Concurrentqueue-a queue Cache Design

Using  System;  Using  System. Collections. Generic;  Using  System. LINQ;  Using  System. Web;  Using  System. Collections. Concurrent;  Namespace  Pdajob. pdaservice. Service {  Public   Class Cachelist <t> { Private   Int Maxsize = 10000  ;  Private   Int Shrinklen = 2000  ;  Private Concurrentqueue <cacheitem <t> _ queue = New Concurrentqueue <cacheitem <t> ();  Public Cachelist ( Int Maxsize,Int  Shrinklen ){  This . Maxsize = Maxsize;  This . Shrinklen = Shrinklen ;}  Public   Void  Add (T item ){  # Region Contract if the value is exceeded If (_ Queue. Count> = Maxsize ){  Lock (This  ){  If (_ Queue. Count> = Maxsize) {cacheitem <T> Outitem;  For ( Int I = 0 ; I <shrinklen; I ++ ) {_ Queue. trydequeue (  Out Outitem );}}}}  # Endregion  _ Queue. enqueue (  New Cacheitem <t> () {DATA = item, addtime = Datetime. Now });}  Public Concurrentqueue <cacheitem <t> Queue {  Get  {  Return  _ Queue ;}}} ///   <Summary>      ///  Cached content  ///   </Summary>      ///   <Typeparam name = "T"> </typeparam>      Public   Class Cacheitem <t> {  Public Datetime addtime { Get ; Set  ;} Public T data { Get ; Set  ;}}} 

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In a multi-threaded environment, multiple threads may read queue. Count> maxsize. Although queue is thread safeCodeIt can cause _ queue to be moved empty again, so you need to add lock