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2024-06-25libexpr: rewrite the parser with pegtl instead of flex/bisoneldritch horrors
this gives about 20% performance improvements on pure parsing. obviously it will be less on full eval, but depending on how much parsing is to be done (e.g. including hackage-packages.nix or not) it's more like 4%-10%. this has been tested (with thousands of core hours of fuzzing) to ensure that the ASTs produced by the new parser are exactly the same as the old one would have produced. error messages will change (sometimes by a lot) and are not yet perfect, but we would rather leave this as is for later. test results for running only the parser (excluding the variable binding code) in a tight loop with inputs and parameters as given are promising: - 40% faster on lix's package.nix at 10000 iterations - 1.3% faster on nixpkgs all-packages.nix at 1000 iterations - equivalent on all of nixpkgs concatenated at 100 iterations (excluding invalid files, each file surrounded with parens) more realistic benchmarks are somewhere in between the extremes, parsing once again getting the largest uplift. other realistic workloads improve by a few percentage points as well, notably system builds are 4% faster. Benchmarks summary (from ./bench/summarize.jq bench/bench-*.json) old/bin/nix --extra-experimental-features 'nix-command flakes' eval -f bench/nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix mean: 0.408s ± 0.025s user: 0.355s | system: 0.033s median: 0.389s range: 0.388s ... 0.442s relative: 1 new/bin/nix --extra-experimental-features 'nix-command flakes' eval -f bench/nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix mean: 0.332s ± 0.024s user: 0.279s | system: 0.033s median: 0.314s range: 0.313s ... 0.361s relative: 0.814 --- old/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' mean: 6.133s ± 0.022s user: 5.395s | system: 0.437s median: 6.128s range: 6.099s ... 6.183s relative: 1 new/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' mean: 5.925s ± 0.025s user: 5.176s | system: 0.456s median: 5.934s range: 5.861s ... 5.943s relative: 0.966 --- GC_INITIAL_HEAP_SIZE=10g old/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' mean: 4.503s ± 0.027s user: 3.731s | system: 0.547s median: 4.499s range: 4.478s ... 4.541s relative: 1 GC_INITIAL_HEAP_SIZE=10g new/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' mean: 4.285s ± 0.031s user: 3.504s | system: 0.571s median: 4.281s range: 4.221s ... 4.328s relative: 0.951 --- old/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello mean: 16.475s ± 0.07s user: 14.088s | system: 1.572s median: 16.495s range: 16.351s ... 16.536s relative: 1 new/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello mean: 15.973s ± 0.013s user: 13.558s | system: 1.615s median: 15.973s range: 15.946s ... 15.99s relative: 0.97 --- Change-Id: Ie66ec2d045dec964632c6541e25f8f0797319ee2
2024-06-17libexpr: add expr memory managementeldritch horrors
with the prepatory work done this mostly means turning plain pointers into unique_ptrs, with all the associated churn that necessitates. we might want to change some of these to box_ptrs at some point as well, but that would be a semantic change that isn't fully appropriate yet. Change-Id: I0c238c118617420650432f4ed45569baa3e3f413
2024-06-17libexpr: store ExprConcatStrings elements as direct vectoreldritch horrors
storing a pointer only adds an unnecessary indirection at runtime. Change-Id: If06dd05effdf1ccb0df0873580f50c775608925d
2024-06-17libexpr: don't immediately throw parser errorseldritch horrors
now that destructors are hooked up we want to give the C skeleton every real chance to actually run them. since bison does not call destructors on values that have been passed to semantic actions even when an action causes an abort we will also have to delete some things manually still. Change-Id: Ia22bdaa9e969b74e17a6c496e35e6c2d86b7d750
2024-06-17libexpr: hook up bison destructors for state objectseldritch horrors
this doesn't help much yet since the state objects themselves also leak all memory they are given, but it is a first necessary step to properly managing parser memory. notably we have to clear $$ when returning from the parser since even the start symbol is subject to automatic deletion by the bison-generated parser before returning control to the call site Change-Id: I80245b0c747308e80923e7f18ce4e1a4898f93b0
2024-05-29util.{hh,cc}: Split out users.{hh,cc}Tom Hubrecht
Change-Id: I1bd92479a2cb7e5c2c2e1541b80474adb05ea0df
