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Fix I-frame retransmission quirks.

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Revamped the I-frame retransmission queue to better comply with Q.921:
Figure B.7/Q.921 (sheet 1 of 10) and Figure B.9/Q.921 (Sheet 5 of 5).  The
changes prevent retransmitting I-frames when the peer is busy (RNR) (Q.921
Section 5.6.5) and eliminate an unnecessary delay sending new I-frames
after an I-frame retransmission.

Related to JIRA LIBPRI-60


git-svn-id: https://origsvn.digium.com/svn/libpri/branches/1.4@2200 2fbb986a-6c06-0410-b554-c9c1f0a7f128
This commit is contained in:
Richard Mudgett 2011-02-14 23:33:56 +00:00
parent e01dce27b7
commit d1cac6352a
2 changed files with 93 additions and 74 deletions
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14
pri_q921.h
View File

@ -163,11 +163,17 @@ typedef union {
struct q921_header h; struct q921_header h;
} q921_h; } q921_h;
enum q921_tx_frame_status {
Q921_TX_FRAME_NEVER_SENT,
Q921_TX_FRAME_PUSHED_BACK,
Q921_TX_FRAME_SENT,
};
typedef struct q921_frame { typedef struct q921_frame {
struct q921_frame *next; /* Next in list */ struct q921_frame *next; /*!< Next in list */
int len; /* Length of header + body */ int len; /*!< Length of header + body */
int transmitted; /* Have we been transmitted */ enum q921_tx_frame_status status; /*!< Tx frame status */
q921_i h; q921_i h; /*!< Actual frame contents. */
} q921_frame; } q921_frame;
#define Q921_INC(j) (j) = (((j) + 1) % 128) #define Q921_INC(j) (j) = (((j) + 1) % 128)

151
q921.c
View File

@ -406,7 +406,7 @@ static int q921_ack_packet(struct q921_link *link, int num)
ctrl = link->ctrl; ctrl = link->ctrl;
for (prev = NULL, f = link->tx_queue; f; prev = f, f = f->next) { for (prev = NULL, f = link->tx_queue; f; prev = f, f = f->next) {
if (!f->transmitted) { if (f->status != Q921_TX_FRAME_SENT) {
break; break;
} }
if (f->h.n_s == num) { if (f->h.n_s == num) {
@ -421,7 +421,7 @@ static int q921_ack_packet(struct q921_link *link, int num)
"-- ACKing N(S)=%d, tx_queue head is N(S)=%d (-1 is empty, -2 is not transmitted)\n", "-- ACKing N(S)=%d, tx_queue head is N(S)=%d (-1 is empty, -2 is not transmitted)\n",
f->h.n_s, f->h.n_s,
link->tx_queue link->tx_queue
? link->tx_queue->transmitted ? link->tx_queue->status == Q921_TX_FRAME_SENT
? link->tx_queue->h.n_s ? link->tx_queue->h.n_s
: -2 : -2
: -1); : -1);
@ -464,22 +464,6 @@ static void reschedule_t203(struct q921_link *link)
} }
#endif #endif
#if 0
static int q921_unacked_iframes(struct q921_link *link)
{
struct q921_frame *f = link->tx_queue;
int cnt = 0;
while (f) {
if (f->transmitted)
cnt++;
f = f->next;
}
return cnt;
}
#endif
static void start_t203(struct q921_link *link) static void start_t203(struct q921_link *link)
{ {
struct pri *ctrl; struct pri *ctrl;
@ -642,8 +626,8 @@ static int q921_send_queued_iframes(struct q921_link *link)
ctrl = link->ctrl; ctrl = link->ctrl;
for (f = link->tx_queue; f; f = f->next) { for (f = link->tx_queue; f; f = f->next) {
if (!f->transmitted) { if (f->status != Q921_TX_FRAME_SENT) {
