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2023-06-07 r/6243 fix(tvix/eval): type check function argument with set patternsterni1-0/+1
C++ Nix forces and typechecks the passed argument even if it is not necessary in order to compute the return value of the function. I discovered this when I thought our formals miscompilation might be that we are too strict, but doesn't look like it in this case. Change-Id: Ifb3c92592293052c489d1e3ae8c7c54e4b6b4dc6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8701 Tested-by: BuildkiteCI Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-26 r/6207 fix(tvix): don't call function eagerly in genList, map & mapAttrssterni1-0/+31
mapAttrs, map and genList call Nix functions provided by the caller and store the result of applying them in a Nix data structure that does not force all of its contents when forced itself. This means that when such a builtin application is forced, the Nix function calls performed by the builtin should not be forced: They may be forced later, but it is also possible that they will never be forced, e.g. in builtins.length (builtins.map (builtins.add 2) [ 1 2 3 ]) it is not necessary to compute a single application of builtins.add. Since request_call_with immediately performs the function call requested, Tvix would compute function applications unnecessarily before this change. Because this was not followed by a request_force, the impact of this was relatively low in Nix code (most functions return a new thunk after being applied), but it was enough to cause a lot of bogus builtins.trace applications when evaluating anything from `lib.modules`. The newly added test includes many cases where Tvix previously incorrectly applied a builtin, breaking a working expression. To fix this we add a new helper to construct a Thunk performing a function application at runtime from a function and argument given as `Value`s. This mimics the compiler's compile_apply(), but does itself not require a compiler, since the necessary Lambda can be constructed independently. I also looked into other builtins that call a Nix function to verify that they don't exhibit such a problem: - Many builtins immediately use the resulting value in a way that makes it necessary to compute all the function calls they do as soon as the outer builtin application is forced: * all * any * filter * groupBy * partition - concatMap needs to (shallowly) force the returned list for concatenation. - foldl' is strict in the application of `op` (I added a comment that makes this explicit). - genericClosure needs to (shallowly) force the resulting list and some keys of the attribute sets inside. Resolves b/272. Change-Id: I1fa53f744bcffc035da84c1f97ed25d146830446 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8651 Autosubmit: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2023-03-22 r/6036 fix(tvix/eval): print unevaluated thunks like Nix doesVincent Ambo1-0/+1
Change-Id: Ie4c563e933f571f45cb4f4efe650d1b65f119e8d Reviewed-on: https://cl.tvl.fyi/c/depot/+/8324 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Autosubmit: tazjin <tazjin@tvl.su>
2023-03-17 r/6026 feat(tvix/eval): report all known spans on infinite recursionVincent Ambo1-4/+38
This reports the span 1. of the code within a thunk, 2. of the place where the thunk was instantiated, 3. of the place where the thunk was first forced, 4. of the place where the thunk was forced again, when yielding an infinite recursion error, which hopefully makes it easier to debug them. The spans are tracked in the ThunkRepr::Blackhole variant when putting a thunk under evaluation. Note that we currently have some loss of span precision in the VM loop when switching between frame types, so spans 3/4 are currently a bit wonky. Working on it. Change-Id: Icbd2a9df903d00e8c2545b3fc46dcd2a9e3e3e55 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8270 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su>
2023-03-17 r/6025 feat(tvix/eval): track span of first force in a thunk blackholeVincent Ambo2-8/+11
This is step 1 towards being able to use all 4 spans that we know when dealing with infinite recursion. It tracks the span at which the force of a thunk was first requested when constructing a blackhole, so that we can highlight the spans of the first and second forces. These are actually the least relevant spans, but the easiest to put in place, more coming soon. Change-Id: I4c7e82f6211b98756439d4148a4191457cc46807 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8269 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-03-13 r/5991 chore(tvix/eval): mark async functions which are called by the VMAdam Joseph2-0/+6