2024-03-18use byte indexed locations for PosIdxeldritch horrors
we now keep not a table of all positions, but a table of all origins and their sizes. position indices are now direct pointers into the virtual concatenation of all parsed contents. this slightly reduces memory usage and time spent in the parser, at the cost of not being able to report positions if the total input size exceeds 4GiB. this limit is not unique to nix though, rustc and clang also limit their input to 4GiB (although at least clang refuses to process inputs that are larger, we will not). this new 4GiB limit probably will not cause any problems for quite a while, all of nixpkgs together is less than 100MiB in size and already needs over 700MiB of memory and multiple seconds just to parse. 4GiB worth of input will easily take multiple minutes and over 30GiB of memory without even evaluating anything. if problems *do* arise we can probably recover the old table-based system by adding some tracking to Pos::Origin (or increasing the size of PosIdx outright), but for time being this looks like more complexity than it's worth. since we now need to read the entire input again to determine the line/column of a position we'll make unsafeGetAttrPos slightly lazy: mostly the set it returns is only used to determine the file of origin of an attribute, not its exact location. the thunks do not add measurable runtime overhead. notably this change is necessary to allow changing the parser since apparently nothing supports nix's very idiosyncratic line ending choice of "anything goes", making it very hard to calculate line/column positions in the parser (while byte offsets are very easy). (cherry picked from commit 5d9fdab3de0ee17c71369ad05806b9ea06dfceda) Change-Id: Ie0b2430cb120c09097afa8c0101884d94f4bbf34
2024-03-18diagnose "unexpected EOF" at EOFeldritch horrors
this needs a string comparison because there seems to be no other way to get that information out of bison. usually the location info is going to be correct (pointing at a bad token), but since EOF isn't a token as such it'll be wrong in that this case. this hasn't shown up much so far because a single line ending *is* a token, so any file formatted in the usual manner (ie, ending in a line ending) would have its EOF position reported correctly. (cherry picked from commit 855fd5a1bb781e4f722c1d757ba43e866d370132) Change-Id: I120c56a962f4286b1ae3b71da7b71ce8ec3e0535
2024-03-18report inherit attr errors at the duplicate nameeldritch horrors
previously we reported the error at the beginning of the binding block (for plain inherits) or the beginning of the attr list (for inherit-from), effectively hiding where exactly the error happened. this also carries over to runtime positions of attributes in sets as reported by unsafeGetAttrPos. we're not worried about this changing observable eval behavior because it *is* marked unsafe, and the new behavior is much more useful. (cherry picked from commit 1edd6fada53553b89847ac3981ac28025857ca02) Change-Id: I2f50eb9f3dc3977db4eb3e3da96f1cb37ccd5174
2024-03-10evaluate inherit (from) exprs only once per directiveeldritch horrors
desugaring inherit-from to syntactic duplication of the source expr also duplicates side effects of the source expr (such as trace calls) and expensive computations (such as derivationStrict). (cherry picked from commit cefd0302b55b3360dbca59cfcb4bf6a750d6cdcf) Change-Id: Iff519f991adef2e51683ba2c552d37a3df7a179e
2024-03-10preserve information about whether/how an attribute was inheritedeldritch horrors
(cherry picked from commit c66ee57edc6cac3571bfbf77d0c0ea4d25b4e805) Change-Id: Ie8606a8b2f5946c87dd4d16b7b46203e199a4cc1
2024-03-09Merge pull request #9925 from 9999years/fmt-cleanupeldritch horrors
Cleanup `fmt.hh` (cherry picked from commit 47a1dbb4b8e7913cbb9b4d604728b912e76e4ca0) Change-Id: Id076a45cb39652f437fe3f8bda10c310a9894777
2024-03-09libexpr: Support structured error classeseldritch horrors
