mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-24 01:00:37 +00:00
poll: make timer polls lockfree
Make sure we don't take a mutex in the normal code path of the timer poll.
This commit is contained in:
Wim Taymans
parent
e0f15e666a
commit
73ee14302f
1 changed files with 64 additions and 33 deletions
|
|
@ -147,9 +147,13 @@ struct _GstPoll
|
|||
GstPollMode mode;
|
||||
|
||||
GMutex *lock;
|
||||
|
||||
/* array of fds, always written to and read from with lock */
|
||||
GArray *fds;
|
||||
/* array of active fds, only written to from the waiting thread with the
|
||||
* lock and read from with the lock or without the lock from the waiting
|
||||
* thread */
|
||||
GArray *active_fds;
|
||||
|
||||
#ifndef G_OS_WIN32
|
||||
GstPollFD control_read_fd;
|
||||
GstPollFD control_write_fd;
|
||||
|
|
@ -163,12 +167,23 @@ struct _GstPoll
|
|||
|
||||
gboolean controllable;
|
||||
gboolean new_controllable;
|
||||
guint waiting;
|
||||
guint control_pending;
|
||||
gboolean flushing;
|
||||
volatile gint waiting;
|
||||
volatile gint control_pending;
|
||||
volatile gint flushing;
|
||||
gboolean timer;
|
||||
volatile gint rebuild;
|
||||
};
|
||||
|
||||
#define IS_FLUSHING(s) (g_atomic_int_get(&(s)->flushing))
|
||||
#define SET_FLUSHING(s,val) (g_atomic_int_set(&(s)->flushing, (val)))
|
||||
|
||||
#define INC_WAITING(s) (g_atomic_int_exchange_and_add(&(s)->waiting, 1))
|
||||
#define DEC_WAITING(s) (g_atomic_int_exchange_and_add(&(s)->waiting, -1))
|
||||
#define GET_WAITING(s) (g_atomic_int_get(&(s)->waiting))
|
||||
|
||||
#define TEST_REBUILD(s) (g_atomic_int_compare_and_exchange(&(s)->rebuild, 1, 0))
|
||||
#define MARK_REBUILD(s) (g_atomic_int_set(&(s)->rebuild, 1))
|
||||
|
||||
static gint
|
||||
find_index (GArray * array, GstPollFD * fd)
|
||||
{
|
||||
|
|
@ -217,14 +232,22 @@ selectable_fds (const GstPoll * set)
|
|||
{
|
||||
guint i;
|
||||
|
||||
g_mutex_lock (set->lock);
|
||||
for (i = 0; i < set->fds->len; i++) {
|
||||
struct pollfd *pfd = &g_array_index (set->fds, struct pollfd, i);
|
||||
|
||||
if (pfd->fd >= FD_SETSIZE)
|
||||
return FALSE;
|
||||
goto too_many;
|
||||
}
|
||||
g_mutex_unlock (set->lock);
|
||||
|
||||
return TRUE;
|
||||
|
||||
too_many:
|
||||
{
|
||||
g_mutex_unlock (set->lock);
|
||||
return FALSE;
|
||||
}
|
||||
}
|
||||
|
||||
/* check if the timeout will convert to a timeout value used for poll()
|
||||
|
|
@ -643,6 +666,7 @@ gst_poll_add_fd_unlocked (GstPoll * set, GstPollFD * fd)
|
|||
|
||||
fd->idx = set->fds->len - 1;
|
||||
#endif
|
||||
MARK_REBUILD (set);
|
||||
} else {
|
||||
GST_WARNING ("%p: couldn't find fd !", set);
|
||||
}
|
||||
|
|
@ -718,6 +742,7 @@ gst_poll_remove_fd (GstPoll * set, GstPollFD * fd)
|
|||
|
||||
/* mark fd as removed by setting the index to -1 */
|
||||
fd->idx = -1;