Given Rust's current lack of support for tail calls, we cannot avoid using `async` for builtins. This is the only way to avoid overflowing the cpu stack when we have arbitrarily deep builtin/interpreted/builtin/interpreted/... "sandwiches" There are only five `async fn` functions which are not builtins (some come in multiple "flavors"): - add_values - resolve_with - force, final_deep_force - nix_eq, nix_cmp_eq - coerce_to_string These can be written iteratively rather than recursively (and in fact nix_eq used to be written that way!). I volunteer to rewrite them. If written iteratively they would no longer need to be `async`. There are two motivations for limiting our reliance on `async` to only the situation (builtins) where we have no other choice: 1. Performance. We don't really have any good measurement of the performance hit that the Box<dyn Future>s impose on us. Right now all of our large (nixpkgs-eval) tests are swamped by the cost of other things (e.g. fork()ing `nix-store`) so we can't really measure it. Builtins tend to be expensive operations anyways (regexp-matching, sorting, etc) that are likely to already cost more than the `async` overhead. 2. Preserving the ability to switch to `musttail` calls. Clang/LLVM recently got `musttail` (mandatory-elimination tail calls). Rust has refused to add this mainly because WASM doesn't support, but WASM `tail_call` has been implemented and was recently moved to phase 4 (standardization). It is very likely that Rust will get tail calls sometime in the next year; if it does, we won't need async anymore. In the meantime, I'd like to avoid adding any further reliance on `async` in places where it wouldn't be straightforward to replace it with a tail call. https://reviews.llvm.org/D99517 https://github.com/WebAssembly/proposals/pull/157 https: //github.com/rust-lang/rfcs/issues/2691#issuecomment-1462152908 Change-Id: Id15945d5a92bf52c16d93456e3437f91d93bdc57 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8290 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Autosubmit: Adam Joseph <adam@westernsemico.com>
2023-03-13 r/5989 feat(tvix/eval): rewrite nix_cmp_ordering to be nonrecursiveAdam Joseph1-45/+46
This rewrites nix_cmp_ordering as an iterative loop, which eliminates the extra pinned-boxing helper function. Change-Id: I33d0ecc913e02affd8fd4c7bc1c9ecfdf4c7deb9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8288 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Autosubmit: Adam Joseph <adam@westernsemico.com>
2023-03-13 r/5979 fix(tvix/eval): implement cppnix JSON-serialisation semanticsVincent Ambo5-38/+100
This drops the usage of serde::Serialize, as the trait can not be used to implement the correct semantics (function colouring!). Instead, a manual JSON serialisation function is written which correctly handles toString, outPath and other similar weirdnesses. Unexpectedly, the eval-okay-tojson test from the C++ Nix test suite now passes, too. This fixes an issue where serialising data structures containing derivations to JSON would fail. Change-Id: I5c39e3d8356ee93a07eda481410f88610f6dd9f8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8209 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-13 r/5978 feat(tvix/eval): give generators human-readable namesVincent Ambo1-2/+2
This adds static strings to generator frames that describe the generator in a human-readable fashion, which are then logged in observers. This makes runtime traces very precise, explaining exactly what is being requested from where. Change-Id: I695659a6bd0b7b0bdee75bc8049651f62b150e0c Reviewed-on: https://cl.tvl.fyi/c/depot/+/8206 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 r/5975 refactor(tvix/eval): move `__toString` calling to a helper functionVincent Ambo2-24/+34
It turns out that this is used not just in coerceToString, but also in toJSON. Change-Id: I1c324b115a0b8bb6d83446d5bf70453c9b90685e Reviewed-on: https://cl.tvl.fyi/c/depot/+/8203 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 r/5969 refactor(tvix/eval): box PathBufVincent Ambo2-5/+5
This shaves another 8 bytes off Value. How did that type get so big?! Change-Id: I65e9b59a1636bd57e3cc4aec5fea16887070b832 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8153 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-13 r/5968 chore(tvix/eval): remove `From<SmolStr> for NixString` instanceVincent Ambo1-4/+3
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/5967 refactor(tvix/eval): simplify NixString representation(s)Vincent Ambo3-65/+37
Instead of the two different representations (which we don't really use much), use a `Box<str>` (which potentially shaves another 8 bytes off `Value`). NixString values themselves are immutable anyways (which was a guarantee we already had with `SmolStr`), so this doesn't change anything else. Change-Id: I1d8454c056c21ecb0aebc473cfb3ae06cd70dbb6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8151 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-03-13 r/5966 refactor(tvix/eval): wrap NixList in RcVincent Ambo1-11/+13
