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import re
import collections
from .. import util
from sqlalchemy import util as sqlautil
from ..util import compat
_relative_destination = re.compile(r'(?:(.+?)@)?(\w+)?((?:\+|-)\d+)')
class RevisionError(Exception):
pass
class RangeNotAncestorError(RevisionError):
def __init__(self, lower, upper):
self.lower = lower
self.upper = upper
super(RangeNotAncestorError, self).__init__(
"Revision %s is not an ancestor of revision %s" %
(lower or "base", upper or "base")
)
class MultipleHeads(RevisionError):
def __init__(self, heads, argument):
self.heads = heads
self.argument = argument
super(MultipleHeads, self).__init__(
"Multiple heads are present for given argument '%s'; "
"%s" % (argument, ", ".join(heads))
)
class ResolutionError(RevisionError):
def __init__(self, message, argument):
super(ResolutionError, self).__init__(message)
self.argument = argument
class RevisionMap(object):
"""Maintains a map of :class:`.Revision` objects.
:class:`.RevisionMap` is used by :class:`.ScriptDirectory` to maintain
and traverse the collection of :class:`.Script` objects, which are
themselves instances of :class:`.Revision`.
"""
def __init__(self, generator):
"""Construct a new :class:`.RevisionMap`.
:param generator: a zero-arg callable that will generate an iterable
of :class:`.Revision` instances to be used. These are typically
:class:`.Script` subclasses within regular Alembic use.
"""
self._generator = generator
@util.memoized_property
def heads(self):
"""All "head" revisions as strings.
This is normally a tuple of length one,
unless unmerged branches are present.
:return: a tuple of string revision numbers.
"""
self._revision_map
return self.heads
@util.memoized_property
def bases(self):
"""All "base" revisions as strings.
These are revisions that have a ``down_revision`` of None,
or empty tuple.
:return: a tuple of string revision numbers.
"""
self._revision_map
return self.bases
@util.memoized_property
def _real_heads(self):
"""All "real" head revisions as strings.
:return: a tuple of string revision numbers.
"""
self._revision_map
return self._real_heads
@util.memoized_property
def _real_bases(self):
"""All "real" base revisions as strings.
:return: a tuple of string revision numbers.
"""
self._revision_map
return self._real_bases
@util.memoized_property
def _revision_map(self):
"""memoized attribute, initializes the revision map from the
initial collection.
"""
map_ = {}
heads = sqlautil.OrderedSet()
_real_heads = sqlautil.OrderedSet()
self.bases = ()
self._real_bases = ()
has_branch_labels = set()
has_depends_on = set()
for revision in self._generator():
if revision.revision in map_:
util.warn("Revision %s is present more than once" %
revision.revision)
map_[revision.revision] = revision
if revision.branch_labels:
has_branch_labels.add(revision)
if revision.dependencies:
has_depends_on.add(revision)
heads.add(revision.revision)
_real_heads.add(revision.revision)
if revision.is_base:
self.bases += (revision.revision, )
if revision._is_real_base:
self._real_bases += (revision.revision, )
# add the branch_labels to the map_. We'll need these
# to resolve the dependencies.
for revision in has_branch_labels:
self._map_branch_labels(revision, map_)
for revision in has_depends_on:
self._add_depends_on(revision, map_)
for rev in map_.values():
for downrev in rev._all_down_revisions:
if downrev not in map_:
util.warn("Revision %s referenced from %s is not present"
% (downrev, rev))
down_revision = map_[downrev]
down_revision.add_nextrev(rev)
if downrev in rev._versioned_down_revisions:
heads.discard(downrev)
_real_heads.discard(downrev)
map_[None] = map_[()] = None
self.heads = tuple(heads)
self._real_heads = tuple(_real_heads)
for revision in has_branch_labels:
self._add_branches(revision, map_, map_branch_labels=False)
return map_
def _map_branch_labels(self, revision, map_):
if revision.branch_labels:
for branch_label in revision._orig_branch_labels:
if branch_label in map_:
raise RevisionError(
"Branch name '%s' in revision %s already "
"used by revision %s" %
(branch_label, revision.revision,
map_[branch_label].revision)
)
map_[branch_label] = revision
def _add_branches(self, revision, map_, map_branch_labels=True):
if map_branch_labels:
self._map_branch_labels(revision, map_)
if revision.branch_labels:
revision.branch_labels.update(revision.branch_labels)
for node in self._get_descendant_nodes(
[revision], map_, include_dependencies=False):
node.branch_labels.update(revision.branch_labels)
parent = node
while parent and \
not parent._is_real_branch_point and \
not parent.is_merge_point:
parent.branch_labels.update(revision.branch_labels)
if parent.down_revision:
parent = map_[parent.down_revision]
else:
break
def _add_depends_on(self, revision, map_):
if revision.dependencies:
revision._resolved_dependencies = tuple(
map_[dep].revision for dep
in util.to_tuple(revision.dependencies)
)
def add_revision(self, revision, _replace=False):
"""add a single revision to an existing map.
