Commit graph

12 commits

Author SHA1 Message Date
Aspen Smith
780b47193a refactor(tvix/eval): Generalize propagation of catchable values
Rather than explicitly checking for Value::Catchable in all builtins,
make the #[builtin] proc macro insert this for all strict arguments by
default, with support for a #[catch] attribute on the argument to
disable this behavior. That attribute hasn't actually been *used*
anywhere here, primarily because the tests pass without it, even for
those builtins which weren't previously checking for Value::Catchable -
if some time passes without this being used I might get rid of support
for it entirely.

There's also a `try_value` macro in builtins directly for the places
where builtins were eg forcing something, then explicitly propagating a
catchable value.

Change-Id: Ie22037b9d3e305e3bdb682d105fe467bd90d53e9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10732
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2024-02-08 19:59:21 +00:00
Vincent Ambo
b3b1f649d6 chore(tvix): fix trivial clippy lints
Relates to b/321.

Change-Id: I37284f89b186e469eb432e2bbedb37aa125a6ad4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9961
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>
2023-11-05 20:28:37 +00:00
Evgeny Zemtsov
c8fcdca4eb feat(tvix/eval): allow extending builtins outside of tvix_eval
The change allows applications that use tvix_serde for parsing
nix-based configuration to extend the language with domain-specific
set of features.

Change-Id: Ia86612308a167c456ecf03e93fe0fbae55b876a6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8848
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2023-06-22 20:19:06 +00:00
Vincent Ambo
025c67bf4d refactor(tvix/eval): flatten call stack of VM using generators
Warning: This is probably the biggest refactor in tvix-eval history,
so far.

This replaces all instances of trampolines and recursion during
evaluation of the VM loop with generators. A generator is an
asynchronous function that can be suspended to yield a message (in our
case, vm::generators::GeneratorRequest) and receive a
response (vm::generators::GeneratorResponsee).

The `genawaiter` crate provides an interpreter for generators that can
drive their execution and lets us move control flow between the VM and
suspended generators.

To do this, massive changes have occured basically everywhere in the
code. On a high-level:

1. The VM is now organised around a frame stack. A frame is either a
   call frame (execution of Tvix bytecode) or a generator frame (a
   running or suspended generator).

   The VM has an outer loop that pops a frame off the frame stack, and
   then enters an inner loop either driving the execution of the
   bytecode or the execution of a generator.

   Both types of frames have several branches that can result in the
   frame re-enqueuing itself, and enqueuing some other work (in the
   form of a different frame) on top of itself. The VM will eventually
   resume the frame when everything "above" it has been suspended.

   In this way, the VM's new frame stack takes over much of the work
   that was previously achieved by recursion.

2. All methods previously taking a VM have been refactored into async
   functions that instead emit/receive generator messages for
   communication with the VM.

   Notably, this includes *all* builtins.

This has had some other effects:

- Some test have been removed or commented out, either because they
  tested code that was mostly already dead (nix_eq) or because they
  now require generator scaffolding which we do not have in place for
  tests (yet).

- Because generator functions are technically async (though no async
  IO is involved), we lose the ability to use much of the Rust
  standard library e.g. in builtins. This has led to many algorithms
  being unrolled into iterative versions instead of iterator
  combinations, and things like sorting had to be implemented from scratch.

- Many call sites that previously saw a `Result<..., ErrorKind>`
  bubble up now only see the result value, as the error handling is
  encapsulated within the generator loop.

  This reduces number of places inside of builtin implementations
  where error context can be attached to calls that can fail.
  Currently what we gain in this tradeoff is significantly more
  detailed span information (which we still need to bubble up, this
  commit does not change the error display).

  We'll need to do some analysis later of how useful the errors turn
  out to be and potentially introduce some methods for attaching
  context to a generator frame again.

This change is very difficult to do in stages, as it is very much an
"all or nothing" change that affects huge parts of the codebase. I've
tried to isolate changes that can be isolated into the parent CLs of
this one, but this change is still quite difficult to wrap one's mind
and I'm available to discuss it and explain things to any reviewer.

