# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).
from __future__ import print_function
import itertools
import os
import shutil
import time
from collections import namedtuple
from contextlib import contextmanager
import pkg_resources
from pkg_resources import safe_name
from .common import safe_mkdir
from .fetcher import Fetcher
from .interpreter import PythonIdentity, PythonInterpreter
from .iterator import Iterator, IteratorInterface
from .orderedset import OrderedSet
from .package import Package, distribution_compatible
from .pep425tags import get_platform, get_supported
from .resolvable import ResolvableRequirement, resolvables_from_iterable
from .resolver_options import ResolverOptionsBuilder
from .tracer import TRACER
from .util import DistributionHelper
[docs]@contextmanager
def patched_packing_env(env):
"""Monkey patch packaging.markers.default_environment"""
old_env = pkg_resources.packaging.markers.default_environment
new_env = lambda: env
pkg_resources._vendor.packaging.markers.default_environment = new_env
try:
yield
finally:
pkg_resources._vendor.packaging.markers.default_environment = old_env
class Untranslateable(Exception):
pass
class Unsatisfiable(Exception):
pass
[docs]class StaticIterator(IteratorInterface):
"""An iterator that iterates over a static list of packages."""
def __init__(self, packages, allow_prereleases=None):
self._packages = packages
self._allow_prereleases = allow_prereleases
def iter(self, req):
for package in self._packages:
if package.satisfies(req, allow_prereleases=self._allow_prereleases):
yield package
class _ResolvedPackages(namedtuple('_ResolvedPackages',
'resolvable packages parent constraint_only')):
@classmethod
def empty(cls):
return cls(None, OrderedSet(), None, False)
def merge(self, other):
if other.resolvable is None:
return _ResolvedPackages(self.resolvable, self.packages, self.parent, self.constraint_only)
return _ResolvedPackages(
self.resolvable,
self.packages & other.packages,
self.parent,
self.constraint_only and other.constraint_only)
class _ResolvableSet(object):
@classmethod
def normalize(cls, name):
return safe_name(name).lower()
def __init__(self, tuples=None):
# A list of _ResolvedPackages
self.__tuples = tuples or []
def _collapse(self):
# Collapse all resolvables by name along with the intersection of all compatible packages.
# If the set of compatible packages is the empty set, then we cannot satisfy all the
# specifications for a particular name (e.g. "setuptools==2.2 setuptools>4".)
#
# We need to return the resolvable since it carries its own network context and configuration
# regarding package precedence. This is arbitrary -- we could just as easily say "last
# resolvable wins" but it seems highly unlikely this will materially affect anybody
# adversely but could be the source of subtle resolution quirks.
resolvables = {}
for resolved_packages in self.__tuples:
key = self.normalize(resolved_packages.resolvable.name)
previous = resolvables.get(key, _ResolvedPackages.empty())
if previous.resolvable is None:
resolvables[key] = resolved_packages
else:
resolvables[key] = previous.merge(resolved_packages)
return resolvables
def _synthesize_parents(self, name):
def render_resolvable(resolved_packages):
return '%s%s' % (
str(resolved_packages.resolvable),
'(from: %s)' % resolved_packages.parent if resolved_packages.parent else '')
return ', '.join(
render_resolvable(resolved_packages) for resolved_packages in self.__tuples
if self.normalize(resolved_packages.resolvable.name) == self.normalize(name))
def _check(self):
# Check whether or not the resolvables in this set are satisfiable, raise an exception if not.
for name, resolved_packages in self._collapse().items():
if not resolved_packages.packages:
raise Unsatisfiable('Could not satisfy all requirements for %s:\n %s' % (
resolved_packages.resolvable, self._synthesize_parents(name)))
def merge(self, resolvable, packages, parent=None):
"""Add a resolvable and its resolved packages."""