This method is for single-revision use cases, it's not
appropriate for fully populating an entire revision map.
"""
map_ = self._revision_map
if not _replace and revision.revision in map_:
util.warn("Revision %s is present more than once" %
revision.revision)
elif _replace and revision.revision not in map_:
raise Exception("revision %s not in map" % revision.revision)
map_[revision.revision] = revision
self._add_branches(revision, map_)
self._add_depends_on(revision, map_)
if revision.is_base:
self.bases += (revision.revision, )
if revision._is_real_base:
self._real_bases += (revision.revision, )
for downrev in revision._all_down_revisions:
if downrev not in map_:
util.warn(
"Revision %s referenced from %s is not present"
% (downrev, revision)
)
map_[downrev].add_nextrev(revision)
if revision._is_real_head:
self._real_heads = tuple(
head for head in self._real_heads
if head not in
set(revision._all_down_revisions).union([revision.revision])
) + (revision.revision,)
if revision.is_head:
self.heads = tuple(
head for head in self.heads
if head not in
set(revision._versioned_down_revisions).union([revision.revision])
) + (revision.revision,)
def get_current_head(self, branch_label=None):
"""Return the current head revision.
If the script directory has multiple heads
due to branching, an error is raised;
:meth:`.ScriptDirectory.get_heads` should be
preferred.
:param branch_label: optional branch name which will limit the
heads considered to those which include that branch_label.
:return: a string revision number.
.. seealso::
:meth:`.ScriptDirectory.get_heads`
"""
current_heads = self.heads
if branch_label:
current_heads = self.filter_for_lineage(current_heads, branch_label)
if len(current_heads) > 1:
raise MultipleHeads(
current_heads,
"%s@head" % branch_label if branch_label else "head")
if current_heads:
return current_heads[0]
else:
return None
def _get_base_revisions(self, identifier):
return self.filter_for_lineage(self.bases, identifier)
def get_revisions(self, id_):
"""Return the :class:`.Revision` instances with the given rev id
or identifiers.
May be given a single identifier, a sequence of identifiers, or the
special symbols "head" or "base". The result is a tuple of one
or more identifiers, or an empty tuple in the case of "base".
In the cases where 'head', 'heads' is requested and the
revision map is empty, returns an empty tuple.
Supports partial identifiers, where the given identifier
is matched against all identifiers that start with the given
characters; if there is exactly one match, that determines the
full revision.
"""
if isinstance(id_, (list, tuple, set, frozenset)):
return sum([self.get_revisions(id_elem) for id_elem in id_], ())
else:
resolved_id, branch_label = self._resolve_revision_number(id_)
return tuple(
self._revision_for_ident(rev_id, branch_label)
for rev_id in resolved_id)
def get_revision(self, id_):
"""Return the :class:`.Revision` instance with the given rev id.
If a symbolic name such as "head" or "base" is given, resolves
the identifier into the current head or base revision. If the symbolic
name refers to multiples, :class:`.MultipleHeads` is raised.
Supports partial identifiers, where the given identifier
is matched against all identifiers that start with the given
characters; if there is exactly one match, that determines the
full revision.
