Revisit how we handle http headers about colossus HOT 4 CLOSED

Does the http spec say these headers can only appear once?

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If I read the spec correctly, it does not say that certain headers can only appear once. In fact the content-type exampled showed two values (separated by comma).

There doesn't seem to be a preference between whether the same field should result in a comma separated listed or just repeated. Either way, it should behave the same. Currently headers is a list, but we could change it to a map of string to list, which would make look up quicker. Maybe we should do that for performance reasons?

from colossus.

Headers used to be a Map[String, Seq[String]], but maps (and basically all scala collections) are unfortunately very slow. I would advise not moving away from the Java List, as last time I benchmarked it was significantly faster than everything else.

I don't think I benchmarked lookup time, but honestly I wouldn't be surprised if scanning the list is still faster than a map lookup. Of course we're talking about an O(n) vs an O(1) operation, but I think you'd need to have a lot of headers for that to actually become significant. But don't take my word for it, definitely would be nice to get some documented numbers on it. Maybe a java HashMap would work.

from colossus.

I don't think there is any critical need to change this at the moment. At the very least it might make sense to wait for the new scala collections to come out. Once we get better at the habit of benchmarking we can look at this again. Closing for now.

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