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tcp_write(): optimize order of valid states checks, most common first.

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added assertion: when the queues are NULL, queuelen must be zero.
remove ACK flags from a PCB, only when we could succesfully sent
an empty ACK packet.
This commit is contained in:
likewise 2004-12-26 01:36:37 +00:00
parent 15257f4524
commit c61f01b206
1 changed files with 75 additions and 52 deletions
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127
src/core/tcp_out.c
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@ -79,10 +79,11 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t copy)
{
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, arg=%p, len=%u, copy=%d)\n", (void *)pcb,
arg, len, (unsigned int)copy));
if (pcb->state == SYN_SENT ||
pcb->state == SYN_RCVD ||
pcb->state == ESTABLISHED ||
pcb->state == CLOSE_WAIT) {
/* connection is in valid state for data transmission? */
if (pcb->state == ESTABLISHED ||
pcb->state == CLOSE_WAIT ||
pcb->state == SYN_SENT ||
pcb->state == SYN_RCVD) {
if (len > 0) {
return tcp_enqueue(pcb, (void *)arg, len, 0, copy, NULL, 0);
}
@ -93,10 +94,20 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t copy)
}
}
/**
* Enqueue data for tranmission
*
* @arg pcb Protocol control block for the TCP connection to enqueue data for.
* @arg arg Pointer to the data to be enqueued for sending.
* @arg len Data length in bytes
* @arg flags
* @arg optdata
* @arg optlen
*/
err_t
tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
u8_t flags, u8_t copy,
u8_t *optdata, u8_t optlen)
u8_t flags, u8_t copy,
u8_t *optdata, u8_t optlen)
{
struct pbuf *p;
struct tcp_seg *seg, *useg, *queue;
@ -107,19 +118,18 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue(pcb=%p, arg=%p, len=%u, flags=%x, copy=%u)\n",
(void *)pcb, arg, len, (unsigned int)flags, (unsigned int)copy));
left = len;
ptr = arg;
/* fail on too much data */
if (len > pcb->snd_buf) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too much data (len=%u > snd_buf=%u)\n", len, pcb->snd_buf));
return ERR_MEM;
}
left = len;
ptr = arg;
/* seqno will be the sequence number of the first segment enqueued
* by the call to this function. */
seqno = pcb->snd_lbb;
queue = NULL;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: queuelen: %u\n", (unsigned int)pcb->snd_queuelen));
/* Check if the queue length exceeds the configured maximum queue
@ -129,17 +139,18 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too long queue %u (max %u)\n", queuelen, TCP_SND_QUEUELEN));
goto memerr;
}
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
if (queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: queue length non-zero and at least one queue non-empty",
pcb->unacked != NULL || pcb->unsent != NULL);
} else {
LWIP_ASSERT("tcp_enqueue: queue length zero and queues empty",
pcb->unacked == NULL && pcb->unsent == NULL);
}
seg = useg = NULL;
seglen = 0;
/* First, break up the data into segments and tuck them together in
* the local "queue" variable. */
useg = queue = seg = NULL;
seglen = 0;
while (queue == NULL || left > 0) {
/* The segment length should be the MSS if the data to be enqueued
@ -155,20 +166,26 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
seg->next = NULL;
seg->p = NULL;
/* first segment of to-be-queued data? */
if (queue == NULL) {
useg = queue = seg;
}
/* subsequent segments of to-be-queued data */
else {
/* Attach the segment to the end of the queued segments. */
LWIP_ASSERT("useg != NULL", useg != NULL);
useg->next = seg;
/* remember last segment of to-be-queued data for next iteration */
useg = seg;
}
/* { useg == seg } */
/* If copy is set, memory should be allocated
* and data copied into pbuf, otherwise data comes from
* ROM or other static memory, and need not be copied. If
* optdata is != NULL, we have options instead of data. */
/* options? */
if (optdata != NULL) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
goto memerr;
@ -176,6 +193,7 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
++queuelen;
seg->dataptr = seg->p->payload;
}
/* copy from volatile memory? */
else if (copy) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_RAM)) == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue : could not allocate memory for pbuf copy size %u\n", seglen));
@ -190,7 +208,7 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
/* do not copy data */
else {
/* first, allocate a pbuf for holding the data.
/* First, allocate a pbuf for holding the data.
* since the referenced data is available at least until it is sent out on the
* link (as it has to be ACKed by the remote party) we can safely use PBUF_ROM
* instead of PBUF_REF here.
