Charlie Marsh
471a1d657d
## Summary This PR enables the proof-of-concept resolver to backtrack by way of using the `pubgrub-rs` crate. Rather than using PubGrub as a _framework_ (implementing the `DependencyProvider` trait, letting PubGrub call us), I've instead copied over PubGrub's primary solver hook (which is only ~100 lines or so) and modified it for our purposes (e.g., made it async). There's a lot to improve here, but it's a start that will let us understand PubGrub's appropriateness for this problem space. A few observations: - In simple cases, the resolver is slower than our current (naive) resolver. I think it's just that the pipelining isn't as efficient as in the naive case, where we can just stream package and version fetches concurrently without any bottlenecks. - A lot of the code here relates to bridging PubGrub with our own abstractions -- so we need a `PubGrubPackage`, a `PubGrubVersion`, etc.
48 lines
1.7 KiB
Rust
48 lines
1.7 KiB
Rust
// SPDX-License-Identifier: MPL-2.0
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use pubgrub::error::PubGrubError;
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use pubgrub::range::Range;
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use pubgrub::report::{DefaultStringReporter, Reporter};
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use pubgrub::solver::{resolve, OfflineDependencyProvider};
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use pubgrub::version::SemanticVersion;
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// https://github.com/dart-lang/pub/blob/master/doc/solver.md#linear-error-reporting
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fn main() {
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let mut dependency_provider = OfflineDependencyProvider::<&str, SemanticVersion>::new();
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#[rustfmt::skip]
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// root 1.0.0 depends on foo ^1.0.0 and baz ^1.0.0
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dependency_provider.add_dependencies(
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"root", (1, 0, 0),
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vec![
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("foo", Range::between((1, 0, 0), (2, 0, 0))),
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("baz", Range::between((1, 0, 0), (2, 0, 0))),
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],
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);
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#[rustfmt::skip]
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// foo 1.0.0 depends on bar ^2.0.0
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dependency_provider.add_dependencies(
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"foo", (1, 0, 0),
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vec![("bar", Range::between((2, 0, 0), (3, 0, 0)))],
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);
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#[rustfmt::skip]
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// bar 2.0.0 depends on baz ^3.0.0
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dependency_provider.add_dependencies(
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"bar", (2, 0, 0),
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vec![("baz", Range::between((3, 0, 0), (4, 0, 0)))],
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);
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// baz 1.0.0 and 3.0.0 have no dependencies
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dependency_provider.add_dependencies("baz", (1, 0, 0), vec![]);
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dependency_provider.add_dependencies("baz", (3, 0, 0), vec![]);
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// Run the algorithm.
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match resolve(&dependency_provider, "root", (1, 0, 0)) {
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Ok(sol) => println!("{:?}", sol),
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Err(PubGrubError::NoSolution(mut derivation_tree)) => {
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derivation_tree.collapse_no_versions();
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eprintln!("{}", DefaultStringReporter::report(&derivation_tree));
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std::process::exit(1);
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}
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Err(err) => panic!("{:?}", err),
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};
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}
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