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QUIC QSM: Stream garbage collection

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This allows QUIC_STREAM objects to be deleted when they are no longer
needed.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20765)
This commit is contained in:
Hugo Landau 2023-04-18 19:30:56 +01:00
parent 9cacba434b
commit 0847e63ee5
5 changed files with 210 additions and 7 deletions
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6
include/internal/quic_stream.h
View File

@ -253,6 +253,12 @@ void ossl_quic_sstream_fin(QUIC_SSTREAM *qss);
*/
int ossl_quic_sstream_get_final_size(QUIC_SSTREAM *qss, uint64_t *final_size);
/*
* Returns 1 iff all bytes (and any FIN, if any) which have been appended to the
* QUIC_SSTREAM so far, and any FIN (if any), have been both sent and acked.
*/
int ossl_quic_sstream_is_totally_acked(QUIC_SSTREAM *qss);
/*
* Resizes the internal ring buffer. All stream data is preserved safely.
*

119
include/internal/quic_stream_map.h
View File

@ -37,6 +37,7 @@ struct quic_stream_list_node_st {
struct quic_stream_st {
QUIC_STREAM_LIST_NODE active_node; /* for use by QUIC_STREAM_MAP */
QUIC_STREAM_LIST_NODE accept_node; /* accept queue of remotely-created streams */
QUIC_STREAM_LIST_NODE ready_for_gc_node; /* queue of streams now ready for GC */
/* Temporary link used by TXP. */
QUIC_STREAM *txp_next;
@ -119,8 +120,117 @@ struct quic_stream_st {
/* A FIN has been retired from the rstream buffer. */
unsigned int recv_fin_retired : 1;
/* The stream's XSO has been deleted. Pending GC. */
/*
* The stream's XSO has been deleted. Pending GC.
*
* Here is how stream deletion works:
*
* - A QUIC_STREAM cannot be deleted until it is neither in the accept
* queue nor has an associated XSO. This condition occurs when and only
* when deleted is true.
*
* - Once there is the case (i.e., no user-facing API object exposing the
* stream), we can delete the stream once we determine that all of our
* protocol obligations requiring us to keep the QUIC_STREAM around have
* been met.
*
* The following frames relate to the streams layer for a specific
* stream:
*
* STREAM
*
* RX Obligations:
* Ignore for a deleted stream.
*
* (This is different from our obligation for a
* locally-initiated stream ID we have not created yet,
* which we must treat as a protocol error. This can be
* distinguished via a simple monotonic counter.)
*
* TX Obligations:
* None, once we've decided to (someday) delete the stream.
*
* STOP_SENDING
*
* We cannot delete the stream until we have finished informing
* the peer that we are not going to be listening to it
* anymore.
*
* RX Obligations:
* When we delete a stream we must have already had a FIN
* or RESET_STREAM we transmitted acknowledged by the peer.
* Thus we can ignore STOP_SENDING frames for deleted
* streams (if they occur, they are probably just
* retransmissions).
*
* TX Obligations:
* _Acknowledged_ receipt of a STOP_SENDING frame by the
* peer (unless the peer's send part has already FIN'd).
*
* RESET_STREAM
*
* We cannot delete the stream until we have finished informing
* the peer that we are not going to be transmitting on it
* anymore.
*
* RX Obligations:
* This indicates the peer is not going to send any more
* data on the stream. We don't need to care about this
* since once a stream is marked for deletion we don't care
* about any data it does send. We can ignore this for
* deleted streams. The important criterion is that the
* peer has been successfully delivered our STOP_SENDING
* frame.
*
* TX Obligations:
* _Acknowledged_ receipt of a RESET_STREAM frame or FIN by
* the peer.
*
* MAX_STREAM_DATA
*
* RX Obligations:
* Ignore. Since we are not going to be sending any more
* data on a stream once it has been marked for deletion,
* we don't need to care about flow control information.
*
* TX Obligations:
* None.
*
* In other words, our protocol obligation is simply:
*
* - either:
* - the peer has acknowledged receipt of a STOP_SENDING frame sent
* by us; -or-
* - we have received a FIN and all preceding segments from the peer
*
* [NOTE: The actual criterion required here is simply 'we have
* received a FIN from the peer'. However, due to reordering and
* retransmissions we might subsequently receive non-FIN segments
* out of order. The FIN means we know the peer will stop
* transmitting on the stream at *some* point, but by sending
* STOP_SENDING we can avoid these needless retransmissions we
* will just ignore anyway. In actuality we could just handle all
* cases by sending a STOP_SENDING. The strategy we choose is to
* only avoid sending a STOP_SENDING and rely on a received FIN
* when we have received all preceding data, as this makes it
* reasonably certain no benefit would be gained by sending
* STOP_SENDING.]
*
* TODO(QUIC): Implement the latter case (currently we just
* always do STOP_SENDING).
*
* and;
*
* - we have drained our send stream (for a finished send stream)
* and got acknowledgement all parts of it including the FIN, or
* sent a RESET_STREAM frame and got acknowledgement of that frame.
*
* Once these conditions are met, we can GC the QUIC_STREAM.
*
*/
unsigned int deleted : 1;
/* Set to 1 once the above conditions are actually met. */
unsigned int ready_for_gc : 1;
};
/*
@ -138,6 +248,7 @@ typedef struct quic_stream_map_st {
LHASH_OF(QUIC_STREAM) *map;
QUIC_STREAM_LIST_NODE active_list;
QUIC_STREAM_LIST_NODE accept_list;
QUIC_STREAM_LIST_NODE ready_for_gc_list;
size_t rr_stepping, rr_counter, num_accept;
QUIC_STREAM *rr_cur;
uint64_t (*get_stream_limit_cb)(int uni, void *arg);
@ -287,6 +398,12 @@ void ossl_quic_stream_map_remove_from_accept_queue(QUIC_STREAM_MAP *qsm,
/* Returns the length of the accept queue. */
size_t ossl_quic_stream_map_get_accept_queue_len(QUIC_STREAM_MAP *qsm);
/*
* Delete streams ready for GC. Pointers to those QUIC_STREAM objects become
* invalid.
*/
void ossl_quic_stream_map_gc(QUIC_STREAM_MAP *qsm);
/*
* QUIC Stream Iterator
* ====================