@ -200,6 +218,7 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
goto memerr;
}
++queuelen;
/* reference the non-volatile payload data */
p->payload = ptr;
seg->dataptr = ptr;
@ -214,7 +233,7 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
++queuelen;
/* Concatenate the headers and data pbufs together. */
pbuf_cat(seg->p, p);
pbuf_cat(seg->p/*header*/, p/*data*/);
p = NULL;
}
@ -226,16 +245,10 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
}
seg->len = seglen;
#if 0 /* Was commented out. TODO: can someone say why this is here? */
if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
++seg->len;
}
#endif
/* Build TCP header. */
/* build TCP header */
if (pbuf_header(seg->p, TCP_HLEN)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: no room for TCP header in pbuf.\n"));
TCP_STATS_INC(tcp.err);
goto memerr;
}
@ -268,7 +281,6 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
ptr = (void *)((char *)ptr + seglen);
}
/* Now that the data to be enqueued has been broken up into TCP
segments in the queue variable, we add them to the end of the
pcb->unsent queue. */
@ -278,6 +290,7 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
else {
for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
}
/* { useg is last segment on the unsent queue, NULL if list is empty } */
/* If there is room in the last pbuf on the unsent queue,
chain the first pbuf on the queue together with that. */
@ -285,24 +298,27 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
TCP_TCPLEN(useg) != 0 &&
!(TCPH_FLAGS(useg->tcphdr) & (TCP_SYN | TCP_FIN)) &&
!(flags & (TCP_SYN | TCP_FIN)) &&
/* fit within max seg size */
useg->len + queue->len <= pcb->mss) {
/* Remove TCP header from first segment. */
/* Remove TCP header from first segment of our to-be-queued list */
pbuf_header(queue->p, -TCP_HLEN);
pbuf_cat(useg->p, queue->p);
useg->len += queue->len;
useg->next = queue->next;
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE | DBG_STATE, ("tcp_enqueue: chaining, new len %u\n", useg->len));
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE | DBG_STATE, ("tcp_enqueue: chaining segments, new len %u\n", useg->len));
if (seg == queue) {
seg = NULL;
}
memp_free(MEMP_TCP_SEG, queue);
}
else {
/* empty list */
if (useg == NULL) {
/* initialize list with this segment */
pcb->unsent = queue;
}
/* enqueue segment */
else {
useg->next = queue;
}
@ -315,9 +331,8 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
pcb->snd_queuelen = queuelen;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %d (after enqueued)\n", pcb->snd_queuelen));
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
LWIP_ASSERT("tcp_enqueue: valid queue length",
pcb->unacked != NULL || pcb->unsent != NULL);
}
/* Set the PSH flag in the last segment that we enqueued, but only
@ -336,7 +351,6 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
}
LWIP_DEBUGF(TCP_QLEN_DEBUG | DBG_STATE, ("tcp_enqueue: %d (with mem err)\n", pcb->snd_queuelen));
return ERR_MEM;
@ -364,7 +378,6 @@ tcp_output(struct tcp_pcb *pcb)
wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
seg = pcb->unsent;
/* useg should point to last segment on unacked queue */
@ -372,24 +385,24 @@ tcp_output(struct tcp_pcb *pcb)
if (useg != NULL) {
for (; useg->next != NULL; useg = useg->next);
}
/* If the TF_ACK_NOW flag is set, we check if there is data that is
to be sent. If data is to be sent out, we'll just piggyback our
acknowledgement with the outgoing segment. If no data will be
sent (either because the ->unsent queue is empty or because the
window doesn't allow it) we'll have to construct an empty ACK
segment and send it. */
/* If the TF_ACK_NOW flag is set and no data will be sent (either
* because the ->unsent queue is empty or because the window does
* not allow it), construct an empty ACK segment and send it.
*
* If data is to be sent, we will just piggyback the ACK (see below).
*/
if (pcb->flags & TF_ACK_NOW &&
(seg == NULL ||
ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
if (p == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
return ERR_BUF;
}
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: sending ACK for %lu\n", pcb->rcv_nxt));
/* remove ACK flags from the PCB, as we send an empty ACK now */
pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
tcphdr = p->payload;
tcphdr->src = htons(pcb->local_port);
@ -406,7 +419,6 @@ tcp_output(struct tcp_pcb *pcb)
tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
IP_PROTO_TCP, p->tot_len);
#endif
ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
IP_PROTO_TCP);
pbuf_free(p);
@ -431,7 +443,7 @@ tcp_output(struct tcp_pcb *pcb)
ntohl(seg->tcphdr->seqno), pcb->lastack));
}
#endif /* TCP_CWND_DEBUG */
/* data available and window allows it to be sent? */
while (seg != NULL &&
ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
#if TCP_CWND_DEBUG
@ -458,21 +470,26 @@ tcp_output(struct tcp_pcb *pcb)
/* put segment on unacknowledged list if length > 0 */
if (TCP_TCPLEN(seg) > 0) {
seg->next = NULL;
/* unacked list is empty? */
if (pcb->unacked == NULL) {
pcb->unacked = seg;
useg = seg;
/* unacked list is not empty? */
} else {
/* In the case of fast retransmit, the packet should not go to the end
* of the unacked queue, but rather at the start. We need to check for
/* In the case of fast retransmit, the packet should not go to the tail
* of the unacked queue, but rather at the head. We need to check for
* this case. -STJ Jul 27, 2004 */
if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))){
/* add segment to head of unacked list */
seg->next = pcb->unacked;
pcb->unacked = seg;
} else {
/* add segment to tail of unacked list */
useg->next = seg;
useg = useg->next;
}
}
/* do not queue empty segments on the unacked list */
} else {
tcp_seg_free(seg);
}
@ -481,6 +498,9 @@ tcp_output(struct tcp_pcb *pcb)
return ERR_OK;
}
/**
* Actually send a TCP segment over IP
*/
static void
tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
{
@ -576,6 +596,7 @@ tcp_rst(u32_t seqno, u32_t ackno,
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %lu ackno %lu.\n", seqno, ackno));
}
/* requeue all unacked segments for retransmission */
void
tcp_rexmit_rto(struct tcp_pcb *pcb)
{
@ -585,22 +606,24 @@ tcp_rexmit_rto(struct tcp_pcb *pcb)
return;
}
/* Move all unacked segments to the unsent queue. */
/* Move all unacked segments to the head of the unsent queue */
for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
/* concatenate unsent queue after unacked queue */
seg->next = pcb->unsent;
/* unsent queue is the concatenated queue (of unacked, unsent) */
pcb->unsent = pcb->unacked;
/* unacked queue is now empty */
pcb->unacked = NULL;
pcb->snd_nxt = ntohl(pcb->unsent->tcphdr->seqno);
/* increment number of retransmissions */
++pcb->nrtx;
/* Don't take any rtt measurements after retransmitting. */
/* Don't take any RTT measurements after retransmitting. */
pcb->rttest = 0;
/* Do the actual retransmission. */
/* Do the actual retransmission */
tcp_output(pcb);
}
void