300 lines
11 KiB
Python
300 lines
11 KiB
Python
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import functools
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import logging
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import os
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from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple, cast
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from pip._vendor.packaging.utils import canonicalize_name
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from pip._vendor.resolvelib import BaseReporter, ResolutionImpossible
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from pip._vendor.resolvelib import Resolver as RLResolver
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from pip._vendor.resolvelib.structs import DirectedGraph
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from pip._internal.cache import WheelCache
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from pip._internal.index.package_finder import PackageFinder
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from pip._internal.operations.prepare import RequirementPreparer
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from pip._internal.req.req_install import InstallRequirement
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from pip._internal.req.req_set import RequirementSet
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from pip._internal.resolution.base import BaseResolver, InstallRequirementProvider
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from pip._internal.resolution.resolvelib.provider import PipProvider
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from pip._internal.resolution.resolvelib.reporter import (
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PipDebuggingReporter,
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PipReporter,
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)
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from .base import Candidate, Requirement
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from .factory import Factory
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if TYPE_CHECKING:
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from pip._vendor.resolvelib.resolvers import Result as RLResult
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Result = RLResult[Requirement, Candidate, str]
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logger = logging.getLogger(__name__)
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class Resolver(BaseResolver):
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_allowed_strategies = {"eager", "only-if-needed", "to-satisfy-only"}
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def __init__(
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self,
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preparer: RequirementPreparer,
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finder: PackageFinder,
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wheel_cache: Optional[WheelCache],
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make_install_req: InstallRequirementProvider,
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use_user_site: bool,
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ignore_dependencies: bool,
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ignore_installed: bool,
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ignore_requires_python: bool,
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force_reinstall: bool,
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upgrade_strategy: str,
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py_version_info: Optional[Tuple[int, ...]] = None,
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):
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super().__init__()
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assert upgrade_strategy in self._allowed_strategies
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self.factory = Factory(
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finder=finder,
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preparer=preparer,
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make_install_req=make_install_req,
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wheel_cache=wheel_cache,
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use_user_site=use_user_site,
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force_reinstall=force_reinstall,
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ignore_installed=ignore_installed,
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ignore_requires_python=ignore_requires_python,
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py_version_info=py_version_info,
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)
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self.ignore_dependencies = ignore_dependencies
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self.upgrade_strategy = upgrade_strategy
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self._result: Optional[Result] = None
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def resolve(
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self, root_reqs: List[InstallRequirement], check_supported_wheels: bool
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) -> RequirementSet:
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collected = self.factory.collect_root_requirements(root_reqs)
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provider = PipProvider(
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factory=self.factory,
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constraints=collected.constraints,
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ignore_dependencies=self.ignore_dependencies,
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upgrade_strategy=self.upgrade_strategy,
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user_requested=collected.user_requested,
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)
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if "PIP_RESOLVER_DEBUG" in os.environ:
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reporter: BaseReporter = PipDebuggingReporter()
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else:
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reporter = PipReporter()
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resolver: RLResolver[Requirement, Candidate, str] = RLResolver(
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provider,
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reporter,
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)
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try:
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limit_how_complex_resolution_can_be = 200000
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result = self._result = resolver.resolve(
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collected.requirements, max_rounds=limit_how_complex_resolution_can_be
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)
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except ResolutionImpossible as e:
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error = self.factory.get_installation_error(
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cast("ResolutionImpossible[Requirement, Candidate]", e),
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collected.constraints,
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)
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raise error from e
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req_set = RequirementSet(check_supported_wheels=check_supported_wheels)
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for candidate in result.mapping.values():
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ireq = candidate.get_install_requirement()
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if ireq is None:
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continue
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# Check if there is already an installation under the same name,
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# and set a flag for later stages to uninstall it, if needed.
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installed_dist = self.factory.get_dist_to_uninstall(candidate)
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if installed_dist is None:
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# There is no existing installation -- nothing to uninstall.
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ireq.should_reinstall = False
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elif self.factory.force_reinstall:
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# The --force-reinstall flag is set -- reinstall.
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ireq.should_reinstall = True
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elif installed_dist.version != candidate.version:
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# The installation is different in version -- reinstall.
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ireq.should_reinstall = True
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elif candidate.is_editable or installed_dist.editable:
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# The incoming distribution is editable, or different in
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# editable-ness to installation -- reinstall.
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ireq.should_reinstall = True
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elif candidate.source_link and candidate.source_link.is_file:
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# The incoming distribution is under file://
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if candidate.source_link.is_wheel:
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# is a local wheel -- do nothing.
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logger.info(
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"%s is already installed with the same version as the "
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"provided wheel. Use --force-reinstall to force an "
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"installation of the wheel.",
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ireq.name,
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)
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continue
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# is a local sdist or path -- reinstall
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ireq.should_reinstall = True
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else:
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continue
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link = candidate.source_link
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if link and link.is_yanked:
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# The reason can contain non-ASCII characters, Unicode
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# is required for Python 2.
