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2024-08-09 r/8466 feat(tvix/eval): Implement builtins.readFileTypeIlan Joselevich1-0/+12
builtins.readFileType was added to Nix back in version 2.14. The tests were also moved out of notyetpassing in addition to the readDir fixtures they depend on. I caught a bug where we previously used std::fs::metadata (via the .metadata() method on File) which follows symlinks so it would always return false for is_symlink(). Instead we now use std::fs::symlink_metadata directly which does not follow symlinks, so tests now pass. This wasn't an issue for builtins.readDir as it uses walkdir and walkdir doesn't follow symlinks either. Change-Id: I58eb97bdb5ec95df4f6882f495f8c572fe7c6793 Reviewed-on: https://cl.tvl.fyi/c/depot/+/12130 Reviewed-by: flokli <flokli@flokli.de> Autosubmit: Ilan Joselevich <personal@ilanjoselevich.com> Tested-by: BuildkiteCI
2024-08-09 r/8463 feat(tvix/eval): Implement Display for io::FileTypeIlan Joselevich1-7/+1
In newer versions of Nix there's a builtins.readFileType builtin, we should try to avoid duplicating the enum -> string conversion by implementating Display before we implement builtins.readFileType. Change-Id: I579e95949a76eb33d2e7bda0000ed84859df765e Reviewed-on: https://cl.tvl.fyi/c/depot/+/12129 Reviewed-by: flokli <flokli@flokli.de> Autosubmit: Ilan Joselevich <personal@ilanjoselevich.com> Tested-by: BuildkiteCI
2024-04-28 r/8025 chore(3p/sources): Bump channels & overlayssterni1-1/+1
- //tvix: address new clippy lints - //users/tazjin: Satisfy gonic module's new need for a playlist folder. - //users/aspen/games: adjust for changed location of df's default init.txt and d_init.txt. Change-Id: I00a2adb506ae866206fb6f88c39c9a6af320380f Reviewed-on: https://cl.tvl.fyi/c/depot/+/11509 Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI Reviewed-by: aspen <root@gws.fyi>
2024-04-09 r/7882 fix(tvix): Avoid buffering file into memory in builtins.hashFileConnor Brewster1-5/+10
Right now `builtins.hashFile` always reads the entire file into memory before hashing, which is not ideal for large files. This replaces `read_to_string` with `open_file` which allows calculating the hash of the file without buffering it entirely into memory. Other callers can continue to buffer into memory if they choose, but they still use the `open_file` VM request and then call `read_to_string` or `read_to_end` on the `std::io::Reader`. Fixes b/380 Change-Id: Ifa1c8324bcee8f751604b0b449feab875c632fda Reviewed-on: https://cl.tvl.fyi/c/depot/+/11236 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2024-02-29 r/7625 feat(tvix/eval): implement `builtins.hashFile`Padraic-O-Mhuiris1-1/+12
The primary addition is the `builtin_hashFile` function which attempts value-path coercion and on success reads the file to a nix_string. Similar to the `builtins_hashString` implementation, the hash is then derived using the `hash_nix_string` function in the introduced hash module which has extracted hashing functionality initially specified in cl/11005. Change-Id: I5e3ef0317223af99488ebb79efc2fb49b4cbc1b6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/11007 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2024-02-13 r/7508 feat(tvix/eval): Box Value::CatchableAspen Smith1-3/+3
This is now the only enum variant for Value that is larger than 8 bytes (it's 16 bytes), so boxing it (especially since it's not perf-critical) allows us to get the Value size down to only 16 bytes! Change-Id: I98598e2b762944448bef982e8ff7da6d6683c4aa Reviewed-on: https://cl.tvl.fyi/c/depot/+/10798 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz> Autosubmit: aspen <root@gws.fyi>
2024-02-02 r/7467 refactor(tvix/eval): Box Value::StringAspen Smith1-9/+6
NixString is *quite* large - like 80 bytes - because of the extra capacity value for BString and because of the context. We want to keep Value small since we're passing it around a lot, so let's box the NixString inside Value::String to save on some memory, and make cloning ostensibly a little cheaper Change-Id: I343c8b4e7f61dc3dcbbaba4382efb3b3e5bbabb2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/10729 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2024-01-31 r/7460 fix(tvix): Represent strings as byte arraysAspen Smith1-1/+6
