import functools import logging import os from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple, cast from pip._vendor.packaging.utils import canonicalize_name from pip._vendor.resolvelib import BaseReporter, ResolutionImpossible from pip._vendor.resolvelib import Resolver as RLResolver from pip._vendor.resolvelib.structs import DirectedGraph from pip._internal.cache import WheelCache from pip._internal.index.package_finder import PackageFinder from pip._internal.operations.prepare import RequirementPreparer from pip._internal.req.req_install import InstallRequirement from pip._internal.req.req_set import RequirementSet from pip._internal.resolution.base import BaseResolver, InstallRequirementProvider from pip._internal.resolution.resolvelib.provider import PipProvider from pip._internal.resolution.resolvelib.reporter import ( PipDebuggingReporter, PipReporter, ) from .base import Candidate, Requirement from .factory import Factory if TYPE_CHECKING: from pip._vendor.resolvelib.resolvers import Result as RLResult Result = RLResult[Requirement, Candidate, str] logger = logging.getLogger(__name__) class Resolver(BaseResolver): _allowed_strategies = {"eager", "only-if-needed", "to-satisfy-only"} def __init__( self, preparer: RequirementPreparer, finder: PackageFinder, wheel_cache: Optional[WheelCache], make_install_req: InstallRequirementProvider, use_user_site: bool, ignore_dependencies: bool, ignore_installed: bool, ignore_requires_python: bool, force_reinstall: bool, upgrade_strategy: str, py_version_info: Optional[Tuple[int, ...]] = None, ): super().__init__() assert upgrade_strategy in self._allowed_strategies self.factory = Factory( finder=finder, preparer=preparer, make_install_req=make_install_req, wheel_cache=wheel_cache, use_user_site=use_user_site, force_reinstall=force_reinstall, ignore_installed=ignore_installed, ignore_requires_python=ignore_requires_python, py_version_info=py_version_info, ) self.ignore_dependencies = ignore_dependencies self.upgrade_strategy = upgrade_strategy self._result: Optional[Result] = None def resolve( self, root_reqs: List[InstallRequirement], check_supported_wheels: bool ) -> RequirementSet: collected = self.factory.collect_root_requirements(root_reqs) provider = PipProvider( factory=self.factory, constraints=collected.constraints, ignore_dependencies=self.ignore_dependencies, upgrade_strategy=self.upgrade_strategy, user_requested=collected.user_requested, ) if "PIP_RESOLVER_DEBUG" in os.environ: reporter: BaseReporter = PipDebuggingReporter() else: reporter = PipReporter() resolver: RLResolver[Requirement, Candidate, str] = RLResolver( provider, reporter, ) try: try_to_avoid_resolution_too_deep = 2000000 result = self._result = resolver.resolve( collected.requirements, max_rounds=try_to_avoid_resolution_too_deep ) except ResolutionImpossible as e: error = self.factory.get_installation_error( cast("ResolutionImpossible[Requirement, Candidate]", e), collected.constraints, ) raise error from e req_set = RequirementSet(check_supported_wheels=check_supported_wheels) for candidate in result.mapping.values(): ireq = candidate.get_install_requirement() if ireq is None: continue # Check if there is already an installation under the same name, # and set a flag for later stages to uninstall it, if needed. installed_dist = self.factory.get_dist_to_uninstall(candidate) if installed_dist is None: # There is no existing installation -- nothing to uninstall. ireq.should_reinstall = False elif self.factory.force_reinstall: # The --force-reinstall flag is set -- reinstall. ireq.should_reinstall = True elif installed_dist.version != candidate.version: # The installation is different in version -- reinstall. ireq.should_reinstall = True elif candidate.is_editable or installed_dist.editable: # The incoming distribution is editable, or different in # editable-ness to installation -- reinstall. ireq.should_reinstall = True elif candidate.source_link and candidate.source_link.is_file: # The incoming distribution is under file:// if candidate.source_link.is_wheel: # is a local wheel -- do nothing. logger.info( "%s is already installed with the same version as the " "provided wheel. Use --force-reinstall to force an " "installation of the wheel.", ireq.name, ) continue # is a local sdist or path -- reinstall ireq.should_reinstall = True else: continue link = candidate.source_link if link and link.is_yanked: # The reason can contain non-ASCII characters, Unicode # is required for Python 2. msg = ( "The candidate selected for download or install is a " "yanked version: {name!r} candidate (version {version} " "at {link})\nReason for being yanked: {reason}" ).format( name=candidate.name, version=candidate.version, link=link, reason=link.yanked_reason or "", ) logger.warning(msg) req_set.add_named_requirement(ireq) reqs = req_set.all_requirements self.factory.preparer.prepare_linked_requirements_more(reqs) return req_set def get_installation_order( self, req_set: RequirementSet ) -> List[InstallRequirement]: """Get order for installation of requirements in RequirementSet. The returned list contains a requirement before another that depends on it. This helps ensure that the environment is kept consistent as they get installed one-by-one. The current implementation creates a topological ordering of the dependency graph, while breaking any cycles in the graph at arbitrary points. We make no guarantees about where the cycle would be broken, other than they would be broken. """ assert self._result is not None, "must call resolve() first" graph = self._result.graph weights = get_topological_weights( graph, expected_node_count=len(self._result.mapping) + 1, ) sorted_items = sorted( req_set.requirements.items(), key=functools.partial(_req_set_item_sorter, weights=weights), reverse=True, ) return [ireq for _, ireq in sorted_items] def get_topological_weights( graph: "DirectedGraph[Optional[str]]", expected_node_count: int ) -> Dict[Optional[str], int]: """Assign weights to each node based on how "deep" they are. This implementation may change at any point in the future without prior notice. We take the length for the longest path to any node from root, ignoring any paths that contain a single node twice (i.e. cycles). This is done through a depth-first search through the graph, while keeping track of the path to the node. Cycles in the graph result would result in node being revisited while also being it's own path. In this case, take no action. This helps ensure we don't get stuck in a cycle. When assigning weight, the longer path (i.e. larger length) is preferred. """ path: Set[Optional[str]] = set() weights: Dict[Optional[str], int] = {} def visit(node: Optional[str]) -> None: if node in path: # We hit a cycle, so we'll break it here. return # Time to visit the children! path.add(node) for child in graph.iter_children(node): visit(child) path.remove(node) last_known_parent_count = weights.get(node, 0) weights[node] = max(last_known_parent_count, len(path)) # `None` is guaranteed to be the root node by resolvelib. visit(None) # Sanity checks assert weights[None] == 0 assert len(weights) == expected_node_count return weights def _req_set_item_sorter( item: Tuple[str, InstallRequirement], weights: Dict[Optional[str], int], ) -> Tuple[int, str]: """Key function used to sort install requirements for installation. Based on the "weight" mapping calculated in ``get_installation_order()``. The canonical package name is returned as the second member as a tie- breaker to ensure the result is predictable, which is useful in tests. """ name = canonicalize_name(item[0]) return weights[name], name