public object GetOrAdd(string key, CacheItemRefreshAction refreshAction, long expiration, int lockTimeout)
{
return GetOrAdd(key, refreshAction, new DefaultCacheItemExpiration(expiration), lockTimeout);
}
public object GetOrAdd(string key, CacheItemRefreshAction refreshAction, ICacheItemExpiration expiration, int lockTimeout)
{
//First try to get the value for the key, if it doesn't exist, then try to add the candidate value.
//It's thread safe. The result "ci" for multiple threads should be the exactly the same value.
CacheItem candidate = new CacheItem(key, null, refreshAction, expiration);
CacheItem ci = SendEvent(OperationType.OP_ADD_OR_GET, candidate) as CacheItem;
if (ci == null)
{
//This should not happen. If it does, then this is a critial bug!
LogManager.Warn("CacheManager:Assert Failure", string.Format("The result of GetOrAdd for key [{0}] is null", key));
return null;
}
//Try to get the value. If there's no valid value, try to refresh it now.
object result = null;
if ((result = ci.Value) == null)
{
Stopwatch sw = new Stopwatch();
sw.Start();
if (!m_refreshSyncSem.WaitOne(lockTimeout))
{
LogManager.Warn("CacheManager", string.Format("Timeout when try to get a refresh token for [{0}]", ci.Key));
}
else
{
sw.Stop();
int remainTime = lockTimeout - (int)sw.ElapsedMilliseconds;
if (remainTime < 0 || remainTime > lockTimeout)
{
LogManager.Warn("CacheManager", string.Format("Invalid remaining time for [{0}], remainTime=[{1}]", ci.Key, remainTime));
remainTime = 0;
}
//Now we are allowed to refresh this key
ci.RefreshSync(remainTime);
//Release the token
int prevCount = m_refreshSyncSem.Release();
LogManager.Info("CacheManager", string.Format("Try to refresh [{0}] done, the previous semaphore count is [{1}]", ci.Key, prevCount));
}
//get the updated value
result = ci.Value;
}
return result;
}
public void Add(string key, object value, CacheItemRefreshAction refreshAction, ICacheItemExpiration expiration)
{
CacheItem ci = new CacheItem(key, value, refreshAction, expiration);
SendEvent(OperationType.OP_ADD, ci);
}
