commit 0e98806859c83c5c5159a2d0173bb5b5c99d85bb
author Yifei Teng <yifeit@fuchsia.infra.roller.google.com> Fri Nov 11 20:38:31 2022 +0000
committer Copybara-Service <copybara-worker@google.com> Fri Nov 11 12:39:42 2022 -0800
tree 2a8d32980f355aa8db353bc25c7b76b9755e13b2
parent b440aa7054af2ddaf9bce885cc16ba3abb00fd03

[roll] Roll fuchsia [fidl][cpp] Stable Encode API for wire types

The primary goal is two-fold:

- Disallow the user from specifying the wire format version. This will
  help us in any future potential wire format changes since the FIDL
  library will be in control of which version to use.
- Simplify the API. The many {Unowned,Owned}EncodedMessage classes have
  a very convoluted API. This CL brings us something much simpler:

    fidl::OwnedEncodeResult result = fidl::Encode(some_object);

It's done by generalizing the existing natural type encoding API to wire
types, using a type erasure helper to hold the different message types.
If the user passes a natural domain object to |fidl::Encode|, it would
internally use the natural encoding logic. If the user passes a wire
domain object, it would use the wire encoding logic.

Performance: the IPC messaging code would not be using |fidl::Encode|.
Instead, it would use the more complicated {Unowned,Owned}EncodedMessage
and also activate vectorization. Thus we are not yet benchmarking
|fidl::Encode|. However, we can measure the performance by changing
the fast UDP library, which does utilize direct encoding, over to this
API in I8e3a684bf872f9a89df9be9fc445203db57655a6. It adds at most 33
nanoseconds of overhead, which is expected of the type erasure
abstraction but not that ideal. I found that there's a bug in our inline
buffer allocation condition -- it checks if the V1 size is bigger than
512 bytes, instead of V2 which is what's being used in practice. After
fixing that, the RecvMsgMeta encoding buffer is allocated inline instead
of boxed. That makes it >100ns faster.

Benchmarks are reproduced here (best viewed if copy out of the gerrit website):

Performance (PS 6): tested changing the fast UDP library over to this API in
I8e3a684bf872f9a89df9be9fc445203db57655a6. It adds at most 33
nanoseconds of overhead.

  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv4/Empty                 slower   1.074-1.089    411.16 +/- 0.46 ns  444.7 +/- 2.5 ns
  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv4/Full                  slower   1.049-1.079    533.2 +/- 5.1 ns    567.2 +/- 2.4 ns
  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv6/Empty                 slower   1.070-1.085    413.6 +/- 2.5 ns    445.58 +/- 0.40 ns
  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv6/Full                  slower   1.038-1.071    557.8 +/- 5.9 ns    588.1 +/- 3.0 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv4/Empty  slower   1.045-1.056    515.5 +/- 2.2 ns    541.67 +/- 0.51 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv4/Full   slower   1.030-1.043    759.8 +/- 4.0 ns    787.34 +/- 0.65 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv6/Empty  slower   1.051-1.055    516.34 +/- 0.80 ns  543.68 +/- 0.28 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv6/Full   slower   1.027-1.042    796.8 +/- 4.0 ns    824.6 +/- 1.8 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv4/Empty                 slower   1.067-1.094    235.37 +/- 0.78 ns  254.2 +/- 2.4 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv4/Full                  slower   1.057-1.072    319.7 +/- 2.1 ns    340.40 +/- 0.18 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv6/Empty                 slower   1.060-1.093    235.3 +/- 1.2 ns    253.3 +/- 2.6 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv6/Full                  slower   1.062-1.068    330.73 +/- 0.48 ns  352.17 +/- 0.46 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv4/Empty  slower   1.069-1.075    298.59 +/- 0.73 ns  320.01 +/- 0.15 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv4/Full   slower   1.040-1.053    503.43 +/- 0.75 ns  526.9 +/- 2.4 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv6/Empty  slower   1.072-1.075    298.20 +/- 0.26 ns  319.98 +/- 0.17 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv6/Full   slower   1.041-1.047    537.97 +/- 0.77 ns  561.65 +/- 0.60 ns

Performance (PS 7, after adding some optimizations):

  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv4/Empty                 slower   1.050-1.091    327.5 +/- 4.8 ns  350.5 +/- 1.6 ns
  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv6/Empty                 slower   1.053-1.101    328.4 +/- 6.2 ns  353.5 +/- 1.2 ns
  fuchsia.network.udp_serde: RecvMsgMeta/Serialize/IPv6/Full                  slower   1.009-1.082    468 +/- 15 ns     488.9 +/- 1.3 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv4/Empty  slower   1.029-1.082    427.8 +/- 6.2 ns  451.5 +/- 4.8 ns
  fuchsia.network.udp_serde: RecvMsgMeta/SerializeThenDeserialize/IPv6/Empty  slower   1.028-1.082    429.6 +/- 5.6 ns  453.2 +/- 5.8 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv4/Empty                 slower   1.102-1.192    236.3 +/- 8.4 ns  270.7 +/- 1.0 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv4/Full                  slower   1.078-1.131    319.5 +/- 7.5 ns  352.71 +/- 0.17 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv6/Empty                 slower   1.093-1.201    235.9 +/- 8.8 ns  270.1 +/- 2.6 ns
  fuchsia.network.udp_serde: SendMsgMeta/Serialize/IPv6/Full                  slower   1.074-1.113    331.8 +/- 5.6 ns  362.81 +/- 0.35 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv4/Empty  slower   1.088-1.145    298.5 +/- 7.4 ns  333.07 +/- 0.29 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv4/Full   slower   1.058-1.072    503.6 +/- 3.0 ns  536.21 +/- 0.26 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv6/Empty  slower   1.096-1.153    298.5 +/- 7.1 ns  335.41 +/- 0.45 ns
  fuchsia.network.udp_serde: SendMsgMeta/SerializeThenDeserialize/IPv6/Full   slower   1.050-1.070    545.0 +/- 4.3 ns  577.64 +/- 0.87 ns

Original-Bug: 82681
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/756422
Original-Revision: ee79d6b197b5041de04178fbda04faafc23c832c
GitOrigin-RevId: 08f97bce4c6fc1d2553beeb8127811e35406182c
Change-Id: Ide6fa40bf61238d2f27d03be2f45aff0ebb9d802