/* This frame has not been sent yet. */ /* This frame needs to be sent. */
break; break;
} }
} }
@ -652,12 +636,20 @@ static int q921_send_queued_iframes(struct q921_link *link)
return 0; return 0;
} }
if (link->peer_rx_busy if (link->peer_rx_busy) {
|| (link->v_s == Q921_ADD(link->v_a, ctrl->timers[PRI_TIMER_K]))) {
/* Don't flood debug trace if not really looking at Q.921 layer. */ /* Don't flood debug trace if not really looking at Q.921 layer. */
if (ctrl->debug & (/* PRI_DEBUG_Q921_STATE | */ PRI_DEBUG_Q921_DUMP)) { if (ctrl->debug & (/* PRI_DEBUG_Q921_STATE | */ PRI_DEBUG_Q921_DUMP)) {
pri_message(ctrl, pri_message(ctrl,
"TEI=%d Couldn't transmit I-frame at this time due to peer busy condition or window shut\n", "TEI=%d Couldn't transmit I-frame at this time due to peer busy condition\n",
link->tei);
}
return 0;
}
if (link->v_s == Q921_ADD(link->v_a, ctrl->timers[PRI_TIMER_K])) {
/* Don't flood debug trace if not really looking at Q.921 layer. */
if (ctrl->debug & (/* PRI_DEBUG_Q921_STATE | */ PRI_DEBUG_Q921_DUMP)) {
pri_message(ctrl,
"TEI=%d Couldn't transmit I-frame at this time due to window shut\n",
link->tei); link->tei);
} }
return 0; return 0;
@ -671,7 +663,30 @@ static int q921_send_queued_iframes(struct q921_link *link)
} }
/* Send it now... */ /* Send it now... */
++f->transmitted; switch (f->status) {
case Q921_TX_FRAME_NEVER_SENT:
if (ctrl->debug & PRI_DEBUG_Q921_STATE) {
pri_message(ctrl,
"TEI=%d Transmitting N(S)=%d, window is open V(A)=%d K=%d\n",
link->tei, link->v_s, link->v_a, ctrl->timers[PRI_TIMER_K]);
}
break;
case Q921_TX_FRAME_PUSHED_BACK:
if (f->h.n_s != link->v_s) {
/* Should never happen. */
pri_error(ctrl,
"TEI=%d Retransmitting frame with old N(S)=%d as N(S)=%d!\n",
link->tei, f->h.n_s, link->v_s);
} else if (ctrl->debug & PRI_DEBUG_Q921_STATE) {
pri_message(ctrl, "TEI=%d Retransmitting frame N(S)=%d now!\n",
link->tei, link->v_s);
}
break;
default:
/* Should never happen. */
pri_error(ctrl, "Unexpected Tx Q frame status: %d", f->status);
break;
}
/* /*
* Send the frame out on the assigned TEI. * Send the frame out on the assigned TEI.
@ -684,26 +699,23 @@ static int q921_send_queued_iframes(struct q921_link *link)
f->h.n_r = link->v_r; f->h.n_r = link->v_r;
f->h.ft = 0; f->h.ft = 0;
f->h.p_f = 0; f->h.p_f = 0;
if (ctrl->debug & PRI_DEBUG_Q921_STATE) {
pri_message(ctrl,
"TEI=%d Transmitting N(S)=%d, window is open V(A)=%d K=%d\n",
link->tei, f->h.n_s, link->v_a, ctrl->timers[PRI_TIMER_K]);
}
q921_transmit(ctrl, (q921_h *) (&f->h), f->len); q921_transmit(ctrl, (q921_h *) (&f->h), f->len);
Q921_INC(link->v_s); Q921_INC(link->v_s);
++frames_txd; ++frames_txd;
if (ctrl->debug & PRI_DEBUG_Q931_DUMP) { if ((ctrl->debug & PRI_DEBUG_Q931_DUMP)
&& f->status == Q921_TX_FRAME_NEVER_SENT) {
/* /*
* The transmit operation might dump the Q.921 header, so logging * The transmit operation might dump the Q.921 header, so logging
* the Q.931 message body after the transmit puts the sections of * the Q.931 message body after the transmit puts the sections of
* the message in the right order in the log. * the message in the right order in the log.