self.__tuples.append(_ResolvedPackages(resolvable, OrderedSet(packages),
parent, resolvable.is_constraint))
self._check()
def get(self, name):
"""Get the set of compatible packages given a resolvable name."""
resolvable, packages, parent, constraint_only = self._collapse().get(
self.normalize(name), _ResolvedPackages.empty())
return packages
def packages(self):
"""Return a snapshot of resolvable => compatible packages set from the resolvable set."""
return list(self._collapse().values())
def extras(self, name):
return set.union(
*[set(tup.resolvable.extras()) for tup in self.__tuples
if self.normalize(tup.resolvable.name) == self.normalize(name)])
def replace_built(self, built_packages):
"""Return a copy of this resolvable set but with built packages.
:param dict built_packages: A mapping from a resolved package to its locally built package.
:returns: A new resolvable set with built package replacements made.
"""
def map_packages(resolved_packages):
packages = OrderedSet(built_packages.get(p, p) for p in resolved_packages.packages)
return _ResolvedPackages(resolved_packages.resolvable, packages,
resolved_packages.parent, resolved_packages.constraint_only)
return _ResolvableSet([map_packages(rp) for rp in self.__tuples])
[docs]class Resolver(object):
"""Interface for resolving resolvable entities into python packages."""
class Error(Exception): pass
def filter_packages_by_interpreter(self, packages):
return [package for package in packages
if package.compatible(self._supported_tags)]
def __init__(self, allow_prereleases=None, interpreter=None, platform=None,
pkg_blacklist=None):
self._interpreter = interpreter or PythonInterpreter.get()
self._platform = platform or get_platform()
# Turn a platform string into something we can actually use
platform_tag, version, impl, abi = platform_to_tags(self._platform, self._interpreter)
self._identity = PythonIdentity(impl, abi, version)
self._allow_prereleases = allow_prereleases
self._blacklist = pkg_blacklist.copy() if pkg_blacklist else {}
self._supported_tags = get_supported(version=version,
platform=platform_tag,
impl=impl,
abi=abi)
def package_iterator(self, resolvable, existing=None):
if existing:
existing = resolvable.compatible(
StaticIterator(existing, allow_prereleases=self._allow_prereleases))
else:
existing = resolvable.packages()
return self.filter_packages_by_interpreter(existing)
def build(self, package, options):
context = options.get_context()
translator = options.get_translator(self._interpreter, self._supported_tags)
with TRACER.timed('Fetching %s' % package.url, V=2):
local_package = Package.from_href(context.fetch(package))
if local_package is None:
raise Untranslateable('Could not fetch package %s' % package)
with TRACER.timed('Translating %s into distribution' % local_package.local_path, V=2):
dist = translator.translate(local_package)
if dist is None:
raise Untranslateable('Package %s is not translateable by %s' % (package, translator))
if not distribution_compatible(dist, self._supported_tags):
raise Untranslateable(
'Could not get distribution for %s on platform %s.' % (package, self._platform))
return dist
def _resolvable_is_blacklisted(self, resolvable_name):
return (
resolvable_name in self._blacklist and
self._interpreter.identity.matches(self._blacklist[resolvable_name])
)
def resolve(self, resolvables, resolvable_set=None):
resolvables = [(resolvable, None) for resolvable in resolvables]
resolvable_set = resolvable_set or _ResolvableSet()
processed_resolvables = set()
processed_packages = {}
distributions = {}
while resolvables:
while resolvables:
resolvable, parent = resolvables.pop(0)
if resolvable in processed_resolvables:
continue
packages = self.package_iterator(resolvable, existing=resolvable_set.get(resolvable.name))
# TODO: Remove blacklist strategy in favor of smart requirement handling
# https://github.com/pantsbuild/pex/issues/456
if not self._resolvable_is_blacklisted(resolvable.name):
resolvable_set.merge(resolvable, packages, parent)
processed_resolvables.add(resolvable)
built_packages = {}
for resolvable, packages, parent, constraint_only in resolvable_set.packages():
if constraint_only:
continue
assert len(packages) > 0, 'ResolvableSet.packages(%s) should not be empty' % resolvable
package = next(iter(packages))
if resolvable.name in processed_packages:
if package == processed_packages[resolvable.name]:
continue
if package not in distributions:
dist = self.build(package, resolvable.options)
built_package = Package.from_href(dist.location)
built_packages[package] = built_package
distributions[built_package] = dist
package = built_package
distribution = distributions[package]
processed_packages[resolvable.name] = package
new_parent = '%s->%s' % (parent, resolvable) if parent else str(resolvable)