C++ nix uses C-style zero-terminated char pointers to represent strings internally - however, up to this point, tvix has used Rust `String` and `str` for string values. Since those are required to be valid utf-8, we haven't been able to properly represent all the string values that Nix supports. To fix that, this change converts the internal representation of the NixString struct from `Box<str>` to `BString`, from the `bstr` crate - this is a wrapper around a `Vec<u8>` with extra functions for treating that byte vector as a "morally string-like" value, which is basically exactly what we need. Since this changes a pretty fundamental assumption about a pretty core type, there are a *lot* of changes in a lot of places to make this work, but I've tried to keep the general philosophy and intent of most of the code in most places intact. Most notably, there's nothing that's been done to make the derivation stuff in //tvix/glue work with non-utf8 strings everywhere, instead opting to just convert to String/str when passing things into that - there *might* be something to be done there, but I don't know what the rules should be and I don't want to figure them out in this change. To deal with OS-native paths in a way that also works in WASM for tvixbolt, this also adds a dependency on the "os_str_bytes" crate. Fixes: b/189 Fixes: b/337 Change-Id: I5e6eb29c62f47dd91af954f5e12bfc3d186f5526 Reviewed-on: https://cl.tvl.fyi/c/depot/+/10200 Reviewed-by: tazjin <tazjin@tvl.su> Reviewed-by: flokli <flokli@flokli.de> Reviewed-by: sterni <sternenseemann@systemli.org> Autosubmit: aspen <root@gws.fyi> Tested-by: BuildkiteCI
2023-09-24 r/6650 fix(tvix/eval): fix b/281 by adding Value::CatchableAdam Joseph1-25/+32
This commit makes catchable errors a variant of Value. The main downside of this approach is that we lose the ability to use Rust's `?` syntax for propagating catchable errors. Change-Id: Ibe89438d8a70dcec29e016df692b5bf88a5cad13 Reviewed-on: https://cl.tvl.fyi/c/depot/+/9289 Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI
2023-07-22 r/6439 feat(tvix/store/proto): use Bytes instead of Vec<u8>Florian Klink1-2/+4
Makes use of https://github.com/tokio-rs/prost/pull/341, which makes our bytes field cheaper to clone. It's a bit annoying to configure due to https://github.com/hyperium/tonic/issues/908, but the workaround does get the job done. Change-Id: I25714600b041bb5432d3adf5859b151e72b12778 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8975 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: flokli <flokli@flokli.de>
2023-07-21 r/6436 refactor(tvix/store): use bytes for node names and symlink targetsFlorian Klink1-1/+2
Some paths might use names that are not valid UTF-8. We should be able to represent them. We don't actually need to touch the PathInfo structures, as they need to represent StorePaths, which come with their own harder restrictions, which can't encode non-UTF8 data. While this doesn't change any of the wire format of the gRPC messages, it does however change the interface of tvix_eval::EvalIO - its read_dir() method does now return a list of Vec<u8>, rather than SmolStr. Maybe this should be OsString instead? Change-Id: I821016d9a58ec441ee081b0b9f01c9240723af0b Reviewed-on: https://cl.tvl.fyi/c/depot/+/8974 Autosubmit: flokli <flokli@flokli.de> Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-06-22 r/6344 feat(tvix/eval): allow extending builtins outside of tvix_evalEvgeny Zemtsov1-0/+1
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
2023-03-13 r/5968 chore(tvix/eval): remove `From<SmolStr> for NixString` instanceVincent Ambo1-5/+4
No longer needed, and in some cases caused some extra work. Change-Id: I64e8e7292573bdc92a9c7a8e470e33f8c526f311 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8152 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-13 r/5964 refactor(tvix/eval): flatten call stack of VM using generatorsVincent Ambo1-13/+19
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
2023-03-04 r/5888 refactor(tvix/eval): remove VM argument from suspended native thunksVincent Ambo1-7/+1
Because they do not use it, and it can not be passed with the coming generator refactoring. Change-Id: I0d96f2357a7ee79cd8a0f401583d4286230d4a6b Reviewed-on: https://cl.tvl.fyi/c/depot/+/8146 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-04 r/5887 refactor(tvix/eval): insert storeDir "builtin" in eval startupVincent Ambo1-10/+0
Instead of using a suspended native thunk, calculate and optionally insert the storeDir builtin when the VM is constructed. We already have the IO handle available at this point and can just check whether a storeDir is present, and insert its absolute value as a builtin. Change-Id: If966eee6ff26dc888b6e888e7c46170c0c346b05 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8145 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-02-03 r/5828 fix(tvix/eval): ensure all evaluated thunks are correctly memoizedVincent Ambo1-2/+1
