import functools import logging from pip._vendor import six 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._internal.exceptions import InstallationError from pip._internal.req.req_install import check_invalid_constraint_type from pip._internal.req.req_set import RequirementSet from pip._internal.resolution.base import BaseResolver from pip._internal.resolution.resolvelib.provider import PipProvider from pip._internal.utils.misc import dist_is_editable from pip._internal.utils.typing import MYPY_CHECK_RUNNING from .base import Constraint from .factory import Factory if MYPY_CHECK_RUNNING: from typing import Dict, List, Optional, Set, Tuple from pip._vendor.resolvelib.resolvers import Result from pip._vendor.resolvelib.structs import Graph 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.resolution.base import InstallRequirementProvider logger = logging.getLogger(__name__) class Resolver(BaseResolver): _allowed_strategies = {"eager", "only-if-needed", "to-satisfy-only"} def __init__( self, preparer, # type: RequirementPreparer finder, # type: PackageFinder wheel_cache, # type: Optional[WheelCache] make_install_req, # type: InstallRequirementProvider use_user_site, # type: bool ignore_dependencies, # type: bool ignore_installed, # type: bool ignore_requires_python, # type: bool force_reinstall, # type: bool upgrade_strategy, # type: str py_version_info=None, # type: Optional[Tuple[int, ...]] lazy_wheel=False, # type: bool ): super(Resolver, self).__init__() if lazy_wheel: logger.warning( 'pip is using lazily downloaded wheels using HTTP ' 'range requests to obtain dependency information. ' 'This experimental feature is enabled through ' '--use-feature=fast-deps and it is not ready for production.' ) 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, lazy_wheel=lazy_wheel, ) self.ignore_dependencies = ignore_dependencies self.upgrade_strategy = upgrade_strategy self._result = None # type: Optional[Result] def resolve(self, root_reqs, check_supported_wheels): # type: (List[InstallRequirement], bool) -> RequirementSet constraints = {} # type: Dict[str, Constraint] user_requested = set() # type: Set[str] requirements = [] for req in root_reqs: if req.constraint: # Ensure we only accept valid constraints problem = check_invalid_constraint_type(req) if problem: raise InstallationError(problem) if not req.match_markers(): continue name = canonicalize_name(req.name) if name in constraints: constraints[name] &= req else: constraints[name] = Constraint.from_ireq(req) else: if req.user_supplied and req.name: user_requested.add(canonicalize_name(req.name)) r = self.factory.make_requirement_from_install_req( req, requested_extras=(), ) if r is not None: requirements.append(r) provider = PipProvider( factory=self.factory, constraints=constraints, ignore_dependencies=self.ignore_dependencies, upgrade_strategy=self.upgrade_strategy, user_requested=user_requested, ) reporter = BaseReporter() resolver = RLResolver(provider, reporter) try: try_to_avoid_resolution_too_deep = 2000000 self._result = resolver.resolve( requirements, max_rounds=try_to_avoid_resolution_too_deep, ) except ResolutionImpossible as e: error = self.factory.get_installation_error(e) six.raise_from(error, e) req_set = RequirementSet(check_supported_wheels=check_supported_wheels) for candidate in self._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. # * There isn't, good -- no uninstalltion needed. # * The --force-reinstall flag is set. Always reinstall. # * The installation is different in version or editable-ness, so # we need to uninstall it to install the new distribution. # * The installed version is the same as the pending distribution. # Skip this distrubiton altogether to save work. installed_dist = self.factory.get_dist_to_uninstall(candidate) if installed_dist is None: ireq.should_reinstall = False elif self.factory.force_reinstall: ireq.should_reinstall = True elif installed_dist.parsed_version != candidate.version: ireq.should_reinstall = True elif dist_is_editable(installed_dist) != candidate.is_editable: 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 = ( u'The candidate selected for download or install is a ' u'yanked version: {name!r} candidate (version {version} ' u'at {link})\nReason for being yanked: {reason}' ).format( name=candidate.name, version=candidate.version, link=link, reason=link.yanked_reason or u'', ) logger.warning(msg) req_set.add_named_requirement(ireq) return req_set def get_installation_order(self, req_set): # type: (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) 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): # type: (Graph) -> 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() # type: Set[Optional[str]] weights = {} # type: Dict[Optional[str], int] def visit(node): # type: (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) == len(graph) return weights def _req_set_item_sorter( item, # type: Tuple[str, InstallRequirement] weights, # type: Dict[Optional[str], int] ): # type: (...) -> 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