Add qlog support for quiche

[bryancall]

[maskit]

There are some code for QLog already but I'm not sure if it's working.

$ git grep qlog  | grep quiche
iocore/net/QUICPacketHandler_quiche.cc:    if (params->qlog_dir() != nullptr) {
iocore/net/QUICPacketHandler_quiche.cc:      char qlog_filepath[PATH_MAX];
iocore/net/QUICPacketHandler_quiche.cc:      sprintf(qlog_filepath, "%s/%.*s.sqlog", Layout::get()->relative(params->qlog_dir()).c_str(),
iocore/net/QUICPacketHandler_quiche.cc:      quiche_conn_set_qlog_path(quiche_con, qlog_filepath, "ats", "");

[brbzull0]

There isn't much control on our side as you said with the qlog, the good think is that it works, I may add some error checks when calling quiche as I was testing with some invalid dir and I never knew.

Also I think we should go for something like this in the config that can let us grow eventually and proivide a more granular configuration:

ts:
  quic:
    qlog:
      base_name: /some/dir/test1

similiar to what provides h2load,

--qlog-file-base=<PATH>                                                      
              Enable qlog output and specify base file name for qlogs.
              Qlog is emitted  for each connection.  For  a given base
              name   "base",    each   output   file    name   becomes         
              "base.M.N.sqlog" where M is worker ID and N is client ID
              (e.g. "base.0.3.sqlog").  Only effective in QUIC runs. 

You provide a base name, which may include a folder and ATS will append the trace_id + the extension to it, so we will end up with something like
/some/dur/test1_b5c9cbf4d41cd60c779f059d749dd3cd5b8.sqlog

1 - @maskit @bryancall what do you guys think about the config change? It's currently proxy.config.quic.qlog_dir?

2 - Also, shouldn't we do this record overridable(conf_remap)? otherwise we may create tons of this if we aren't careful.

[maskit]

1. I'm fine with the config change. I don't remember current filename format, but the change would just makes /abc/xyz/123.qlog to /abc/xyz-123.qlog.
2. Yes, we need some control on that. Currently qlog is enabled by setting a path to config_dir and unsetting it disables qlog. Having "ts.quic.qlog.enable" may make it easier to enable/disable qlog by conf_remap.

[brbzull0]

1. I'm fine with the config change. I don't remember current filename format, but the change would just makes /abc/xyz/123.qlog to /abc/xyz-123.qlog.

done #9461

Having "ts.quic.qlog.enable" may make it easier to enable/disable qlog by conf_remap.

I have question on this regard, isn't the config remap hook happening at a later stage than where we enable/disable qlogs?

[maskit]

Ah, right. We probably need a SNI action for it instead.