This fixes a very complicated bug (b/246). Evaluation progresses *much* further after this, leading to several less complicated bugs likely being uncovered by this What was the problem? ===================== Previously, when evaluating a thunk, we had a code path that looked like this: match *thunk { ThunkRepr::Evaluated(Value::Thunk(ref inner_thunk)) => { let inner_repr = inner_thunk.0.borrow().clone(); drop(thunk); self.0.replace(inner_repr); } /* ... */ } This code path created a copy of the inner `ThunkRepr` of a nested thunk, and moved that copy into the `ThunkRepr` of the parent. The effect of this was that the original `ThunkRepr` (unforced!) lived on in the original thunk, without the memoization of the subsequent forcing applying to it. This had the result that Tvix would repeatedly evaluate these thunks without ever memoizing them, if they occured repeatedly as shared inner thunks. Most notably, this would *always* occur when builtins.import was used. What's the solution? ==================== I have completely rewritten `Thunk::force_trampoline_self` to make all flows that can occur in it explicit. I have also removed the outer loop inside of that function, and resorted to more use of trampolining instead. The function is now well-commented and it should be possible to read it from top-to-bottom and get a general sense of what is going on, though the trampolining itself (which is implemented in the VM) needs to be at least partially understood for this. What's the new problem(s)? ========================== One new (known) problem is that we have to construct `Error` instances in all error types here, but we do not have spans available in some thunk-related situations. Due to b/238 we cannot ask the VM for an arbitrary span from the callsite leading to the force. This means that there are now code paths where, under certain conditions, causing an evaluation error during thunk forcing will panic. To fix this we will need to investigate and fix b/238, and/or add a span tracking mechanism to thunks themselves. What other impacts does this have? ================================== With this commit, eval of nixpkgs mostly succeeds (things like stdenv evaluate to the same hashes for us and C++ Nix, meaning we now construct identical derivations without eval breaking). Due to this we progress much further into nixpkgs, which lets us uncover more additional bugs. For example, after this commit we can quickly see that cl/7949 introduces some kind of behavioural issue and should not be merged as-is (this was not apparent before). Additionally, tvix-eval is now seemingly very fast. When doing performance analysis of a nixpkgs eval, we now mostly see the code path for shelling out to C++ Nix to add things to the store in there. We still need those code paths, so we can not (yet) do a performance analysis beyond that. Change-Id: I738525bad8bc5ede5d8c737f023b14b8f4160612 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8012 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-20 r/5707 refactor(tvix/eval): directly return builtin tuples from macroVincent Ambo1-4/+1
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>
2023-01-17 r/5675 refactor(tvix/eval): remove `Box` in new_suspended_nativeVincent Ambo1-2/+2
This is unnecessary, Rc already provides all the boxing we need. Change-Id: I08cf0939c48da43f04c847526c7e5dae5336d528 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7749 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2023-01-04 r/5581 refactor(tvix/eval): streamline construction of globals/builtinsVincent Ambo1-100/+11
Previously the construction of globals (a compiler-only concept) and builtins (a (now) user-facing API) was intermingled between multiple different modules, and kind of difficult to understand. The complexity of this had grown in large part due to the implementation of `builtins.import`, which required the notorious "knot-tying" trick using Rc::new_cyclic (see cl/7097) for constructing the set of globals. As part of the new `Evaluation` API users should have the ability to bring their own builtins, and control explicitly whether or not impure builtins are available (regardless of whether they're compiled in or not). To streamline the construction and allow the new API features to work, this commit restructures things by making these changes: 1. The `tvix_eval::builtins` module is now only responsible for exporting sets of builtins. It no longer has any knowledge of whether or not certain sets (e.g. only pure, or pure+impure) are enabled, and it has no control over which builtins are globally available (this is now handled in the compiler). 