"""
resolved_id, branch_label = self._resolve_revision_number(id_)
if len(resolved_id) > 1:
raise MultipleHeads(resolved_id, id_)
elif resolved_id:
resolved_id = resolved_id[0]
return self._revision_for_ident(resolved_id, branch_label)
def _resolve_branch(self, branch_label):
try:
branch_rev = self._revision_map[branch_label]
except KeyError:
try:
nonbranch_rev = self._revision_for_ident(branch_label)
except ResolutionError:
raise ResolutionError(
"No such branch: '%s'" % branch_label, branch_label)
else:
return nonbranch_rev
else:
return branch_rev
def _revision_for_ident(self, resolved_id, check_branch=None):
if check_branch:
branch_rev = self._resolve_branch(check_branch)
else:
branch_rev = None
try:
revision = self._revision_map[resolved_id]
except KeyError:
# do a partial lookup
revs = [x for x in self._revision_map
if x and x.startswith(resolved_id)]
if branch_rev:
revs = self.filter_for_lineage(revs, check_branch)
if not revs:
raise ResolutionError(
"No such revision or branch '%s'" % resolved_id,
resolved_id)
elif len(revs) > 1:
raise ResolutionError(
"Multiple revisions start "
"with '%s': %s..." % (
resolved_id,
", ".join("'%s'" % r for r in revs[0:3])
), resolved_id)
else:
revision = self._revision_map[revs[0]]
if check_branch and revision is not None:
if not self._shares_lineage(
revision.revision, branch_rev.revision):
raise ResolutionError(
"Revision %s is not a member of branch '%s'" %
(revision.revision, check_branch), resolved_id)
return revision
def filter_for_lineage(
self, targets, check_against, include_dependencies=False):
id_, branch_label = self._resolve_revision_number(check_against)
shares = []
if branch_label:
shares.append(branch_label)
if id_:
shares.extend(id_)
return [
tg for tg in targets
if self._shares_lineage(
tg, shares, include_dependencies=include_dependencies)]
def _shares_lineage(
self, target, test_against_revs, include_dependencies=False):
if not test_against_revs:
return True
if not isinstance(target, Revision):
target = self._revision_for_ident(target)
test_against_revs = [
self._revision_for_ident(test_against_rev)
if not isinstance(test_against_rev, Revision)
else test_against_rev
for test_against_rev
in util.to_tuple(test_against_revs, default=())
]
return bool(
set(self._get_descendant_nodes([target],
include_dependencies=include_dependencies))
.union(self._get_ancestor_nodes([target],
include_dependencies=include_dependencies))
.intersection(test_against_revs)
)
def _resolve_revision_number(self, id_):
if isinstance(id_, compat.string_types) and "@" in id_:
branch_label, id_ = id_.split('@', 1)
else:
branch_label = None
# ensure map is loaded
self._revision_map
if id_ == 'heads':
if branch_label:
return self.filter_for_lineage(
self.heads, branch_label), branch_label
else:
return self._real_heads, branch_label
elif id_ == 'head':
current_head = self.get_current_head(branch_label)
if current_head:
return (current_head, ), branch_label
else:
return (), branch_label
elif id_ == 'base' or id_ is None:
return (), branch_label
else:
return util.to_tuple(id_, default=None), branch_label
def _relative_iterate(
self, destination, source, is_upwards,
implicit_base, inclusive, assert_relative_length):
if isinstance(destination, compat.string_types):
match = _relative_destination.match(destination)
if not match:
return None
else:
return None
relative = int(match.group(3))
symbol = match.group(2)
branch_label = match.group(1)
reldelta = 1 if inclusive and not symbol else 0
if is_upwards:
if branch_label:
from_ = "%s@head" % branch_label
elif symbol:
if symbol.startswith("head"):
from_ = symbol
else:
from_ = "%s@head" % symbol
else:
from_ = "head"
to_ = source
else:
if branch_label:
to_ = "%s@base" % branch_label
elif symbol:
to_ = "%s@base" % symbol
else:
to_ = "base"
from_ = source
revs = list(
self._iterate_revisions(
from_, to_,
inclusive=inclusive, implicit_base=implicit_base))
if symbol:
if branch_label:
symbol_rev = self.get_revision(
"%s@%s" % (branch_label, symbol))
else:
symbol_rev = self.get_revision(symbol)
if symbol.startswith("head"):
index = 0
elif symbol == "base":
index = len(revs) - 1
else:
range_ = compat.range(len(revs) - 1, 0, -1)
for index in range_:
if symbol_rev.revision == revs[index].revision:
break
else:
index = 0
else:
index = 0
if is_upwards:
revs = revs[index - relative - reldelta:]
if not index and assert_relative_length and \
len(revs) < abs(relative - reldelta):
raise RevisionError(
"Relative revision %s didn't "
"produce %d migrations" % (destination, abs(relative)))
else:
revs = revs[0:index - relative + reldelta]
if not index and assert_relative_length and \
len(revs) != abs(relative) + reldelta:
raise RevisionError(
"Relative revision %s didn't "
"produce %d migrations" % (destination, abs(relative)))
return iter(revs)
def iterate_revisions(
self, upper, lower, implicit_base=False, inclusive=False,
assert_relative_length=True):
"""Iterate through script revisions, starting at the given
upper revision identifier and ending at the lower.
