fix: performance regression when parsing links from legacy repositori…

…es (python-poetry#6442)

Resolves: python-poetry#6436

Measurements of `poetry lock` with warm cache with example
pyproject.toml from python-poetry#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|

`backports.cached-property` is used in order to support
cached_property on Python 3.7. 

Co-authored-by: Jarrod Moore <jmo@jmo.name>
Co-authored-by: Bjorn Neergaard <bjorn@neersighted.com>

pyproject.toml

@@ -46,6 +46,7 @@ python = "^3.7"
 
 poetry-core = "^1.1.0"
 poetry-plugin-export = "^1.0.6"
+"backports.cached-property" = { version = "^1.0.2", python = "<3.8" }
 cachecontrol = { version = "^0.12.9", extras = ["filecache"] }
 cachy = "^0.3.0"
 cleo = "^1.0.0a5"

src/poetry/repositories/link_sources/base.py

@@ -3,13 +3,15 @@
 import logging
 import re
 
-from abc import abstractmethod
 from typing import TYPE_CHECKING
+from typing import DefaultDict
+from typing import List
 
 from packaging.utils import canonicalize_name
 from poetry.core.packages.package import Package
 from poetry.core.semver.version import Version
 
+from poetry.utils._compat import cached_property
 from poetry.utils.patterns import sdist_file_re
 from poetry.utils.patterns import wheel_file_re
 
@@ -20,6 +22,8 @@
     from packaging.utils import NormalizedName
     from poetry.core.packages.utils.link import Link
 
+    LinkCache = DefaultDict[NormalizedName, DefaultDict[Version, List[Link]]]
+
 
 logger = logging.getLogger(__name__)
 
@@ -44,16 +48,8 @@ def __init__(self, url: str) -> None:
     def url(self) -> str:
         return self._url
 
-    def versions(self, name: str) -> Iterator[Version]:
-        name = canonicalize_name(name)
-        seen: set[Version] = set()
-
-        for link in self.links:
-            pkg = self.link_package_data(link)
-
-            if pkg and pkg.name == name and pkg.version not in seen:
-                seen.add(pkg.version)
-                yield pkg.version
+    def versions(self, name: NormalizedName) -> Iterator[Version]:
+        yield from self._link_cache[name]
 
     @property
     def packages(self) -> Iterator[Package]:
@@ -64,9 +60,10 @@ def packages(self) -> Iterator[Package]:
                 yield pkg
 
     @property
-    @abstractmethod
     def links(self) -> Iterator[Link]:
-        raise NotImplementedError()
+        for links_per_version in self._link_cache.values():
+            for links in links_per_version.values():
+                yield from links
 
     @classmethod
     def link_package_data(cls, link: Link) -> Package | None:
@@ -102,11 +99,7 @@ def link_package_data(cls, link: Link) -> Package | None:
     def links_for_version(
         self, name: NormalizedName, version: Version
     ) -> Iterator[Link]:
-        for link in self.links:
-            pkg = self.link_package_data(link)
-
-            if pkg and pkg.name == name and pkg.version == version:
-                yield link
+        yield from self._link_cache[name][version]
 
     def clean_link(self, url: str) -> str:
         """Makes sure a link is fully encoded.  That is, if a ' ' shows up in
@@ -127,3 +120,7 @@ def yanked(self, name: NormalizedName, version: Version) -> str | bool:
         if reasons:
             return "\n".join(sorted(reasons))
         return True
+
+    @cached_property
+    def _link_cache(self) -> LinkCache:
+        raise NotImplementedError()

src/poetry/repositories/link_sources/html.py

@@ -3,16 +3,19 @@
 import urllib.parse
 import warnings
 
+from collections import defaultdict
 from html import unescape
 from typing import TYPE_CHECKING
 
 from poetry.core.packages.utils.link import Link
 
 from poetry.repositories.link_sources.base import LinkSource
+from poetry.utils._compat import cached_property
 
 
 if TYPE_CHECKING:
-    from collections.abc import Iterator
+    from poetry.repositories.link_sources.base import LinkCache
+
 
 with warnings.catch_warnings():
     warnings.simplefilter("ignore")
@@ -25,8 +28,9 @@ def __init__(self, url: str, content: str) -> None:
 
         self._parsed = html5lib.parse(content, namespaceHTMLElements=False)
 
-    @property
-    def links(self) -> Iterator[Link]:
+    @cached_property
+    def _link_cache(self) -> LinkCache:
+        links: LinkCache = defaultdict(lambda: defaultdict(list))
         for anchor in self._parsed.findall(".//a"):
             if anchor.get("href"):
                 href = anchor.get("href")
@@ -44,7 +48,11 @@ def links(self) -> Iterator[Link]:
                 if link.ext not in self.SUPPORTED_FORMATS:
                     continue
 