2. The compiler module is now responsible for both constructing the final attribute set of builtins from the set of builtins supplied by a user, as well as for populating its globals (that is identifiers which are available at the top-level scope). 3. The `Evaluation` API now carries a `builtins` field which is populated with the pure builtins by default, and can be extended by users. 4. The `import` feature has been moved into the compiler, as a special case. In general, builtins no longer have the ability to reference the "fix point" of the globals set. This should not change any functionality, and in fact preserves minor differences between Tvix/Nix that we already had (such as `builtins.builtins` not existing). Change-Id: Icdf5dd50eb81eb9260d89269d6e08b1e67811a2c Reviewed-on: https://cl.tvl.fyi/c/depot/+/7738 Reviewed-by: sterni <sternenseemann@systemli.org> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2022-12-21 r/5466 refactor(tvix/eval): use light spans in builtins.importVincent Ambo1-6/+2
Change-Id: I05732073155b430575babb6f076bf465aef98857 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7581 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-12-21 r/5465 feat(tvix/eval): builtins.storeDirAdam Joseph1-1/+11
Returns the store directory through EvalIO::store_dir. Note that this is _optional_ in Tvix, as an evaluation can occur in a context where there simply is no store directory. In those contexts, `builtins.storeDir` returns `null` in Tvix. This would only happen in contexts like Tvixbolt (or completely unrelated use-cases) in practice. Co-Authored-By: Vincent Ambo <tazjin@tvl.su> Change-Id: I5a752c7e89b2f75bd7efb082dbfa5b25e3b1ff3b Reviewed-on: https://cl.tvl.fyi/c/depot/+/7452 Autosubmit: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-12-21 r/5464 refactor(tvix/eval): use `EvalIO::read_dir` for equivalent builtinVincent Ambo1-28/+20
Change-Id: I6d782c07166f51587d2f1d06607823268debb5d5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7574 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-12-21 r/5463 refactor(tvix/eval): use `EvalIO::path_exists` for the builtinVincent Ambo1-1/+2
Change-Id: I49822ce30137777865e7370ee86666636e277b35 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7573 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-12-21 r/5460 refactor(tvix/eval): use EvalIO::read_to_string in impure builtinsVincent Ambo1-21/+16
With this change, the behaviour of reading a string from a file path is controlled by the provided `EvalIO` structure. This is a huge step towards abstracting away I/O behaviour correctly. Change-Id: Ifde8e46cd863b16e0301dca45a434ad27560399f Reviewed-on: https://cl.tvl.fyi/c/depot/+/7567 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-12-21 r/5457 refactor(tvix/eval): add a LightSpan type for lighter span trackingVincent Ambo1-1/+2
This type carries the information required for calculating a span (i.e. the chunk and offset), instead of the span itself. The span is then only calculated in cases where it is required (when throwing errors). This reduces the eval time for `builtins.length (builtins.attrNames (import <nixpkgs> {}))` by *one third*! The data structure in chunks that carries span information reduces in-memory size by trading off the speed of retrieving span information. This is because the span information is only actually required when throwing errors (or emitting warnings). However, somewhere along the way we grew a dependency on carrying span information in thunks (for correctly reporting error chains). Hitting the code paths for span retrieval was expensive, and carrying the spans in a different way would still be less cache-efficient. This change is the best tradeoff I could come up with. Refs: b/229. Change-Id: I27d4c4b5c5f9be90ac47f2db61941e123a78a77b Reviewed-on: https://cl.tvl.fyi/c/depot/+/7558 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-12-03 r/5379 feat(tvix/eval): Continue removing leakage of BTreeMap.Lyle Mantooth1-25/+23
Fixes b/212. Based on feedback in https://cl.tvl.fyi/c/depot/+/7492, all uses of `NixAttrs::from_map` have been removed. Only `from_iter` and `from_kv` remain. Change-Id: I52e25f73018c2aa1843197427516b7a852503e2c Reviewed-on: https://cl.tvl.fyi/c/depot/+/7500 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Autosubmit: IslandUsurper <lyle@menteeth.us>
2022-12-02 r/5366 feat(tvix/eval): crude caching builtins.importAdam Joseph1-6/+16
