name : legacy_resolve.py """Dependency Resolution The dependency resolution in pip is performed as follows: for top-level requirements: a. only one spec allowed per project, regardless of conflicts or not. otherwise a "double requirement" exception is raised b. they override sub-dependency requirements. for sub-dependencies a. "first found, wins" (where the order is breadth first) """ # The following comment should be removed at some point in the future. # mypy: strict-optional=False # mypy: disallow-untyped-defs=False import logging import sys from collections import defaultdict from itertools import chain from pip._vendor.packaging import specifiers from pip._internal.exceptions import ( BestVersionAlreadyInstalled, DistributionNotFound, HashError, HashErrors, UnsupportedPythonVersion, ) from pip._internal.utils.logging import indent_log from pip._internal.utils.misc import ( dist_in_install_path, dist_in_usersite, ensure_dir, normalize_version_info, ) from pip._internal.utils.packaging import ( check_requires_python, get_requires_python, ) from pip._internal.utils.typing import MYPY_CHECK_RUNNING if MYPY_CHECK_RUNNING: from typing import Callable, DefaultDict, List, Optional, Set, Tuple from pip._vendor import pkg_resources from pip._internal.distributions import AbstractDistribution from pip._internal.network.session import PipSession from pip._internal.index 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 InstallRequirementProvider = Callable[ [str, InstallRequirement], InstallRequirement ] logger = logging.getLogger(__name__) def _check_dist_requires_python( dist, # type: pkg_resources.Distribution version_info, # type: Tuple[int, int, int] ignore_requires_python=False, # type: bool ): # type: (...) -> None """ Check whether the given Python version is compatible with a distribution's "Requires-Python" value. :param version_info: A 3-tuple of ints representing the Python major-minor-micro version to check. :param ignore_requires_python: Whether to ignore the "Requires-Python" value if the given Python version isn't compatible. :raises UnsupportedPythonVersion: When the given Python version isn't compatible. """ requires_python = get_requires_python(dist) try: is_compatible = check_requires_python( requires_python, version_info=version_info, ) except specifiers.InvalidSpecifier as exc: logger.warning( "Package %r has an invalid Requires-Python: %s", dist.project_name, exc, ) return if is_compatible: return version = '.'.join(map(str, version_info)) if ignore_requires_python: logger.debug( 'Ignoring failed Requires-Python check for package %r: ' '%s not in %r', dist.project_name, version, requires_python, ) return raise UnsupportedPythonVersion( 'Package {!r} requires a different Python: {} not in {!r}'.format( dist.project_name, version, requires_python, )) class Resolver(object): """Resolves which packages need to be installed/uninstalled to perform \ the requested operation without breaking the requirements of any package. """ _allowed_strategies = {"eager", "only-if-needed", "to-satisfy-only"} def __init__( self, preparer, # type: RequirementPreparer session, # type: PipSession finder, # type: PackageFinder 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, ...]] ): # type: (...) -> None super(Resolver, self).__init__() assert upgrade_strategy in self._allowed_strategies if py_version_info is None: py_version_info = sys.version_info[:3] else: py_version_info = normalize_version_info(py_version_info) self._py_version_info = py_version_info self.preparer = preparer self.finder = finder self.session = session # This is set in resolve self.require_hashes = None # type: Optional[bool] self.upgrade_strategy = upgrade_strategy self.force_reinstall = force_reinstall self.ignore_dependencies = ignore_dependencies self.ignore_installed = ignore_installed self.ignore_requires_python = ignore_requires_python self.use_user_site = use_user_site self._make_install_req = make_install_req self._discovered_dependencies = \ defaultdict(list) # type: DefaultDict[str, List] def resolve(self, requirement_set): # type: (RequirementSet) -> None """Resolve what operations need to be done As a side-effect of this method, the packages (and their dependencies) are downloaded, unpacked and prepared for installation. This preparation is done by ``pip.operations.prepare``. Once PyPI has static dependency metadata available, it would be possible to move the preparation to become a step separated from dependency resolution. """ # make the wheelhouse if self.preparer.wheel_download_dir: ensure_dir(self.preparer.wheel_download_dir) # If any top-level requirement has a hash specified, enter # hash-checking mode, which requires hashes from all. root_reqs = ( requirement_set.unnamed_requirements + list(requirement_set.requirements.values()) ) self.require_hashes = ( requirement_set.require_hashes or any(req.has_hash_options for req in root_reqs) ) # Display where finder is looking for packages search_scope = self.finder.search_scope locations = search_scope.get_formatted_locations() if locations: logger.info(locations) # Actually prepare the files, and collect any exceptions. Most hash # exceptions cannot be checked ahead of time, because # req.populate_link() needs to be called before we can make decisions # based on link type. discovered_reqs = [] # type: List[InstallRequirement] hash_errors = HashErrors() for req in chain(root_reqs, discovered_reqs): try: discovered_reqs.extend( self._resolve_one(requirement_set, req) ) except HashError as exc: exc.req = req