AlkantarClanX12
Your IP : 3.135.208.189
# 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