(for upgrading users, please see the notes at the bottom)
Bazel brought a lot of nice things to the table, such as rebuilds based on
content changes instead of modification times, caching of build products,
detection of incorrect build rules via a sandbox, and so on. Rewriting the build
in Bazel was also an opportunity to improve on the Makefile-based build we had
prior, which was pretty poor: most dependencies were external or not pinned, and
the build graph was poorly defined and mostly serialized. It was not uncommon
for fresh checkouts to fail due to floating dependencies, or for things to break
when trying to switch to an older commit.
For day-to-day development, I think Bazel served us reasonably well - we could
generally switch between branches while being confident that builds would be
correct and reasonably fast, and not require full rebuilds (except on Windows,
where the lack of a sandbox and the TS rules would cause build breakages when TS
files were renamed/removed).
Bazel achieves that reliability by defining rules for each programming language
that define how source files should be turned into outputs. For the rules to
work with Bazel's sandboxing approach, they often have to reimplement or
partially bypass the standard tools that each programming language provides. The
Rust rules call Rust's compiler directly for example, instead of using Cargo,
and the Python rules extract each PyPi package into a separate folder that gets
added to sys.path.
These separate language rules allow proper declaration of inputs and outputs,
and offer some advantages such as caching of build products and fine-grained
dependency installation. But they also bring some downsides:
- The rules don't always support use-cases/platforms that the standard language
tools do, meaning they need to be patched to be used. I've had to contribute a
number of patches to the Rust, Python and JS rules to unblock various issues.
- The dependencies we use with each language sometimes make assumptions that do
not hold in Bazel, meaning they either need to be pinned or patched, or the
language rules need to be adjusted to accommodate them.
I was hopeful that after the initial setup work, things would be relatively
smooth-sailing. Unfortunately, that has not proved to be the case. Things
frequently broke when dependencies or the language rules were updated, and I
began to get frustrated at the amount of Anki development time I was instead
spending on build system upkeep. It's now about 2 years since switching to
Bazel, and I think it's time to cut losses, and switch to something else that's
a better fit.
The new build system is based on a small build tool called Ninja, and some
custom Rust code in build/. This means that to build Anki, Bazel is no longer
required, but Ninja and Rust need to be installed on your system. Python and
Node toolchains are automatically downloaded like in Bazel.
This new build system should result in faster builds in some cases:
- Because we're using cargo to build now, Rust builds are able to take advantage
of pipelining and incremental debug builds, which we didn't have with Bazel.
It's also easier to override the default linker on Linux/macOS, which can
further improve speeds.
- External Rust crates are now built with opt=1, which improves performance
of debug builds.
- Esbuild is now used to transpile TypeScript, instead of invoking the TypeScript
compiler. This results in faster builds, by deferring typechecking to test/check
time, and by allowing more work to happen in parallel.
As an example of the differences, when testing with the mold linker on Linux,
adding a new message to tags.proto (which triggers a recompile of the bulk of
the Rust and TypeScript code) results in a compile that goes from about 22s on
Bazel to about 7s in the new system. With the standard linker, it's about 9s.
Some other changes of note:
- Our Rust workspace now uses cargo-hakari to ensure all packages agree on
available features, preventing unnecessary rebuilds.
- pylib/anki is now a PEP420 implicit namespace, avoiding the need to merge
source files and generated files into a single folder for running. By telling
VSCode about the extra search path, code completion now works with generated
files without needing to symlink them into the source folder.
- qt/aqt can't use PEP420 as it's difficult to get rid of aqt/__init__.py.
Instead, the generated files are now placed in a separate _aqt package that's
added to the path.
- ts/lib is now exposed as @tslib, so the source code and generated code can be
provided under the same namespace without a merging step.
- MyPy and PyLint are now invoked once for the entire codebase.
- dprint will be used to format TypeScript/json files in the future instead of
the slower prettier (currently turned off to avoid causing conflicts). It can
automatically defer to prettier when formatting Svelte files.
- svelte-check is now used for typechecking our Svelte code, which revealed a
few typing issues that went undetected with the old system.
- The Jest unit tests now work on Windows as well.
If you're upgrading from Bazel, updated usage instructions are in docs/development.md and docs/build.md. A summary of the changes:
- please remove node_modules and .bazel
- install rustup (https://rustup.rs/)
- install rsync if not already installed (on windows, use pacman - see docs/windows.md)
- install Ninja (unzip from https://github.com/ninja-build/ninja/releases/tag/v1.11.1 and
place on your path, or from your distro/homebrew if it's 1.10+)
- update .vscode/settings.json from .vscode.dist
The old `media_files_did_export` hook has been kept around for use with
the legacy apkg exporter (an add-on uses it), and a new
`legacy_export_progress` hook has been added so we can get progress
from the new colpkg exporter until we move over fully to the new code.
