463 lines
18 KiB
Python
463 lines
18 KiB
Python
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"""Dependency Resolution
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The dependency resolution in pip is performed as follows:
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for top-level requirements:
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a. only one spec allowed per project, regardless of conflicts or not.
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otherwise a "double requirement" exception is raised
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b. they override sub-dependency requirements.
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for sub-dependencies
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a. "first found, wins" (where the order is breadth first)
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"""
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# The following comment should be removed at some point in the future.
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# mypy: strict-optional=False
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import logging
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import sys
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from collections import defaultdict
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from itertools import chain
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from typing import DefaultDict, Iterable, List, Optional, Set, Tuple
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from pip._vendor.packaging import specifiers
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from pip._vendor.pkg_resources import Distribution
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from pip._internal.cache import WheelCache
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from pip._internal.exceptions import (
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BestVersionAlreadyInstalled,
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DistributionNotFound,
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HashError,
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HashErrors,
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UnsupportedPythonVersion,
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)
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from pip._internal.index.package_finder import PackageFinder
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from pip._internal.models.link import Link
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from pip._internal.operations.prepare import RequirementPreparer
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from pip._internal.req.req_install import (
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InstallRequirement,
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check_invalid_constraint_type,
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)
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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.utils.compatibility_tags import get_supported
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from pip._internal.utils.logging import indent_log
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from pip._internal.utils.misc import dist_in_usersite, normalize_version_info
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from pip._internal.utils.packaging import check_requires_python, get_requires_python
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logger = logging.getLogger(__name__)
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DiscoveredDependencies = DefaultDict[str, List[InstallRequirement]]
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def _check_dist_requires_python(
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dist, # type: Distribution
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version_info, # type: Tuple[int, int, int]
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ignore_requires_python=False, # type: bool
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):
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# type: (...) -> None
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"""
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Check whether the given Python version is compatible with a distribution's
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"Requires-Python" value.
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:param version_info: A 3-tuple of ints representing the Python
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major-minor-micro version to check.
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:param ignore_requires_python: Whether to ignore the "Requires-Python"
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value if the given Python version isn't compatible.
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:raises UnsupportedPythonVersion: When the given Python version isn't
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compatible.
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"""
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requires_python = get_requires_python(dist)
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try:
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is_compatible = check_requires_python(
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requires_python, version_info=version_info
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)
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except specifiers.InvalidSpecifier as exc:
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logger.warning(
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"Package %r has an invalid Requires-Python: %s", dist.project_name, exc
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)
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return
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if is_compatible:
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return
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version = ".".join(map(str, version_info))
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if ignore_requires_python:
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logger.debug(
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"Ignoring failed Requires-Python check for package %r: " "%s not in %r",
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dist.project_name,
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version,
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requires_python,
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)
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return
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raise UnsupportedPythonVersion(
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"Package {!r} requires a different Python: {} not in {!r}".format(
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dist.project_name, version, requires_python
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)
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)
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class Resolver(BaseResolver):
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"""Resolves which packages need to be installed/uninstalled to perform \
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the requested operation without breaking the requirements of any package.
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"""
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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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):
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# type: (...) -> None
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super().__init__()
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assert upgrade_strategy in self._allowed_strategies
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if py_version_info is None:
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py_version_info = sys.version_info[:3]
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else:
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py_version_info = normalize_version_info(py_version_info)
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self._py_version_info = py_version_info
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self.preparer = preparer
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self.finder = finder
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self.wheel_cache = wheel_cache
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self.upgrade_strategy = upgrade_strategy
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self.force_reinstall = force_reinstall
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self.ignore_dependencies = ignore_dependencies
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self.ignore_installed = ignore_installed
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self.ignore_requires_python = ignore_requires_python
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self.use_user_site = use_user_site
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self._make_install_req = make_install_req
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self._discovered_dependencies = defaultdict(
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list
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) # type: DiscoveredDependencies
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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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"""Resolve what operations need to be done
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As a side-effect of this method, the packages (and their dependencies)
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are downloaded, unpacked and prepared for installation. This
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preparation is done by ``pip.operations.prepare``.
