On Wed, Feb 25, 2015 at 10:49 AM, Ted Ross <tr...@redhat.com> wrote:

> Would it be safe to assume that any operations on driver->io are not
> thread safe?
>
> Dispatch is a multi-threaded application.  It looks to me as though
> io->error is a resource shared across the threads in an unsafe way.
>

Interesting... so this is what the docs say:

/**
 * A ::pn_io_t manages IO for a group of pn_socket_t handles.  A
 * pn_io_t object may have zero or one pn_selector_t selectors
 * associated with it (see ::pn_io_selector()).  If one is associated,
 * all the pn_socket_t handles managed by a pn_io_t must use that
 * pn_selector_t instance.
 *
 * The pn_io_t interface is single-threaded. All methods are intended
 * to be used by one thread at a time, except that multiple threads
 * may use:
 *
 *   ::pn_write()
 *   ::pn_send()
 *   ::pn_recv()
 *   ::pn_close()
 *   ::pn_selector_select()
 *
 * provided at most one thread is calling ::pn_selector_select() and
 * the other threads are operating on separate pn_socket_t handles.
 */

I think this has been somewhat modified by the constraints from the windows
implementation, and I'm not sure I understand completely what the
constraints are there, or entirely what is being described above, but on
the posix front, the pn_io_t is little more than just a holder for an error
slot, and you should have one of these per thread. It shouldn't be a
problem to use send/recv/etc from multiple threads though so long as you
pass in the pn_io_t from the current thread.

--Rafael

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