-                yield link
+                pkg = self.link_package_data(link)
+                if pkg:
+                    links[pkg.name][pkg.version].append(link)
+
+        return links
 
 
 class SimpleRepositoryPage(HTMLPage):

src/poetry/utils/_compat.py

@@ -13,6 +13,12 @@
 else:
     from importlib import metadata
 
+if sys.version_info < (3, 8):
+    # compatibility for python <3.8
+    from backports.cached_property import cached_property
+else:
+    from functools import cached_property
+
 WINDOWS = sys.platform == "win32"
 
 
@@ -53,4 +59,12 @@ def list_to_shell_command(cmd: list[str]) -> str:
     )
 
 
-__all__ = ["WINDOWS", "decode", "encode", "list_to_shell_command", "metadata", "to_str"]
+__all__ = [
+    "WINDOWS",
+    "cached_property",
+    "decode",
+    "encode",
+    "list_to_shell_command",
+    "metadata",
+    "to_str",
+]

tests/repositories/link_sources/test_base.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from collections import defaultdict
 from typing import TYPE_CHECKING
 from unittest.mock import PropertyMock
 
@@ -24,16 +25,22 @@ def link_source(mocker: MockerFixture) -> LinkSource:
     url = "https://example.org"
     link_source = LinkSource(url)
     mocker.patch(
-        f"{LinkSource.__module__}.{LinkSource.__qualname__}.links",
+        f"{LinkSource.__module__}.{LinkSource.__qualname__}._link_cache",
         new_callable=PropertyMock,
-        return_value=iter(
-            [
-                Link(f"{url}/demo-0.1.0.tar.gz"),
-                Link(f"{url}/demo-0.1.0_invalid.tar.gz"),
-                Link(f"{url}/invalid.tar.gz"),
-                Link(f"{url}/demo-0.1.0-py2.py3-none-any.whl"),
-                Link(f"{url}/demo-0.1.1.tar.gz"),
-            ]
+        return_value=defaultdict(
+            lambda: defaultdict(list),
+            {
+                canonicalize_name("demo"): defaultdict(
+                    list,
+                    {
+                        Version.parse("0.1.0"): [
+                            Link(f"{url}/demo-0.1.0.tar.gz"),
+                            Link(f"{url}/demo-0.1.0-py2.py3-none-any.whl"),
+                        ],
+                        Version.parse("0.1.1"): [Link(f"{url}/demo-0.1.1.tar.gz")],
+                    },
+                ),
+            },
         ),
     )
     return link_source
@@ -63,7 +70,7 @@ def test_link_package_data(filename: str, expected: Package | None) -> None:
     ],
 )
 def test_versions(name: str, expected: set[Version], link_source: LinkSource) -> None:
-    assert set(link_source.versions(name)) == expected
+    assert set(link_source.versions(canonicalize_name(name))) == expected
 
 
 def test_packages(link_source: LinkSource) -> None:

tests/repositories/link_sources/test_html.py

@@ -2,6 +2,7 @@
 
 import pytest
 
+from packaging.utils import canonicalize_name
 from poetry.core.packages.utils.link import Link
 from poetry.core.semver.version import Version
 
@@ -90,4 +91,4 @@ def test_yanked(yanked_attrs: tuple[str, str], expected: bool | str) -> None:
     content = DEMO_TEMPLATE.format(anchors)
     page = HTMLPage("https://example.org", content)
 
-    assert page.yanked("demo", Version.parse("0.1")) == expected
+    assert page.yanked(canonicalize_name("demo"), Version.parse("0.1")) == expected

tests/repositories/test_legacy_repository.py

@@ -102,25 +102,12 @@ def test_page_invalid_version_link() -> None:
     assert page is not None
 
     links = list(page.links)
-    assert len(links) == 2
+    assert len(links) == 1
 
-    versions = list(page.versions("poetry"))
+    versions = list(page.versions(canonicalize_name("poetry")))
     assert len(versions) == 1
     assert versions[0].to_string() == "0.1.0"
 
-    invalid_link = None
-
-    for link in links:
-        if link.filename.startswith("poetry-21"):
-            invalid_link = link
-            break
-
-    links_010 = list(page.links_for_version(canonicalize_name("poetry"), versions[0]))
-    assert invalid_link not in links_010
-
-    assert invalid_link
-    assert not page.link_package_data(invalid_link)
-
     packages = list(page.packages)
     assert len(packages) == 1
     assert packages[0].name == "poetry"