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factor out incremeant of m_acked_seq_nr, m_fast_resend_seq_nr and m_loss_seq_nr to make it more robust. Should fix issues where m_acked_seq_nr sometimes could get stuck pointing behind the last acked sequence number

This commit is contained in:
Arvid Norberg 2010-12-05 03:03:56 +00:00
parent 03bd547f40
commit 2f115bc1aa
1 changed files with 50 additions and 31 deletions
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81
src/utp_stream.cpp
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@ -297,6 +297,7 @@ struct utp_socket_impl
void parse_sack(boost::uint16_t packet_ack, char const* ptr, int size, int* acked_bytes
, ptime const now, boost::uint32_t& min_rtt);
void write_payload(char* ptr, int size);
void maybe_inc_acked_seq_nr();
void ack_packet(packet* p, ptime const& receive_time
, boost::uint32_t& min_rtt, boost::uint16_t seq_nr);
void write_sack(char* buf, int size) const;
@ -1332,11 +1333,11 @@ void utp_socket_impl::parse_sack(boost::uint16_t packet_ack, char const* ptr
, this, m_duplicate_acks, m_fast_resend_seq_nr);
ack_packet(p, now, min_rtt, ack_nr);
}
else if ((m_acked_seq_nr + 1) == ack_nr)
else
{
// this packet must have been acked by a previous
// this packet might have been acked by a previous
// selective ack
m_acked_seq_nr = ack_nr;
maybe_inc_acked_seq_nr();
}
}
@ -1351,6 +1352,8 @@ void utp_socket_impl::parse_sack(boost::uint16_t packet_ack, char const* ptr
if (ack_nr == m_seq_nr) break;
}
TORRENT_ASSERT(m_outbuf.at((m_acked_seq_nr + 1) & ACK_MASK) || ((m_seq_nr - m_acked_seq_nr) & ACK_MASK) <= 1);
// we received more than dup_ack_limit ACKs in this SACK message.
// trigger fast re-send
if (dups >= dup_ack_limit && compare_less_wrap(m_fast_resend_seq_nr, last_ack, 0xffff))
@ -1719,6 +1722,13 @@ bool utp_socket_impl::resend_packet(packet* p, bool fast_resend)
h->timestamp_difference_microseconds = m_reply_micro;
p->send_time = time_now_hires();
h->timestamp_microseconds = boost::uint32_t(total_microseconds(p->send_time - min_time()));
if (h->extension == 0)
{
// if extension != 0, there might be a SACK in the header
// and we can't update the ack field (since the SACK bits
// depend on it). If it's zero however, we can update it.
h->ack_nr = m_ack_nr;
}
error_code ec;
m_sm->send_packet(udp::endpoint(m_remote_address, m_port)
@ -1767,10 +1777,42 @@ void utp_socket_impl::experienced_loss(int seq_nr)
// we'll get a timeout in about one second
}
void utp_socket_impl::maybe_inc_acked_seq_nr()
{
bool incremented = false;
// don't pass m_seq_nr, since we move into sequence
// numbers that haven't been sent yet, and aren't
// supposed to be in m_outbuf
while (((m_acked_seq_nr + 1) & ACK_MASK) != m_seq_nr
&& m_outbuf.at((m_acked_seq_nr + 1) & ACK_MASK) == 0)
{
// increment the fast resend sequence number
if (m_fast_resend_seq_nr == m_acked_seq_nr)
m_fast_resend_seq_nr = (m_fast_resend_seq_nr + 1) & ACK_MASK;
m_acked_seq_nr = (m_acked_seq_nr + 1) & ACK_MASK;
incremented = true;
}
if (!incremented) return;
// update loss seq number if it's less than the packet
// that was just acked. If loss seq nr is greater, it suggests
// that we're still in a window that has experienced loss
if (compare_less_wrap(m_loss_seq_nr, m_acked_seq_nr, ACK_MASK))
m_loss_seq_nr = m_acked_seq_nr;
m_duplicate_acks = 0;
}
void utp_socket_impl::ack_packet(packet* p, ptime const& receive_time
, boost::uint32_t& min_rtt, boost::uint16_t seq_nr)
{
TORRENT_ASSERT(p);
// verify that the packet we're removing was in fact sent
// with the sequence number we expect
TORRENT_ASSERT(((utp_header*)p->buf)->seq_nr == seq_nr);
if (!p->need_resend)
{
TORRENT_ASSERT(m_bytes_in_flight >= p->size - p->header_size);
@ -1786,19 +1828,7 @@ void utp_socket_impl::ack_packet(packet* p, ptime const& receive_time
}
// increment the acked sequence number counter
if (((m_acked_seq_nr + 1) & ACK_MASK) == seq_nr)
{
m_acked_seq_nr = seq_nr;
// update loss seq number if it's less than the packet
// that was just acked. If loss seq nr is greater, it suggests
// that we're still in a window that has experienced loss
if (compare_less_wrap(m_loss_seq_nr, m_acked_seq_nr, ACK_MASK))
m_loss_seq_nr = m_acked_seq_nr;
m_duplicate_acks = 0;
}
// increment the fast resend sequence number
if (m_fast_resend_seq_nr == seq_nr)
m_fast_resend_seq_nr = (m_fast_resend_seq_nr + 1) & ACK_MASK;
maybe_inc_acked_seq_nr();
boost::uint32_t rtt = boost::uint32_t(total_microseconds(receive_time - p->send_time));
if (receive_time < p->send_time)
@ -2244,25 +2274,14 @@ bool utp_socket_impl::incoming_packet(char const* buf, int size
if (m_fast_resend_seq_nr == ack_nr)
m_fast_resend_seq_nr = (m_fast_resend_seq_nr + 1) & ACK_MASK;
packet* p = (packet*)m_outbuf.remove(ack_nr);
if (!p)
{
if (((m_acked_seq_nr + 1) & ACK_MASK) == ack_nr)
m_acked_seq_nr = ack_nr;
continue;
}
if (!p) continue;
acked_bytes += p->size - p->header_size;
ack_packet(p, receive_time, min_rtt, ack_nr);
}
// update loss seq number if it's less than the packet
// that was just acked. If loss seq nr is greater, it suggests
// that we're still in a window that has experienced loss
if (compare_less_wrap(m_loss_seq_nr, m_acked_seq_nr, ACK_MASK))
m_loss_seq_nr = m_acked_seq_nr;
m_duplicate_acks = 0;
if (compare_less_wrap(m_fast_resend_seq_nr, (m_acked_seq_nr + 1) & ACK_MASK, ACK_MASK))
m_fast_resend_seq_nr = (m_acked_seq_nr + 1) & ACK_MASK;
maybe_inc_acked_seq_nr();
}
// look for extended headers