perf: cache comparison key for choosing the next package to resolve

[radoering]

The comparison key for choosing the next dependency to be resolved from the list of unsatisfied dependencies is calculated again and again until the dependency is chosen and removed from the list. Especially for dependencies, which have many dependencies themselves, calculating the comparison key can take some time. Therefore, it makes sense to cache the comparison key of each dependency.

The time for locking #10195 goes down from about 24 seconds to 20 seconds with this PR.

Since the _get_min function was a private function of _choose_next, I had to move it for caching. I also updated the comments. (I did not change the logic.)

Summary by Sourcery

Cache the comparison key used to determine the next package to resolve, improving performance.

Enhancements:

• Cache the comparison key for each dependency to avoid redundant calculations, especially for dependencies with many sub-dependencies.
• Move the _get_min function to enable caching of the comparison key.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request optimizes the dependency resolution process by caching the comparison key used to determine the next dependency to resolve. It introduces a Preference class and refactors the logic for calculating the comparison key into a dedicated function, which is then cached using functools.cache. This change improves performance by avoiding redundant calculations, especially for dependencies with many sub-dependencies.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Introduces a Preference class to encapsulate the criteria for choosing which dependency to solve first.	Adds a Preference class with constants DIRECT_ORIGIN, NO_CHOICE, USE_LATEST, LOCKED, and DEFAULT. The Preference class is used to define the priority of dependencies during the resolution process.	src/poetry/mixology/version_solver.py
Caches the comparison key used for choosing the next dependency to resolve.	Introduces _get_comp_key to calculate the comparison key for a given dependency. Uses functools.cache to cache the results of _get_comp_key in _get_comp_key_cached. The _choose_next function now uses the cached comparison key _get_comp_key_cached to select the next dependency.	src/poetry/mixology/version_solver.py
Refactors the logic for determining the comparison key of a dependency.	The logic previously embedded within _choose_next is extracted into a separate _get_comp_key function. The _get_comp_key function calculates a tuple consisting of preference, number of dependencies with upper bounds, a boolean indicating the presence of dependencies, and the number of available packages. The function now returns a tuple of (preference, -num_deps_upper_bound, not has_deps, -num_packages) to serve as priority for choosing the next package to resolve.	src/poetry/mixology/version_solver.py

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[sourcery-ai]

Hey @radoering - I've reviewed your changes - here's some feedback:

Overall Comments:

• It might be worth exploring if functools.lru_cache would be a better fit than functools.cache here, given that the number of unique dependencies might be quite large.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟡 Complexity: 1 issue found
• 🟢 Documentation: all looks good

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