The traversal uses strictly the `down_revision`
marker inside each migration script, so
it is a requirement that upper >= lower,
else you'll get nothing back.
The iterator yields :class:`.Revision` objects.
"""
relative_upper = self._relative_iterate(
upper, lower, True, implicit_base,
inclusive, assert_relative_length
)
if relative_upper:
return relative_upper
relative_lower = self._relative_iterate(
lower, upper, False, implicit_base,
inclusive, assert_relative_length
)
if relative_lower:
return relative_lower
return self._iterate_revisions(
upper, lower, inclusive=inclusive, implicit_base=implicit_base)
def _get_descendant_nodes(
self, targets, map_=None, check=False, include_dependencies=True):
if include_dependencies:
fn = lambda rev: rev._all_nextrev
else:
fn = lambda rev: rev.nextrev
return self._iterate_related_revisions(
fn, targets, map_=map_, check=check
)
def _get_ancestor_nodes(
self, targets, map_=None, check=False, include_dependencies=True):
if include_dependencies:
fn = lambda rev: rev._all_down_revisions
else:
fn = lambda rev: rev._versioned_down_revisions
return self._iterate_related_revisions(
fn, targets, map_=map_, check=check
)
def _iterate_related_revisions(self, fn, targets, map_, check=False):
if map_ is None:
map_ = self._revision_map
seen = set()
todo = collections.deque()
for target in targets:
todo.append(target)
if check:
per_target = set()
while todo:
rev = todo.pop()
if check:
per_target.add(rev)
if rev in seen:
continue
seen.add(rev)
todo.extend(
map_[rev_id] for rev_id in fn(rev))
yield rev
if check and per_target.intersection(targets).difference([target]):
raise RevisionError(
"Requested revision %s overlaps with "
"other requested revisions" % target.revision)
def _iterate_revisions(
self, upper, lower, inclusive=True, implicit_base=False):
"""iterate revisions from upper to lower.
The traversal is depth-first within branches, and breadth-first
across branches as a whole.
"""
requested_lowers = self.get_revisions(lower)
# some complexity to accommodate an iteration where some
# branches are starting from nothing, and others are starting
# from a given point. Additionally, if the bottom branch
# is specified using a branch identifier, then we limit operations
# to just that branch.
limit_to_lower_branch = \
isinstance(lower, compat.string_types) and lower.endswith('@base')
uppers = util.dedupe_tuple(self.get_revisions(upper))
if not uppers and not requested_lowers:
raise StopIteration()
upper_ancestors = set(self._get_ancestor_nodes(uppers, check=True))
if limit_to_lower_branch:
lowers = self.get_revisions(self._get_base_revisions(lower))
elif implicit_base and requested_lowers:
lower_ancestors = set(
self._get_ancestor_nodes(requested_lowers)
)
lower_descendants = set(
self._get_descendant_nodes(requested_lowers)
)
base_lowers = set()
candidate_lowers = upper_ancestors.\
difference(lower_ancestors).\
difference(lower_descendants)
for rev in candidate_lowers:
for downrev in rev._all_down_revisions:
if self._revision_map[downrev] in candidate_lowers:
break
else:
base_lowers.add(rev)
lowers = base_lowers.union(requested_lowers)
elif implicit_base:
base_lowers = set(self.get_revisions(self._real_bases))
lowers = base_lowers.union(requested_lowers)
elif not requested_lowers:
lowers = set(self.get_revisions(self._real_bases))
else:
lowers = requested_lowers
# represents all nodes we will produce
total_space = set(
rev.revision for rev in upper_ancestors).intersection(
rev.revision for rev
in self._get_descendant_nodes(lowers, check=True)
)
if not total_space:
raise RangeNotAncestorError(lower, upper)
# organize branch points to be consumed separately from
# member nodes
branch_todo = set(
rev for rev in
(self._revision_map[rev] for rev in total_space)
if rev._is_real_branch_point and
len(total_space.intersection(rev._all_nextrev)) > 1
)
# it's not possible for any "uppers" to be in branch_todo,
# because the ._all_nextrev of those nodes is not in total_space
#assert not branch_todo.intersection(uppers)
todo = collections.deque(
r for r in uppers if r.revision in total_space)
# iterate for total_space being emptied out
total_space_modified = True
while total_space:
if not total_space_modified:
raise RevisionError(
"Dependency resolution failed; iteration can't proceed")
total_space_modified = False
# when everything non-branch pending is consumed,
# add to the todo any branch nodes that have no
# descendants left in the queue
if not todo:
todo.extendleft(
sorted(
(
rev for rev in branch_todo
if not rev._all_nextrev.intersection(total_space)
),
# favor "revisioned" branch points before
# dependent ones
key=lambda rev: 0 if rev.is_branch_point else 1
)
)
branch_todo.difference_update(todo)
# iterate nodes that are in the immediate todo
while todo:
rev = todo.popleft()
total_space.remove(rev.revision)
total_space_modified = True
# do depth first for elements within branches,
# don't consume any actual branch nodes
todo.extendleft([
self._revision_map[downrev]
for downrev in reversed(rev._all_down_revisions)
if self._revision_map[downrev] not in branch_todo
and downrev in total_space])
if not inclusive and rev in requested_lowers:
continue
yield rev
assert not branch_todo
class Revision(object):
"""Base class for revisioned objects.
