RFR JDK-8153353: HPACK implementation

[Pavel Rappo]

Hi Roger, thanks for looking into this!

Changes are done in-place.

Do you think issues marked as [*] could be addressed incrementally after the
initial push?

> On 11 Apr 2016, at 16:18, Roger Riggs <Roger.Riggs at oracle.com> wrote:
> 
> Hi Pavel,
> 
> Though this is  an implementation only package, it could use a few more comments
> to support maintainers.  In the package.html, a couple of hints about what classes are
> the external interface would be useful and an example of use in Encode and/or Decode
> would help a lot.

[*]

> The tests use randomness and should have @key randomness in the tests.
> 
> To allow reproducibility, the tests should print the seeds used and be able to be restarted
> with a seed.  The testlibrary has a convenient factory for Random that logs the seed.
> 
> See jdk.testlibrary.RandomFactory
> 
> * @library /lib/testlibrary/
> * @build jdk.testlibrary.RandomFactory
> 
> and use it as:
>    private static final Random random = RandomFactory.getRandom();

Since these tests are "white box", I find it hard to inject
jdk.testlibrary.RandomFactory into them, given they are compiled-in
java.httpclient module.

Would it be an acceptable work around to manually log-and-set seeds for any PRNG
used in tests?

113     private final Random rnd;
114     {
115         long seed = System.currentTimeMillis();
116         System.out.println(seed);
117         rnd = new Random(seed);
118     }

> IntegerReader:
>  - It would be useful to have a reference to the spec for variable length integers: i.e.  rfc 7541 5.1 Integer Representation

[*] I have it in my TODO list.

> - Line 129, 53: inconsistent IAE's in some the valid condition is included in the exception message,
>   but in others the *in*valid condition is included but without any indication of which is which.
> 
> - line 109/110:  style put 'while' on same line as '}' from do so it does not look like a separate statement.
> 
> IntegerWriter:
> - line 40:  perhaps 'value' or 'v' would be more readable than 'i' which is often thought of as a local value.

Done.

I've also converted JUnit tests into TestNG ones, as it's de facto standard in
core-libs tests. Fixed remainder operator '%' mentioned by Simone, which I guess
now reads better (and explained the intention as an assert):

474     public int lengthOf(CharSequence value, int start, int end) {
475         int len = 0;
476         for (int i = start; i < end; i++) {
477             char c = value.charAt(i);
478             len += INSTANCE.codeOf(c).length;
479         }
480         // Integer division with ceiling, assumption:
481         assert (len / 8 + (len % 8 != 0 ? 1 : 0)) == (len + 7) / 8 : len;
482         return (len + 7) / 8;
483     }