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7 commits

Author SHA1 Message Date
Dmitri Tikhonov
052a1c28ad Drop support for versions Q037, Q038, and Q042 2018-05-09 14:01:46 -04:00
Dmitri Tikhonov
10c492f0b6 Update copyright year; add CONTRIBUTORS.txt 2018-04-02 15:17:56 -04:00
Amol Deshpande
5d77f141aa updated to upstream ran all tests again. 2018-03-12 19:56:06 -07:00
Amol Deshpande
461e84d874 compiles in debug/release. tests pass (in debug config at least) 2018-03-12 15:25:01 -07:00
Dmitri Tikhonov
16a9b66aaa Latest changes
- [OPTIMIZATION] Merge series of ACKs if possible

  Parsed single-range ACK frames (that is the majority of frames) are
  saved in the connection and their processing is deferred until the
  connection is ticked.  If several ACKs come in a series between
  adjacent ticks, we check whether the latest ACK is a strict superset
  of the saved ACK.  If it is, the older ACK is not processed.

  If ACK frames can be merged, they are merged and only one of them is
  either processed or saved.

- [OPTIMIZATION] Speed up ACK verification by simplifying send history.

  Never generate a gap in the sent packet number sequence.  This reduces
  the send history to a single number instead of potentially a series of
  packet ranges and thereby speeds up ACK verification.

  By default, detecting a gap in the send history is not fatal: only a
  single warning is generated per connection.  The connection can continue
  to operate even if the ACK verification code is not able to detect some
  inconsistencies.

- [OPTIMIZATION] Rearrange the lsquic_send_ctl struct

  The first part of struct lsquic_send_ctl now consists of members that
  are used in lsquic_send_ctl_got_ack() (in the absense of packet loss,
  which is the normal case).  To speed up reads and writes, we no longer
  try to save space by using 8- and 16-bit integers.  Use regular integer
  width for everything.

- [OPTIMIZATION] Cache size of sent packet.

- [OPTIMIZATION] Keep track of the largest ACKed in packet_out

  Instead of parsing our own ACK frames when packet has been acked,
  use the value saved in the packet_out structure when the ACK frame
  was generated.

- [OPTIMIZATION] Take RTT sampling conditional out of ACK loop

- [OPTIMIZATION] ACK processing: only call clock_gettime() if needed

- [OPTIMIZATION] Several code-level optimizations to ACK processing.

- Fix: http_client: fix -I flag; switch assert() to abort()
2018-03-09 14:17:39 -05:00
Dmitri Tikhonov
c51ce3387f Latest changes
- [API Change] Sendfile-like functionality is gone.  The stream no
  longer opens files and deals with file descriptors.  (Among other
  things, this makes the code more portable.)  Three writing functions
  are provided:

    lsquic_stream_write
    lsquic_stream_writev
    lsquic_stream_writef    (NEW)

  lsquic_stream_writef() is given an abstract reader that has function
  pointers for size() and read() functions which the user can implement.
  This is the most flexible way.  lsquic_stream_write() and
  lsquic_stream_writev() are now both implemented as wrappers around
  lsquic_stream_writef().

- [OPTIMIZATION] When writing to stream, be it within or without the
  on_write() callback, place data directly into packet buffer,
  bypassing auxiliary data structures.  This reduces amount of memory
  required, for the amount of data that can be written is limited
  by the congestion window.

  To support writes outside the on_write() callback, we keep N
  outgoing packet buffers per connection which can be written to
  by any stream.  One half of these are reserved for the highest
  priority stream(s), the other half for all other streams.  This way,
  low-priority streams cannot write instead of high-priority streams
  and, on the other hand, low-priority streams get a chance to send
  their packets out.

  The algorithm is as follows:

  - When user writes to stream outside of the callback:
    - If this is the highest priority stream, place it onto the
      reserved N/2 queue or fail.
        (The actual size of this queue is dynamic -- MAX(N/2, CWND) --
         rather than N/2, allowing high-priority streams to write as
         much as can be sent.)
    - If the stream is not the highest priority, try to place the
      data onto the reserved N/2 queue or fail.
  - When tick occurs *and* more packets can be scheduled:
    - Transfer packets from the high N/2 queue to the scheduled
      queue.
    - If more scheduling is allowed:
      - Call on_write callbacks for highest-priority streams,
        placing resulting packets directly onto the scheduled queue.
    - If more scheduling is allowed:
      - Transfer packets from the low N/2 queue to the scheduled
        queue.
    - If more scheduling is allowed:
      - Call on_write callbacks for non-highest-priority streams,
        placing resulting packets directly onto the scheduled queue

  The number N is currently 20, but it could be varied based on
  resource usage.

- If stream is created due to incoming headers, make headers readable
  from on_new.

- Outgoing packets are no longer marked non-writeable to prevent placing
  more than one STREAM frame from the same stream into a single packet.
  This property is maintained via code flow and an explicit check.
  Packets for stream data are allocated using a special function.

- STREAM frame elision is cheaper, as we only perform it if a reset
  stream has outgoing packets referencing it.

- lsquic_packet_out_t is smaller, as stream_rec elements are now
  inside a union.
2017-10-31 09:35:58 -04:00
Dmitri Tikhonov
50aadb33c7 LSQUIC Client: Initial release 2017-09-22 17:00:03 -04:00