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fix reassembly, ticking and sliding

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This commit is contained in:
frekky 2017-07-04 21:44:12 +02:00
parent eee0d14a69
commit 6e7099866f
2 changed files with 40 additions and 32 deletions
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70
src/window.c
View file

@ -158,8 +158,7 @@ window_process_incoming_fragment(struct frag_buffer *w, fragment *f)
ssize_t dest = WRAP(w->chunk_start + offset);
if (offset > w->length - w->windowsize) {
w->oos++;
WDEBUG("incoming frag far ahead: offs %u > %u, cs %u[%" L "u], id %u[%" L "u]",
WDEBUG("incoming frag ahead: offs %u > %u, cs %u[%" L "u], id %u[%" L "u]",
offset, w->length - w->windowsize, w->start_seq_id, w->chunk_start,
f->seqID, dest);
offset -= w->length - w->windowsize;
@ -204,6 +203,7 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, size_t *len, uint8_
{
size_t woffs, start;
size_t maxlen = *len;
size_t fraglen = 0;
uint8_t *dest; //, *fdata_start;
*len = 0;
dest = data;
@ -246,18 +246,17 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, size_t *len, uint8_
woffs, f->seqID, curseq);
}
if (f->start || consecutive_frags >= 1) {
found_frags++;
consecutive_frags++;
if (drop == 0) {
/* Copy next fragment to buffer if not going to drop */
memcpy(dest, f->data, MIN(f->len, maxlen));
}
if (f->len > maxlen) {
WDEBUG("Data buffer too small: drop packet! Reassembled %" L "u bytes.", *len);
WDEBUG("Data buffer too small: drop packet! Reassembled %" L "u bytes.", fraglen);
drop = 1;
}
dest += f->len;
*len += f->len;
fraglen += f->len;
maxlen -= f->len;
if (compression) {
@ -267,9 +266,9 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, size_t *len, uint8_
}
}
WDEBUG("reassemble: id %u, len %" L "u, offs %" \
L "u, total %" L "u, maxlen %" L "u, found %" L "u, consecutive %" L "u",
f->seqID, f->len, dest - data, *len, maxlen, found_frags, consecutive_frags);
WDEBUG("reassemble: id %u [%" L "u], len %" L "u, offs %" \
L "u, total %" L "u, maxlen %" L "u, found %" L "u/%" L "u, consecutive %" L "u",
woffs, f->seqID, f->len, dest - data, *len, maxlen, found_frags, w->numitems, consecutive_frags);
if (f->end == 1) {
WDEBUG("Found end of chunk! (seqID %u, chunk len %" L "u, datalen %" L "u)",
@ -286,6 +285,9 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, size_t *len, uint8_
return 0;
}
if (!drop)
*len = fraglen;
WDEBUG("Reassembled %" L "ub from %" L "u frags; comp=%u; holes=%u",
*len, consecutive_frags, *compression, holes);
/* Clear all used fragments, going backwards from last processed */
@ -312,11 +314,12 @@ window_sending(struct frag_buffer *w, struct timeval *nextresend)
oldest.tv_sec = 0;
oldest.tv_usec = 0;
if (nextresend) {
nextresend->tv_sec = 0;
nextresend->tv_usec = 0;
}
if (w->numitems == 0) {
if (nextresend) {
nextresend->tv_sec = 0;
nextresend->tv_usec = 0;
}
return 0;
}
@ -324,18 +327,18 @@ window_sending(struct frag_buffer *w, struct timeval *nextresend)
for (size_t i = 0; i < w->windowsize; i++) {
f = &w->frags[WRAP(w->window_start + i)];
if (f->len == 0 || f->acks >= 1) continue;
if (f->len == 0 || f->acks >= 1 || f->retries > w->max_retries)
continue;
if (f->retries < 1 || f->lastsent.tv_sec == 0) {
/* Sending frag for first time
* Note: if retries==0 then lastsent MUST also be 0 */
if (f->retries < 1) {
/* Sending frag for first time */
tosend++;
} else {
/* Frag has been sent before so lastsent is a valid timestamp */
timersub(&now, &f->lastsent, &age);
if (!timercmp(&age, &w->timeout, <) && f->retries < w->max_retries) {
/* ACK timeout: Frag will be resent */
if (!timercmp(&age, &w->timeout, <)) {
/* ACK timeout: Frag will be resent if not to be dropped */
tosend++;
