C # ReaderWriterLock

A ReaderWriterLock is used to implement a synchronous Cache to control the read/write operations on the Cache.

using System;  using System.Collections.Generic;  using System.Linq;  using System.Text;  using System.Threading;    namespace ReadWriteLockSlimTest  {      class SynchronizedCache      {          private ReaderWriterLockSlim cacheLock = new ReaderWriterLockSlim();          private Dictionary<int, string> innerCache = new Dictionary<int, string>();            public string Read(int key)          {              cacheLock.EnterReadLock();              try              {                  return innerCache[key];              }              finally              {                  cacheLock.ExitWriteLock();              }          }            public void Add(int key, string value)          {              cacheLock.EnterWriteLock();              try              {                  innerCache.Add(key, value);              }              finally              {                  cacheLock.ExitWriteLock();              }          }            public bool AddWithTimeout(int key, string value, int timeout)          {              if (cacheLock.TryEnterWriteLock(timeout))              {                  try                  {                      innerCache.Add(key, value);                  }                  finally                  {                      cacheLock.ExitWriteLock();                  }                  return true;              }              else              {                  return false;              }          }            public AddOrUpdateStatus AddOrUpdate(int key, string value)          {              cacheLock.EnterUpgradeableReadLock();              try              {                  string result = null;                  if (innerCache.TryGetValue(key, out result))                  {                      if (result == value)                      {                          return AddOrUpdateStatus.Unchanged;                      }                      else                      {                          cacheLock.EnterWriteLock();                          try                          {                              innerCache[key] = value;                          }                          finally                          {                              cacheLock.ExitWriteLock();                          }                          return AddOrUpdateStatus.Updated;                      }                  }                  else                  {                      cacheLock.EnterWriteLock();                      try                      {                          innerCache.Add(key, value);                      }                      finally                      {                          cacheLock.ExitWriteLock();                      }                      return AddOrUpdateStatus.Added;                  }              }              finally              {                  cacheLock.ExitUpgradeableReadLock();              }          }            public void Delete(int key)          {              cacheLock.EnterWriteLock();              try              {                  innerCache.Remove(key);              }              finally              {                  cacheLock.ExitWriteLock();              }          }            public enum AddOrUpdateStatus          {              Added,              Updated,              Unchanged          };      }  }