3
ssl/quic/quic_channel.c
View File

@ -1372,6 +1372,9 @@ static void ch_tick(QUIC_TICK_RESULT *res, void *arg, uint32_t flags)
/* Write any data to the network due to be sent. */
ch_tx(ch);
/* Do stream GC. */
ossl_quic_stream_map_gc(&ch->qsm);
/* Determine the time at which we should next be ticked. */
res->tick_deadline = ch_determine_next_tick_deadline(ch);

21
ssl/quic/quic_sstream.c
View File

@ -372,6 +372,27 @@ size_t ossl_quic_sstream_get_buffer_avail(QUIC_SSTREAM *qss)
return ring_buf_avail(&qss->ring_buf);
}
int ossl_quic_sstream_is_totally_acked(QUIC_SSTREAM *qss)
{
UINT_RANGE r;
uint64_t cur_size;
if ((qss->have_final_size && !qss->acked_final_size)
|| ossl_list_uint_set_num(&qss->acked_set) != 1)
return 0;
r = ossl_list_uint_set_head(&qss->acked_set)->range;
cur_size = qss->ring_buf.head_offset;
/*
* The invariants of UINT_SET guarantee a single list element if we have a
* single contiguous range, which is what we should have if everything has
* been acked.
*/
assert(r.end + 1 <= cur_size);
return r.start == 0 && r.end + 1 == cur_size;
}
void ossl_quic_sstream_adjust_iov(size_t len,
OSSL_QTX_IOVEC *iov,
size_t num_iov)

