Use bounded channels for peer events

[ImplOfAnImpl]

This fixes #664 (note that as we've discussed earlier, the solution proposed in the issue itself is redundant; using a bounded channel for peer events should be enough).

P.S. I've based this PR on top of #1183 to simplify merging.

[TheQuantumPhysicist]

Please fix the minor issues I mentioned then we'll go ahead and merge.

[iljakuklic]

Just noticed that StreamMap stores the channels in a Vec and polls them in order defined by the order of elements in the vec. This may give some peers advantage over others. For example the first connection will be in the first position and, as far as I can see, will stay there until disconnected.

Do we want to address this? Is it possible to periodically shuffle the elements or something like that?

[ImplOfAnImpl]

Just noticed that StreamMap stores the channels in a Vec and polls them in order defined by the order of elements in the vec. This may give some peers advantage over others. For example the first connection will be in the first position and, as far as I can see, will stay there until disconnected.

Do we want to address this? Is it possible to periodically shuffle the elements or something like that?

As far as I can see, StreamMap::poll_next_entry chooses starting index randomly, so this should not be a problem.

[iljakuklic]

As far as I can see, StreamMap::poll_next_entry chooses starting index randomly, so this should not be a problem.

Ok, good. Thanks for finding out.