# We patch packaging.markers.default_environment here so we find optional reqs for the
# platform we're building the PEX for, rather than the one we're on.
with patched_packing_env(self._identity.pkg_resources_env(self._platform)):
resolvables.extend(
(ResolvableRequirement(req, resolvable.options), new_parent) for req in
distribution.requires(extras=resolvable_set.extras(resolvable.name)))
resolvable_set = resolvable_set.replace_built(built_packages)
# We may have built multiple distributions depending upon if we found transitive dependencies
# for the same package. But ultimately, resolvable_set.packages() contains the correct version
# for all packages. So loop through it and only return the package version in
# resolvable_set.packages() that is found in distributions.
dists = []
# No point in proceeding if distributions is empty
if not distributions:
return dists
for resolvable, packages, parent, constraint_only in resolvable_set.packages():
if constraint_only:
continue
assert len(packages) > 0, 'ResolvableSet.packages(%s) should not be empty' % resolvable
package = next(iter(packages))
dists.append(distributions[package])
return dists
[docs]class CachingResolver(Resolver):
"""A package resolver implementing a package cache."""
@classmethod
def filter_packages_by_ttl(cls, packages, ttl, now=None):
now = now if now is not None else time.time()
return [package for package in packages
if package.remote or package.local and (now - os.path.getmtime(package.local_path)) < ttl]
def __init__(self, cache, cache_ttl, *args, **kw):
self.__cache = cache
self.__cache_ttl = cache_ttl
safe_mkdir(self.__cache)
super(CachingResolver, self).__init__(*args, **kw)
# Short-circuiting package iterator.
def package_iterator(self, resolvable, existing=None):
iterator = Iterator(fetchers=[Fetcher([self.__cache])],
allow_prereleases=self._allow_prereleases)
packages = self.filter_packages_by_interpreter(resolvable.compatible(iterator))
if packages and self.__cache_ttl:
packages = self.filter_packages_by_ttl(packages, self.__cache_ttl)
return itertools.chain(
packages,
super(CachingResolver, self).package_iterator(resolvable, existing=existing)
)
# Caching sandwich.
def build(self, package, options):
# cache package locally
if package.remote:
package = Package.from_href(options.get_context().fetch(package, into=self.__cache))
os.utime(package.local_path, None)
# build into distribution
dist = super(CachingResolver, self).build(package, options)
# if distribution is not in cache, copy
target = os.path.join(self.__cache, os.path.basename(dist.location))
if not os.path.exists(target):
shutil.copyfile(dist.location, target + '~')
os.rename(target + '~', target)
os.utime(target, None)
return DistributionHelper.distribution_from_path(target)
[docs]def resolve(requirements,
fetchers=None,
interpreter=None,
platform=None,
context=None,
precedence=None,
cache=None,
cache_ttl=None,
allow_prereleases=None,
pkg_blacklist=None):
"""Produce all distributions needed to (recursively) meet `requirements`
:param requirements: An iterator of Requirement-like things, either
:class:`pkg_resources.Requirement` objects or requirement strings.
:keyword fetchers: (optional) A list of :class:`Fetcher` objects for locating packages. If
unspecified, the default is to look for packages on PyPI.
:keyword interpreter: (optional) A :class:`PythonInterpreter` object to use for building
distributions and for testing distribution compatibility.