The size of a `Vector<Value>` is 64 *bytes*, which is quite large, and it bloated the entire Value type to this size. This change adds an indirection for the inner vector through Rc. Initially I tried to use a Box, but this breaks pointer equality guarantees for the Vector when it is small enough to be inlined. This reduces the size of Value from 64 to 32 bytes. Change-Id: Ic3211e861b1966c78b2c3d536ba291fea92647fd Reviewed-on: https://cl.tvl.fyi/c/depot/+/8150 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-13 r/5964 refactor(tvix/eval): flatten call stack of VM using generatorsVincent Ambo6-662/+232
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 r/5963 feat(tvix/eval): implement generator-based Nix equality logicVincent Ambo1-1/+181
Adds a `Value::neo_nix_eq` method (the `neo_` prefix will be dropped when we flip over to the generator implementation of the VM) which implements Nix equality semantics using async, generator-based comparisons. Instead of tracking the "kind" of equality that is being compared (see the pointer-equality doc) through a pair of booleans, I've introduced an enum that explicitly lists the possible comparisons. Change-Id: I3354cc1470eeccb3000a5ae24f2418db1a7a2edc Reviewed-on: https://cl.tvl.fyi/c/depot/+/8241 Tested-by: BuildkiteCI Reviewed-by: Adam Joseph <adam@westernsemico.com>
2023-03-13 r/5961 feat(tvix/eval): implement asynchronous list sorting algorithmVincent Ambo1-0/+47
In order to implement an asynchronous builtins.sort (required for moving builtins to generators), we need an `async` sorting algorithm as our comparators involve invoking a Nix function. This commit implements a fairly simple, optimised bubble sort as the sorting algorithm used in our `async fn sort_by`. There don't seem to be any crates providing async versions of things like this, and they might actually be pretty hard to implement generically due to some constraints about how `async` works. Note that this algorithm is less efficient than the hybrid "timsort/mergesort/insert sort" used in the Rust standard library. I tried to write a merge sort implementation, but ran into isuses with the sort becoming unstable because our comparators can not yield equality. This is the simplest implementation which I know to be correct. Note that as of this commit this is *not* covered by the Tvix test suite, but it will be as soon as the rest of the generator code lands. Change-Id: Ia9a604f7dd941d6acc9212c902e0e637ed75bebc Reviewed-on: https://cl.tvl.fyi/c/depot/+/8239 Reviewed-by: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI
2023-03-07 r/5899 feat(tvix/eval): introduce generators moduleVincent Ambo1-1/+1
This module contains the request/response types for generators requesting actions from the VM. For most of these, an async helper function is added that will be used inside of generator functions to make use of these requests/responses instead of constructing them directly. Change-Id: I1e085f88adaf784a34867957a0e82532d3a83d7c Reviewed-on: https://cl.tvl.fyi/c/depot/+/8148 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-04 r/5888 refactor(tvix/eval): remove VM argument from suspended native thunksVincent Ambo1-4/+4
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/5886 feat(tvix/eval): add SharedThunkSetVincent Ambo1-0/+11
This is a ThunkSet wrapped to be shareable, which will be required once ThunkSets are embedded in futures. Change-Id: I5a067b7972ac86e4d354c75ef05c86b2284c1137 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8144 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-04 r/5885 fix(tvix/eval): ThunkSet does not need mutable pointersVincent Ambo1-2/+2
Change-Id: Iea248870a0ea5d38cb02ff059c968fbd563570b6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8143 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-04 r/5884 chore(tvix/eval): implement From<OrdMap<..>> for NixAttrsVincent Ambo1-0/+6
Again simplifying some code down the line, where bits of code that construct attribute sets already have the final structure available. Change-Id: I0bb7a1daa63298122b51be73d35d695a4f73f8b0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8140 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-03-03 r/5870 chore(tvix/eval): fix clippy warningsVincent Ambo2-17/+17
Change-Id: I4c02f0104c455ac00a3f299c1fbf75cbb08e8972 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8142 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su>
2023-03-03 r/5869 refactor(tvix/eval): remove useless map callVincent Ambo1-5/+1