* *
* Also the dump is done here so the Q.931 part is decoded only * Also dump the Q.931 part only once instead of for every
* once instead of for every retransmission. * retransmission.
*/ */
q931_dump(ctrl, link->tei, (q931_h *) f->h.data, f->len - 4, 1); q931_dump(ctrl, link->tei, (q931_h *) f->h.data, f->len - 4, 1);
} }
f->status = Q921_TX_FRAME_SENT;
} }
if (frames_txd) { if (frames_txd) {
@ -934,7 +946,7 @@ static struct q921_link *pri_find_tei(struct pri *ctrl, int sapi, int tei)
/* This is the equivalent of a DL-DATA request, as well as the I-frame queued up outcome */ /* This is the equivalent of a DL-DATA request, as well as the I-frame queued up outcome */
int q921_transmit_iframe(struct q921_link *link, void *buf, int len, int cr) int q921_transmit_iframe(struct q921_link *link, void *buf, int len, int cr)
{ {
q921_frame *f, *prev=NULL; struct q921_frame *f, *prev=NULL;
struct pri *ctrl; struct pri *ctrl;
ctrl = link->ctrl; ctrl = link->ctrl;
@ -979,7 +991,7 @@ int q921_transmit_iframe(struct q921_link *link, void *buf, int len, int cr)
prev = f; prev = f;
} }
f = calloc(1, sizeof(q921_frame) + len + 2); f = calloc(1, sizeof(struct q921_frame) + len + 2);
if (f) { if (f) {
Q921_INIT(link, f->h); Q921_INIT(link, f->h);
switch (ctrl->localtype) { switch (ctrl->localtype) {
@ -999,7 +1011,7 @@ int q921_transmit_iframe(struct q921_link *link, void *buf, int len, int cr)
/* Put new frame on queue tail. */ /* Put new frame on queue tail. */
f->next = NULL; f->next = NULL;
f->transmitted = 0; f->status = Q921_TX_FRAME_NEVER_SENT;
f->len = len + 4; f->len = len + 4;
memcpy(f->h.data, buf, len); memcpy(f->h.data, buf, len);
if (prev) if (prev)
@ -1016,17 +1028,30 @@ int q921_transmit_iframe(struct q921_link *link, void *buf, int len, int cr)
} }
break; break;
} }
if (link->peer_rx_busy) {
if (link->peer_rx_busy || (link->v_s == Q921_ADD(link->v_a, ctrl->timers[PRI_TIMER_K]))) {
if (ctrl->debug & PRI_DEBUG_Q921_STATE) { if (ctrl->debug & PRI_DEBUG_Q921_STATE) {
pri_message(ctrl, pri_message(ctrl,
"TEI=%d Just queued I-frame due to peer busy condition or window shut\n", "TEI=%d Just queued I-frame due to peer busy condition\n",
link->tei); link->tei);
} }
break; break;
} }
q921_send_queued_iframes(link); if (!q921_send_queued_iframes(link)) {
/*
* No frames sent even though we just put a frame on the queue.
*
* Special debug message/test here because we want to say what
* happened to the Q.931 message just queued but we don't want
* to flood the debug trace if we are not really looking at the
* Q.921 layer.
