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MINOR: fd: make fd_clr_running() return the previous value instead

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It's an AND so it destroys information and due to this there's a call
place where we have to perform two reads to know the previous value
then to change it. With a fetch-and-and instead, in a single operation
we can know if the bit was previously present, which is more efficient.
This commit is contained in:
Willy Tarreau 2022-07-09 15:57:17 +02:00
parent a707d02657
commit d6e1987612
2 changed files with 5 additions and 6 deletions
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6
include/haproxy/fd.h
View File

@ -408,12 +408,12 @@ static inline ulong fd_get_running(int fd, uint desired_tgid)
return ret; return ret;
} }
/* remove tid_bit from the fd's running mask and returns the bits that remain /* remove tid_bit from the fd's running mask and returns the value before the
* after the atomic operation. * atomic operation, so that the caller can know if it was present.
*/ */
static inline long fd_clr_running(int fd) static inline long fd_clr_running(int fd)
{ {
return _HA_ATOMIC_AND_FETCH(&fdtab[fd].running_mask, ~ti->ltid_bit); return _HA_ATOMIC_FETCH_AND(&fdtab[fd].running_mask, ~ti->ltid_bit);
} }
/* Prepares <fd> for being polled on all permitted threads of this group ID /* Prepares <fd> for being polled on all permitted threads of this group ID

5
src/fd.c
View File

@ -378,7 +378,7 @@ void fd_delete(int fd)
HA_ATOMIC_OR(&fdtab[fd].running_mask, ti->ltid_bit); HA_ATOMIC_OR(&fdtab[fd].running_mask, ti->ltid_bit);
HA_ATOMIC_STORE(&fdtab[fd].thread_mask, 0); HA_ATOMIC_STORE(&fdtab[fd].thread_mask, 0);
if (fd_clr_running(fd) == 0) if (fd_clr_running(fd) == ti->ltid_bit)
_fd_delete_orphan(fd); _fd_delete_orphan(fd);
} }
@ -594,8 +594,7 @@ int fd_update_events(int fd, uint evts)
* This is detected by both thread_mask and running_mask being 0 after * This is detected by both thread_mask and running_mask being 0 after
* we remove ourselves last. * we remove ourselves last.
*/ */
if ((fdtab[fd].running_mask & ti->ltid_bit) && if (fd_clr_running(fd) == ti->ltid_bit && !fdtab[fd].thread_mask) {
fd_clr_running(fd) == 0 && !fdtab[fd].thread_mask) {
_fd_delete_orphan(fd); _fd_delete_orphan(fd);
return FD_UPDT_CLOSED; return FD_UPDT_CLOSED;
} }