Add ssl:getstat/1 and ssl:getstat/2

[essen]

These functions call getstat on the underlying TCP socket.
The only way to do this before now was to use a hack, either
by looking inside the #sslsocket{} record directly, or by
not using the SSL listen/accept functions and upgrading
from a TCP socket that is kept around for the purpose of
calling getstat later on.

A separate commit also exports the type inet:stat_option/0
to be able to use it in the ssl module's specs.

Rebase of #929 against master, along with requested test fixes.

[OTP-Maintainer]

Patch has passed first testings and has been assigned to be reviewed

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I am a script, I am not human

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[IngelaAndin]

Have not had time to analyse this yet but currently tests are failing. This should be the most relevant part of the log:

*** CT Error Notification 2016-03-22 04:30:59.955 ***
ssl_basic_SUITE:getstat failed on line 603
Reason: {badmatch,[false,true]}

Full error description and stacktrace

*** User 2016-03-22 04:30:59.955 ***
ssl_test_lib:97
Server Msg: ok

=== Ended at 2016-03-22 04:30:59
=== Location: [{ssl_basic_SUITE,getstat,603},
{test_server,ts_tc,1533},
{test_server,run_test_case_eval1,1053},
{test_server,run_test_case_eval,985}]
=== Reason: no match of right hand side value [false,true]
in function ssl_basic_SUITE:getstat/1 (ssl_basic_SUITE.erl, line 603)
in call from test_server:ts_tc/3 (test_server.erl, line 1533)
in call from test_server:run_test_case_eval1/6 (test_server.erl, line 1053)
in call from test_server:run_test_case_eval/9 (test_server.erl, line 985)

[essen]

@IngelaAndin I can't reproduce.

Considering the code, what happens is probably a timing issue, so I introduced two timer:sleep(100) after sending and before checking that the send stats were updated. I hope that's OK.

[OTP-Maintainer]

Patch has passed first testings and has been assigned to be reviewed

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I am a script, I am not human

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[IngelaAndin]

This PR has been stalled in waiting for my rewrite of ssl to use gen_statem. I included in a first version into our builds yesterday, and it will be merged for 19-RC1. I know that it will take care of some timing issues and hopefully these issues too.

[essen]

This wasn't merged for 19-RC1 (or wasn't in the README). Is this still going in for 19?

[IngelaAndin]

This is a small addition in comparison to the gen_statem rewrite, and does not have a big impact on other parts, so it may till make it for 19. Several ssl PR are stalled as gen_statem rewrite has been prioritized. I just put this one into the test machinery again. Alas the case is failing on 22 of 28 machines

ssl_basic_SUITE:getstat failed on line 651
Reason: {badmatch,[false,true]}

I understand that this is due to timing issues in the test case. We need to try and find a way around this. I will try to help but to be frank I have some other things higher on the prio list at the moment.

[essen]

Fair enough, statem is more important, just tell me when you got time.

[IngelaAndin]

I changed you timer:sleep to _ = ssl:connection_information(Socket), which makes things alot better.
Alas a few platforms will still get the result:

** CT Error Notification 2016-06-03 05:05:00.438 ***
ssl_basic_SUITE:getstat failed on line 734
Reason: {badmatch,[false,true]}

 732:     wait_for_send(PassiveC),
  733:     {ok, SStats} = ssl:getstat(PassiveC, [send_cnt, send_oct, send_avg]),
  734:     [true] = lists:usort([proplists:get_value(Name, SStats) =/= proplists:get_value(Name, InitialStats)
  735:         || Name <- [send_cnt, send_oct, send_avg]]),

[essen]

Which platforms?

[IngelaAndin]

Linux, windows7 and openbsd 5.9. I am not sure if is true for all of the failing machines but at least one of them is slow machine.

[IngelaAndin]

It is 5 failing out of 33 so far (still 10 machines running and 2 aborted) . Before my change it failed on 20+ machines.

[IngelaAndin]

You can not depend on send_avg having changed. I changed the test to just use send_cnt and sned_oct hopefully it will pass now.

[essen]

Ah right, it's an average... feels silly

[IngelaAndin]

Merged with my updates to the tests.

[essen]

Thanks!