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Update descendant_last_cycle on nghttp2_stream_next_outbound_item 

Previously, we updated descendant_last_cycle in
nghttp2_stream_reschedule, which is called after non-zero DATA frame.
But this was not optimal since we still had old descendant_last_cycle,
and new stream was scheduled based on it.  Now descendant_last_cycle
is updated in nghttp2_stream_next_outbound_item, which is called when
stream with highest priority is selected from queue.  And new stream
is scheduled based on it.  This commit also removes 0-reset of
descendant_last_cycle and cycle in nghttp2_stream_reschedule.  This
could help making them lower, so that they are not overflow.  But
there is a pattern that it doesn't work, and we are not sure they are
really useful at this moment.
This commit is contained in:
Tatsuhiro Tsujikawa 2015-12-07 22:43:15 +09:00
parent 7ca9ead36b
commit 72f815d535
2 changed files with 13 additions and 18 deletions
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28
lib/nghttp2_stream.c
View File

@ -207,25 +207,13 @@ void nghttp2_stream_reschedule(nghttp2_stream *stream) {
dep_stream = stream->dep_prev;
for (; dep_stream; stream = dep_stream, dep_stream = dep_stream->dep_prev) {
if (nghttp2_pq_size(&dep_stream->obq) == 1) {
dep_stream->descendant_last_cycle = 0;
stream->cycle = 0;
} else {
/* We update descendant_last_cycle here, and we don't do it when
no data is written for stream. This effectively means that
we treat these streams as if they are not scheduled at all.
This does not cause disruption in scheduling machinery. It
just makes new streams scheduled a bit early. */
dep_stream->descendant_last_cycle = stream->cycle;
nghttp2_pq_remove(&dep_stream->obq, &stream->pq_entry);
nghttp2_pq_remove(&dep_stream->obq, &stream->pq_entry);
stream->cycle =
stream_next_cycle(stream, dep_stream->descendant_last_cycle);
stream->seq = dep_stream->descendant_next_seq++;
stream->cycle =
stream_next_cycle(stream, dep_stream->descendant_last_cycle);
stream->seq = dep_stream->descendant_next_seq++;
nghttp2_pq_push(&dep_stream->obq, &stream->pq_entry);
}
nghttp2_pq_push(&dep_stream->obq, &stream->pq_entry);
DEBUGF(fprintf(stderr, "stream: stream=%d obq resched cycle=%ld\n",
stream->stream_id, stream->cycle));
@ -861,9 +849,15 @@ int nghttp2_stream_in_dep_tree(nghttp2_stream *stream) {
nghttp2_outbound_item *
nghttp2_stream_next_outbound_item(nghttp2_stream *stream) {
nghttp2_pq_entry *ent;
nghttp2_stream *si;
for (;;) {
if (stream_active(stream)) {
/* Update ascendant's descendant_last_cycle here, so that we can
assure that new stream is scheduled based on it. */
for (si = stream; si->dep_prev; si = si->dep_prev) {
si->dep_prev->descendant_last_cycle = si->cycle;
}
return stream->item;
}
ent = nghttp2_pq_top(&stream->obq);

3
lib/nghttp2_stream.h
View File

@ -419,7 +419,8 @@ int nghttp2_stream_in_dep_tree(nghttp2_stream *stream);
void nghttp2_stream_reschedule(nghttp2_stream *stream);
/*
* Returns a stream which has highest priority.
* Returns a stream which has highest priority, updating
* descendant_last_cycle of selected stream's ancestors.
*/
nghttp2_outbound_item *
nghttp2_stream_next_outbound_item(nghttp2_stream *stream);