Before this, tvix was spending most of its time furiously re-parsing and re-compiling nixpkgs, each time hoping to get a different result... Change-Id: I1c0cfbf9af622c276275b1f2fb8d4e976f1b5533 Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7361 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-11-08 r/5269 feat(tvix/eval): Add docstrings as documentation for builtinsGriffin Smith1-0/+1
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 r/5268 feat(tvix/eval): Give names to builtin argumentsGriffin Smith1-2/+5
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 r/5266 refactor(tvix/eval): Define impure builtins using the macroGriffin Smith1-48/+56
Similar to what we did with pure builtins, define the impure builtins within a module at the top-level using the new #[builtins] attribute macro Change-Id: Ie5d5135d00bb65e651531df6eadba642cd4eb08e Reviewed-on: https://cl.tvl.fyi/c/depot/+/7202 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-27 r/5213 feat(tvix/eval): builtins.import without RefCellAdam Joseph1-14/+24
CL/6867 added support for builtins.import, which required a cyclic reference import->globals->builtins->import. This was implemented using a RefCell, which makes it possible to mutate the builtins during evaluation. The commit message for CL/6867 expressed a desire to eliminate this possibility: This opens up a potentially dangerous footgun in which we could mutate the builtins at runtime leading to different compiler invocations seeing different builtins, so it'd be nice to have some kind of "finalised" status for them or some such, but I'm not sure how to represent that atm. This CL replaces the RefCell with Rc::new_cyclic(), making the globals/builtins immutable once again. At VM runtime (once opcodes start executing) everything is the same as before this CL, except that the Rc<RefCell<>> introduced by CL/6867 is turned into an rc::Weak<>. The function passed to Rc::new_cyclic works very similarly to overlays in nixpkgs: a function takes its own result as an argument. However instead of laziness "breaking the cycle", Rust's Rc::new_cyclic() instead uses an rc::Weak. This is done to prevent memory leaks rather than divergence. This CL also resolves the following TODO from CL/6867: // TODO: encapsulate this import weirdness in builtins The main disadvantage of this CL is the fact that the VM now must ensure that it holds a strong reference to the globals while a program is executing; failure to do so will cause a panic when the weak reference in the builtins is upgrade()d. In theory it should be possible to create strong reference cycles the same way Rc::new_cyclic() creates weak cycles, but these cycles would cause a permanent memory leak -- without either an rc::Weak or RefCell there is no way to break the cycle. At some point we will have to implement some form of cycle collection; whatever library we choose for that purpose is likely to provide an "immutable strong reference cycle" primitive similar to Rc::new_cyclic(), and we should be able to simply drop it in. Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: I34bb5821628eb97e426bdb880b02e2097402adb7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7097 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-19 r/5159 feat(tvix/eval): deduplicate overlap between Closure and ThunkAdam Joseph1-1/+4
This commit deduplicates the Thunk-like functionality from Closure and unifies it with Thunk. Specifically, we now have one and only one way of breaking reference cycles in the Value-graph: Thunk. No other variant contains a RefCell. This should make it easier to reason about the behavior of the VM. InnerClosure and UpvaluesCarrier are no longer necessary. This refactoring allowed an improvement in code generation: `Rc<RefCell<>>`s are now created only for closures which do not have self-references or deferred upvalues, instead of for all closures. OpClosure has been split into two separate opcodes: - OpClosure creates non-recursive closures with no deferred upvalues. The VM will not create an `Rc<RefCell<>>` when executing this instruction. - OpThunkClosure is used for closures with self-references or deferred upvalues. The VM will create a Thunk when executing this opcode, but the Thunk will start out already in the `ThunkRepr::Evaluated` state, rather than in the `ThunkRepr::Suspeneded` state. To avoid confusion, OpThunk has been renamed OpThunkSuspended. Thanks to @sterni for suggesting that all this could be done without adding an additional variant to ThunkRepr. This does however mean that there will be mutating accesses to `ThunkRepr::Evaluated`, which was not previously the case. The field `is_finalised:bool` has been added to `Closure` to ensure that these mutating accesses are performed only on finalised Closures. Both the check and the field are present only if `#[cfg(debug_assertions)]`. Change-Id: I04131501029772f30e28da8281d864427685097f Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7019 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-16 r/5141 fix(tvix/eval): don't coerce variable name to stringsterni1-3/+3