:keyword versions: (optional) a list of string versions, of the form ["33", "32"],
or None. The first version will be assumed to support our ABI.
:keyword platform: (optional) specify the exact platform you want valid
tags for, or None. If None, use the local system platform.
:keyword impl: (optional) specify the exact implementation you want valid
tags for, or None. If None, use the local interpreter impl.
:keyword abi: (optional) specify the exact abi you want valid
tags for, or None. If None, use the local interpreter abi.
:keyword context: (optional) A :class:`Context` object to use for network access. If
unspecified, the resolver will attempt to use the best available network context.
:keyword precedence: (optional) An ordered list of allowable :class:`Package` classes
to be used for producing distributions. For example, if precedence is supplied as
``(WheelPackage, SourcePackage)``, wheels will be preferred over building from source, and
eggs will not be used at all. If ``(WheelPackage, EggPackage)`` is suppplied, both wheels and
eggs will be used, but the resolver will not resort to building anything from source.
:keyword cache: (optional) A directory to use to cache distributions locally.
:keyword cache_ttl: (optional integer in seconds) If specified, consider non-exact matches when
resolving requirements. For example, if ``setuptools==2.2`` is specified and setuptools 2.2 is
available in the cache, it will always be used. However, if a non-exact requirement such as
``setuptools>=2,<3`` is specified and there exists a setuptools distribution newer than
cache_ttl seconds that satisfies the requirement, then it will be used. If the distribution
is older than cache_ttl seconds, it will be ignored. If ``cache_ttl`` is not specified,
resolving inexact requirements will always result in making network calls through the
``context``.
:keyword allow_prereleases: (optional) Include pre-release and development versions. If
unspecified only stable versions will be resolved, unless explicitly included.
:keyword pkg_blacklist: (optional) A blacklist dict (str->str) that maps package name to
an interpreter constraint. If a package name is in the blacklist and its interpreter
constraint matches the target interpreter, skip the requirement. This is needed to ensure
that universal requirement resolves for a target interpreter version do not error out on
interpreter specific requirements such as backport libs like `functools32`.
For example, a valid blacklist is {'functools32': 'CPython>3'}.
NOTE: this keyword is a temporary fix and will be reverted in favor of a long term solution
tracked by: https://github.com/pantsbuild/pex/issues/456
:returns: List of :class:`pkg_resources.Distribution` instances meeting ``requirements``.
:raises Unsatisfiable: If ``requirements`` is not transitively satisfiable.
:raises Untranslateable: If no compatible distributions could be acquired for
a particular requirement.
This method improves upon the setuptools dependency resolution algorithm by maintaining sets of
all compatible distributions encountered for each requirement rather than the single best
distribution encountered for each requirement. This prevents situations where ``tornado`` and
``tornado==2.0`` could be treated as incompatible with each other because the "best
distribution" when encountering ``tornado`` was tornado 3.0. Instead, ``resolve`` maintains the
set of compatible distributions for each requirement as it is encountered, and iteratively filters
the set. If the set of distributions ever becomes empty, then ``Unsatisfiable`` is raised.
.. versionchanged:: 0.8
A number of keywords were added to make requirement resolution slightly easier to configure.
The optional ``obtainer`` keyword was replaced by ``fetchers``, ``translator``, ``context``,
``threads``, ``precedence``, ``cache`` and ``cache_ttl``, also all optional keywords.
.. versionchanged:: 1.0
The ``translator`` and ``threads`` keywords have been removed. The choice of threading
policy is now implicit. The choice of translation policy is dictated by ``precedence``
directly.
.. versionchanged:: 1.0
``resolver`` is now just a wrapper around the :class:`Resolver` and :class:`CachingResolver`
classes.