|
||||
MARK_REBUILD (set);
|
||||
} else {
|
||||
GST_WARNING ("%p: couldn't find fd !", set);
|
||||
}
|
||||
|
|
@ -769,6 +794,7 @@ gst_poll_fd_ctl_write (GstPoll * set, GstPollFD * fd, gboolean active)
|
|||
gst_poll_update_winsock_event_mask (set, idx, FD_WRITE | FD_CONNECT,
|
||||
active);
|
||||
#endif
|
||||
MARK_REBUILD (set);
|
||||
} else {
|
||||
GST_WARNING ("%p: couldn't find fd !", set);
|
||||
}
|
||||
|
|
@ -799,6 +825,7 @@ gst_poll_fd_ctl_read_unlocked (GstPoll * set, GstPollFD * fd, gboolean active)
|
|||
#else
|
||||
gst_poll_update_winsock_event_mask (set, idx, FD_READ | FD_ACCEPT, active);
|
||||
#endif
|
||||
MARK_REBUILD (set);
|
||||
} else {
|
||||
GST_WARNING ("%p: couldn't find fd !", set);
|
||||
}
|
||||
|
|
@ -870,6 +897,7 @@ gst_poll_fd_ignored (GstPoll * set, GstPollFD * fd)
|
|||
WinsockFd *wfd = &g_array_index (set->fds, WinsockFd, idx);
|
||||
|
||||
wfd->ignored_event_mask = wfd->event_mask & (FD_READ | FD_WRITE);
|
||||
MARK_REBUILD (set);
|
||||
}
|
||||
|
||||
g_mutex_unlock (set->lock);
|
||||
|
|
@ -1132,25 +1160,27 @@ gint
|
|||
gst_poll_wait (GstPoll * set, GstClockTime timeout)
|
||||
{
|
||||
gboolean restarting;
|
||||
gboolean is_timer;
|
||||
int res;
|
||||
gint old_waiting;
|
||||
|
||||
g_return_val_if_fail (set != NULL, -1);
|
||||
|
||||
g_mutex_lock (set->lock);
|
||||
|
||||
GST_DEBUG ("timeout :%" GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
|
||||
|
||||
is_timer = set->timer;
|
||||
|
||||
/* add one more waiter */
|
||||
old_waiting = INC_WAITING (set);
|
||||
|
||||
/* we cannot wait from multiple threads unless we are a timer */
|
||||
if (G_UNLIKELY (set->waiting > 0 && !set->timer))
|
||||
if (G_UNLIKELY (old_waiting > 0 && !is_timer))
|
||||
goto already_waiting;
|
||||
|
||||
/* flushing, exit immediatly */
|
||||
if (G_UNLIKELY (set->flushing))
|
||||
if (G_UNLIKELY (IS_FLUSHING (set)))
|
||||
goto flushing;
|
||||
|
||||
/* add one more waiter */
|
||||
set->waiting++;
|
||||
|
||||
do {
|
||||
GstPollMode mode;
|
||||
|
||||
|
|
@ -1159,16 +1189,18 @@ gst_poll_wait (GstPoll * set, GstClockTime timeout)
|
|||
|
||||
mode = choose_mode (set, timeout);
|
||||
|
||||
if (TEST_REBUILD (set)) {
|
||||
g_mutex_lock (set->lock);
|
||||
#ifndef G_OS_WIN32
|
||||
g_array_set_size (set->active_fds, set->fds->len);
|
||||
memcpy (set->active_fds->data, set->fds->data,
|
||||
set->fds->len * sizeof (struct pollfd));
|
||||
g_array_set_size (set->active_fds, set->fds->len);
|
||||
memcpy (set->active_fds->data, set->fds->data,
|
||||
set->fds->len * sizeof (struct pollfd));
|
||||
#else
|
||||
if (!gst_poll_prepare_winsock_active_sets (set))
|
||||
goto winsock_error;
|
||||
if (!gst_poll_prepare_winsock_active_sets (set))
|
||||
goto winsock_error;
|
||||
#endif
|
||||
|
||||
