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162 lines
5.2 KiB
162 lines
5.2 KiB
#if MYSQL_6_10
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// Copyright ?2016, 2018, Oracle and/or its affiliates. All rights reserved.
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//
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// MySQL Connector/NET is licensed under the terms of the GPLv2
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// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most
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// MySQL Connectors. There are special exceptions to the terms and
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// conditions of the GPLv2 as it is applied to this software, see the
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// FLOSS License Exception
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// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published
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// by the Free Software Foundation; version 2 of the License.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with this program; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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using System;
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using System.Collections.Generic;
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using System.Linq;
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namespace Externals.MySql.Data.MySqlClient
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{
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internal class TableCache
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{
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private static readonly BaseTableCache cache;
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static TableCache()
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{
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cache = new BaseTableCache(480 /* 8 hour max by default */);
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}
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public static void AddToCache(string commandText, ResultSet resultSet)
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{
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cache.AddToCache(commandText, resultSet);
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}
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public static ResultSet RetrieveFromCache(string commandText, int cacheAge)
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{
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return (ResultSet)cache.RetrieveFromCache(commandText, cacheAge);
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}
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public static void RemoveFromCache(string commandText)
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{
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cache.RemoveFromCache(commandText);
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}
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public static void DumpCache()
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{
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cache.Dump();
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}
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}
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/// <summary>
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/// Defines the basic operations to be performed on the table cache.
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/// </summary>
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internal class BaseTableCache
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{
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/// <summary>
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/// The maximum age allowed for cache entries.
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/// </summary>
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protected int MaxCacheAge;
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private Dictionary<string, CacheEntry> cache = new Dictionary<string, CacheEntry>();
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public BaseTableCache(int maxCacheAge)
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{
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MaxCacheAge = maxCacheAge;
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}
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/// <summary>
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/// Adds the given command and result set to the cache.
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/// </summary>
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/// <param name="commandText">The command to store in the cache.</param>
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/// <param name="resultSet">The resultset associated to the stored command.</param>
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public virtual void AddToCache(string commandText, object resultSet)
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{
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CleanCache();
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CacheEntry entry = new CacheEntry();
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entry.CacheTime = DateTime.Now;
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entry.CacheElement = resultSet;
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lock (cache)
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{
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if (cache.ContainsKey(commandText)) return;
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cache.Add(commandText, entry);
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}
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}
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/// <summary>
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/// Retrieves the specified command from the cache.
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/// </summary>
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/// <param name="commandText">The command to retrieve.</param>
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/// <param name="cacheAge">The allowed age for the cache entry.</param>
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/// <returns></returns>
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public virtual object RetrieveFromCache(string commandText, int cacheAge)
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{
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CleanCache();
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lock (cache)
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{
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if (!cache.ContainsKey(commandText)) return null;
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CacheEntry entry = cache[commandText];
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if (DateTime.Now.Subtract(entry.CacheTime).TotalSeconds > cacheAge) return null;
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return entry.CacheElement;
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}
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}
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/// <summary>
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/// Removes the specified command from the cache.
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/// </summary>
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/// <param name="commandText">The command to remove from the cache.</param>
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public void RemoveFromCache(string commandText)
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{
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lock (cache)
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{
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if (!cache.ContainsKey(commandText)) return;
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cache.Remove(commandText);
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}
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}
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/// <summary>
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/// Clears the cache.
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/// </summary>
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public virtual void Dump()
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{
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lock (cache)
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cache.Clear();
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}
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/// <summary>
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/// Removes cache entries older than the value defined by <see cref="MaxCacheAge"/>.
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/// </summary>
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protected virtual void CleanCache()
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{
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DateTime now = DateTime.Now;
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List<string> keysToRemove = new List<string>();
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lock (cache)
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{
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keysToRemove.AddRange(from key in cache.Keys let diff = now.Subtract(cache[key].CacheTime) where diff.TotalSeconds > MaxCacheAge select key);
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foreach (string key in keysToRemove)
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cache.Remove(key);
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}
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}
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private struct CacheEntry
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{
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public DateTime CacheTime;
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public object CacheElement;
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}
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}
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}
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#endif
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