Execute span processor OnEnd in reverse order #1174
Description
If span processors are intended for more than just exporters, then it would be nice if OnEnd was called on the processors in reverse order. This makes it possible to create a span filter that removes short spans for example since EndTime is obviously only available on end and it's critical that the filter runs before the exporter.
I was able to hack it into span.End like so:
i := len(sps)
rev := make([]SpanProcessor, i)
for sp := range sps {
i--
rev[i] = sp
}
for _, sp := range rev {
sp.OnEnd(sd)
}