Change-Id: Ifb59ef148ea4fab613f2e4efb133c04baafa3a98 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8141 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-03-03 r/5868 refactor(tvix/eval): enhance debug output for bytecode dumpsVincent Ambo1-0/+16
This adds addresses of thunk and closure chunks to the debug output displayed when dumping bytecode. This makes it possible to see in the dump which thunks are referenced by constants in other thunks. Change-Id: I2c98de5227e7cb415666cd3134c947a56979dc80 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8137 Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-02-16 r/5857 refactor(tvix/eval): remove redundant cloneAaqa Ishtyaq1-4/+4
This CL removes redundant clone from value which is going to be dropped without further use. Change-Id: Ibd2a724853c5cfbf8ca40bf0b3adf0fab89b9be5 Signed-off-by: Aaqa Ishtyaq <aaqaishtyaq@gmail.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/8125 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2023-02-13 r/5849 chore(tvix/eval): clippy warn is length zeroAaqa Ishtyaq1-1/+1
This CL address clippy warning about finding the zero length of something using `is_empty()` instead of `len() == 0`. Change-Id: I2b36c7c7b65b733609fc0dcd33be06f9d772bc9b Signed-off-by: Aaqa Ishtyaq <aaqaishtyaq@gmail.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/8029 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2023-02-03 r/5832 refactor(tvix/eval): wrap `Builtin` type in a BoxVincent Ambo1-20/+30
This reduces the size of `Builtin` from 88 (!) bytes to 8, and as the largest variant of `Value`, the size of that type from 96 to 64. The next largest type is NixList, clocking in at 64 bytes. This has noticeable performance impact. In an implementation without disk I/O, evaluating nixpkgs.stdenv looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.151 s ± 0.003 s [User: 1.041 s, System: 0.109 s] Range (min … max): 1.147 s … 1.155 s 10 runs After this change, it looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.046 s ± 0.004 s [User: 0.954 s, System: 0.092 s] Range (min … max): 1.041 s … 1.053 s 10 runs Change-Id: I5ab7cc02a9a450c0227daf1f1f72966358311ebb Reviewed-on: https://cl.tvl.fyi/c/depot/+/8027 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-02-03 r/5828 fix(tvix/eval): ensure all evaluated thunks are correctly memoizedVincent Ambo1-45/+185
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>
2023-02-02 r/5821 chore(tvix/eval): elaborate on internal types in Value::type_ofVincent Ambo1-6/+8
This aids in debugging quite substantially. Change-Id: Ic43232aa6165ae1c3db7ac2701938e1dfeeb418c Reviewed-on: https://cl.tvl.fyi/c/depot/+/8013 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de> Autosubmit: tazjin <tazjin@tvl.su>
2023-01-26 r/5763 chore(tvix/eval): remove dead commentVincent Ambo1-1/+1
Change-Id: Icedb7f272e5067569b8dbf1c2d8b0fdd352b8e12 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7936 Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: flokli <flokli@flokli.de>
2023-01-25 r/5757 test(tvix/eval): add test for total_fmt_floatFlorian Klink1-0/+28
Change-Id: If6c478ee3d2e4ecf5ef92289614f86535ad05cb7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7927 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: flokli <flokli@flokli.de>
2023-01-25 r/5756 refactor(tvix/eval): extract float formatting into a helperVincent Ambo1-71/+75
This keeps the actual TotalDisplay implementation readable, as this float formatting code suddenly made up the majority of its implementation. Change-Id: I2c0d00e4a691e0b8ffbc72680f680e16feef4bee Reviewed-on: https://cl.tvl.fyi/c/depot/+/7925 Reviewed-by: flokli <flokli@flokli.de> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2023-01-25 r/5753 feat(tvix/eval): use lexical-core to format floatFlorian Klink1-2/+86
Apparently our naive implementation of float formatting, which simply used {:.5}, and trimmed trailing "0" strings not sufficient. It wrongly trimmed numbers with zeroes but no decimal point, like `10000` got trimmed to `1`. Nix uses `std::to_string` on the double, which according to https://en.cppreference.com/w/cpp/string/basic_string/to_string is equivalent to `std::sprintf(buf, "%f", value)`. https://en.cppreference.com/w/cpp/io/c/fprintf mentions this is treated like this: > Precision specifies the exact number of digits to appear after > the decimal point character. The default precision is 6. In the > alternative implementation decimal point character is written even if > no digits follow it. For infinity and not-a-number conversion style > see notes. This doesn't seem to be the case though, and Nix uses scientific notation in some cases. There's a whole bunch of strategies to determine which is a more compact notation, and which notation should be used for a given number. https://github.com/rust-lang/rust/issues/24556 