Uwsgi Plugin serialization format

[tiras-j]

RE: My recent PR we know that marshal is dangerous but fast. However doing some rudimentary testing I think using struct + simple byte concat is faster on pre-Python3.5 (apparently someone decided to overhaul the marshal serialization I suppose). Here's a rudimentary test script I used to run some very basic timings. Using this approach means we have to deal with unicode vs. bytes ourselves, but since clog converts lines into UTF-8 anyways I don't think that will be much of an issue. How about stream names? It doesn't look like the ScribeLogger converts that to UTF-8, so we might need to reconstitute the unicode format by storing the encoding somehow.

Anyways, struct + raw bytes would be safer than marshal and would work in this case since we can make some strong assumptions about the arguments. I'll look into changing it but I think we should get the current PR in first just to fix the marshal.loads problem.

[asottile]

iirc the thrift stuff allows either UTF-8 bytes or text, so encoding the stream name should be safe