[PATCH] Comm::Connection and friends

I've already split out what I can from the cleanup branch and submitted
separately. This patch consists of the remaining changes which are hard
to separate.

In general overview:
  The premise underlying this whole patch is that instead of copying and
re-copying and re-lookups for the FD related data we can take the
ConnectionDetail class which is generated to store a few bits of IP
information about newly accept()'d connections and make it persist
across the whole of Squid.

  It has been renamed from ConnectionDetails to Comm::Connection and has
absorbed a few FD data fields from other classes long the code paths.
Its scope is to hold an FD (or potential FD) plus meta data.

Comm::Connection are valid before, during and after the period when
their particular FD is open. The meta data may be used beforehand to
setup the FD (in the case of peer FDs), and it may remain in use after
FD closure until logging or all linked job and call objects have
detected the closure and terminated. A global function
Comm::IsConnOpen() may be used on the pointer objects to detect whether
they point at an active connection.

  Most of the patch is simple parameter changes to functions and methods
to pass a "cont Comm::ConnectionPointer &" instead of an "int FD". Along
with class FD fields being converted to these object pointers.

In order to support this alteration there have been behavioural changes to:

  the socket accept() Job
   Comm::TcpAcceptor altered to spawn Comm::Connection objects and to
operate with one controlling their active/closed state.

  FTP data channel handling Calls.
   efficiency improvements making use of Comm::Connection as a feedback
channel between TcpAcceptor and FtpStateData to cancel the listening
Job. Most of the underlying logic change is already in trunk to use the
Subscription API.

  Peer selection
   updated to spawn a set of Comm::Connection objects. To do this it is
updated to determine *all* peers including DIRECT ones. Doing the DNS
lookup instead of leaving it to comm_connect() on the other side of
FwdState. It also absorbs the outgoing address selection from FwdState
and can now specify details of local+remote ends of an outgoing TCP link.

  Forwarding
   updated to handle the new outputs from peer selection and to open
sequentially.

  pconn handling
    updated to use destination IP/port and hold a Comm::Connection
instead of domain name indexing an FD. This allows us to maintain idle
pools and re-use FD more efficiently with virtual-hosted servers. Along
with maintaining certainty that the pconn selected actually goes to the
exact destination IP:port needed by forwarding.
  (unchanged since it was audited individually earlier)

  comm layer outgoing connections
   now have a control job Comm::ConnOpener to do this. Due to the peer
selection and forwarding changes this is a much simpler operation.
  (unchanged since it was audited individually earlier)

  http / tunnel / gopher / whois / ftp
   updated to receive a server and client Comm::Connection object from
forwarding. To operate on those until they close or are finished with.
  (they are a step or two away from being fully polished independent
async jobs, I consider that outside this patch scope).

  SNMP / ICP / HTCP / DNS port listeners
   updated to work with Comm::Connection holding their listening socket
meta data. This is a side-effect of the ICP and Comm read/write/timeout
changes.

This patch closes the following bugs:
   http://bugs.squid-cache.org/show_bug.cgi?id=2561
   http://bugs.squid-cache.org/show_bug.cgi?id=3050
   http://bugs.squid-cache.org/show_bug.cgi?id=3177

By passing FD meta data as Comm::Connection it forms the groundwork to
also close these bugs quite easily:
   http://bugs.squid-cache.org/show_bug.cgi?id=2279
   http://bugs.squid-cache.org/show_bug.cgi?id=692
   http://bugs.squid-cache.org/show_bug.cgi?id=2558

I believe these are also fixed or nearly so, but have not tested. They
fall into one of the two categories above:
  http://bugs.squid-cache.org/show_bug.cgi?id=3108
  http://bugs.squid-cache.org/show_bug.cgi?id=3045

Amos

-- 
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