hash_errors.append(exc) if hash_errors: raise hash_errors def _is_upgrade_allowed(self, req): # type: (InstallRequirement) -> bool if self.upgrade_strategy == "to-satisfy-only": return False elif self.upgrade_strategy == "eager": return True else: assert self.upgrade_strategy == "only-if-needed" return req.is_direct def _set_req_to_reinstall(self, req): # type: (InstallRequirement) -> None """ Set a requirement to be installed. """ # Don't uninstall the conflict if doing a user install and the # conflict is not a user install. if ((not self.use_user_site or dist_in_usersite(req.satisfied_by)) and dist_in_install_path(req.satisfied_by)): req.conflicts_with = req.satisfied_by req.satisfied_by = None def _check_skip_installed(self, req_to_install): # type: (InstallRequirement) -> Optional[str] """Check if req_to_install should be skipped. This will check if the req is installed, and whether we should upgrade or reinstall it, taking into account all the relevant user options. After calling this req_to_install will only have satisfied_by set to None if the req_to_install is to be upgraded/reinstalled etc. Any other value will be a dist recording the current thing installed that satisfies the requirement. Note that for vcs urls and the like we can't assess skipping in this routine - we simply identify that we need to pull the thing down, then later on it is pulled down and introspected to assess upgrade/ reinstalls etc. :return: A text reason for why it was skipped, or None. """ if self.ignore_installed: return None req_to_install.check_if_exists(self.use_user_site) if not req_to_install.satisfied_by: return None if self.force_reinstall: self._set_req_to_reinstall(req_to_install) return None if not self._is_upgrade_allowed(req_to_install): if self.upgrade_strategy == "only-if-needed": return 'already satisfied, skipping upgrade' return 'already satisfied' # Check for the possibility of an upgrade. For link-based # requirements we have to pull the tree down and inspect to assess # the version #, so it's handled way down. if not req_to_install.link: try: self.finder.find_requirement(req_to_install, upgrade=True) except BestVersionAlreadyInstalled: # Then the best version is installed. return 'already up-to-date' except DistributionNotFound: # No distribution found, so we squash the error. It will # be raised later when we re-try later to do the install. # Why don't we just raise here? pass self._set_req_to_reinstall(req_to_install) return None def _get_abstract_dist_for(self, req): # type: (InstallRequirement) -> AbstractDistribution """Takes a InstallRequirement and returns a single AbstractDist \ representing a prepared variant of the same. """ assert self.require_hashes is not None, ( "require_hashes should have been set in Resolver.resolve()" ) if req.editable: return self.preparer.prepare_editable_requirement( req, self.require_hashes, self.use_user_site, self.finder, ) # satisfied_by is only evaluated by calling _check_skip_installed, # so it must be None here. assert req.satisfied_by is None skip_reason = self._check_skip_installed(req) if req.satisfied_by: return self.preparer.prepare_installed_requirement( req, self.require_hashes, skip_reason ) upgrade_allowed = self._is_upgrade_allowed(req) # We eagerly populate the link, since that's our "legacy" behavior. req.populate_link(self.finder, upgrade_allowed, self.require_hashes) abstract_dist = self.preparer.prepare_linked_requirement( req, self.session, self.finder, self.require_hashes ) # NOTE # The following portion is for determining if a certain package is # going to be re-installed/upgraded or not and reporting to the user. # This should probably get cleaned up in a future refactor. # req.req is only avail after unpack for URL # pkgs repeat check_if_exists to uninstall-on-upgrade # (#14) if not self.ignore_installed: req.check_if_exists(self.use_user_site) if req.satisfied_by: should_modify = ( self.upgrade_strategy != "to-satisfy-only" or self.force_reinstall or self.ignore_installed or req.link.scheme == 'file' ) if should_modify: self._set_req_to_reinstall(req) else: logger.info( 'Requirement already satisfied (use --upgrade to upgrade):' ' %s', req, ) return abstract_dist def _resolve_one( self, requirement_set, # type: RequirementSet req_to_install # type: InstallRequirement ): # type: (...) -> List[InstallRequirement] """Prepare a single requirements file. :return: A list of additional InstallRequirements to also install. """ # Tell user what we are doing for this requirement: # obtain (editable), skipping, processing (local url), collecting # (remote url or package name) if req_to_install.constraint or req_to_install.prepared: return [] req_to_install.prepared = True # register tmp src for cleanup in case something goes wrong requirement_set.reqs_to_cleanup.append(req_to_install) abstract_dist = self._get_abstract_dist_for(req_to_install) # Parse and return dependencies dist = abstract_dist.get_pkg_resources_distribution() # 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): 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 req_to_install.is_direct = True 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) if not req_to_install.editable and not req_to_install.satisfied_by: # XXX: --no-install leads this to report 'Successfully # downloaded' for only non-editable reqs, even though we took # action on them. requirement_set.successfully_downloaded.append(req_to_install) 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): 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