public static bool ConcurrentUpdate <T>(string gkey, MemcachedConcurrentUpdater <T> updater, out T updatedData)
{
if (updater == null)
{
throw new ArgumentNullException("updater");
}
var client = GetClientInstance();
updatedData = default(T);
int tryTimes = 0;
MemcachedClient.CasResult casRst;
ulong unique;
do
{
if (tryTimes >= 5)
{
throw new ApplicationException("已经尝试了5次，都无法访问memcached服务");
}
if (tryTimes >= 2)
{
Thread.Sleep(50);
}
T originalDate;
CacheItem tmp = client.Gets(gkey, out unique) as CacheItem;
if (tmp == null || tmp.Data == null)
{
originalDate = default(T);
}
else
{
originalDate = (T)tmp.Data;
}
bool needUpdate;
updatedData = updater(originalDate, out needUpdate);
if (needUpdate == false)
{
return(false);
}
var itemData = new NeverExpiredCacheItem(gkey, updatedData, null);
if (unique == 0) // 说明还不存在，需要新增
{
casRst = client.Add(gkey, itemData) ? MemcachedClient.CasResult.Stored : MemcachedClient.CasResult.NotStored;
}
else
{
casRst = client.CheckAndSet(gkey, itemData, unique); // 满足条件则更新缓存
}
tryTimes++;
} while (casRst != MemcachedClient.CasResult.Stored); // 这种写法防止并发冲突
return(true);
}
public static bool ConcurrentUpdateFromDistributedCache <T>(string key, MemcachedConcurrentUpdater <T> updater, out T updatedData)
{
return(MemcachedCacheHelper.ConcurrentUpdate(key, updater, out updatedData));
}