Change-Id: I8aa878dee009901feb453c489ce37c12fa3a31a8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7026 Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: Adam Joseph <adam@westernsemico.com> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-10 r/5097 fix(tvix/eval): Actually trace spans for thunksGriffin Smith1-1/+1
Currently, the span on *all* thunk force errors is the span at which the thunk is forced, which for recursive thunk forcing ends up just being the same span over and over again. This changes the span on thunk force errors to be the span at which point the thunk is *created*, which is a bit more helpful (though the printing atm is a little... crowded). To make this work, we have to thread through the span at which a thunk is created into a field on the thunk itself. Change-Id: I81474810a763046e2eb3a8f07acf7d8ec708824a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6932 Autosubmit: grfn <grfn@gws.fyi> Reviewed-by: Adam Joseph <adam@westernsemico.com> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-10 r/5096 feat(tvix/eval): Implement builtins.getEnvGriffin Smith1-1/+7
Change-Id: I09f512a60989a37184e73e521d4a3aa23f33a1a8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6922 Autosubmit: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI Reviewed-by: Adam Joseph <adam@westernsemico.com> Reviewed-by: kanepyork <rikingcoding@gmail.com>
2022-10-10 r/5095 feat(tvix/eval): Implement builtins.readFileGriffin Smith1-1/+7
Change-Id: If3fd0b087009a2bfbad8bb7aca0aa20de906eb12 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6921 Tested-by: BuildkiteCI Reviewed-by: Adam Joseph <adam@westernsemico.com> Reviewed-by: kanepyork <rikingcoding@gmail.com> Autosubmit: grfn <grfn@gws.fyi> Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-10 r/5088 feat(tvix/eval): Implement builtins.pathExistsGriffin Smith1-6/+7
Change-Id: Ife8a690e9036868964771893ab29a9ae3a2d2365 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6919 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-10 r/5083 feat(tvix/eval): Support builtins.readDirWilliam Carroll1-2/+39
Co-authored-by: Griffin Smith <root@gws.fyi> Change-Id: I5ff19efbe87d8f571f22ab0480500505afa624c5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6552 Autosubmit: wpcarro <wpcarro@gmail.com> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-08 r/5068 feat(tvix/tests): Import default.nix inside directoryGriffin Smith1-1/+4
This requires actually passing the source directory into `interpret` in the eval tests, but otherwise this is fairly straightforward - if we're trying to import a directory, just push `default.nix` onto it and import that instead. Change-Id: I0b7d4234f81977e78d14dfa651bf0cf9721017e5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6893 Autosubmit: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-10-08 r/5063 feat(tvix/eval): fancy-format parse errors returned by rnixVincent Ambo1-2/+3
This change is quite verbose, so a little bit of explaining: 1. To correctly format parse errors, errors must be able to return more than one annotated span (the parser returns a list of errors for each span). To accomplish this, the structure of how the `Diagnostic` struct which formats an error is constructed has changed to delegate the creation of the `SpanLabel` vector to the kind of error. 2. The rnix structures don't have human-readable output formats by default, so some verbose methods for formatting them in human-readable ways have been added in the errors module. We might want to move these out into a submodule. 3. In many cases, the errors returned by rnix are a bit strange - so while we format them with all information that is easily available they may look weird or not necessarily help users. Consider this CL only a first step in the right direction. Change-Id: Ie7dd74751af9e7ecb35d751f8b087aae5ae6e2e8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6871 Reviewed-by: sterni <sternenseemann@systemli.org> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-07 r/5050 feat(tvix/eval): coerce values to paths when importingVincent Ambo1-12/+1
