We're not actually using it in production right now because it doesn't
shut its sockets down cleanly enough. This is a better option than
reverting the functionality or keeping production downgraded until
we sort out a handler that cleanly closes the sockets.
This makes it easier for the tests (and supervisor) to guarantee to be
able to connect to the server socket.
Also this patch moves freeing the mirror supervisor into the server
thread.
Changing behaviour so that instead of rebinding after a successful
migration and continuing as an ordinary server, we simply quit with a
0 exit code and let our caller restart us as a server if they want to.
This means that everything in listen.c, listen.h, and anything making
reference to a rebind address is unneeded.
Now that we have 3 mutexes lying around, it's important that we check
and free these if necessary if error() is called in any thread that can
hold them. To do this, we now have flexthread.c, which defines a
flexthread_mutex struct. This is a wrapper around a pthread_mutex_t and
a pthread_t. The idea is that in the error handler, the thread can
check whether it holds the mutex and can free it if and only if it does.
This is important because pthread fast mutexes can be freed by *any*
thread, not just the thread which holds them.
Note: it is only ever safe for a thread to check if it holds the mutex
itself. It is *never* safe to check if another thread holds a mutex
without first locking that mutex, which makes the whole operation rather
pointless.
trouble and into predictable cleanup functions (one for each of serve,
client & control contexts). We use 'fatal' to mean 'kill the thread' and
'error' to mean 'don't kill the thread', assuming some recovery action,
except I don't use error anywhere yet.
If you compile with:
DEBUG=true rake build
then all the commands get a --debug flag as an option which will make
the server dump crazy amounts of data to stderr.
All parameters now have switches. The one gotcha is the parameter which
was overloaded - s_length_or_filename to params_readwrite - is only
pretending to be a length at the moment. If you pass a filename it'll
still work, but the help messages don't mention that. I'll split the
parameter into two in a later commit.
