RFR JDK-8153353: HPACK implementation

[Pavel Rappo]

> On 12 Apr 2016, at 16:56, Roger Riggs <Roger.Riggs at Oracle.com> wrote:
> 
> Since you have a TestHelper class you could put it there and not duplicate the code in several tests.

Thanks! Done.

http://cr.openjdk.java.net/~prappo/8153353/webrev.00/test/java/net/httpclient/http2/java.httpclient/sun/net/httpclient/hpack/TestHelper.java.html

  32     public static Random newRandom() {
  33         long seed = System.currentTimeMillis();
  34         System.out.println("new java.util.Random(" + seed + ")");
  35         return new Random(seed);
  36     }

>>> 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.
> it could be as simple as referring to "RFC 7541 section 5.1 Integer Representation."

I have a TODO item on changing all exceptions' messages to more informative ones. 
I'd prefer to bulk-address it later.

>> 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;
>> 
> You don't believe the expression is equivalent? 
>> 482         return (len + 7) / 8;
>> 483     }

I do. They are equivalent within the range 0 <= len <= (Integer.MAX_VALUE - 7)
I just thought my belief should be supported with an assertion [1] :-)

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[1] https://docs.oracle.com/javase/7/docs/technotes/guides/language/assert.html#usage-invariants