ticks << 16) | (GlobId & 0x0FFFF);
                ++GlobId;
            }
            return id;
        }

        public long Id { get; private set; }

        public override ITable Evaluate(IRequest context) {
            // Is the result available in the context?
            var childTable = context.Query.GetCachedTable(Id.ToString());
            if (childTable == null) {
                // No so evaluate the child and cache it
                childTable = Child.Evaluate(context);
                context.Query.CacheTable(Id.ToString(), childTable);
            }

            return childTable;
        }

        protected override void GetData(SerializeData data) {
            data.SetValue("Id", Id);
        }
    }
}