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flutter / third_party / protobuf / 1cf8214e4daa1d0dd9777c987697e82c2a3c6584
commit1cf8214e4daa1d0dd9777c987697e82c2a3c6584[log] [tgz]
authorJoshua Haberman <haberman@google.com>Thu May 12 13:57:50 2022 -0700
committerCopybara-Service <copybara-worker@google.com>Thu May 12 13:58:19 2022 -0700
treeb970759a2481eafc5b8e74cdc67f5d8881beeadf
parentc3cfd09b0184bcbdade71a3d788df02c83e897f2 [diff]
Changed upb's arena alignment from 16 to 8.

upb has traditionally returned 16-byte-aligned pointers from arena allocation.  This was out of an abundance of caution, since users could theoretically be using upb arenas to allocate memory that is then used for SSE/AVX values (eg. [`__m128`](https://docs.microsoft.com/en-us/cpp/cpp/m128?view=msvc-170), which require 16-byte alignment.

In practice, the protobuf C++ arena has used 8-byte alignment for 8 years with no significant problems I know of arising from SSE etc.

Reducing the alignment requirement to 8 will save memory.  It will also help with compatibility on 32-bit architectures where `malloc()` only returns 8-byte aligned memory.  The immediate motivation is to fix the win32 build for Python protobuf.

PiperOrigin-RevId: 448331777
7 files changed
tree: b970759a2481eafc5b8e74cdc67f5d8881beeadf
  1. .bazelci/
  2. .github/
  3. bazel/
  4. benchmarks/
  5. cmake/
  6. docs/
  7. python/
  8. third_party/
  9. upb/
  10. upbc/
  11. .bazelignore
  12. .bazelrc
  13. .clang-format
  14. .gitignore
  15. BUILD
  16. CONTRIBUTING.md
  17. DESIGN.md
  18. LICENSE
  19. README.md
  20. WORKSPACE
README.md

μpb: small, fast C protos

μpb (often written ‘upb’) is a small protobuf implementation written in C.

upb is the core runtime for protobuf languages extensions in Ruby, PHP, and (soon) Python.

While upb offers a C API, the C API & ABI are not stable. For this reason, upb is not generally offered as a C library for direct consumption, and there are no releases.

Features

upb has comparable speed to protobuf C++, but is an order of magnitude smaller in code size.

Like the main protobuf implementation in C++, it supports:

  • a generated API (in C)
  • reflection
  • binary & JSON wire formats
  • text format serialization
  • all standard features of protobufs (oneofs, maps, unknown fields, extensions, etc.)
  • full conformance with the protobuf conformance tests

upb also supports some features that C++ does not:

  • optional reflection: generated messages are agnostic to whether reflection will be linked in or not.
  • no global state: no pre-main registration or other global state.
  • fast reflection-based parsing: messages loaded at runtime parse just as fast as compiled-in messages.

However there are a few features it does not support:

  • text format parsing
  • deep descriptor verification: upb's descriptor validation is not as exhaustive as protoc.

Install

For Ruby, use RubyGems:

$ gem install google-protobuf

For PHP, use PECL:

$ sudo pecl install protobuf

Alternatively, you can build and install upb using vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
./vcpkg install upb

The upb port in vcpkg is kept up to date by microsoft team members and community contributors.

If the version is out of date, please create an issue or pull request on the vcpkg repository.

Contributing

Please see CONTRIBUTING.md.