BUG/MEDIUM: pollers: Use a global list for fd shared between threads.
With the old model, any fd shared by multiple threads, such as listeners
or dns sockets, would only be updated on one threads, so that could lead
to missed event, or spurious wakeups.
To avoid this, add a global list for fd that are shared, using the same
implementation as the fd cache, and only remove entries from this list
when every thread as updated its poller.
[wt: this will need to be backported to 1.8 but differently so this patch
must not be backported as-is]
diff --git a/include/types/fd.h b/include/types/fd.h
index 0902e7f..aa18ebe 100644
--- a/include/types/fd.h
+++ b/include/types/fd.h
@@ -117,6 +117,7 @@
unsigned long polled_mask; /* mask of thread IDs currently polling this fd */
unsigned long update_mask; /* mask of thread IDs having an update for fd */
struct fdlist_entry cache; /* Entry in the fdcache */
+ struct fdlist_entry update; /* Entry in the global update list */
void (*iocb)(int fd); /* I/O handler */
void *owner; /* the connection or listener associated with this fd, NULL if closed */
unsigned char state; /* FD state for read and write directions (2*3 bits) */