mirror of https://github.com/pypa/pip
260 lines
9.9 KiB
Python
260 lines
9.9 KiB
Python
import functools
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import logging
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from pip._vendor import six
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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._internal.exceptions import InstallationError
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from pip._internal.req.req_install import check_invalid_constraint_type
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from pip._internal.req.req_set import RequirementSet
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from pip._internal.resolution.base import BaseResolver
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from pip._internal.resolution.resolvelib.provider import PipProvider
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from pip._internal.utils.misc import dist_is_editable
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from pip._internal.utils.typing import MYPY_CHECK_RUNNING
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from .base import Constraint
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from .factory import Factory
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if MYPY_CHECK_RUNNING:
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from typing import Dict, List, Optional, Set, Tuple
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from pip._vendor.resolvelib.resolvers import Result
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from pip._vendor.resolvelib.structs import Graph
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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.resolution.base import InstallRequirementProvider
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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, # type: RequirementPreparer
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finder, # type: PackageFinder
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wheel_cache, # type: Optional[WheelCache]
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make_install_req, # type: InstallRequirementProvider
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use_user_site, # type: bool
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ignore_dependencies, # type: bool
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ignore_installed, # type: bool
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ignore_requires_python, # type: bool
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force_reinstall, # type: bool
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upgrade_strategy, # type: str
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py_version_info=None, # type: Optional[Tuple[int, ...]]
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lazy_wheel=False, # type: bool
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):
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super(Resolver, self).__init__()
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if lazy_wheel:
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logger.warning(
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'pip is using lazily downloaded wheels using HTTP '
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'range requests to obtain dependency information. '
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'This experimental feature is enabled through '
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'--use-feature=fast-deps and it is not ready for production.'
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)
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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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lazy_wheel=lazy_wheel,
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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 = None # type: Optional[Result]
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def resolve(self, root_reqs, check_supported_wheels):
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# type: (List[InstallRequirement], bool) -> RequirementSet
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constraints = {} # type: Dict[str, Constraint]
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user_requested = set() # type: Set[str]
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requirements = []
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for req in root_reqs:
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if req.constraint:
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# Ensure we only accept valid constraints
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problem = check_invalid_constraint_type(req)
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if problem:
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raise InstallationError(problem)
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if not req.match_markers():
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continue
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name = canonicalize_name(req.name)
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if name in constraints:
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constraints[name] &= req
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else:
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constraints[name] = Constraint.from_ireq(req)
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else:
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if req.user_supplied and req.name:
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user_requested.add(canonicalize_name(req.name))
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r = self.factory.make_requirement_from_install_req(
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req, requested_extras=(),
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)
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if r is not None:
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requirements.append(r)
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provider = PipProvider(
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factory=self.factory,
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constraints=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=user_requested,
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)
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reporter = BaseReporter()
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resolver = RLResolver(provider, reporter)
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try:
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try_to_avoid_resolution_too_deep = 2000000
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self._result = resolver.resolve(
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requirements, max_rounds=try_to_avoid_resolution_too_deep,
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)
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except ResolutionImpossible as e:
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error = self.factory.get_installation_error(e)
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six.raise_from(error, e)
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req_set = RequirementSet(check_supported_wheels=check_supported_wheels)
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for candidate in self._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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# * There isn't, good -- no uninstalltion needed.
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# * The --force-reinstall flag is set. Always reinstall.
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# * The installation is different in version or editable-ness, so
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# we need to uninstall it to install the new distribution.
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# * The installed version is the same as the pending distribution.
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# Skip this distrubiton altogether to save work.
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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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ireq.should_reinstall = False
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elif self.factory.force_reinstall:
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ireq.should_reinstall = True
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elif installed_dist.parsed_version != candidate.version:
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ireq.should_reinstall = True
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elif dist_is_editable(installed_dist) != candidate.is_editable:
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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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u'The candidate selected for download or install is a '
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u'yanked version: {name!r} candidate (version {version} '
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u'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 u'<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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return req_set
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def get_installation_order(self, req_set):
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# type: (RequirementSet) -> 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, while breaking any cycles in the graph at arbitrary
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points. We make no guarantees about where the cycle would be broken,
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other than they 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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graph = self._result.graph
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weights = get_topological_weights(graph)
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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(graph):
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# type: (Graph) -> 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 take the length for the longest path to any node from root, ignoring any
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paths that contain a single node twice (i.e. cycles). This is done through
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a depth-first search through the graph, while keeping track of the path to
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the node.
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Cycles in the graph result would result in node being revisited while also
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being it's 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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"""
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path = set() # type: Set[Optional[str]]
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weights = {} # type: Dict[Optional[str], int]
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def visit(node):
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# type: (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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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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# `None` is guaranteed to be the root node by resolvelib.
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visit(None)
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# Sanity checks
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assert weights[None] == 0
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assert len(weights) == len(graph)
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return weights
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def _req_set_item_sorter(
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item, # type: Tuple[str, InstallRequirement]
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weights, # type: Dict[Optional[str], int]
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):
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# type: (...) -> 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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