provides some pointers into various rabbit holes for those interested. This gist seems to be that currently a different formatting is not exposed in rust directly, at least not for public consumption. There is the [lexical-core](https://github.com/Alexhuszagh/rust-lexical) crate though, which provides a way to format floats with various strategies and formats. Change our implementation of `TotalDisplay` for the `Value::Float` case to use that. We still need to do some post-processing, because Nix always adds the sign in scientific notation (and there's no way to configure lexical-core to do that), and lexical-core in some cases keeps the trailing zeros. Even with all that in place, there as a difference in `eval-okay- fromjson.nix` (from tvix-tests), which I couldn't get to work. I updated the fixture to a less problematic number. With this, the testsuite passes again, and does for the upcoming CL introducing builtins.fromTOML, and enabling the nix testsuite bits for it, too. Change-Id: Ie6fba5619e1d9fd7ce669a51594658b029057acc Reviewed-on: https://cl.tvl.fyi/c/depot/+/7922 Tested-by: BuildkiteCI Autosubmit: flokli <flokli@flokli.de> Reviewed-by: tazjin <tazjin@tvl.su>
2023-01-20 r/5715 refactor(tvix/eval): keep globals alive through VM structVincent Ambo2-7/+42
This forces users to pass the fully constructed set of globals to the VM, making it harder to accidentally "lose" the set while weak references to it still exist. This doesn't modify any functionality, but is laying the foundation for simplifying some of the builtins behaviour that has grown more complex again. Change-Id: I5120f97861c65dc46d90b8a4e2c92ad32cc53e03 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7877 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-20 r/5706 feat(tvix/eval): add error contexts to annotate error kindsVincent Ambo1-4/+2
This makes it possible for users to add additional context to an error, which will then be rendered as an additional secondary span in the formatted error output. We should strive to do this basically anywhere errors are raised that can occur multiple times, *especially* during type casts. This was triggered by me debugging a type cast error attached to a fairly large-ish span (a builtin invocation). Change-Id: I51be41fabee00cf04de973935daf34fe6424e76f Reviewed-on: https://cl.tvl.fyi/c/depot/+/7849 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-17 r/5676 refactor(tvix/eval): non-hacky suspended native thunksVincent Ambo1-55/+35
Instead of having a representation of suspended native thunks that involves constructing a fake code chunk, make these thunks a first-class part of the internal thunk representation. The previous code was not that simple to understand, and actually contained a critical bug which could lead to Tvix crashes. This version fixes the particular instance of that bug, but instead uncovers another (b/238) which can still lead to Tvix crashes. Fixes: b/237. Change-Id: I771d03864084d63953bdbb518fec94487481f839 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7750 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-17 r/5675 refactor(tvix/eval): remove `Box` in new_suspended_nativeVincent Ambo1-3/+1
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>
2023-01-17 r/5670 refactor(tvix/value): use proptest strategies from imbl crateVincent Ambo4-70/+39
Instead of going through Vec/BTreeMap for generating our internal types, use the proptest strategies from imbl. The one thing I couldn't figure out in the previous implementation is where the ranges/sizes of generated collections came from. The strategies in proptest use different types (Range, with an unknown default value, and SizeRange with 0..100). I've opted to specify 0..100 directly, but we can probably make it configurable. Change-Id: I749bc4c703fe424099240cab822b1642e5216361 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7791 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-16 r/5663 chore(tvix/eval): add other required items to public APIVincent Ambo1-2/+2
External implementors of builtins must be able to force values, which necessitates publishing a bunch more items from the crate. Change-Id: I8f6b8ae88156aae417dbe630a698d123d0c1c8d4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7830 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-12 r/5654 fix(tvix/eval): len_without_is_empty clippy warnAaqa Ishtyaq2-0/+12
This CL addresses clippy warning len_without_is_empty which expects `.is_empty()` method to be present when implementing `.len()` method for an item. Change-Id: I8878db630b9ef5853649a906b764a33299bb5dc8 Signed-off-by: Aaqa Ishtyaq <aaqaishtyaq@gmail.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7806 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-12 r/5652 feat(tvix/eval): implement builtins.toJSONVincent Ambo5-9/+41