The :class:`.Revision` class is the base of the more public-facing
:class:`.Script` object, which represents a migration script.
The mechanics of revision management and traversal are encapsulated
within :class:`.Revision`, while :class:`.Script` applies this logic
to Python files in a version directory.
"""
nextrev = frozenset()
"""following revisions, based on down_revision only."""
_all_nextrev = frozenset()
revision = None
"""The string revision number."""
down_revision = None
"""The ``down_revision`` identifier(s) within the migration script.
Note that the total set of "down" revisions is
down_revision + dependencies.
"""
dependencies = None
"""Additional revisions which this revision is dependent on.
From a migration standpoint, these dependencies are added to the
down_revision to form the full iteration. However, the separation
of down_revision from "dependencies" is to assist in navigating
a history that contains many branches, typically a multi-root scenario.
"""
branch_labels = None
"""Optional string/tuple of symbolic names to apply to this
revision's branch"""
def __init__(
self, revision, down_revision,
dependencies=None, branch_labels=None):
self.revision = revision
self.down_revision = tuple_rev_as_scalar(down_revision)
self.dependencies = tuple_rev_as_scalar(dependencies)
self._resolved_dependencies = ()
self._orig_branch_labels = util.to_tuple(branch_labels, default=())
self.branch_labels = set(self._orig_branch_labels)
def __repr__(self):
args = [
repr(self.revision),
repr(self.down_revision)
]
if self.dependencies:
args.append("dependencies=%r" % self.dependencies)
if self.branch_labels:
args.append("branch_labels=%r" % self.branch_labels)
return "%s(%s)" % (
self.__class__.__name__,
", ".join(args)
)
def add_nextrev(self, revision):
self._all_nextrev = self._all_nextrev.union([revision.revision])
if self.revision in revision._versioned_down_revisions:
self.nextrev = self.nextrev.union([revision.revision])
@property
def _all_down_revisions(self):
return util.to_tuple(self.down_revision, default=()) + \
self._resolved_dependencies
@property
def _versioned_down_revisions(self):
return util.to_tuple(self.down_revision, default=())
@property
def is_head(self):
"""Return True if this :class:`.Revision` is a 'head' revision.
This is determined based on whether any other :class:`.Script`
within the :class:`.ScriptDirectory` refers to this
:class:`.Script`. Multiple heads can be present.
"""
return not bool(self.nextrev)
@property
def _is_real_head(self):
return not bool(self._all_nextrev)
@property
def is_base(self):
"""Return True if this :class:`.Revision` is a 'base' revision."""
return self.down_revision is None
@property
def _is_real_base(self):
"""Return True if this :class:`.Revision` is a "real" base revision,
e.g. that it has no dependencies either."""
# we use self.dependencies here because this is called up
# in initialization where _real_dependencies isn't set up
# yet
return self.down_revision is None and self.dependencies is None
@property
def is_branch_point(self):
"""Return True if this :class:`.Script` is a branch point.
A branchpoint is defined as a :class:`.Script` which is referred
to by more than one succeeding :class:`.Script`, that is more
than one :class:`.Script` has a `down_revision` identifier pointing
here.
"""
return len(self.nextrev) > 1
@property
def _is_real_branch_point(self):
"""Return True if this :class:`.Script` is a 'real' branch point,
taking into account dependencies as well.
"""
return len(self._all_nextrev) > 1
@property
def is_merge_point(self):
"""Return True if this :class:`.Script` is a merge point."""
return len(self._versioned_down_revisions) > 1
def tuple_rev_as_scalar(rev):
if not rev:
return None
elif len(rev) == 1:
return rev[0]
else:
return rev
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