*/
if ((ctrl->debug & (PRI_DEBUG_Q921_STATE | PRI_DEBUG_Q921_DUMP))
== PRI_DEBUG_Q921_STATE) {
pri_message(ctrl, "TEI=%d Just queued I-frame due to window shut\n",
link->tei);
}
}
} else { } else {
pri_error(ctrl, "!! Out of memory for Q.921 transmit\n"); pri_error(ctrl, "!! Out of memory for Q.921 transmit\n");
return -1; return -1;
@ -1073,14 +1098,13 @@ static void q921_dump_iqueue_info(struct q921_link *link)
{ {
struct pri *ctrl; struct pri *ctrl;
struct q921_frame *f; struct q921_frame *f;
int pending = 0, unacked = 0; int pending = 0;
int unacked = 0;
ctrl = link->ctrl; ctrl = link->ctrl;
unacked = pending = 0;
for (f = link->tx_queue; f; f = f->next) { for (f = link->tx_queue; f; f = f->next) {
if (f->transmitted) { if (f->status == Q921_TX_FRAME_SENT) {
unacked++; unacked++;
} else { } else {
pending++; pending++;
@ -2217,11 +2241,11 @@ static void update_v_a(struct q921_link *link, int n_r)
link->v_a = n_r; link->v_a = n_r;
} }
/*! \brief Is V(A) <= N(R) <= V(S) ? */
static int n_r_is_valid(struct q921_link *link, int n_r) static int n_r_is_valid(struct q921_link *link, int n_r)
{ {
int x; int x;
/* Is V(A) <= N(R) <= V(S) */
for (x = link->v_a; x != n_r && x != link->v_s; Q921_INC(x)) { for (x = link->v_a; x != n_r && x != link->v_s; Q921_INC(x)) {
} }
if (x != n_r) { if (x != n_r) {
@ -2346,37 +2370,27 @@ static pri_event *q921_rr_rx(struct q921_link *link, q921_h *h)
static int q921_invoke_retransmission(struct q921_link *link, int n_r) static int q921_invoke_retransmission(struct q921_link *link, int n_r)
{ {
int frames_txd = 0; struct q921_frame *f;
int frames_supposed_to_tx = 0;
q921_frame *f;
unsigned int local_v_s = link->v_s;
struct pri *ctrl; struct pri *ctrl;
ctrl = link->ctrl; ctrl = link->ctrl;
/* All acked frames should already have been removed from the queue. */ /*
for (f = link->tx_queue; f && f->transmitted; f = f->next) { * All acked frames should already have been removed from the queue.
if (ctrl->debug & PRI_DEBUG_Q921_STATE) { * Push back all sent frames.
pri_message(ctrl, "TEI=%d Retransmitting frame N(S)=%d now!\n", */
link->tei, f->h.n_s); for (f = link->tx_queue; f && f->status == Q921_TX_FRAME_SENT; f = f->next) {
} f->status = Q921_TX_FRAME_PUSHED_BACK;
/* Give the other side our current N(R) */ /* Sanity check: Is V(A) <= N(S) <= V(S)? */
f->h.n_r = link->v_r; if (!n_r_is_valid(link, f->h.n_s)) {
f->h.p_f = 0; pri_error(ctrl,
q921_transmit(ctrl, (q921_h *) (&f->h), f->len); "Tx Q frame with invalid N(S)=%d. Must be (V(A)=%d) <= N(S) <= (V(S)=%d)\n",
frames_txd++; f->h.n_s, link->v_a, link->v_s);
} }
while (local_v_s != n_r) {
Q921_DEC(local_v_s);
frames_supposed_to_tx++;
} }
if (frames_supposed_to_tx != frames_txd) { link->v_s = n_r;
pri_error(ctrl, "!!!!!!!!!!!! Should have only transmitted %d frames!\n", frames_supposed_to_tx); return q921_send_queued_iframes(link);
}
return frames_txd;
} }
static pri_event *q921_rej_rx(struct q921_link *link, q921_h *h) static pri_event *q921_rej_rx(struct q921_link *link, q921_h *h)
@ -2494,7 +2508,6 @@ static pri_event *q921_iframe_rx(struct q921_link *link, q921_h *h, int len)
delay_q931_receive = 0; delay_q931_receive = 0;
/* FIXME: Verify that it's a command ... */ /* FIXME: Verify that it's a command ... */
if (link->own_rx_busy) { if (link->own_rx_busy) {
/* XXX: Note: There's a difference in th P/F between both states */
/* DEVIATION: Handle own rx busy */ /* DEVIATION: Handle own rx busy */
} else if (h->i.n_s == link->v_r) { } else if (h->i.n_s == link->v_r) {
Q921_INC(link->v_r); Q921_INC(link->v_r);