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# Copyright (C) 2009 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
"""Implementation of Graph algorithms when we have already loaded everything.
"""
cdef extern from "python-compat.h":
pass
cdef extern from "Python.h":
ctypedef int Py_ssize_t
ctypedef struct PyObject:
pass
object PyTuple_New(Py_ssize_t n)
Py_ssize_t PyTuple_GET_SIZE(object t)
PyObject * PyTuple_GET_ITEM(object t, Py_ssize_t o)
void PyTuple_SET_ITEM(object t, Py_ssize_t o, object v)
Py_ssize_t PyList_GET_SIZE(object l)
PyObject * PyList_GET_ITEM(object l, Py_ssize_t o)
int PyList_SetItem(object l, Py_ssize_t o, object l) except -1
int PyList_Append(object l, object v) except -1
int PyDict_CheckExact(object d)
Py_ssize_t PyDict_Size(object d) except -1
PyObject * PyDict_GetItem(object d, object k)
int PyDict_SetItem(object d, object k, object v) except -1
int PyDict_DelItem(object d, object k) except -1
int PyDict_Next(object d, Py_ssize_t *pos, PyObject **k, PyObject **v)
void Py_INCREF(object)
from bzrlib import revision
cdef object NULL_REVISION
NULL_REVISION = revision.NULL_REVISION
cdef class _KnownGraphNode:
"""Represents a single object in the known graph."""
cdef object key
cdef object parents
cdef object children
cdef public long gdfo
cdef int seen
def __init__(self, key):
cdef int i
self.key = key
self.parents = None
self.children = []
# Greatest distance from origin
self.gdfo = -1
self.seen = 0
property child_keys:
def __get__(self):
cdef _KnownGraphNode child
keys = []
for child in self.children:
PyList_Append(keys, child.key)
return keys
cdef clear_references(self):
self.parents = None
self.children = None
def __repr__(self):
cdef _KnownGraphNode node
parent_keys = []
if self.parents is not None:
for node in self.parents:
parent_keys.append(node.key)
child_keys = []
if self.children is not None:
for node in self.children:
child_keys.append(node.key)
return '%s(%s gdfo:%s par:%s child:%s)' % (
self.__class__.__name__, self.key, self.gdfo,
parent_keys, child_keys)
cdef _KnownGraphNode _get_list_node(lst, Py_ssize_t pos):
cdef PyObject *temp_node
temp_node = PyList_GET_ITEM(lst, pos)
return <_KnownGraphNode>temp_node
cdef _KnownGraphNode _get_parent(parents, Py_ssize_t pos):
cdef PyObject *temp_node
cdef _KnownGraphNode node
temp_node = PyTuple_GET_ITEM(parents, pos)
return <_KnownGraphNode>temp_node
# TODO: slab allocate all _KnownGraphNode objects.
# We already know how many we are going to need, except for a couple of
# ghosts that could be allocated on demand.
cdef class KnownGraph:
"""This is a class which assumes we already know the full graph."""
cdef public object _nodes
cdef object _known_heads
cdef public int do_cache
def __init__(self, parent_map, do_cache=True):
"""Create a new KnownGraph instance.
:param parent_map: A dictionary mapping key => parent_keys
"""
# tests at pre-allocating the node dict actually slowed things down
self._nodes = {}
# Maps {sorted(revision_id, revision_id): heads}
self._known_heads = {}
self.do_cache = int(do_cache)
self._initialize_nodes(parent_map)
self._find_gdfo()
def __dealloc__(self):
cdef _KnownGraphNode child
cdef Py_ssize_t pos
cdef PyObject *temp_node
while PyDict_Next(self._nodes, &pos, NULL, &temp_node):
child = <_KnownGraphNode>temp_node
child.clear_references()
cdef _KnownGraphNode _get_or_create_node(self, key):
cdef PyObject *temp_node
cdef _KnownGraphNode node
temp_node = PyDict_GetItem(self._nodes, key)
if temp_node == NULL:
node = _KnownGraphNode(key)
PyDict_SetItem(self._nodes, key, node)
else:
node = <_KnownGraphNode>temp_node
return node
def _initialize_nodes(self, parent_map):
"""Populate self._nodes.
After this has finished:
- self._nodes will have an entry for every entry in parent_map.
