fix: performance regression when parsing links from legacy repositories

[radoering]

Resolves: #6436

Measurements of poetry lock with warm cache with example pyproject.toml from #6436:

test case	time in s	peak memory usage in MB
legacy repository (before)	422	113
legacy repository (after)	3	118
pypi repository	1	92

Usage of @cached_property would be nice, but unfortunately is not available in Python 3.7 and @property combined with @cached as proposed in https://docs.python.org/3/library/functools.html#functools.cached_property results in memory leaks (flake8-bugbear B019).

[MasterNayru]

This is like what I did but way better. Woohoo! I am so happy to have been even the slightest bit helpful in making Poetry a better tool for everyone.

I have run this against other projects that I was seeing performance issues with internally and can see that performance in dependency resolution has dramatically improved.

I can't stress enough the importance of having this performance issue fixed and in a release branch (whether it be this PR or some other one). The performance drop with the logic as it stands on v1.2.0 just makes using poetry in environments where a secondary repo is used practically unusable. I have had two backends show this same performance issue, one being pypicloud which seems to direct clients to pypi.org when it does not have a package, and AWS CodeArtifact, which can be configured to pull packages from pypi.org itself. I would just hate to have people advocate against tools like this or be hesitant to upgrade.

[radoering]

As proposed by @neersighted on discord, I added backports.cached-property in order to support cached_property on Python 3.7. This simplifies things a bit. It's in a separate commit, so we can decide if it's worth it.

[neersighted]

LGTM overall, I have high confidence in backporting this -- one minor nit that we can skip if you don't like it.

[radoering]

pre-commit.ci autofix

[poetry-bot]

The backport to 1.2 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-1.2 1.2
# Navigate to the new working tree
cd .worktrees/backport-1.2
# Create a new branch
git switch --create backport-6442-to-1.2
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 c4b2253793cd6b41a99e25e479e40b776cca0a0e
# Push it to GitHub
git push --set-upstream origin backport-6442-to-1.2
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-1.2

Then, create a pull request where the base branch is 1.2 and the compare/head branch is backport-6442-to-1.2.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.