// 10 seconds.
/// <summary>
/// Waits on the channel with the given timeout using one of the
/// cached selectors.
/// </summary>
/// <remarks>
/// Waits on the channel with the given timeout using one of the
/// cached selectors. It also removes any cached selectors that are
/// idle for a few seconds.
/// </remarks>
/// <param name="channel"/>
/// <param name="ops"/>
/// <param name="timeout"/>
/// <returns/>
/// <exception cref="System.IO.IOException"/>
internal virtual int Select(SelectableChannel channel, int ops, long timeout)
{
SocketIOWithTimeout.SelectorPool.SelectorInfo info = Get(channel);
SelectionKey key = null;
int ret = 0;
try
{
while (true)
{
long start = (timeout == 0) ? 0 : Time.Now();
key = channel.Register(info.selector, ops);
ret = info.selector.Select(timeout);
if (ret != 0)
{
return(ret);
}
if (Thread.CurrentThread().IsInterrupted())
{
throw new ThreadInterruptedException("Interrupted while waiting for " + "IO on channel "
+ channel + ". " + timeout + " millis timeout left.");
}
/* Sometimes select() returns 0 much before timeout for
* unknown reasons. So select again if required.
*/
if (timeout > 0)
{
timeout -= Time.Now() - start;
if (timeout <= 0)
{
return(0);
}
}
}
}
finally
{
if (key != null)
{
key.Cancel();
}
//clear the canceled key.
try
{
info.selector.SelectNow();
}
catch (IOException e)
{
Log.Info("Unexpected Exception while clearing selector : ", e);
// don't put the selector back.
info.Close();
return(ret);
}
Release(info);
}
}
/// <summary>puts selector back at the end of LRU list of free selectos.</summary>
/// <remarks>
/// puts selector back at the end of LRU list of free selectos.
/// Also invokes trimIdleSelectors().
/// </remarks>
/// <param name="info"/>
private void Release(SocketIOWithTimeout.SelectorPool.SelectorInfo info)
{
lock (this)
{
long now = Time.Now();
TrimIdleSelectors(now);
info.lastActivityTime = now;
info.queue.AddLast(info);
}
}
/// <summary>Takes one selector from end of LRU list of free selectors.</summary>
/// <remarks>
/// Takes one selector from end of LRU list of free selectors.
/// If there are no selectors awailable, it creates a new selector.
/// Also invokes trimIdleSelectors().
/// </remarks>
/// <param name="channel"/>
/// <returns></returns>
/// <exception cref="System.IO.IOException"/>
private SocketIOWithTimeout.SelectorPool.SelectorInfo Get(SelectableChannel channel
)
{
lock (this)
{
SocketIOWithTimeout.SelectorPool.SelectorInfo selInfo = null;
SelectorProvider provider = channel.Provider();
// pick the list : rarely there is more than one provider in use.
SocketIOWithTimeout.SelectorPool.ProviderInfo pList = providerList;
while (pList != null && pList.provider != provider)
{
pList = pList.next;
}
if (pList == null)
{
//LOG.info("Creating new ProviderInfo : " + provider.toString());
pList = new SocketIOWithTimeout.SelectorPool.ProviderInfo();
pList.provider = provider;
pList.queue = new List <SocketIOWithTimeout.SelectorPool.SelectorInfo>();
pList.next = providerList;
providerList = pList;
}
List <SocketIOWithTimeout.SelectorPool.SelectorInfo> queue = pList.queue;
if (queue.IsEmpty())
{
Selector selector = provider.OpenSelector();
selInfo = new SocketIOWithTimeout.SelectorPool.SelectorInfo();
selInfo.selector = selector;
selInfo.queue = queue;
}
else
{
selInfo = queue.RemoveLast();
}
TrimIdleSelectors(Time.Now());
return(selInfo);
}
}
/// <summary>Closes selectors that are idle for IDLE_TIMEOUT (10 sec).</summary>
/// <remarks>
/// Closes selectors that are idle for IDLE_TIMEOUT (10 sec). It does not
/// traverse the whole list, just over the one that have crossed
/// the timeout.
/// </remarks>
private void TrimIdleSelectors(long now)
{
long cutoff = now - IdleTimeout;
for (SocketIOWithTimeout.SelectorPool.ProviderInfo pList = providerList; pList !=
null; pList = pList.next)
{
if (pList.queue.IsEmpty())
{
continue;
}
for (IEnumerator <SocketIOWithTimeout.SelectorPool.SelectorInfo> it = pList.queue.
GetEnumerator(); it.HasNext();)
{
SocketIOWithTimeout.SelectorPool.SelectorInfo info = it.Next();
if (info.lastActivityTime > cutoff)
{
break;
}
it.Remove();
info.Close();
}
}
}