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Once PyPI has static dependency metadata available, it would be
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possible to move the preparation to become a step separated from
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dependency resolution.
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"""
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requirement_set = RequirementSet(check_supported_wheels=check_supported_wheels)
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for req in root_reqs:
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if req.constraint:
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check_invalid_constraint_type(req)
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requirement_set.add_requirement(req)
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# Actually prepare the files, and collect any exceptions. Most hash
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# exceptions cannot be checked ahead of time, because
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# _populate_link() needs to be called before we can make decisions
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# based on link type.
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discovered_reqs = [] # type: List[InstallRequirement]
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hash_errors = HashErrors()
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for req in chain(requirement_set.all_requirements, discovered_reqs):
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try:
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discovered_reqs.extend(self._resolve_one(requirement_set, req))
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except HashError as exc:
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exc.req = req
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hash_errors.append(exc)
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if hash_errors:
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raise hash_errors
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return requirement_set
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def _is_upgrade_allowed(self, req):
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# type: (InstallRequirement) -> bool
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if self.upgrade_strategy == "to-satisfy-only":
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return False
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elif self.upgrade_strategy == "eager":
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return True
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else:
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assert self.upgrade_strategy == "only-if-needed"
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return req.user_supplied or req.constraint
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def _set_req_to_reinstall(self, req):
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# type: (InstallRequirement) -> None
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"""
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Set a requirement to be installed.
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"""
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# Don't uninstall the conflict if doing a user install and the
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# conflict is not a user install.
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if not self.use_user_site or dist_in_usersite(req.satisfied_by):
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req.should_reinstall = True
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req.satisfied_by = None
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def _check_skip_installed(self, req_to_install):
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# type: (InstallRequirement) -> Optional[str]
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"""Check if req_to_install should be skipped.
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This will check if the req is installed, and whether we should upgrade
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or reinstall it, taking into account all the relevant user options.
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After calling this req_to_install will only have satisfied_by set to
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None if the req_to_install is to be upgraded/reinstalled etc. Any
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other value will be a dist recording the current thing installed that
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satisfies the requirement.
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Note that for vcs urls and the like we can't assess skipping in this
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routine - we simply identify that we need to pull the thing down,
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then later on it is pulled down and introspected to assess upgrade/
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reinstalls etc.
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:return: A text reason for why it was skipped, or None.
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"""
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if self.ignore_installed:
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return None
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req_to_install.check_if_exists(self.use_user_site)
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if not req_to_install.satisfied_by:
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return None
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if self.force_reinstall:
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self._set_req_to_reinstall(req_to_install)
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return None
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if not self._is_upgrade_allowed(req_to_install):
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if self.upgrade_strategy == "only-if-needed":
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return "already satisfied, skipping upgrade"
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return "already satisfied"
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# Check for the possibility of an upgrade. For link-based
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# requirements we have to pull the tree down and inspect to assess
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# the version #, so it's handled way down.
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if not req_to_install.link:
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try:
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self.finder.find_requirement(req_to_install, upgrade=True)
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except BestVersionAlreadyInstalled:
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# Then the best version is installed.
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return "already up-to-date"
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except DistributionNotFound:
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# No distribution found, so we squash the error. It will
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# be raised later when we re-try later to do the install.
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# Why don't we just raise here?
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pass
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self._set_req_to_reinstall(req_to_install)
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return None
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def _find_requirement_link(self, req):
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# type: (InstallRequirement) -> Optional[Link]
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upgrade = self._is_upgrade_allowed(req)
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best_candidate = self.finder.find_requirement(req, upgrade)
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if not best_candidate:
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return None
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# Log a warning per PEP 592 if necessary before returning.