While preparing PRs like #9753, I've had to change error messages in dozens of code paths. It would be nice if instead of EvalError("expected 'boolean' but found '%1%'", showType(v)) we could write TypeError(v, "boolean") or similar. Then, changing the error message could be a mechanical refactor with the compiler pointing out places the constructor needs to be changed, rather than the error-prone process of grepping through the codebase. Structured errors would also help prevent the "same" error from having multiple slightly different messages, and could be a first step towards error codes / an error index. This PR reworks the exception infrastructure in `libexpr` to support exception types with different constructor signatures than `BaseError`. Actually refactoring the exceptions to use structured data will come in a future PR (this one is big enough already, as it has to touch every exception in `libexpr`). The core design is in `eval-error.hh`. Generally, errors like this: state.error("'%s' is not a string", getAttrPathStr()) .debugThrow<TypeError>() are transformed like this: state.error<TypeError>("'%s' is not a string", getAttrPathStr()) .debugThrow() The type annotation has moved from `ErrorBuilder::debugThrow` to `EvalState::error`. (cherry picked from commit c6a89c1a1659b31694c0fbcd21d78a6dd521c732) Change-Id: Iced91ba4e00ca9e801518071fb43798936cbd05a
2024-03-09don't repeatedly look up ast internal symbolseldritch horrors
these symbols are used a *lot*, so it makes sense to cache them. this mostly increases clarity of the code (however clear one may wish to call the parser desugaring here), but it also provides a small performance benefit. (cherry picked from commit 09a1128d9e2ff0ae6176784938047350d6f8a782) Change-Id: I73d9f66be4555168e048cb2d542277251580c2d1
2024-03-09decouple parser and EvalStateeldritch horrors
there's no reason the parser itself should be doing semantic analysis like bindVars. split this bit apart (retaining the previous name in EvalState) and have the parser really do *only* parsing, decoupled from EvalState. (cherry picked from commit b596cc9e7960b9256bcd557334d81e9d555be5a2) Change-Id: I481a7623afc783e9d28a6eb4627552cf8a780986
2024-03-09slim down parser.yeldritch horrors
most EvalState and Expr members defined here could be elsewhere, where they'd be easier to maintain (not being embedded in a file with arcane syntax) and *somewhat* more faithfully placed according to the path of the file they're defined in. (cherry picked from commit e1aa585964c3d864ebff0030584f3349a539d615) Change-Id: Ibc704567462bb40f37cda05d8fadd465519db5f5
2024-03-09rename ParserState::{makeCurPos -> at}eldritch horrors
most instances of this being used do not refer to the "current" position, sometimes not even to one reasonably close by. it could also be called `makePos` instead, but `at` seems clear in context. (cherry picked from commit 835a6c7bcfd0b22acc16f31de5fc7bb650d52017) Change-Id: I17cab8a6cc14cac5b64624431957bfcf04140809
2024-03-09move ParseData to own header, rename to ParserStateeldritch horrors
ParserState better describes what this struct really is. the parser really does modify its state (most notably position and symbol tables), so calling it that rather than obliquely "data" (which implies being input only) makes sense. (cherry picked from commit 007605616477f4f0d8a0064c375b1d3cf6188ac5) Change-Id: I92feaec796530e1d4d0f7d4fba924229591cea95
2024-03-09make parser utility functions members of ParseDataeldritch horrors
all of them need access to parser state in some way. make them members to allow this without fussing so much. (cherry picked from commit 1b09b80afac27c67157d4b315c237fa7bb9b8d08) Change-Id: I3145c95666a5617b735eff7cb403c54c0fe86347
2024-03-09simplify parse error reportingeldritch horrors
since nix doesn't use the bison `error` terminal anywhere any invocation of yyerror will immediately cause a failure. since we're *already* leaking tons of memory whatever little bit bison allocates internally doesn't much matter any more, and we'll be replacing the parser soon anyway. coincidentally this now also matches the error behavior of URIs when they are disabled or ~/ paths in pure eval mode, duplicate attr detection etc. (cherry picked from commit e8d9de967fe47a7f9324b0022a2ef50df59f419d) Change-Id: I560c50d11dceddc2d7cf9ed2c6c631a309ce574e
2024-03-09remove ParserFormalseldritch horrors
this is a proper subset of Formals anyway, so let's just use those and avoid the extra allocations and moves. (cherry picked from commit f07388bf985c2440413f398cf93d5f5840d1ec8c) Change-Id: I4508c9c9c918cbaaed649dc753eb86f5cafc7ab6
2024-03-04Merge pull request #9582 from pennae/misc-optseldritch horrors
a packet of small optimizations (cherry picked from commit ee439734e924eb337a869ff2e48aff8b989198bc) Change-Id: I125d870710750a32a0dece48f39a3e9132b0d023
2024-02-15Fix the buildThéophane Hufschmitt
bef68e53b9d08c99873a5bc60568b7351934ad51 (backport of 31ebc6028b3682969d86a7b39ae87131c41cc604) accidentally broke the build because of a change in the constructor of `SourcePath` between 2.18 and master. Fix that.