The _pb2 files are built for both the host and target architectures
(which seems superfluous - we may be able to fix that in the future).
Our script wrote the files into the build folder and then moved them
into the correct place, but because builds are not sandboxed on Windows,
the two actions were racy, and could cause each other to fail. Solved
by writing the files directly into their target locations.
* The importer list have a Hook
Previously, add-on 175027074 simply edited the list once. It became impossible
since the list became a function. Hence I need a filter to add the list here.
@kelciour (nice to meet you by the way), you may be interested by it too (at
least if I believe efb1ce46d4 )
I would have preferred to use `anki.importing.base.Importer` instead of
`Any`. However, this leads to
> Name "anki.importing.base.Importer" is not defined [name-defined]
when I run test.
Helps to solve this would be welcomed
* mention the hook may not last too long (dae)
* Add py3.9 to hooks
This follows examples from efb1ce46d4 I assume the
hooks were missed because those were not considered types but strings.
I did not even try to run pyupgrade and did the change manually, then used bazel format
* remove wildcard import in find.py, and change Any to object (dae)
It's a tiny library that has not been updated in years, and it was
leading to a warning on startup:
DeprecationWarning: invalid escape sequence \W
return re.sub("\W+", "", string)
This adds Python 3.9 and 3.10 typing syntax to files that import
attributions from __future___. Python 3.9 should be able to cope with
the 3.10 syntax, but Python 3.8 will no longer work.
On Windows/Mac, install the latest Python 3.9 version from python.org.
There are currently no orjson wheels for Python 3.10 on Windows/Mac,
which will break the build unless you have Rust installed separately.
On Linux, modern distros should have Python 3.9 available already. If
you're on an older distro, you'll need to build Python from source first.
In order to split backend.proto into a more manageable size, the protobuf
handling needed to be updated. This took more time than I would have
liked, as each language handles protobuf differently:
- The Python Protobuf code ignores "package" directives, and relies
solely on how the files are laid out on disk. While it would have been
nice to keep the generated files in a private subpackage, Protobuf gets
confused if the files are located in a location that does not match
their original .proto layout, so the old approach of storing them in
_backend/ will not work. They now clutter up pylib/anki instead. I'm
rather annoyed by that, but alternatives seem to be having to add an extra
level to the Protobuf path, making the other languages suffer, or trying
to hack around the issue by munging sys.modules.
- Protobufjs fails to expose packages if they don't start with a capital
letter, despite the fact that lowercase packages are the norm in most
languages :-( This required a patch to fix.
- Rust was the easiest, as Prost is relatively straightforward compared
to Google's tools.
The Protobuf files are now stored in /proto/anki, with a separate package
for each file. I've split backend.proto into a few files as a test, but
the majority of that work is still to come.
The Python Protobuf building is a bit of a hack at the moment, hard-coding
"proto" as the top level folder, but it seems to get the job done for now.
Also changed the workspace name, as there seems to be a number of Bazel
repos moving away from the more awkward reverse DNS naming style.
The explicit flush was clearing undo history, and the hook will need
re-working to support propagating OpChanges correctly. It will likely
come back as a GUI hook, instead of one in pylib.
- QueueConfig is only used by the scheduler
- DeckConfig was being used in places that Config should have been used
- Add "Dict" to the name so that the bare name is free for use with a
stronger type.
- anki._backend stores the protobuf files and rsbackend.py code
- pylib modules import protobuf messages directly from the
_pb2 files, and explicitly export any will be returned or consumed
by public pylib functions, so that calling code can import from pylib
- the "rsbackend" no longer imports and re-exports protobuf messages
- pylib can just consume them directly.
- move errors to errors.py
Still todo:
- rsbridge
- finishing the work on rsbackend, and check what we need to add
back to the original file location to avoid breaking add-ons
Running and testing should be working on the three platforms, but
there's still a fair bit that needs to be done:
- Wheel building + testing in a venv still needs to be implemented.
- Python requirements still need to be compiled with piptool and pinned;
need to compile on all platforms then merge
- Cargo deps in cargo/ and rslib/ need to be cleaned up, and ideally
unified into one place
- Currently using rustls to work around openssl compilation issues
on Linux, but this will break corporate proxies with custom SSL
authorities; need to conditionally use openssl or use
https://github.com/seanmonstar/reqwest/pull/1058
- Makefiles and docs still need cleaning up
- It may make sense to reparent ts/* to the top level, as we don't
nest the other modules under a specific language.
- rspy and pylib must always be updated in lock-step, so merging
rspy into pylib as a private module would simplify things.
- Merging desktop-ftl and mobile-ftl into the core ftl would make
managing and updating translations easier.
- Obsolete scripts need removing.
- And probably more.