Fixes: b/238, b/237, b/251 and potentially others.
Change-Id: I39244163ff5bbecd169fe7b274df19262b515699
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8104
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00
Vincent Ambo
7d0456fa0e feat(tvix/eval): let builtin macro capture external state
This adds a feature to the `#[builtins]` macro which lets users
specify an additional state type to (optionally) thread through to
builtins when constructing them.

This makes it possible for builtins-macro users to pass external state
handles (specifically, in our case, known path tracking) into a set of
builtins.

Change-Id: I3ade20d333fc3ba90a80822cdfa5f87a9cfada75
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7840
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-01-20 15:39:51 +00:00
Vincent Ambo
f12f938166 refactor(tvix/eval): directly return builtin tuples from macro
All invocations of the builtin macro had to previously filter through
the `builtin_tuple` function, but it's more sensible to directly
return these from the macro.

Change-Id: I45600ba84d56c9528d3e92570461c319eea595ce
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7825
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
2023-01-20 15:39:51 +00:00
Vincent Ambo
88432235ae fix(tvix/eval): VM & Builtin* types have to be public
... without them, using the new Builtins API is basically impossible
for library consumers.

Change-Id: Ice0557a2e55e12d812f51bf5a99e6b8c91ad1b91
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7755
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-01-06 12:15:23 +00:00
Vincent Ambo
908cebf35c fix(tvix/builtin-macros): parse multi-line docstrings correctly
Having a multi-line docstring yields multiple doc-attributes in order,
however we were previously discarding all but the first one.

This reduces them into a single string instead, which can then be
displayed as multi-line documentation.

Change-Id: I1f237956cdea2e4c746d3f13744e0373c1c645a6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7594
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2022-12-21 23:05:22 +00:00
Griffin Smith
76d7671c8a feat(tvix/eval): Add docstrings as documentation for builtins
Add a new `documentation: Option<&'static str>` field to Builtin, and
populate it in the `#[builtins]` macro with the docstring of the builtin
function, if any.

Change-Id: Ic68fdf9b314d15a780731974234e2ae43f6a44b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7205
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2022-11-08 13:42:37 +00:00
Griffin Smith
a1015ba1d7 feat(tvix/eval): Give names to builtin arguments
Refactor the arguments of a Builtin to be a vec of a new BuiltinArgument
struct, which contains the old strictness boolean and also a static
`name` str - this is automatically determined via the ident for the
corresponding function argument in the proc-macro case, and passed in in
the cases where we're still manually calling Builtin::new.

Currently this name is unused, but in the future this can be used as
part of a documentation system for builtins.

Change-Id: Ib9dadb15b69bf8c9ea1983a4f4f197294a2394a6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7204
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2022-11-08 13:42:37 +00:00
Griffin Smith
dad07a8bc0 refactor(tvix/eval): Be clearer about public interface
Some new top-level re-exports (specifically VM, Builtin, and ErrorKind)
were added to lib.rs in tvix/eval to allow the builtin-macros tests to
work - we should be clear which of these are part of the public
interface (I think it's reasonable for ErrorKind to be) and which
aren't (specifically I'm not sure VM and Builtin necessarily should be,
at least yet).

Change-Id: I3bbeaa63cdda9227224cd3bc298a9bb8da4deb7c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7203
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2022-11-08 13:42:37 +00:00
Griffin Smith
645d0c06e5 feat(tvix/eval): Add a proc-macro for defining builtins
Add a single new proc macro to a new proc-macro crate,
`tvix-eval-proc-macros` for defining an inline module containing nix
builtins, and automatically generating a function within that module
which returns a list of those builtins as `tvix_eval::value::Builtin`.

Change-Id: Ie4afae438914d2af93d15637151a49b4c68aa352
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7198
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
2022-11-08 13:42:37 +00:00