} else if (timercmp(&age, &oldest, >)) {
/* Hasn't timed out yet and is oldest so far */
@ -344,7 +347,7 @@ window_sending(struct frag_buffer *w, struct timeval *nextresend)
}
}
if (nextresend) {
if (nextresend && w->max_retries > 0) {
/* nextresend = time before oldest fragment (not being sent now)
* will be re-sent = timeout - age */
timersub(&w->timeout, &oldest, nextresend);
@ -368,11 +371,12 @@ window_get_next_sending_fragment(struct frag_buffer *w, int *other_ack)
for (size_t i = 0; i < w->windowsize; i++) {
f = &w->frags[WRAP(w->window_start + i)];
if (f->acks >= 1 || f->len == 0) continue;
if (f->acks >= 1 || f->len == 0 || f->retries > w->max_retries)
continue;
timersub(&now, &f->lastsent, &age);
if (f->retries >= 1 && f->retries < w->max_retries && !timercmp(&age, &w->timeout, <)) {
if (f->retries >= 1 && !timercmp(&age, &w->timeout, <)) {
/* Resending fragment due to ACK timeout */
WDEBUG("Retrying frag %u (%ld ms old/timeout %ld ms), retries: %u/max %u/total %u",
f->seqID, timeval_to_ms(&age), timeval_to_ms(&w->timeout), f->retries, w->max_retries, w->resends);
@ -396,7 +400,8 @@ window_get_next_sending_fragment(struct frag_buffer *w, int *other_ack)
f->start &= 1;
f->end &= 1;
f->retries++;
gettimeofday(&f->lastsent, NULL);
f->lastsent.tv_sec = now.tv_sec;
f->lastsent.tv_usec = now.tv_usec;
return f;
}
@ -469,12 +474,14 @@ window_tick(struct frag_buffer *w)
{
unsigned slide = 0;
for (size_t i = 0; i < w->windowsize; i++) {
// TODO are ACKs required for reduced arrival guarantee?
fragment *f = &w->frags[WRAP(w->window_start + i)];
if (f->len > 0 && (f->acks >= 1 || (w->max_retries == 0 && f->lastsent.tv_sec != 0))) {
/* count consecutive fragments from start of window that are ACK'd */
if (f->len > 0 && (f->acks >= 1 || f->retries > w->max_retries)) {
/* count consecutive fragments from start of window that are ACK'd
* or that have been sent/retried maximum times */
slide++;
} else break;
} else {
break;
}
}
if (slide > 0) window_slide(w, slide, w->direction == WINDOW_SENDING);
}
@ -492,29 +499,30 @@ window_add_outgoing_data(struct frag_buffer *w, uint8_t *data, size_t len, uint8
}
compressed &= 1;
size_t offset = 0;
fragment *f = &w->frags[w->last_write];
fragment *f;
WDEBUG("add_outgoing_data: chunk len %" L "u -> %" L "u frags, max fragsize %u",
len, n, w->maxfraglen);
for (size_t i = 0; i < n; i++) {
f = &w->frags[w->last_write];
/* copy in new data and reset frag stats */
f->len = MIN(len - offset, w->maxfraglen);
f->seqID = w->cur_seq_id;
f->compressed = compressed;
f->start = (i == 0) ? 1 : 0;
f->end = (i == n - 1) ? 1 : 0;
f->retries = 0;
f->acks = 0;
f->ack_other = -1;
f->lastsent.tv_sec = 0;
f->lastsent.tv_usec = 0;
WDEBUG(" frags[%" L "u]: len %" L "u, seqID %u, s %u, end %u, dOffs %" L "u",
w->last_write, f->len, f->seqID, f->start, f->end, offset);
memcpy(f->data, data + offset, f->len);
w->last_write = WRAP(w->last_write + 1);
w->cur_seq_id = WRAPSEQ(w->cur_seq_id + 1);
w->numitems ++;
WDEBUG(" fragment len %" L "u, seqID %u, s %u, end %u, dOffs %" L "u",
f->len, f->seqID, f->start, f->end, offset);
memcpy(f->data, data + offset, f->len);
offset += f->len;
}
return n;

2
src/window.h
View file

@ -53,7 +53,7 @@ struct frag_buffer {
unsigned maxfraglen; /* Max outgoing fragment data size */
unsigned cur_seq_id; /* Next unused sequence ID */
unsigned start_seq_id; /* lowest seqID that exists in buffer (at index chunk_start) */
unsigned max_retries; /* max number of resends before dropping (-1 = never drop) */
unsigned max_retries; /* max number of resends before dropping */
unsigned resends; /* number of fragments resent or number of dupes received */
unsigned oos; /* Number of out-of-sequence fragments received */
int direction; /* WINDOW_SENDING or WINDOW_RECVING */