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Hi Joel,
well I had not anticipated that it's common to have three threads
on a socket running, each doing their own task on it. The problems
stem from the third deleting thread, right? Reading + Writing seem
to be unproblematic as it stands?
Kind Regards,
Michael
Am 11.08.2015 um 16:38 schrieb Joel Cunningham:
LwIP has not had supported for full duplex sockets in any
release versions. On the master branch, there is some initial
support under the flag LWIP_NETCONN_FULLDUPLEX, but I think the
feature is pretty early in development. Here is the comment
from the opt.h, noting the alpha state of this:
/** LWIP_NETCONN_FULLDUPLEX==1: Enable code that allows reading
from one thread,
* writing from a 2nd thread and closing from a 3rd thread at
the same time.
* ATTENTION: This is currently really alpha! Some requirements:
* - LWIP_NETCONN_SEM_PER_THREAD==1 is required to use one
socket/netconn from
* multiple threads at once
* - sys_mbox_free() has to unblock receive tasks waiting on
recvmbox/acceptmbox
* and prevent a task pending on this during/after deletion
*/
#ifndef LWIP_NETCONN_FULLDUPLEX
#define LWIP_NETCONN_FULLDUPLEX 0
#endif
Joel
On Aug 10, 2015, at 05:08 PM, Michael Steinberg
<address@hidden> wrote:
Hello,
you make it sound like this was a limitation of
lwip... but if at all,
it would only be one of the berkeley socket API
emulation layer...
That being said, the socket API uses the netconn API,
which in turn uses
mailboxes for receiving packets from the lwip
core/driver. I cannot see
any additional locking operation on the path from recv
to
sys_mailbox_fetch, so I don't think a send would block
during a
receive... Socket state is touched though, one would
have to see, if
there's conflicting state overlap on the send and
receive paths...
In constrained environments, I would argue that
berkeley socket API is
not the weapon of choice anyways (actually I would
argue that for any
environment, hehe)
Kind Regards,
Michael
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