g_mutex_unlock (set->lock);
|
||||
g_mutex_unlock (set->lock);
|
||||
}
|
||||
|
||||
switch (mode) {
|
||||
case GST_POLL_MODE_AUTO:
|
||||
|
|
@ -1316,15 +1348,16 @@ gst_poll_wait (GstPoll * set, GstClockTime timeout)
|
|||
}
|
||||
}
|
||||
|
||||
g_mutex_lock (set->lock);
|
||||
|
||||
if (!set->timer)
|
||||
if (!is_timer) {
|
||||
g_mutex_lock (set->lock);
|
||||
gst_poll_check_ctrl_commands (set, res, &restarting);
|
||||
g_mutex_unlock (set->lock);
|
||||
}
|
||||
|
||||
/* update the controllable state if needed */
|
||||
set->controllable = set->new_controllable;
|
||||
|
||||
if (G_UNLIKELY (set->flushing)) {
|
||||
if (G_UNLIKELY (IS_FLUSHING (set))) {
|
||||
/* we got woken up and we are flushing, we need to stop */
|
||||
errno = EBUSY;
|
||||
res = -1;
|
||||
|
|
@ -1332,30 +1365,28 @@ gst_poll_wait (GstPoll * set, GstClockTime timeout)
|
|||
}
|
||||
} while (G_UNLIKELY (restarting));
|
||||
|
||||
set->waiting--;
|
||||
|
||||
g_mutex_unlock (set->lock);
|
||||
DEC_WAITING (set);
|
||||
|
||||
return res;
|
||||
|
||||
/* ERRORS */
|
||||
already_waiting:
|
||||
{
|
||||
g_mutex_unlock (set->lock);
|
||||
DEC_WAITING (set);
|
||||
errno = EPERM;
|
||||
return -1;
|
||||
}
|
||||
flushing:
|
||||
{
|
||||
g_mutex_unlock (set->lock);
|
||||
DEC_WAITING (set);
|
||||
errno = EBUSY;
|
||||
return -1;
|
||||
}
|
||||
#ifdef G_OS_WIN32
|
||||
winsock_error:
|
||||
{
|
||||
set->waiting--;
|
||||
g_mutex_unlock (set->lock);
|
||||
DEC_WAITING (set);
|
||||
return -1;
|
||||
}
|
||||
#endif
|
||||
|
|
@ -1405,7 +1436,7 @@ gst_poll_set_controllable (GstPoll * set, gboolean controllable)
|
|||
|
||||
/* delay the change of the controllable state if we are waiting */
|
||||
set->new_controllable = controllable;
|
||||
if (set->waiting == 0)
|
||||
if (GET_WAITING (set) == 0)
|
||||
set->controllable = controllable;
|
||||
|
||||
g_mutex_unlock (set->lock);
|
||||
|
|
@ -1441,7 +1472,7 @@ gst_poll_restart (GstPoll * set)
|
|||
|
||||
g_mutex_lock (set->lock);
|
||||
|
||||
if (set->controllable && set->waiting > 0) {
|
||||
if (set->controllable && GET_WAITING (set) > 0) {
|
||||
#ifndef G_OS_WIN32
|
||||
gint result;
|
||||
|
||||
|
|
@ -1476,9 +1507,9 @@ gst_poll_set_flushing (GstPoll * set, gboolean flushing)
|
|||
g_mutex_lock (set->lock);
|
||||
|
||||
/* update the new state first */
|
||||
set->flushing = flushing;
|
||||
SET_FLUSHING (set, flushing);
|
||||
|
||||
if (flushing && set->controllable && set->waiting > 0) {
|
||||
if (flushing && set->controllable && GET_WAITING (set) > 0) {
|
||||
/* we are flushing, controllable and waiting, wake up the waiter. When we
|
||||
* stop the flushing operation we don't clear the wakeup fd here, this will
|
||||
* happen in the _wait() thread. */
|
||||
|
|
|
|||
Loading…
Reference in a new issue