using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using NewLife.Log;
using XCode.DataAccessLayer;
namespace XCode.Cache
{
/// <summary>实体缓存</summary>
/// <typeparam name="TEntity">实体类型</typeparam>
public class EntityCache<TEntity> : CacheBase<TEntity>, IEntityCache where TEntity : Entity<TEntity>, new()
{
#region 基本
private EntityList<TEntity> _Entities;
/// <summary>实体集合。无数据返回空集合而不是null</summary>
public EntityList<TEntity> Entities
{
get
{
XCache.CheckShowStatics(ref NextShow, ref Total, ShowStatics);
// 两种情况更新缓存：1，缓存过期；2，不允许空但是集合又是空
Boolean isnull = !AllowNull && _Entities == null;
if (isnull || DateTime.Now > ExpiredTime)
{
lock (this)
{
isnull = !AllowNull && _Entities == null;
if (isnull || DateTime.Now > ExpiredTime)
{
// 异步更新时，如果为空，表明首次，同步获取数据
if (Asynchronous && !isnull)
{
// 这里直接计算有效期，避免每次判断缓存有效期时进行的时间相加而带来的性能损耗
// 设置时间放在获取缓存之前，让其它线程不要空等
ExpiredTime = DateTime.Now.AddSeconds(Expriod);
Times++;
if (Debug)
{
String reason = ExpiredTime <= DateTime.MinValue ? "第一次" : (isnull ? "无缓存数据" : Expriod + "秒过期");
DAL.WriteLog("异步更新实体缓存（第{2}次）：{0} 原因：{1}", typeof(TEntity).FullName, reason, Times);
}
ThreadPool.QueueUserWorkItem(FillWaper, isnull);
}
else
{
Times++;
if (Debug)
{
String reason = ExpiredTime <= DateTime.MinValue ? "第一次" : (isnull ? "无缓存数据" : Expriod + "秒过期");
DAL.WriteLog("更新实体缓存（第{2}次）：{0} 原因：{1} {3}", typeof(TEntity).FullName, reason, Times, XTrace.GetCaller(2, 2));
}
FillWaper(isnull);
// 这里直接计算有效期，避免每次判断缓存有效期时进行的时间相加而带来的性能损耗
// 设置时间放在获取缓存之后，避免缓存尚未拿到，其它线程拿到空数据
ExpiredTime = DateTime.Now.AddSeconds(Expriod);
}
}
else
Interlocked.Increment(ref Shoot2);
}
}
else
Interlocked.Increment(ref Shoot1);
Using = true;
return _Entities ?? EntityList<TEntity>.Empty;
}
}
private void FillWaper(Object state)
{
try
{
InvokeFill(delegate { _Entities = FillListMethod(); });
// 清空
if (_Entities != null && _Entities.Count < 1) _Entities = null;
if (Debug) DAL.WriteLog("完成更新缓存（第{1}次）：{0}", typeof(TEntity).FullName, Times);
}
catch (Exception ex)
{
XTrace.WriteException(ex);
}
}
private DateTime _ExpiredTime;
/// <summary>缓存过期时间</summary>
public DateTime ExpiredTime
{
get { return _ExpiredTime; }
set { _ExpiredTime = value; }
}
/// <summary>缓存更新次数</summary>
private Int64 Times;
private Int32 _Expriod = 60;
/// <summary>过期时间。单位是秒，默认60秒</summary>
public Int32 Expriod
{
get { return _Expriod; }
set { _Expriod = value; }
}
private FillListDelegate<TEntity> _FillListMethod;
/// <summary>填充数据的方法</summary>
public FillListDelegate<TEntity> FillListMethod
{
get
{
if (_FillListMethod == null) _FillListMethod = Entity<TEntity>.FindAll;
return _FillListMethod;
}
set { _FillListMethod = value; }
}
private Boolean _Asynchronous;
/// <summary>异步更新</summary>
public Boolean Asynchronous
{
get { return _Asynchronous; }
set { _Asynchronous = value; }
}
private Boolean _AllowNull;
/// <summary>允许缓存空对象</summary>
public Boolean AllowNull
{
get { return _AllowNull; }
set { _AllowNull = value; }
}
/// <summary>清除缓存</summary>
public void Clear(String reason = null)
{
if (_Entities != null && _Entities.Count > 0 && Debug) DAL.WriteLog("清空实体缓存：{0} 原因：{1}", typeof(TEntity).FullName, reason);
ExpiredTime = DateTime.Now;
_Entities = null;
}
private Boolean _Using;
/// <summary>是否在使用缓存</summary>
internal Boolean Using { get { return _Using; } private set { _Using = value; } }
#endregion
#region 统计
/// <summary>总次数</summary>
public Int32 Total;
/// <summary>第一次命中</summary>
public Int32 Shoot1;
/// <summary>第二次命中</summary>
public Int32 Shoot2;
/// <summary>下一次显示时间</summary>
public DateTime NextShow;
/// <summary>显示统计信息</summary>
public void ShowStatics()
{
if (Total > 0)
{
StringBuilder sb = new StringBuilder();
sb.AppendFormat("实体缓存<{0}>", typeof(TEntity).Name);
sb.AppendFormat("总次数{0}", Total);
if (Shoot1 > 0) sb.AppendFormat("，一级命中{0}（{1:P02}）", Shoot1, (Double)Shoot1 / Total);
if (Shoot2 > 0) sb.AppendFormat("，二级命中{0}（{1:P02}）", Shoot2, (Double)Shoot2 / Total);
XTrace.WriteLine(sb.ToString());
}
}
#endregion
#region IEntityCache 成员
EntityList<IEntity> IEntityCache.Entities
{
get
{
List<TEntity> old = Entities;
if (old == null) return null;
EntityList<IEntity> list = new EntityList<IEntity>();
foreach (TEntity item in old)
{
list.Add(item);
}
return list;
}
}
/// <summary>根据指定项查找</summary>
/// <param name="name">属性名</param>
/// <param name="value">属性值</param>
/// <returns></returns>
public IEntity Find(string name, object value) { return Entities.Find(name, value); }
/// <summary>根据指定项查找</summary>
/// <param name="name">属性名</param>
/// <param name="value">属性值</param>
/// <returns></returns>
public EntityList<IEntity> FindAll(string name, object value)
{
List<TEntity> old = Entities.FindAll(name, value);
if (old == null) return null;
EntityList<IEntity> list = new EntityList<IEntity>();
foreach (TEntity item in old)
{
list.Add(item);
}
return list;
}
/// <summary>检索与指定谓词定义的条件匹配的所有元素。</summary>
/// <param name="match">条件</param>
/// <returns></returns>
public EntityList<IEntity> FindAll(Predicate<IEntity> match)
{
List<TEntity> old = Entities.FindAll(e => match(e));
if (old == null) return null;
EntityList<IEntity> list = new EntityList<IEntity>();
foreach (TEntity item in old)
{
list.Add(item);
}
return list;
}
#endregion
}
/// <summary>填充数据的方法</summary>
/// <typeparam name="TEntity">实体类型</typeparam>
/// <returns></returns>
public delegate EntityList<TEntity> FillListDelegate<TEntity>() where TEntity : Entity<TEntity>, new();
}
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