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link = best_candidate.link
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if link.is_yanked:
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reason = link.yanked_reason or "<none given>"
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msg = (
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# Mark this as a unicode string to prevent
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# "UnicodeEncodeError: 'ascii' codec can't encode character"
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# in Python 2 when the reason contains non-ascii characters.
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"The candidate selected for download or install is a "
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"yanked version: {candidate}\n"
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"Reason for being yanked: {reason}"
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).format(candidate=best_candidate, reason=reason)
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logger.warning(msg)
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return link
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def _populate_link(self, req):
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# type: (InstallRequirement) -> None
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"""Ensure that if a link can be found for this, that it is found.
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Note that req.link may still be None - if the requirement is already
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installed and not needed to be upgraded based on the return value of
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_is_upgrade_allowed().
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If preparer.require_hashes is True, don't use the wheel cache, because
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cached wheels, always built locally, have different hashes than the
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files downloaded from the index server and thus throw false hash
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mismatches. Furthermore, cached wheels at present have undeterministic
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contents due to file modification times.
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"""
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if req.link is None:
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req.link = self._find_requirement_link(req)
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if self.wheel_cache is None or self.preparer.require_hashes:
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return
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cache_entry = self.wheel_cache.get_cache_entry(
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link=req.link,
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package_name=req.name,
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supported_tags=get_supported(),
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)
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if cache_entry is not None:
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logger.debug("Using cached wheel link: %s", cache_entry.link)
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if req.link is req.original_link and cache_entry.persistent:
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req.original_link_is_in_wheel_cache = True
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req.link = cache_entry.link
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def _get_dist_for(self, req):
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# type: (InstallRequirement) -> Distribution
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"""Takes a InstallRequirement and returns a single AbstractDist \
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representing a prepared variant of the same.
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"""
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if req.editable:
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return self.preparer.prepare_editable_requirement(req)
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# satisfied_by is only evaluated by calling _check_skip_installed,
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# so it must be None here.
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assert req.satisfied_by is None
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skip_reason = self._check_skip_installed(req)
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if req.satisfied_by:
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return self.preparer.prepare_installed_requirement(req, skip_reason)
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# We eagerly populate the link, since that's our "legacy" behavior.
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self._populate_link(req)
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dist = self.preparer.prepare_linked_requirement(req)
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# NOTE
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# The following portion is for determining if a certain package is
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# going to be re-installed/upgraded or not and reporting to the user.
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# This should probably get cleaned up in a future refactor.
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# req.req is only avail after unpack for URL
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# pkgs repeat check_if_exists to uninstall-on-upgrade
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# (#14)
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if not self.ignore_installed:
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req.check_if_exists(self.use_user_site)
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if req.satisfied_by:
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should_modify = (
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self.upgrade_strategy != "to-satisfy-only"
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or self.force_reinstall
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or self.ignore_installed
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or req.link.scheme == "file"
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)
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if should_modify:
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self._set_req_to_reinstall(req)
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else:
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logger.info(
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"Requirement already satisfied (use --upgrade to upgrade):" " %s",
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req,
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)
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return dist
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def _resolve_one(
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self,
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requirement_set, # type: RequirementSet
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req_to_install, # type: InstallRequirement
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):
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# type: (...) -> List[InstallRequirement]
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"""Prepare a single requirements file.
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:return: A list of additional InstallRequirements to also install.
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"""
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# Tell user what we are doing for this requirement:
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# obtain (editable), skipping, processing (local url), collecting
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# (remote url or package name)
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if req_to_install.constraint or req_to_install.prepared:
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return []
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req_to_install.prepared = True
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|
|
|
||
|
|
# Parse and return dependencies
|
||
|
|
dist = self._get_dist_for(req_to_install)
