MEDIUM: stream-int: always call si_chk_rcv() when we make room in the buffer
Instead of clearing the SI_FL_WAIT_ROOM flag and losing the information
about the need from the producer to be woken up, we now call si_chk_rcv()
immediately. This is cheap to do and it could possibly be further improved
by only doing it when SI_FL_WAIT_ROOM was still set, though this will
require some extra auditing of the code paths.
The only remaining place where the flag was cleared without a call to
si_chk_rcv() is si_alloc_ibuf(), but since this one is called from a
receive path woken up from si_chk_rcv() or not having failed, the
clearing was not necessary anymore either.
And there was one place in stream_int_notify() where si_chk_rcv() was
called with SI_FL_WAIT_ROOM still explicitly set so this place was
adjusted in order to clear the flag prior to calling si_chk_rcv().
Now we don't have any situation where we randomly clear SI_FL_WAIT_ROOM
without trying to wake the other side up, nor where we call si_chk_rcv()
with the flag set, so this flag should accurately represent a failed
attempt at putting data into the buffer.
diff --git a/include/proto/stream_interface.h b/include/proto/stream_interface.h
index c0f7cda..2d3fe56 100644
--- a/include/proto/stream_interface.h
+++ b/include/proto/stream_interface.h
@@ -315,9 +315,8 @@
}
/* Try to allocate a buffer for the stream-int's input channel. It relies on
- * channel_alloc_buffer() for this so it abides by its rules. It returns 0 in
- * case of failure, non-zero otherwise. The stream-int's flag SI_FL_WAIT_ROOM
- * is cleared before trying. If no buffer are available, the requester,
+ * channel_alloc_buffer() for this so it abides by its rules. It returns 0 on
+ * failure, non-zero otherwise. If no buffer is available, the requester,
* represented by <wait> pointer, will be added in the list of objects waiting
* for an available buffer, and SI_FL_WAIT_ROOM will be set on the stream-int.
* The requester will be responsible for calling this function to try again
@@ -327,7 +326,6 @@
{
int ret;
- si->flags &= ~SI_FL_WAIT_ROOM;
ret = channel_alloc_buffer(si_ic(si), wait);
if (!ret)
si_cant_put(si);
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 3372fc2..b29cb2f 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -480,8 +480,10 @@
if (likely((oc->flags & (CF_SHUTW|CF_WRITE_PARTIAL|CF_DONT_READ)) == CF_WRITE_PARTIAL &&
channel_may_recv(oc) &&
- (si_opposite(si)->flags & SI_FL_WAIT_ROOM)))
+ (si_opposite(si)->flags & SI_FL_WAIT_ROOM))) {
+ si_opposite(si)->flags &= ~SI_FL_WAIT_ROOM;
si_chk_rcv(si_opposite(si));
+ }
}
/* Notify the other side when we've injected data into the IC that
@@ -513,8 +515,10 @@
/* check if the consumer has freed some space either in the
* buffer or in the pipe.
*/
- if (channel_may_recv(ic) && new_len < last_len)
+ if (channel_may_recv(ic) && new_len < last_len) {
si->flags &= ~SI_FL_WAIT_ROOM;
+ si_chk_rcv(si);
+ }
}
if (si->flags & SI_FL_WAIT_ROOM) {
@@ -561,7 +565,6 @@
struct stream_interface *si = cs->data;
struct channel *ic = si_ic(si);
struct channel *oc = si_oc(si);
- int wait_room = si->flags & SI_FL_WAIT_ROOM;
/* If we have data to send, try it now */
if (!channel_is_empty(oc) && !(si->wait_event.wait_reason & SUB_CAN_SEND))
@@ -597,10 +600,6 @@
stream_int_notify(si);
channel_release_buffer(ic, &(si_strm(si)->buffer_wait));
- /* Try to run again if we free'd some room in the process */
- if (wait_room && !(si->flags & SI_FL_WAIT_ROOM))
- tasklet_wakeup(si->wait_event.task);
-
return 0;
}
@@ -769,7 +768,7 @@
* have updated it if there has been a completed I/O.
*/
si->flags &= ~SI_FL_WAIT_ROOM;
- tasklet_wakeup(si->wait_event.task);
+ si_chk_rcv(si);
if (!(ic->flags & (CF_READ_NOEXP|CF_DONT_READ)) && !tick_isset(ic->rex))
ic->rex = tick_add_ifset(now_ms, ic->rto);
}