[PATCH 0/3] http: support fine-tuning curl's keepalive behavior

This short series introduces a few new http.* configuration options to control curl's behavior around TCP keepalive packets. The details are spelled out in the final patch, but the gist is:

  - http.keepAliveIdle specifies how long in seconds to wait on an idle
    connection before beginning to send keepalive packets.

  - http.keepAliveInterval does the same but controls the interval
    between successive keepalive packets.

  - http.keepAliveCount specifies how many keepalive packets to send
    before closing down the connection.

The first two commits of the series are general code clean-up of a couple of small things I noticed while reading through the http.c code, and the final patch implements these new options.

I couldn't think of a great way to test these new configuration settings, and given the simplicity of the final patch I opted for no tests there. But if someone has a good idea of how to test this behavior, please let me know.

In either case, thanks in advance for your review!

Taylor Blau (3):
  http.c: introduce `set_long_from_env()` for convenience
  http.c: inline `set_curl_keepalive()`
  http.c: allow custom TCP keepalive behavior via config

 Documentation/config/http.adoc | 18 ++++++++++++
 http.c                         | 54 +++++++++++++++++++++++++---------
 2 files changed, 58 insertions(+), 14 deletions(-)

base-commit: 683c54c999c301c2cd6f715c411407c413b1d84e