This enables the use of string paths (and, in the future, derivations), as long as their string values represent an absolute path. Change-Id: I4b198efeb70415ed52f58bd1da6fa79a24dad14c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6866 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-10-07 r/5049 feat(tvix/eval): add method for emitting runtime warningsVincent Ambo1-4/+4
This lets the VM emit warnings when it encounters situations that should only be warned about at runtime. For starters, this is used to pass through compilation warnings that come up when `import` is used. Change-Id: I0c4bc8c534d699999887c430d93629fadfa662c4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6868 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-10-07 r/5048 feat(tvix/eval): insert `import` into the builtins itselfVincent Ambo1-2/+6
Adding `import` to builtins causes causes a bootstrap cycle because the `import` builtin needs to be initialised with the set of globals before being inserted into the globals, which also must contain itself. To break out of the cycle this hack wraps the builtins passed to the compiler in an `Rc` (probably sensible anyways, as they will end up getting cloned a bunch), containing a RefCell which gives us mutable access to the builtins. This opens up a potentially dangerous footgun in which we could mutate the builtins at runtime leading to different compiler invocations seeing different builtins, so it'd be nice to have some kind of "finalised" status for them or some such, but I'm not sure how to represent that atm. Change-Id: I25f8d4d2a7e8472d401c8ba2f4bbf9d86ab2abcb Reviewed-on: https://cl.tvl.fyi/c/depot/+/6867 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-06 r/5041 feat(tvix/eval): initial implementation of `builtins.import`Vincent Ambo1-5/+79
This adds an initial working version of builtins.import which encapsulates the entire functionality of `import` within the builtin itself, without requiring any changes in the compiler or VM. The key insight that enables this is that we can simply return a Thunk from `import` that is constructed from the output of running the compiler and - ta-da! - no other component needs to know about it. A couple of notes: * builtins.import needs to capture variables like the SourceCode structure. This means it can not currently be constructed the same way as other builtins and has special handling, which leaks out to `eval.rs`. I have postponed dealing with that until we have this working a bit more. * the `globals` are not yet passed through * the error representation for the new variants is absolutely not done yet, we probably want to switch to something that supports cause-chaining now (like miette) * there is no mechanism for emitting warnings at runtime; we need to add that Change-Id: I3117a7ae3ff2432bf44f5ff05ad35f47faca31d5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6857 Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: wpcarro <wpcarro@gmail.com> Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-04 r/5027 feat(tvix/eval): implement `builtins.currentTime`Vincent Ambo1-2/+12
Returns time since epoch in seconds. This has a slight behaviour difference from Nix, in that we don't pin the time between REPL entries (Nix pins it for the program lifetime), but this is probably inconsequential as long as it is pinned during an evaluation. Change-Id: I010c02e93097a209d8ad69e278397c7e30e54c86 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6846 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: wpcarro <wpcarro@gmail.com>
2022-10-04 r/5026 refactor(tvix/eval): allow impure Value builtinsVincent Ambo1-3/+22
Allows impure builtins that have a different shape than a Rust function pointer; specifically this is required for builtins.currentTime which does not work in WASM. Change-Id: I1362d8eeafe770ce4d1c5ebe4d119aeb0abb5c9b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6849 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: wpcarro <wpcarro@gmail.com>
2022-09-22 r/4954 feat(tvix/eval): Sketch out impure builtinsGriffin Smith1-0/+7
Sketch out a new set of "impure" builtins, which supplement the existing set of "pure" builtins but are gated behind a feature flag, which allows them to be omitted by crates depending on tvix-eval that only want pure evaluation, such as tvixbolt. Change-Id: I2736017b5c9b4776bbba8758e108ec84887abd66 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6655 Reviewed-by: wpcarro <wpcarro@gmail.com> Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: tazjin <tazjin@tvl.su>