[ENet-discuss] Incorrectly reported connection under heavy load

[Krasimir Marinov]

Just a small addition...

The erroneous case 2. is missing the first line:
host.c:enet_host_connect:250: peer 0x7f4e604d1a10: connecting to port 48418

The last lines, starting with ">>>", of both cases are "my" connect
callback, being called with the argument supplied to ENetPeer instance
created after enet_host_connect() call.


On Wed, Nov 27, 2013 at 4:15 PM, Krasimir Marinov <krasi at jklsemi.com> wrote:

> I've been load testing an application, mainly based on ENet, and noticed
> erroneous behaviour for some of the connection being initiated.
>
> The test is performed on localhost and perform ~60K connections sending ~
> 120K messages.
>
> The error is that initiating connection to let's say port X I got
> confirmation (ENet connected callback) for port Y.
> Here are log traces that visualise the sequence of events under which the
> behaviour is observed:
>
> 1. Correct connect:
> host.c:enet_host_connect:250: peer 0x7f4e604d1a10: connecting to port 40041
> protocol.c:enet_protocol_handle_incoming_commands:1078: peer
> 0x7f4e604d1a10: port 40041
> protocol.c:enet_protocol_handle_incoming_commands:1127: peer
> 0x7f4e604d1a10: command ENET_PROTOCOL_COMMAND_VERIFY_CONNECT
> >>>2f00000000000000000000000000000000000000000000000000000000000000<00000000>:(conn
> 0x7f4dc8030190, peer 0x7f4e604d1a10): connected to port 40041
>
> 2. Incorrect connect:
> protocol.c:enet_protocol_handle_incoming_commands:1078: peer
> 0x7f4e604d1a10: port 48418
> protocol.c:enet_protocol_handle_incoming_commands:1133: peer
> 0x7f4e604d1a10: command ENET_PROTOCOL_COMMAND_DISCONNECT
> peer.c:enet_peer_reset:372: peer 0x7f4e604d1a10
> protocol.c:enet_protocol_handle_incoming_commands:1078: peer
> 0x7f4e604d1a10: port 56265
> protocol.c:enet_protocol_handle_incoming_commands:1112: peer
> 0x7f4e604d1a10: command ENET_PROTOCOL_COMMAND_ACKNOWLEDGE
> protocol.c:enet_protocol_handle_incoming_commands:1145: peer
> 0x7f4e604d1a10: command ENET_PROTOCOL_COMMAND_SEND_RELIABLE
> >>>2f00000000000000000000000000000000000000000000000000000000000000<00000000>:(conn
> 0x7f4dc800ac00, peer 0x7f4e604d1a10): connected to port 56265
>
> What happens, in 2., is that a peer that I've just created to connect
> receives an "unexpected" disconnect message and resets the peer,
> peer.c:enet_peer_reset:372: peer 0x7f4e604d1a10, which doesn't clear the
> user supplied data (ENetPeer->data) and when the peer is reused I get
> incorrect data attached to it.
>
> I've applied the following patch to protocol.c, which seems to work.
> Unfortunately I'm unable to predict all positive/negative consequences of
> it, so I'm asking for another opinion/ideas :). Here is the patch (simply
> skip processing disconnect messages when in state CONNECTING):
>
> protocol.c
> 817c817,818
> <     if (peer -> state == ENET_PEER_STATE_DISCONNECTED || peer -> state
> == ENET_PEER_STATE_ZOMBIE || peer -> state ==
> ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT)
> ---
> >     if (peer -> state == ENET_PEER_STATE_DISCONNECTED || peer -> state
> == ENET_PEER_STATE_ZOMBIE || peer -> state ==
> ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT
> >         || peer->state == ENET_PEER_STATE_CONNECTING)
>
>
> Regards,
> Krasi
>
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