"""
builder = ResolverOptionsBuilder(fetchers=fetchers,
allow_prereleases=allow_prereleases,
precedence=precedence,
context=context)
if cache:
resolver = CachingResolver(cache,
cache_ttl,
allow_prereleases=allow_prereleases,
interpreter=interpreter,
platform=platform,
pkg_blacklist=pkg_blacklist)
else:
resolver = Resolver(allow_prereleases=allow_prereleases,
interpreter=interpreter,
platform=platform,
pkg_blacklist=pkg_blacklist)
return resolver.resolve(resolvables_from_iterable(requirements, builder))
[docs]def resolve_multi(requirements,
fetchers=None,
interpreters=None,
platforms=None,
context=None,
precedence=None,
cache=None,
cache_ttl=None,
allow_prereleases=None,
pkg_blacklist=None):
"""A generator function that produces all distributions needed to meet `requirements`
for multiple interpreters and/or platforms.
:param requirements: An iterator of Requirement-like things, either
:class:`pkg_resources.Requirement` objects or requirement strings.
:keyword fetchers: (optional) A list of :class:`Fetcher` objects for locating packages. If
unspecified, the default is to look for packages on PyPI.
:keyword interpreters: (optional) An iterable of :class:`PythonInterpreter` objects to use
for building distributions and for testing distribution compatibility.
:keyword platforms: (optional) An iterable of PEP425-compatible platform strings to use for
filtering compatible distributions. If unspecified, the current platform is used, as
determined by `Platform.current()`.
:keyword context: (optional) A :class:`Context` object to use for network access. If
unspecified, the resolver will attempt to use the best available network context.
:keyword precedence: (optional) An ordered list of allowable :class:`Package` classes
to be used for producing distributions. For example, if precedence is supplied as
``(WheelPackage, SourcePackage)``, wheels will be preferred over building from source, and
eggs will not be used at all. If ``(WheelPackage, EggPackage)`` is suppplied, both wheels and
eggs will be used, but the resolver will not resort to building anything from source.
:keyword cache: (optional) A directory to use to cache distributions locally.
:keyword cache_ttl: (optional integer in seconds) If specified, consider non-exact matches when
resolving requirements. For example, if ``setuptools==2.2`` is specified and setuptools 2.2 is
available in the cache, it will always be used. However, if a non-exact requirement such as
``setuptools>=2,<3`` is specified and there exists a setuptools distribution newer than
cache_ttl seconds that satisfies the requirement, then it will be used. If the distribution
is older than cache_ttl seconds, it will be ignored. If ``cache_ttl`` is not specified,
resolving inexact requirements will always result in making network calls through the
``context``.
:keyword allow_prereleases: (optional) Include pre-release and development versions. If
unspecified only stable versions will be resolved, unless explicitly included.
:keyword pkg_blacklist: (optional) A blacklist dict (str->str) that maps package name to
an interpreter constraint. If a package name is in the blacklist and its interpreter
constraint matches the target interpreter, skip the requirement. This is needed to ensure
that universal requirement resolves for a target interpreter version do not error out on
interpreter specific requirements such as backport libs like `functools32`.
For example, a valid blacklist is {'functools32': 'CPython>3'}.
NOTE: this keyword is a temporary fix and will be reverted in favor of a long term solution
tracked by: https://github.com/pantsbuild/pex/issues/456
:yields: All :class:`pkg_resources.Distribution` instances meeting ``requirements``.
:raises Unsatisfiable: If ``requirements`` is not transitively satisfiable.
:raises Untranslateable: If no compatible distributions could be acquired for
a particular requirement.
"""
interpreters = interpreters or [PythonInterpreter.get()]
platforms = platforms or [get_platform()]
seen = set()
for interpreter in interpreters:
for platform in platforms:
for resolvable in resolve(requirements,
fetchers,
interpreter,
platform,
context,
precedence,
cache,
cache_ttl,
allow_prereleases,
pkg_blacklist=pkg_blacklist):
if resolvable not in seen:
seen.add(resolvable)
yield resolvable