Implements `Serialize` for `tvix_eval::Value`. Special care is taken with serialisation of attribute sets, and forcing of thunks. The tests should cover both cases well. Change-Id: I9bb135bacf6f87bc6bd0bd88cef0a42308e6c335 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7803 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su>
2023-01-10 r/5640 feat(tvix/eval): implement serde::Deserialize for ValueRyan Lahfa4-44/+92
Co-Authored-By: Vincent Ambo <tazjin@tvl.su> Change-Id: Ib6f7d1f4f4faac36b44f5f75cccc57bf912cf606 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7626 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2023-01-08 r/5629 fix(tvix/eval): fix last uses of Vec<Value> -> NixList in builtinsVincent Ambo1-11/+6
Change-Id: I0d71b82eb7ddc1e457b0996b0668006f55f56751 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7790 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2023-01-04 r/5582 fix(tvix/eval): ' is allowed in nonfirst position in Nix identifierssterni1-1/+1
With this is_valid_nix_identifier should line up with the upstream lexer definition: ID [a-zA-Z\_][a-zA-Z0-9\_\'\-]* While we're working on this, add a simple test checking the various formatting rules. Interestingly, it would not be suitable as an identity test, since you have to write { "assert" = null; } in order to avoid an evaluation error, but C++ Nix is happy to print this as { assert = null; } – maybe should be considered to be a bug. Change-Id: I0a4e1ccb5033a80f3767fb8d1c4bba08d303c5d8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7744 Autosubmit: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-12-29 r/5542 refactor(tvix/eval): remove extra Rc<..> around Value::AttrsVincent Ambo2-3/+14
The `im::OrdMap` is already small and cheap to copy while sharing memory, so this is not required anymore. Only the `KV` variant may have slightly larger content, but in practice this doesn't seem to make a difference when comparing the two variants and this one is less complicated. Change-Id: I64a563b209a2444125653777551373cb2989ca7d Reviewed-on: https://cl.tvl.fyi/c/depot/+/7677 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-12-29 r/5541 refactor(tvix/eval): persistent, memory-sharing OrdMap for NixAttrsVincent Ambo4-56/+55
This uses the `im::OrdMap` for `NixAttrs` to enable sharing of memory between different iterations of a map. This slightly speeds up eval, but not significantly. Future work might include benchmarking whether using a `HashMap` and only ordering in cases where order is actually required would help. This switches to a fork of `im` that fixes some bugs with its OrdMap implementation. Change-Id: I2f6a5ff471b6d508c1e8a98b13f889f49c0d9537 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7676 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-12-29 r/5540 refactor(tvix/eval): use im::Vector directly where possibleVincent Ambo2-13/+13
The conversion from im::Vector -> Vec is cheaper for NixList construction (of course), so where possible we should make use of that. This updates most builtins dealing with lists to use Vector directly, and marks the function constructing NixList from Vec as deprecated so that we get appropriate warnings in places where it's still in use. These places are currently inside of JSON serialisation logic which is in flux right now, so lets leave them as-is until it's stabilised. Change-Id: I037f12a2800f2576db4d9526bd935efd079163f0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7671 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-12-29 r/5534 refactor(tvix/eval): use im::Vector for NixList representationVincent Ambo1-29/+29
This is a persistent, structurally sharing data structure which is more efficient in some of our use-cases. I have verified the efficiency improvement using `hyperfine` repeatedly over expressions on nixpkgs. Lists are not the most performance-critical structure in Nix (that would be attribute sets), but we can already see a small (~5-10%) improvement. Note that there are a handful of cases where we still go via `Vec` that need to be fixed, most notable for `builtins.sort` which can not currently be implemented directly using `im::Vector` because of a restrictive type bound. Change-Id: I237cc50cbd7629a046e5a5e4601fbb40355e551d Reviewed-on: https://cl.tvl.fyi/c/depot/+/7670 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-12-25 r/5486 fix(tvix/eval): fix current clippy warningsVincent Ambo5-10/+9
It's been a while since the last time, so quite a lot of stuff has accumulated here. Change-Id: I0762827c197b30a917ff470fd8ae8f220f6ba247 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7597 Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI