Fix compression format: needs to have the zlib header around deflate.

[marshallpierce]

Also add an example cli tool to make it easy to construct serialized
histograms of various flavors. Seems like it might come in handy for
someone beyond me.

Fixes #62.

[jonhoo]

Hmm, tests/serialization.rs fails to compile: https://travis-ci.org/jonhoo/hdrsample/jobs/285870400#L810

[jonhoo]

Also, for the command-line tool, it'd be nice to also have an argument to turn on auto-resize.
Apart from that LGTM.

[algermissen]

Thanks for doing this so quickly!

I just tried the branch version:

• Added impl Counter for i32 locally

• produced binary with

  let mut buf = File::create("foo2.hist").expect("ok io");
  let nbytes = V2DeflateSerializer::new()
    .serialize(&hist, &mut buf).expect("ok");
  buf.sync_all().expect("OK");
  

• The binary is attached: foo2.hist.zip

• The base64 version is HISTFAAAAFl4AS2KOw5AUBREr+OJiOIVopOIiFKh0ShQ2JfCDizD3sQS3PeZTOYkM9NcdyUimwQRmfic33P9QvHgZBCMmhQLGYUiV1pKWhZf73Qw6ESt74ORnokfyTUHhg==

• Created hgrm text file and imported that into http://hdrhistogram.github.io/HdrHistogram/plotFiles.html

Result:

• base64 works(!) in https://hdrhistogram.github.io/HdrHistogramJSDemo/decoding-demo.html
• hgrm text file works in http://hdrhistogram.github.io/HdrHistogram/plotFiles.html UI

Thanks a lot!

[marshallpierce]

Ah, there's a build with no default features. I'll add cfg as needed. Auto resize sounds good too.

@algermissen Glad it's working! Adding Counter for i32 shouldn't really be doing anything important, though. Negative values aren't supported anyway. I tried it with just plain old u64 and interop worked with the JS demo and some throwaway tools I made with the Java impl.

One other thing is that this is a backwards-incompatible change if people have caches of old histograms serialized with the plain deflate compression. If that is an issue for people we can resuscitate the old form to let them transcode the old form into the new form.

[jonhoo]

You can use all(feature = "serialization", test) here I believe

[jonhoo]

Ah, yes, that came as a result of #56.

For the example binary, we should use required-features instead of this nasty whole-module cfg gate.

As for backwards compatibility, I think we should make the change, and then provide a fix for those in need if complaints should arise.

[jonhoo]

@marshallpierce if you think we might want to add other things, perhaps this should become a bin, and not just an example?

[marshallpierce]

Not a bad idea, but I think I'd like to incubate things a bit as an example before we ship it as something semi-official.