2024-01-21Fix symlink handlingEelco Dolstra
This restores the symlink handling behaviour prior to 94812cca98fbb157e5f64a15a85a2b852d289feb. Fixes #9298. (cherry picked from commit 31ebc6028b3682969d86a7b39ae87131c41cc604)
2023-08-18Delete `EvalState::addToSearchPath`John Ericson
This function is now trivial enough that it doesn't need to exist. `EvalState` can still be initialized with a custom search path, but we don't have a need to mutate the search path after it has been constructed, and I don't see why we would need to in the future. Fixes #8229
2023-07-31Move evaluator settings (type and global) to separate file/headerJohn Ericson
2023-07-21parser: merge nested dynamic attributesNaïm Favier
Fixes https://github.com/NixOS/nix/issues/7115
2023-07-10Merge pull request #8579 from obsidiansystems/findPath-cleanup-2John Ericson
Further search path cleanups
2023-07-10libexpr: remove std::move() for `basePath` in parser, it has no effectYingchi Long
2023-07-09Clean up `SearchPath`John Ericson
- Better types - Own header / C++ file pair - Test factored out methods - Pass parsed thing around more than strings Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
2023-07-09Clean up `resolveSearchPathElem`John Ericson
We should use `std::optional<std::string>` not `std::pair<bool, std::string>` for an optional string.
2023-06-29Merge pull request #8600 from inclyc/libexpr/fix-leaking-in-stripIndentationRobert Hensing
libexpr: fix leaking `es2` in stripIndentation (parser.y)
2023-06-28libexpr: fix leaking `es2` in stripIndentation (parser.y)Yingchi Long
2023-06-23Use a struct not `std::pair` for `SearchPathElem`John Ericson
I got very confused trying to keep all the `first` and `second` straight reading the code, *especially* as there is also another `(boolean, string)` pair type also being used. Named fields is much better. There are other cleanups that we can do (for example, the existing TODO), but we can do them later. Doing them now would just make this harder to review.
2023-06-23libexpr: remove unused token `ATTRPATH` in token declarationYingchi Long
2023-06-13Allow tarball URLs to redirect to a lockable immutable URLEelco Dolstra
Previously, for tarball flakes, we recorded the original URL of the tarball flake, rather than the URL to which it ultimately redirects. Thus, a flake URL like http://example.org/patchelf-latest.tar that redirects to http://example.org/patchelf-<revision>.tar was not really usable. We couldn't record the redirected URL, because sites like GitHub redirect to CDN URLs that we can't rely on to be stable. So now we use the redirected URL only if the server returns the `x-nix-is-immutable` or `x-amz-meta-nix-is-immutable` headers in its response.
2023-04-06Origin: Use SourcePathEelco Dolstra
2023-04-06Backport SourcePath from the lazy-trees branchEelco Dolstra
This introduces the SourcePath type from lazy-trees as an abstraction for accessing files from inputs that may not be materialized in the real filesystem (e.g. Git repositories). Currently, however, it's just a wrapper around CanonPath, so it shouldn't change any behaviour. (On lazy-trees, SourcePath is a <InputAccessor, CanonPath> tuple.)
2023-03-20Move enabled experimental feature to libutil structJohn Ericson
This is needed in subsequent commits to allow the settings and CLI args infrastructure itself to read this setting.
2023-03-02Remove FormatOrString and remaining uses of format()Eelco Dolstra
2023-02-16ExprOpHasAttr,ExprSelect,stripIndentation,binds,formals: delete losts objectsEt7f3
We are looking for *$ because it indicate that it was constructed with a new but not release. De-referencing shallow copy so deleting as whole might create dangling pointer that's why we move it so we delete a empty containers + the nice perf boost.
2023-02-12ExprString: Avoid copy of stringEt7f3
2023-02-12parser: use implicit ruleEt7f3
2023-01-19Revert "Revert "Merge pull request #6204 from layus/coerce-string""Guillaume Maudoux
This reverts commit 9b33ef3879a764bed4cc2404a08344c3a697a646.
2023-01-18Revert "Merge pull request #6204 from layus/coerce-string"Robert Hensing
This reverts commit a75b7ba30f1e4f8b15e810fd18e63ee9552e0815, reversing changes made to 9af16c5f742300e831a2cc400e43df1e22f87f31.
2023-01-02Merge remote-tracking branch 'origin/master' into coerce-stringEelco Dolstra
2022-12-13Restore display of source lines for stdin/string inputsEelco Dolstra
2022-12-13Introduce AbstractPosEelco Dolstra
This makes the position object used in exceptions abstract, with a method getSource() to get the source code of the file in which the error originated. This is needed for lazy trees because source files don't necessarily exist in the filesystem, and we don't want to make libutil depend on the InputAccessor type in libfetcher.
2022-12-12Support flake references in the old CLIEelco Dolstra
Fixes #7026.
2022-12-12Move isUri() and resolveUri() out of filetransfer.ccEelco Dolstra
These are purely related to NIX_PATH / -I command line parsing, so put them in libexpr.