worker: Do not use references for async callbacks

[jmillan]

If the callback is not executed in the same uv_loop iteration, the access to such values upon executing the callback is undefined.

[jmillan]

TODO: CHANGELOG

[ibc]

What is this fixing?

[jmillan]

What is this fixing?

If the packet is not sent in the current loop iteration, ie: if uv_udp_try_send() cannot send the packet immediately and we need to use uv_udp_send() which will send the packet when possible (not in this iteration) and notify us when that is done, we will run the send callback in the future. In such future, the variables passed by reference to the callback will NOT exist, because they were in the stack, back in such previous iteration when uv_udp_send() was called.

Accessing references to stack variables that do not exist anymore has undefined behaviour, so we may be probably calling the transport congestion PacketSent() methods with garbage.

Also, this reminded me that we were having a crash with jemalloc at work, and this may well be related.

[ibc]

I see. Good. Approved, like my txuleton. Look:

[jmillan]

I see. Good. Approved, like my txuleton

0xdeadbeef

[ibc]

Plus good dessert and 3 wines and patxaran