private void OnExchangeCompleted(Object sender, EventArgs e)
{
Exchange exchange = (Exchange)sender;
/*
* Logging in this method leads to significant performance loss.
* Uncomment logging code only for debugging purposes.
*/
if (exchange.Origin == Origin.Local)
{
// this endpoint created the Exchange by issuing a request
Exchange.KeyID keyID = new Exchange.KeyID(exchange.CurrentRequest.ID, null);
Exchange.KeyToken keyToken = new Exchange.KeyToken(exchange.CurrentRequest.Token);
if (log.IsDebugEnabled)
{
log.Debug("Exchange completed: Cleaning up " + keyToken);
}
_exchangesByToken.Remove(keyToken);
// in case an empty ACK was lost
_exchangesByID.Remove(keyID);
}
else // Origin.Remote
{
// this endpoint created the Exchange to respond a request
Response response = exchange.CurrentResponse;
if (response != null && response.Type != MessageType.ACK)
{
// only response MIDs are stored for ACK and RST, no reponse Tokens
Exchange.KeyID midKey = new Exchange.KeyID(response.ID, null);
//if (log.IsDebugEnabled)
// log.Debug("Remote ongoing completed, cleaning up " + midKey);
_exchangesByID.Remove(midKey);
}
Request request = exchange.CurrentRequest;
if (request != null && (request.HasOption(OptionType.Block1) || response != null && response.HasOption(OptionType.Block2)))
{
Exchange.KeyUri uriKey = new Exchange.KeyUri(request.URI, request.Source);
if (log.IsDebugEnabled)
{
log.Debug("Remote ongoing completed, cleaning up " + uriKey);
}
Exchange exc;
_ongoingExchanges.TryRemove(uriKey, out exc);
}
// Remove all remaining NON-notifications if this exchange is an observe relation
ObserveRelation relation = exchange.Relation;
if (relation != null)
{
RemoveNotificatoinsOf(relation);
}
}
}
/// <inheritdoc/>
public Exchange ReceiveRequest(Request request)
{
/*
* This request could be
* - Complete origin request => deliver with new exchange
* - One origin block => deliver with ongoing exchange
* - Complete duplicate request or one duplicate block (because client got no ACK)
* =>
* if ACK got lost => resend ACK
* if ACK+response got lost => resend ACK+response
* if nothing has been sent yet => do nothing
* (Retransmission is supposed to be done by the retransm. layer)
*/
Exchange.KeyID keyId = new Exchange.KeyID(request.ID, request.Source);
/*
* The differentiation between the case where there is a Block1 or
* Block2 option and the case where there is none has the advantage that
* all exchanges that do not need blockwise transfer have simpler and
* faster code than exchanges with blockwise transfer.
*/
if (!request.HasOption(OptionType.Block1) && !request.HasOption(OptionType.Block2))
{
Exchange exchange = new Exchange(request, Origin.Remote);
Exchange previous = _deduplicator.FindPrevious(keyId, exchange);
if (previous == null)
{
exchange.Completed += OnExchangeCompleted;
return(exchange);
}
else
{
if (log.IsInfoEnabled)
{
log.Info("Duplicate request: " + request);
}
request.Duplicate = true;
return(previous);
}
}
else
{
Exchange.KeyUri keyUri = new Exchange.KeyUri(request.URI, request.Source);
if (log.IsDebugEnabled)
{
log.Debug("Looking up ongoing exchange for " + keyUri);
}
Exchange ongoing;
if (_ongoingExchanges.TryGetValue(keyUri, out ongoing))
{
Exchange prev = _deduplicator.FindPrevious(keyId, ongoing);
if (prev != null)
{
if (log.IsInfoEnabled)
{
log.Info("Duplicate ongoing request: " + request);
}
request.Duplicate = true;
}
else
{
// the exchange is continuing, we can (i.e., must) clean up the previous response
if (ongoing.CurrentResponse.Type != MessageType.ACK && !ongoing.CurrentResponse.HasOption(OptionType.Observe))
{
keyId = new Exchange.KeyID(ongoing.CurrentResponse.ID, null);
if (log.IsDebugEnabled)
{
log.Debug("Ongoing exchange got new request, cleaning up " + keyId);
}
_exchangesByID.Remove(keyId);
}
}
return(ongoing);
}
else
{
// We have no ongoing exchange for that request block.
/*
* Note the difficulty of the following code: The first message
* of a blockwise transfer might arrive twice due to a
* retransmission. The new Exchange must be inserted in both the
* hash map 'ongoing' and the deduplicator. They must agree on
* which exchange they store!
*/
Exchange exchange = new Exchange(request, Origin.Remote);
Exchange previous = _deduplicator.FindPrevious(keyId, exchange);
if (previous == null)
{
if (log.IsDebugEnabled)
{
log.Debug("New ongoing request, storing " + keyUri + " for " + request);
}
exchange.Completed += OnExchangeCompleted;
_ongoingExchanges[keyUri] = exchange;
return(exchange);
}
else
{
if (log.IsInfoEnabled)
{
log.Info("Duplicate initial request: " + request);
}
request.Duplicate = true;
return(previous);
}
} // if ongoing
} // if blockwise
}
/// <inheritdoc/>
public void SendResponse(Exchange exchange, Response response)
{
if (response.ID == Message.None)
{
response.ID = System.Threading.Interlocked.Increment(ref _currentID) % (1 << 16);
}
/*
* The response is a CON or NON or ACK and must be prepared for these
* - CON => ACK / RST // we only care to stop retransmission
* - NON => RST // we only care for observe
* - ACK => nothing!
* If this response goes lost, we must be prepared to get the same
* CON/NON request with same MID again. We then find the corresponding
* exchange and the ReliabilityLayer resends this response.
*/
// If this is a CON notification we now can forget all previous NON notifications
if (response.Type == MessageType.CON || response.Type == MessageType.ACK)
{
ObserveRelation relation = exchange.Relation;
if (relation != null)
{
RemoveNotificatoinsOf(relation);
}
}
// Blockwise transfers are identified by URI and remote endpoint
if (response.HasOption(OptionType.Block2))
{
Request request = exchange.CurrentRequest;
Exchange.KeyUri keyUri = new Exchange.KeyUri(request.URI, response.Destination);
// Observe notifications only send the first block, hence do not store them as ongoing
if (exchange.ResponseBlockStatus != null && !response.HasOption(OptionType.Observe))
{
// Remember ongoing blockwise GET requests
if (Utils.Put(_ongoingExchanges, keyUri, exchange) == null)
{
if (log.IsDebugEnabled)
{
log.Debug("Ongoing Block2 started late, storing " + keyUri + " for " + request);
}
}
else
{
if (log.IsDebugEnabled)
{
log.Debug("Ongoing Block2 continued, storing " + keyUri + " for " + request);
}
}
}
else
{
if (log.IsDebugEnabled)
{
log.Debug("Ongoing Block2 completed, cleaning up " + keyUri + " for " + request);
}
Exchange exc;
_ongoingExchanges.TryRemove(keyUri, out exc);
}
}
// Insert CON and NON to match ACKs and RSTs to the exchange
// Do not insert ACKs and RSTs.
if (response.Type == MessageType.CON || response.Type == MessageType.NON)
{
Exchange.KeyID keyID = new Exchange.KeyID(response.ID, null);
_exchangesByID[keyID] = exchange;
}
// Only CONs and Observe keep the exchange active
if (response.Type != MessageType.CON && response.Last)
{
exchange.Complete = true;
}
}