|
||
|
|
# This will raise UnsupportedPythonVersion if the given Python
|
||
|
|
# version isn't compatible with the distribution's Requires-Python.
|
||
|
|
_check_dist_requires_python(
|
||
|
|
dist,
|
||
|
|
version_info=self._py_version_info,
|
||
|
|
ignore_requires_python=self.ignore_requires_python,
|
||
|
|
)
|
||
|
|
|
||
|
|
more_reqs = [] # type: List[InstallRequirement]
|
||
|
|
|
||
|
|
def add_req(subreq, extras_requested):
|
||
|
|
# type: (Distribution, Iterable[str]) -> None
|
||
|
|
sub_install_req = self._make_install_req(
|
||
|
|
str(subreq),
|
||
|
|
req_to_install,
|
||
|
|
)
|
||
|
|
parent_req_name = req_to_install.name
|
||
|
|
to_scan_again, add_to_parent = requirement_set.add_requirement(
|
||
|
|
sub_install_req,
|
||
|
|
parent_req_name=parent_req_name,
|
||
|
|
extras_requested=extras_requested,
|
||
|
|
)
|
||
|
|
if parent_req_name and add_to_parent:
|
||
|
|
self._discovered_dependencies[parent_req_name].append(add_to_parent)
|
||
|
|
more_reqs.extend(to_scan_again)
|
||
|
|
|
||
|
|
with indent_log():
|
||
|
|
# We add req_to_install before its dependencies, so that we
|
||
|
|
# can refer to it when adding dependencies.
|
||
|
|
if not requirement_set.has_requirement(req_to_install.name):
|
||
|
|
# 'unnamed' requirements will get added here
|
||
|
|
# 'unnamed' requirements can only come from being directly
|
||
|
|
# provided by the user.
|
||
|
|
assert req_to_install.user_supplied
|
||
|
|
requirement_set.add_requirement(req_to_install, parent_req_name=None)
|
||
|
|
|
||
|
|
if not self.ignore_dependencies:
|
||
|
|
if req_to_install.extras:
|
||
|
|
logger.debug(
|
||
|
|
"Installing extra requirements: %r",
|
||
|
|
",".join(req_to_install.extras),
|
||
|
|
)
|
||
|
|
missing_requested = sorted(
|
||
|
|
set(req_to_install.extras) - set(dist.extras)
|
||
|
|
)
|
||
|
|
for missing in missing_requested:
|
||
|
|
logger.warning("%s does not provide the extra '%s'", dist, missing)
|
||
|
|
|
||
|
|
available_requested = sorted(
|
||
|
|
set(dist.extras) & set(req_to_install.extras)
|
||
|
|
)
|
||
|
|
for subreq in dist.requires(available_requested):
|
||
|
|
add_req(subreq, extras_requested=available_requested)
|
||
|
|
|
||
|
|
return more_reqs
|
||
|
|
|
||
|
|
def get_installation_order(self, req_set):
|
||
|
|
# type: (RequirementSet) -> List[InstallRequirement]
|
||
|
|
"""Create the installation order.
|
||
|
|
|
||
|
|
The installation order is topological - requirements are installed
|
||
|
|
before the requiring thing. We break cycles at an arbitrary point,
|
||
|
|
and make no other guarantees.
|
||
|
|
"""
|
||
|
|
# The current implementation, which we may change at any point
|
||
|
|
# installs the user specified things in the order given, except when
|
||
|
|
# dependencies must come earlier to achieve topological order.
|
||
|
|
order = []
|
||
|
|
ordered_reqs = set() # type: Set[InstallRequirement]
|
||
|
|
|
||
|
|
def schedule(req):
|
||
|
|
# type: (InstallRequirement) -> None
|
||
|
|
if req.satisfied_by or req in ordered_reqs:
|
||
|
|
return
|
||
|
|
if req.constraint:
|
||
|
|
return
|
||
|
|
ordered_reqs.add(req)
|
||
|
|
for dep in self._discovered_dependencies[req.name]:
|
||
|
|
schedule(dep)
|
||
|
|
order.append(req)
|
||
|
|
|
||
|
|
for install_req in req_set.requirements.values():
|
||
|
|
schedule(install_req)
|
||
|
|
return order
|