Summary:
Previously we stored an `IntervalSet` in each `WriteAckFrame`. We don't need to do this, as by the time we are writing an `ACK` the `IntervalSet` is complete. Instead of bothering with the `IntervalSet` operations, we can simply serialize it to a reverse-sorted `vector.`
Additionally this has some micro-optimizations for filling the ACK frame, with a new function for getting varint size.
Reviewed By: yangchi
Differential Revision: D19397728
fbshipit-source-id: ba6958fb36a4681edaa8394b1bcbbec3472e177d
Summary:
The retransmission buffer tracks stream frame data we have sent that is currently unacked. We keep this as a sorted `deque`. This isn't so bad for performance, but we can do better if we break ourselves of the requirement that it be sorted (removing a binary search on ACK).
To do this we make the buffer a map of offset -> `StreamBuffer`.
There were two places that were dependent on the sorted nature of the list.
1. For partial reliablity we call `shrinkBuffers` to remove all unacked buffers less than an offset. For this we now have to do it with a full traversal of the retransmission buffer instead of only having to do an O(offset) search. In the future we could make this better by only lazily deleting from the retransmission buffer on ACK or packet loss.
2. We used the start of the retransmission buffer to determine if a delivery callback could be fired for a given offset. We need some new state to track this. Instead of tracking unacked buffers, we now track acked ranges using the existing `IntervalSet`. This set should be small for the typical case, as we think most ACKs will come in order and just cause existing ranges to merge.
Reviewed By: yangchi
Differential Revision: D18609467
fbshipit-source-id: 13cd2164352f1183362be9f675c1bdc686426698
Summary:
The function indeed compares a Stream frame to a buffer, not an Ack
frame to a buffer.
Reviewed By: sharma95
Differential Revision: D18000632
fbshipit-source-id: fbbc36378404f8f52a199114af48b9020d0569e8
Summary:
Use the custom variant type for write frames as well, now that
we use them for read frames.
Reviewed By: mjoras
Differential Revision: D17776862
fbshipit-source-id: 47093146d0f1565c22e5393ed012c70e2e23d279
Summary:
Make a custom variant type for PacketHeader. By not relying on boost::variant
this reduces the code size of the implementation.
This uses a combination of a union type as well as a enum type to emulate a variant
Reviewed By: yangchi
Differential Revision: D17187589
fbshipit-source-id: 00c2b9b8dd3f3e73af766d84888b13b9d867165a
Summary:
Prior to this diff we would clone out an entire flow control's worth of data from the writebuffer and then clone out a smaller portion of that to write into the packet builder. This is extremely wasteful when we have a large flow control window.
Additionally we would always write the stream data length field even when we are going to fill the remainder of the packet with the current stream frame. By first calculating the amount of data that needs to can be written and writing the header, we can now omit the data length field when we can fill the whole packet.
Reviewed By: yangchi
Differential Revision: D15769514
fbshipit-source-id: 95ac74eebcde87dd06de54405d7f69c42362e29c
Summary:
With partial reliability we adjust retransmission queue on skips; we need to account for that when we match buffers in retransmission queue.
In fully reliable mode an ack frame must always match a single buffer from re-tranmission queue (offset, length and eom).
In partially reliable mode we can run into two more scenarios in addition to the above:
* re-transmisison buffer for which the ack frame arrived has been removed fully
* re-transmisison buffer for which the ack frame arrived has been removed partially
If full buffer is missing - ignore the ack.
If part of the buffer is missing, make sure that the adjusted offset and length match to that found in the ack frame.
Reviewed By: yangchi
Differential Revision: D15301304
fbshipit-source-id: f281fa30957c1c13c42c05684984f9a1acaa4e34
Summary:
There is a race condition with min data frame (skip) and ack frame when it comes to retransmission buffer.
Sometimes, we receive both min data and ack frames, the min data frame gets processed first and it clears out retransmission buffer (expected), but then we get to process the ack frame and there is that CHECK that expects the retransmission buffer to have at least one unacked buffer in it - there is none and then the app crashes.
Reviewed By: siyengar
Differential Revision: D14908630
fbshipit-source-id: d8bcd70291e1fd3618065fdeb44bedc6ac66bcaa