- ghosts will have a parent_keys = None,
- all nodes found will also have child_keys populated with all known
child keys,
"""
cdef PyObject *temp_key, *temp_parent_keys, *temp_node
cdef Py_ssize_t pos, pos2, num_parent_keys
cdef _KnownGraphNode node
cdef _KnownGraphNode parent_node
if not PyDict_CheckExact(parent_map):
raise TypeError('parent_map should be a dict of {key:parent_keys}')
# for key, parent_keys in parent_map.iteritems():
pos = 0
while PyDict_Next(parent_map, &pos, &temp_key, &temp_parent_keys):
key = <object>temp_key
parent_keys = <object>temp_parent_keys
num_parent_keys = len(parent_keys)
node = self._get_or_create_node(key)
# We know how many parents, so we could pre allocate an exact sized
# tuple here
parent_nodes = PyTuple_New(num_parent_keys)
# We use iter here, because parent_keys maybe be a list or tuple
for pos2 from 0 <= pos2 < num_parent_keys:
parent_node = self._get_or_create_node(parent_keys[pos2])
# PyTuple_SET_ITEM will steal a reference, so INCREF first
Py_INCREF(parent_node)
PyTuple_SET_ITEM(parent_nodes, pos2, parent_node)
PyList_Append(parent_node.children, node)
node.parents = parent_nodes
def _find_tails(self):
cdef PyObject *temp_node
cdef _KnownGraphNode node
cdef Py_ssize_t pos
tails = []
pos = 0
while PyDict_Next(self._nodes, &pos, NULL, &temp_node):
node = <_KnownGraphNode>temp_node
if node.parents is None or PyTuple_GET_SIZE(node.parents) == 0:
node.gdfo = 1
PyList_Append(tails, node)
return tails
def _find_gdfo(self):
cdef _KnownGraphNode node
cdef _KnownGraphNode child
cdef PyObject *temp
cdef Py_ssize_t pos
cdef int replace
cdef Py_ssize_t last_item
cdef long next_gdfo
pending = self._find_tails()
last_item = PyList_GET_SIZE(pending) - 1
while last_item >= 0:
# Avoid pop followed by push, instead, peek, and replace
# timing shows this is 930ms => 770ms for OOo
node = _get_list_node(pending, last_item)
last_item = last_item - 1
next_gdfo = node.gdfo + 1
for pos from 0 <= pos < PyList_GET_SIZE(node.children):
child = _get_list_node(node.children, pos)
if next_gdfo > child.gdfo:
child.gdfo = next_gdfo
child.seen = child.seen + 1
if child.seen == PyTuple_GET_SIZE(child.parents):
# This child is populated, queue it to be walked
last_item = last_item + 1
if last_item < PyList_GET_SIZE(pending):
Py_INCREF(child) # SetItem steals a ref
PyList_SetItem(pending, last_item, child)
else:
PyList_Append(pending, child)
# We have queued this node, we don't need to track it
# anymore
child.seen = 0
def heads(self, keys):
"""Return the heads from amongst keys.
This is done by searching the ancestries of each key. Any key that is
reachable from another key is not returned; all the others are.
This operation scales with the relative depth between any two keys. It
uses gdfo to avoid walking all ancestry.
:param keys: An iterable of keys.
:return: A set of the heads. Note that as a set there is no ordering
information. Callers will need to filter their input to create
order if they need it.
"""
cdef PyObject *maybe_node
cdef PyObject *maybe_heads
cdef PyObject *temp_node
cdef _KnownGraphNode node
cdef Py_ssize_t pos, last_item
cdef long min_gdfo
heads_key = frozenset(keys)
maybe_heads = PyDict_GetItem(self._known_heads, heads_key)
if maybe_heads != NULL:
return <object>maybe_heads
# Not cached, compute it ourselves
candidate_nodes = {}
for key in keys:
maybe_node = PyDict_GetItem(self._nodes, key)
if maybe_node == NULL:
raise KeyError('key %s not in nodes' % (key,))
PyDict_SetItem(candidate_nodes, key, <object>maybe_node)
maybe_node = PyDict_GetItem(candidate_nodes, NULL_REVISION)
if maybe_node != NULL:
# NULL_REVISION is only a head if it is the only entry
candidate_nodes.pop(NULL_REVISION)
if not candidate_nodes:
return frozenset([NULL_REVISION])
# The keys changed, so recalculate heads_key
heads_key = frozenset(candidate_nodes)
if PyDict_Size(candidate_nodes) < 2:
return heads_key
cleanup = []
pending = []
# we know a gdfo cannot be longer than a linear chain of all nodes
min_gdfo = PyDict_Size(self._nodes) + 1
# Build up nodes that need to be walked, note that starting nodes are
# not added to seen()
pos = 0
while PyDict_Next(candidate_nodes, &pos, NULL, &temp_node):
node = <_KnownGraphNode>temp_node
if node.parents is not None:
pending.extend(node.parents)
if node.gdfo < min_gdfo:
min_gdfo = node.gdfo
# Now do all the real work
last_item = PyList_GET_SIZE(pending) - 1
while last_item >= 0:
node = _get_list_node(pending, last_item)
last_item = last_item - 1
if node.seen:
# node already appears in some ancestry
continue
PyList_Append(cleanup, node)
node.seen = 1
if node.gdfo <= min_gdfo:
continue
if node.parents is not None and PyTuple_GET_SIZE(node.parents) > 0:
for pos from 0 <= pos < PyTuple_GET_SIZE(node.parents):
parent_node = _get_parent(node.parents, pos)
last_item = last_item + 1
if last_item < PyList_GET_SIZE(pending):
Py_INCREF(parent_node) # SetItem steals a ref
PyList_SetItem(pending, last_item, parent_node)
else:
PyList_Append(pending, parent_node)
heads = []
pos = 0
while PyDict_Next(candidate_nodes, &pos, NULL, &temp_node):
node = <_KnownGraphNode>temp_node
if not node.seen:
PyList_Append(heads, node.key)
heads = frozenset(heads)
for pos from 0 <= pos < PyList_GET_SIZE(cleanup):
node = _get_list_node(cleanup, pos)
node.seen = 0
if self.do_cache:
PyDict_SetItem(self._known_heads, heads_key, heads)
return heads
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