libmemcached "protocol error" and "Server sent data for key not in request"

[christopher at baus.net]

> Ah, this is the same issue related Alermo's problems in a different
> thread.
> And I think I have a solution, at least to the delay issue:
>
> in memcached in set_cork(), change it to:
> void set_cork() (conn *c, int val) {
>    if (c->is_corked == val) return;
>    c->is_corked = val;
> #ifdef TCP_NOPUSH
>    setsockopt(c->sfd, IPPROTO_TCP, TCP_NOPUSH, &val, sizeof(val));
>    val!=val;
>    setsockopt(c->sfd, IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val));
> #endif
> }
>

I think you mean

val ~= val;

> And I don't think it will break compatability with Linux.

Not sure.  The manual says TCP_CORK is not compatible with TCP_NODELAY.

http://www.rt.com/man/tcp.4.html

I think it would be easier to read if TCP_NOPUSH wasn't redefined. 
Corking is abstracted here anyway.  Might as well put all the platform
specific stuff was in this function.

For instance:

void set_cork() (conn *c, int val) {
   if (c->is_corked == val) return;
   c->is_corked = val;
#if defined(TCP_NOPUSH)
   setsockopt(c->sfd, IPPROTO_TCP, TCP_NOPUSH, &val, sizeof(val));
   val ~= val;
   setsockopt(c->sfd, IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val));
#endif
#if defined(TCP_CORK) && !defined(TCP_NOPUSH)
   setsockopt(c->sfd, IPPROTO_TCP, TCP_CORK, &val, sizeof(val));
#endif
}