203 lines
6.9 KiB
Python
203 lines
6.9 KiB
Python
"""Cache Management
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"""
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import errno
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import hashlib
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import logging
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import os
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from pip._vendor.packaging.utils import canonicalize_name
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from pip._internal import index
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from pip._internal.compat import expanduser
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from pip._internal.download import path_to_url
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from pip._internal.utils.temp_dir import TempDirectory
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from pip._internal.wheel import InvalidWheelFilename, Wheel
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logger = logging.getLogger(__name__)
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class Cache(object):
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"""An abstract class - provides cache directories for data from links
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:param cache_dir: The root of the cache.
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:param format_control: A pip.index.FormatControl object to limit
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binaries being read from the cache.
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:param allowed_formats: which formats of files the cache should store.
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('binary' and 'source' are the only allowed values)
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"""
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def __init__(self, cache_dir, format_control, allowed_formats):
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super(Cache, self).__init__()
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self.cache_dir = expanduser(cache_dir) if cache_dir else None
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self.format_control = format_control
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self.allowed_formats = allowed_formats
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_valid_formats = {"source", "binary"}
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assert self.allowed_formats.union(_valid_formats) == _valid_formats
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def _get_cache_path_parts(self, link):
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"""Get parts of part that must be os.path.joined with cache_dir
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"""
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# We want to generate an url to use as our cache key, we don't want to
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# just re-use the URL because it might have other items in the fragment
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# and we don't care about those.
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key_parts = [link.url_without_fragment]
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if link.hash_name is not None and link.hash is not None:
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key_parts.append("=".join([link.hash_name, link.hash]))
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key_url = "#".join(key_parts)
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# Encode our key url with sha224, we'll use this because it has similar
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# security properties to sha256, but with a shorter total output (and
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# thus less secure). However the differences don't make a lot of
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# difference for our use case here.
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hashed = hashlib.sha224(key_url.encode()).hexdigest()
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# We want to nest the directories some to prevent having a ton of top
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# level directories where we might run out of sub directories on some
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# FS.
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parts = [hashed[:2], hashed[2:4], hashed[4:6], hashed[6:]]
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return parts
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def _get_candidates(self, link, package_name):
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can_not_cache = (
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not self.cache_dir or
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not package_name or
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not link
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)
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if can_not_cache:
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return []
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canonical_name = canonicalize_name(package_name)
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formats = index.fmt_ctl_formats(
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self.format_control, canonical_name
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)
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if not self.allowed_formats.intersection(formats):
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return []
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root = self.get_path_for_link(link)
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try:
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return os.listdir(root)
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except OSError as err:
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if err.errno in {errno.ENOENT, errno.ENOTDIR}:
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return []
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raise
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def get_path_for_link(self, link):
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"""Return a directory to store cached items in for link.
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"""
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raise NotImplementedError()
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def get(self, link, package_name):
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"""Returns a link to a cached item if it exists, otherwise returns the
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passed link.
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"""
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raise NotImplementedError()
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def _link_for_candidate(self, link, candidate):
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root = self.get_path_for_link(link)
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path = os.path.join(root, candidate)
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return index.Link(path_to_url(path))
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def cleanup(self):
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pass
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class SimpleWheelCache(Cache):
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"""A cache of wheels for future installs.
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"""
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def __init__(self, cache_dir, format_control):
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super(SimpleWheelCache, self).__init__(
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cache_dir, format_control, {"binary"}
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)
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def get_path_for_link(self, link):
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"""Return a directory to store cached wheels for link
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Because there are M wheels for any one sdist, we provide a directory
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to cache them in, and then consult that directory when looking up
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cache hits.
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We only insert things into the cache if they have plausible version
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numbers, so that we don't contaminate the cache with things that were
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not unique. E.g. ./package might have dozens of installs done for it
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and build a version of 0.0...and if we built and cached a wheel, we'd
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end up using the same wheel even if the source has been edited.
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:param link: The link of the sdist for which this will cache wheels.
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"""
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parts = self._get_cache_path_parts(link)
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# Store wheels within the root cache_dir
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return os.path.join(self.cache_dir, "wheels", *parts)
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def get(self, link, package_name):
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candidates = []
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for wheel_name in self._get_candidates(link, package_name):
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try:
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wheel = Wheel(wheel_name)
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except InvalidWheelFilename:
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continue
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if not wheel.supported():
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# Built for a different python/arch/etc
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continue
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candidates.append((wheel.support_index_min(), wheel_name))
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if not candidates:
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return link
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return self._link_for_candidate(link, min(candidates)[1])
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class EphemWheelCache(SimpleWheelCache):
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"""A SimpleWheelCache that creates it's own temporary cache directory
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"""
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def __init__(self, format_control):
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self._temp_dir = TempDirectory(kind="ephem-wheel-cache")
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self._temp_dir.create()
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super(EphemWheelCache, self).__init__(
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self._temp_dir.path, format_control
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)
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def cleanup(self):
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self._temp_dir.cleanup()
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class WheelCache(Cache):
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"""Wraps EphemWheelCache and SimpleWheelCache into a single Cache
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This Cache allows for gracefully degradation, using the ephem wheel cache
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when a certain link is not found in the simple wheel cache first.
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"""
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def __init__(self, cache_dir, format_control):
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super(WheelCache, self).__init__(
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cache_dir, format_control, {'binary'}
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)
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self._wheel_cache = SimpleWheelCache(cache_dir, format_control)
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self._ephem_cache = EphemWheelCache(format_control)
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def get_path_for_link(self, link):
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return self._wheel_cache.get_path_for_link(link)
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def get_ephem_path_for_link(self, link):
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return self._ephem_cache.get_path_for_link(link)
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def get(self, link, package_name):
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retval = self._wheel_cache.get(link, package_name)
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if retval is link:
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retval = self._ephem_cache.get(link, package_name)
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return retval
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def cleanup(self):
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self._wheel_cache.cleanup()
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self._ephem_cache.cleanup()
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