0x1998 - MANAGER

Düzenlenen Dosya: pack.py

# Copyright (C) 2010, 2011 Sebastian Thiel (byronimo@gmail.com) and contributors # # This module is part of GitDB and is released under # the New BSD License: http://www.opensource.org/licenses/bsd-license.php """Module containing a database to deal with packs""" from gitdb.db.base import ( FileDBBase, ObjectDBR, CachingDB ) from gitdb.util import LazyMixin from gitdb.exc import ( BadObject, UnsupportedOperation, AmbiguousObjectName ) from gitdb.pack import PackEntity from functools import reduce import os import glob __all__ = ('PackedDB', ) #{ Utilities class PackedDB(FileDBBase, ObjectDBR, CachingDB, LazyMixin): """A database operating on a set of object packs""" # sort the priority list every N queries # Higher values are better, performance tests don't show this has # any effect, but it should have one _sort_interval = 500 def __init__(self, root_path): super().__init__(root_path) # list of lists with three items: # * hits - number of times the pack was hit with a request # * entity - Pack entity instance # * sha_to_index - PackIndexFile.sha_to_index method for direct cache query # self._entities = list() # lazy loaded list self._hit_count = 0 # amount of hits self._st_mtime = 0 # last modification data of our root path def _set_cache_(self, attr): if attr == '_entities': self._entities = list() self.update_cache(force=True) # END handle entities initialization def _sort_entities(self): self._entities.sort(key=lambda l: l[0], reverse=True) def _pack_info(self, sha): """:return: tuple(entity, index) for an item at the given sha :param sha: 20 or 40 byte sha :raise BadObject: **Note:** This method is not thread-safe, but may be hit in multi-threaded operation. The worst thing that can happen though is a counter that was not incremented, or the list being in wrong order. So we safe the time for locking here, lets see how that goes""" # presort ? if self._hit_count % self._sort_interval == 0: self._sort_entities() # END update sorting for item in self._entities: index = item[2](sha) if index is not None: item[0] += 1 # one hit for you self._hit_count += 1 # general hit count return (item[1], index) # END index found in pack # END for each item # no hit, see whether we have to update packs # NOTE: considering packs don't change very often, we safe this call # and leave it to the super-caller to trigger that raise BadObject(sha) #{ Object DB Read def has_object(self, sha): try: self._pack_info(sha) return True except BadObject: return False # END exception handling def info(self, sha): entity, index = self._pack_info(sha) return entity.info_at_index(index) def stream(self, sha): entity, index = self._pack_info(sha) return entity.stream_at_index(index) def sha_iter(self): for entity in self.entities(): index = entity.index() sha_by_index = index.sha for index in range(index.size()): yield sha_by_index(index) # END for each index # END for each entity def size(self): sizes = [item[1].index().size() for item in self._entities] return reduce(lambda x, y: x + y, sizes, 0) #} END object db read #{ object db write def store(self, istream): """Storing individual objects is not feasible as a pack is designed to hold multiple objects. Writing or rewriting packs for single objects is inefficient""" raise UnsupportedOperation() #} END object db write #{ Interface def update_cache(self, force=False): """ Update our cache with the actually existing packs on disk. Add new ones, and remove deleted ones. We keep the unchanged ones :param force: If True, the cache will be updated even though the directory does not appear to have changed according to its modification timestamp. :return: True if the packs have been updated so there is new information, False if there was no change to the pack database""" stat = os.stat(self.root_path()) if not force and stat.st_mtime <= self._st_mtime: return False # END abort early on no change self._st_mtime = stat.st_mtime # packs are supposed to be prefixed with pack- by git-convention # get all pack files, figure out what changed pack_files = set(glob.glob(os.path.join(self.root_path(), "pack-*.pack"))) our_pack_files = {item[1].pack().path() for item in self._entities} # new packs for pack_file in (pack_files - our_pack_files): # init the hit-counter/priority with the size, a good measure for hit- # probability. Its implemented so that only 12 bytes will be read entity = PackEntity(pack_file) self._entities.append([entity.pack().size(), entity, entity.index().sha_to_index]) # END for each new packfile # removed packs for pack_file in (our_pack_files - pack_files): del_index = -1 for i, item in enumerate(self._entities): if item[1].pack().path() == pack_file: del_index = i break # END found index # END for each entity assert del_index != -1 del(self._entities[del_index]) # END for each removed pack # reinitialize prioritiess self._sort_entities() return True def entities(self): """:return: list of pack entities operated upon by this database""" return [item[1] for item in self._entities] def partial_to_complete_sha(self, partial_binsha, canonical_length): """:return: 20 byte sha as inferred by the given partial binary sha :param partial_binsha: binary sha with less than 20 bytes :param canonical_length: length of the corresponding canonical representation. It is required as binary sha's cannot display whether the original hex sha had an odd or even number of characters :raise AmbiguousObjectName: :raise BadObject: """ candidate = None for item in self._entities: item_index = item[1].index().partial_sha_to_index(partial_binsha, canonical_length) if item_index is not None: sha = item[1].index().sha(item_index) if candidate and candidate != sha: raise AmbiguousObjectName(partial_binsha) candidate = sha # END handle full sha could be found # END for each entity if candidate: return candidate # still not found ? raise BadObject(partial_binsha) #} END interface
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