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zero-cost-nas/.eggs/gitdb-4.0.10-py3.8.egg/gitdb/db/pack.py

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+# 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