68
ssl/quic/quic_stream_map.c
View File

@ -53,12 +53,16 @@ static QUIC_STREAM *list_next(QUIC_STREAM_LIST_NODE *l, QUIC_STREAM_LIST_NODE *n
return (QUIC_STREAM *)(((char *)n) - off);
}
#define active_next(l, s) list_next((l), &(s)->active_node, \
offsetof(QUIC_STREAM, active_node))
#define accept_next(l, s) list_next((l), &(s)->accept_node, \
offsetof(QUIC_STREAM, accept_node))
#define accept_head(l) list_next((l), (l), \
offsetof(QUIC_STREAM, accept_node))
#define active_next(l, s) list_next((l), &(s)->active_node, \
offsetof(QUIC_STREAM, active_node))
#define accept_next(l, s) list_next((l), &(s)->accept_node, \
offsetof(QUIC_STREAM, accept_node))
#define ready_for_gc_next(l, s) list_next((l), &(s)->ready_for_gc_node, \
offsetof(QUIC_STREAM, ready_for_gc_node))
#define accept_head(l) list_next((l), (l), \
offsetof(QUIC_STREAM, accept_node))
#define ready_for_gc_head(l) list_next((l), (l), \
offsetof(QUIC_STREAM, ready_for_gc_node))
static unsigned long hash_stream(const QUIC_STREAM *s)
{
@ -83,6 +87,8 @@ int ossl_quic_stream_map_init(QUIC_STREAM_MAP *qsm,
qsm->map = lh_QUIC_STREAM_new(hash_stream, cmp_stream);
qsm->active_list.prev = qsm->active_list.next = &qsm->active_list;
qsm->accept_list.prev = qsm->accept_list.next = &qsm->accept_list;
qsm->ready_for_gc_list.prev = qsm->ready_for_gc_list.next
= &qsm->ready_for_gc_list;
qsm->rr_stepping = 1;
qsm->rr_counter = 0;
qsm->rr_cur = NULL;
@ -145,6 +151,13 @@ void ossl_quic_stream_map_release(QUIC_STREAM_MAP *qsm, QUIC_STREAM *stream)
if (stream == NULL)
return;
if (stream->active_node.next != NULL)
list_remove(&qsm->active_list, &stream->active_node);
if (stream->accept_node.next != NULL)
list_remove(&qsm->accept_list, &stream->accept_node);
if (stream->ready_for_gc_node.next != NULL)
list_remove(&qsm->ready_for_gc_list, &stream->ready_for_gc_node);
ossl_quic_sstream_free(stream->sstream);
stream->sstream = NULL;
@ -228,6 +241,31 @@ static int stream_has_data_to_send(QUIC_STREAM *s)
return (shdr.is_fin && shdr.len == 0) || shdr.offset < fc_limit;
}
static int qsm_ready_for_gc(QUIC_STREAM_MAP *qsm, QUIC_STREAM *qs)
{
int recv_stream_fully_drained = 0; /* TODO(QUIC): Optimisation */
/*
* If sstream has no FIN, we auto-reset it at marked-for-deletion time, so
* we don't need to worry about that here.
*/
assert(!qs->deleted
|| qs->sstream == NULL
|| qs->reset_stream
|| ossl_quic_sstream_get_final_size(qs, NULL));
return
qs->deleted
&& (qs->rstream == NULL
|| recv_stream_fully_drained
|| qs->acked_stop_sending)
&& (qs->sstream == NULL
|| (!qs->reset_stream
&& ossl_quic_sstream_is_totally_acked(qs->sstream))
|| (qs->reset_stream
&& qs->acked_reset_stream));
}
void ossl_quic_stream_map_update_state(QUIC_STREAM_MAP *qsm, QUIC_STREAM *s)
{
int should_be_active, allowed_by_stream_limit = 1;
@ -243,8 +281,15 @@ void ossl_quic_stream_map_update_state(QUIC_STREAM_MAP *qsm, QUIC_STREAM *s)
allowed_by_stream_limit = (stream_ordinal < stream_limit);
}
if (!s->ready_for_gc) {
s->ready_for_gc = qsm_ready_for_gc(qsm, s);
if (s->ready_for_gc)
list_insert_tail(&qsm->ready_for_gc_list, &s->ready_for_gc_node);
}
should_be_active
= allowed_by_stream_limit
&& !s->ready_for_gc
&& ((!s->peer_reset_stream && s->rstream != NULL
&& (s->want_max_stream_data
|| ossl_quic_rxfc_has_cwm_changed(&s->rxfc, 0)))
@ -325,6 +370,17 @@ size_t ossl_quic_stream_map_get_accept_queue_len(QUIC_STREAM_MAP *qsm)
return qsm->num_accept;
}
void ossl_quic_stream_map_gc(QUIC_STREAM_MAP *qsm)
{
QUIC_STREAM *qs, *qsn;
for (qs = ready_for_gc_head(&qsm->ready_for_gc_list); qs != NULL; qs = qsn) {
qsn = ready_for_gc_next(&qsm->ready_for_gc_list, qs);
ossl_quic_stream_map_release(qsm, qs);
}
}
/*
* QUIC Stream Iterator
* ====================