• copy from https://svn.apache.org/repos/asf/httpd/httpd/trunk
• includes proposed backport patch for Apache httpd 2.4.17
  • improved https:// throughput
  • vastly improved http:// throughput
  • several stability and logging improvements
  • connection reuse: virtual hosts that have exactly the same TLS setup
    (certificates, protocol, ciphers and all) allow using a single HTTP/2
    connection.
  • h2c: first HTTP/1.1 request on a connection will announce additionally
    available and more preferred protocols in the Upgrade response
    header.
  • H2Direct is by default on for cleartext connections where h2c is an
    allowed protocol. Or, the other way around, it is always disabled unless
    h2/h2c is configured.
  • TLS handshake is triggered earlier, allowing all connection hooks which
    register behind mod_ssl to see negotiated values.
  • new experimental directives H2TLSWarmUpSize and H2TLSCoolDownSecs
    that specify how TLS record sizes should used during the lifetime of a
    connection.
    • H2TLSWarmUpSize: amount of bytes to send in small (~1300 bytes) chunks,
      so that packets fit inside a single MTU. After this many bytes have
      been sent, data is written with max size of 16 KB when possible.
    • H2TLSCoolDownSecs: number of idle seconds to pass before a warmed
      up TLS connection falls back to small chunks again.
      Set both to 0 to always write max chunks. Defaults are 1 MB and 1 second.
  • HTTP/2 priorities are now respected when scheduling streams for handling.
    This effects which queued task is handled first whenever a worker becomes
    available.
  • New directive H2ModernTLSOnly on|off that checks connections for
    TLS protocol version and negotiated ciphers, so that HTTP/2 connections
    only happen on modern TLS and none of the ciphers in the black
    list from RFC 7540 are used.
  • 'HTTP/2.0' is written in log files when requests are served via mod_http2.
• updated test cases from Apache tests
• configure now builds the sandbox by default, too many user problems
  otherwise