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msg = (
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"The candidate selected for download or install is a "
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"yanked version: {name!r} candidate (version {version} "
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"at {link})\nReason for being yanked: {reason}"
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).format(
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name=candidate.name,
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version=candidate.version,
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link=link,
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reason=link.yanked_reason or "<none given>",
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)
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logger.warning(msg)
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req_set.add_named_requirement(ireq)
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reqs = req_set.all_requirements
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self.factory.preparer.prepare_linked_requirements_more(reqs)
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for req in reqs:
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req.prepared = True
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req.needs_more_preparation = False
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return req_set
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def get_installation_order(
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self, req_set: RequirementSet
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) -> List[InstallRequirement]:
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"""Get order for installation of requirements in RequirementSet.
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The returned list contains a requirement before another that depends on
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it. This helps ensure that the environment is kept consistent as they
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get installed one-by-one.
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The current implementation creates a topological ordering of the
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dependency graph, giving more weight to packages with less
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or no dependencies, while breaking any cycles in the graph at
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arbitrary points. We make no guarantees about where the cycle
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would be broken, other than it *would* be broken.
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"""
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assert self._result is not None, "must call resolve() first"
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if not req_set.requirements:
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# Nothing is left to install, so we do not need an order.
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return []
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graph = self._result.graph
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weights = get_topological_weights(graph, set(req_set.requirements.keys()))
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sorted_items = sorted(
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req_set.requirements.items(),
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key=functools.partial(_req_set_item_sorter, weights=weights),
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reverse=True,
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)
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return [ireq for _, ireq in sorted_items]
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def get_topological_weights(
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graph: "DirectedGraph[Optional[str]]", requirement_keys: Set[str]
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) -> Dict[Optional[str], int]:
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"""Assign weights to each node based on how "deep" they are.
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This implementation may change at any point in the future without prior
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notice.
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We first simplify the dependency graph by pruning any leaves and giving them
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the highest weight: a package without any dependencies should be installed
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first. This is done again and again in the same way, giving ever less weight
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to the newly found leaves. The loop stops when no leaves are left: all
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remaining packages have at least one dependency left in the graph.
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Then we continue with the remaining graph, by taking the length for the
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longest path to any node from root, ignoring any paths that contain a single
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node twice (i.e. cycles). This is done through a depth-first search through
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the graph, while keeping track of the path to the node.
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Cycles in the graph result would result in node being revisited while also
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being on its own path. In this case, take no action. This helps ensure we
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don't get stuck in a cycle.
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When assigning weight, the longer path (i.e. larger length) is preferred.
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We are only interested in the weights of packages that are in the
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requirement_keys.
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"""
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path: Set[Optional[str]] = set()
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weights: Dict[Optional[str], int] = {}
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def visit(node: Optional[str]) -> None:
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if node in path:
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# We hit a cycle, so we'll break it here.
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return
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# Time to visit the children!
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path.add(node)
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for child in graph.iter_children(node):
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visit(child)
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path.remove(node)
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if node not in requirement_keys:
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return
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last_known_parent_count = weights.get(node, 0)
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weights[node] = max(last_known_parent_count, len(path))
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# Simplify the graph, pruning leaves that have no dependencies.
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# This is needed for large graphs (say over 200 packages) because the
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# `visit` function is exponentially slower then, taking minutes.
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# See https://github.com/pypa/pip/issues/10557
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# We will loop until we explicitly break the loop.
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while True:
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leaves = set()
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for key in graph:
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if key is None:
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continue
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for _child in graph.iter_children(key):
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# This means we have at least one child
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break
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else:
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# No child.
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leaves.add(key)
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if not leaves:
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# We are done simplifying.
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break
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# Calculate the weight for the leaves.
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weight = len(graph) - 1
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for leaf in leaves:
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if leaf not in requirement_keys:
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continue
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weights[leaf] = weight
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# Remove the leaves from the graph, making it simpler.
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for leaf in leaves:
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graph.remove(leaf)
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# Visit the remaining graph.
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# `None` is guaranteed to be the root node by resolvelib.
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visit(None)
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# Sanity check: all requirement keys should be in the weights,
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# and no other keys should be in the weights.
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difference = set(weights.keys()).difference(requirement_keys)
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assert not difference, difference
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return weights
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def _req_set_item_sorter(
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item: Tuple[str, InstallRequirement],
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weights: Dict[Optional[str], int],
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) -> Tuple[int, str]:
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"""Key function used to sort install requirements for installation.
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Based on the "weight" mapping calculated in ``get_installation_order()``.
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The canonical package name is returned as the second member as a tie-
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breaker to ensure the result is predictable, which is useful in tests.
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"""
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name = canonicalize_name(item[0])
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return weights[name], name
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