diff --git a/lib/nghttp2_stream.c b/lib/nghttp2_stream.c index 3e848d8e..70325bc3 100644 --- a/lib/nghttp2_stream.c +++ b/lib/nghttp2_stream.c @@ -30,14 +30,32 @@ #include "nghttp2_session.h" #include "nghttp2_helper.h" +/* Maximum distance between any two stream's cycle in the same + prirority queue. Imagine stream A's cycle is A, and stream B's + cycle is B, and A < B. The cycle is unsigned 32 bit integer, it + may get overflow. Because of how we calculate the next cycle + value, if B - A is less than or equals to + NGHTTP2_MAX_CYCLE_DISTANCE, A and B are in the same scale, in other + words, B is really greater than or equal to A. Otherwise, A is a + result of overflow, and it is actually A > B if we consider that + fact. */ +#define NGHTTP2_MAX_CYCLE_DISTANCE (16384 * 256 + 255) + static int stream_less(const void *lhsx, const void *rhsx) { const nghttp2_stream *lhs, *rhs; lhs = nghttp2_struct_of(lhsx, nghttp2_stream, pq_entry); rhs = nghttp2_struct_of(rhsx, nghttp2_stream, pq_entry); - return lhs->cycle < rhs->cycle || - (lhs->cycle == rhs->cycle && lhs->seq < rhs->seq); + if (lhs->cycle == rhs->cycle) { + return lhs->seq < rhs->seq; + } + + if (lhs->cycle < rhs->cycle) { + return rhs->cycle - lhs->cycle <= NGHTTP2_MAX_CYCLE_DISTANCE; + } + + return lhs->cycle - rhs->cycle > NGHTTP2_MAX_CYCLE_DISTANCE; } void nghttp2_stream_init(nghttp2_stream *stream, int32_t stream_id, @@ -116,14 +134,14 @@ static int stream_subtree_active(nghttp2_stream *stream) { /* * Returns next cycle for |stream|. */ -static void stream_next_cycle(nghttp2_stream *stream, uint64_t last_cycle) { - size_t penalty; +static void stream_next_cycle(nghttp2_stream *stream, uint32_t last_cycle) { + uint32_t penalty; - penalty = - stream->last_writelen * NGHTTP2_MAX_WEIGHT + stream->pending_penalty; + penalty = (uint32_t)stream->last_writelen * NGHTTP2_MAX_WEIGHT + + stream->pending_penalty; stream->cycle = last_cycle + penalty / (uint32_t)stream->weight; - stream->pending_penalty = (uint32_t)(penalty % (uint32_t)stream->weight); + stream->pending_penalty = penalty % (uint32_t)stream->weight; } static int stream_obq_push(nghttp2_stream *dep_stream, nghttp2_stream *stream) { @@ -229,9 +247,9 @@ void nghttp2_stream_reschedule(nghttp2_stream *stream) { void nghttp2_stream_change_weight(nghttp2_stream *stream, int32_t weight) { nghttp2_stream *dep_stream; - uint64_t last_cycle; + uint32_t last_cycle; int32_t old_weight; - size_t wlen_penalty; + uint32_t wlen_penalty; if (stream->weight == weight) { return; @@ -254,7 +272,7 @@ void nghttp2_stream_change_weight(nghttp2_stream *stream, int32_t weight) { nghttp2_pq_remove(&dep_stream->obq, &stream->pq_entry); - wlen_penalty = stream->last_writelen * NGHTTP2_MAX_WEIGHT; + wlen_penalty = (uint32_t)stream->last_writelen * NGHTTP2_MAX_WEIGHT; /* Compute old stream->pending_penalty we used to calculate stream->cycle */ @@ -270,7 +288,9 @@ void nghttp2_stream_change_weight(nghttp2_stream *stream, int32_t weight) { place */ stream_next_cycle(stream, last_cycle); - if (stream->cycle < dep_stream->descendant_last_cycle) { + if (stream->cycle < dep_stream->descendant_last_cycle && + (dep_stream->descendant_last_cycle - stream->cycle) <= + NGHTTP2_MAX_CYCLE_DISTANCE) { stream->cycle = dep_stream->descendant_last_cycle; } diff --git a/lib/nghttp2_stream.h b/lib/nghttp2_stream.h index b5d07592..da0e5d53 100644 --- a/lib/nghttp2_stream.h +++ b/lib/nghttp2_stream.h @@ -147,9 +147,9 @@ struct nghttp2_stream { /* Received body so far */ int64_t recv_content_length; /* Base last_cycle for direct descendent streams. */ - uint64_t descendant_last_cycle; + uint32_t descendant_last_cycle; /* Next scheduled time to sent item */ - uint64_t cycle; + uint32_t cycle; /* Next seq used for direct descendant streams */ uint64_t descendant_next_seq; /* Secondary key for prioritization to break a tie for cycle. This