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deps.py
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deps.py
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from contextlib import suppress
from .exceptions import BundleError, ItemDependencyError, NoSuchItem
from .items import ALLOWED_ITEM_AUTO_ATTRIBUTES, Item
from .items.actions import Action
from .utils.plot import explain_item_dependency_loop
from .utils.text import bold, mark_for_translation as _
from .utils.ui import io
class ItemDependencyLoop(ItemDependencyError):
"""
Raised when there is a loop in item dependencies.
"""
def __init__(self, items):
self.items = items
def __repr__(self):
return "<ItemDependencyLoop between {} items>".format(len(self.items))
def __str__(self):
return "\n".join(explain_item_dependency_loop(self.items))
class TagFillerItem(Item):
BUNDLE_ATTRIBUTE_NAME = "__tagfiller__"
ITEM_TYPE_NAME = "empty_tag"
def sdict(self):
return {}
def resolve_selector(selector, items, originating_item_id=None, originating_tag=None):
"""
Given an item selector (e.g. 'bundle:foo' or 'file:/bar'), return
all items matching that selector from the given list of items.
"""
if selector.startswith("!"):
negate = lambda b: not b
selector = selector[1:]
else:
negate = lambda b: b
try:
selector_type, selector_name = selector.split(":", 1)
except ValueError:
raise ValueError(_("invalid item selector: {}").format(selector))
if selector_type == "bundle":
return filter(
lambda item:
negate(item.bundle.name == selector_name) and
item.id != originating_item_id,
items,
)
elif selector_type == "tag":
if not selector_name: # "tag:"
return filter(
lambda item: negate(bool(item.tags)) and originating_tag not in item.tags,
items,
)
else:
return filter(
lambda item: negate(selector_name in item.tags) and item.id != originating_item_id,
items,
)
elif not selector_name: # "file:"
return filter(
lambda item:
negate(item.ITEM_TYPE_NAME == selector_type) and
item.id != originating_item_id,
items,
)
else: # single item
if negate(False):
return filter(lambda item: item.id != selector, items)
else:
return [find_item(selector, items)]
def find_item(item_id, items):
"""
Returns the first item with the given ID within the given list of
items.
"""
try:
item = list(filter(lambda item: item.id == item_id, items))[0]
except IndexError:
raise NoSuchItem(_("item not found: {}").format(item_id))
return item
def _flatten_dependencies(items):
"""
This will cause all dependencies - direct AND inherited - to be
listed in item._flattened_deps.
"""
for item in items:
if not hasattr(item, '_flattened_deps'):
_flatten_deps_for_item(item, items)
def _flatten_deps_for_item(item, items):
"""
Recursively retrieves and returns a list of all inherited
dependencies of the given item.
This can handle loops, but will ignore them.
"""
item._flattened_deps = {item.id for item in item._deps}
item._flattened_deps_needs = {item.id for item in item._deps_needs | item._deps_needed_by}
for dep_item in item._deps:
# Don't recurse if we have already resolved nested
# dependencies for this item. Also serves as a guard
# against infinite recursion when there are loops.
if not hasattr(dep_item, '_flattened_deps'):
_flatten_deps_for_item(dep_item, items)
item._flattened_deps.update(dep_item._flattened_deps)
item._flattened_deps_needs.update(dep_item._flattened_deps_needs)
def _add_incoming_needs(items):
"""
For each item, records all items that need that item in
._incoming_needs.
"""
mapping = {}
for item in items:
for other_item_id in item._flattened_deps_needs:
mapping.setdefault(other_item_id, set())
mapping[other_item_id].add(item)
for item in items:
item._incoming_needs = mapping.get(item.id, set())
def _prepare_auto_attrs(items):
for item in items:
auto_attrs = item.get_auto_attrs(items)
# remove next line in 5.0 when killing get_auto_deps
auto_attrs['needs'] = set(auto_attrs.get('needs', set())) | set(item.get_auto_deps(items))
for key, value in auto_attrs.items():
if key not in ALLOWED_ITEM_AUTO_ATTRIBUTES:
raise ValueError(_("get_auto_attrs() on {item} returned illegal key {key}").format(
item=item.id,
key=repr(key),
))
setattr(item, key, set(getattr(item, key)) | set(value))
def _prepare_deps(items):
selector_cache = {}
for item in items:
item._deps = set() # holds all item ids blocking execution of that item
for dep_type, deps in (
('after', set(item.after)),
('needs', set(item.needs)),
):
setattr(item, '_deps_' + dep_type, set())
for dep in deps:
try:
resolved_deps = selector_cache[dep]
except KeyError:
try:
resolved_deps = tuple(resolve_selector(dep, items))
except NoSuchItem:
raise ItemDependencyError(_(
"'{item}' in bundle '{bundle}' has a dependency ({dep_type}) "
"on '{dep}', which doesn't exist"
).format(
item=item.id,
bundle=item.bundle.name,
dep=dep,
dep_type=dep_type,
))
selector_cache[dep] = resolved_deps
# Don't put the item itself into its own deps.
resolved_deps = tuple(filter(lambda i: i.id != item.id, resolved_deps))
item._deps.update(resolved_deps)
getattr(item, '_deps_' + dep_type).update(resolved_deps)
def _inject_canned_actions(items):
"""
Looks for canned actions like "svc_upstart:mysql:reload" in items,
created actions for them and add those to the list of items.
"""
actions = set()
for item in items:
for canned_action_name, canned_action_attrs in item.get_canned_actions().items():
canned_action_id = f"{item.id}:{canned_action_name}"
canned_action_attrs.update({'triggered': True})
action = Action(
item.bundle,
canned_action_id,
canned_action_attrs,
skip_name_validation=True,
)
actions.add(action)
items.update(actions)
def _inject_tag_filler_items(items, bundles):
"""
Creates TagFillerItems to ensure each tag has at least one item.
This is important so even if there are no user-defined items with
a tag, that tag can still be used to chain dependencies.
[item:A] --needs--> [tag:B] --needs--> [item:C]
Users will assume that item:A will implicitly depend on item:C, but
if tag:B doesn't resolve to any items, that connection won't be
made.
"""
for bundle in bundles:
for tag, attrs in bundle.bundle_attrs.get('tags', {}).items():
if not tuple(resolve_selector(f"tag:{tag}", items)):
items.add(TagFillerItem(bundle, tag, {'tags': {tag}}))
def _inject_concurrency_blockers(items, node_os, node_os_version):
"""
Looks for items with BLOCK_CONCURRENT set and inserts daisy-chain
dependencies to force a sequential apply.
"""
# find every item type that cannot be applied in parallel
item_types = set()
for item in items:
item._deps_concurrency = set()
if item.block_concurrent(node_os, node_os_version):
item_types.add(item.__class__)
# Now that we have collected all relevant types,
# we must group them together when they overlap. E.g.:
#
# Type1.block_concurrent(...) == ["type1", "type2"]
# Type2.block_concurrent(...) == ["type2", "type3"]
# Type4.block_concurrent(...) == ["type4"]
#
# becomes
#
# ["type1", "type2", "type3"]
# ["type4"]
#
# because the first two types overlap in blocking type2. This is
# necessary because existing dependencies from type3 to type1 need
# to be taken into account when generating the daisy-chains
# connecting the three types. If we processed blockers for Type1 and
# Type2 independently, we might end up with two very different
# chains for Type2, which may cause circular dependencies.
chain_groups = []
for item_type in item_types:
block_concurrent = {item_type.ITEM_TYPE_NAME}
block_concurrent.update(item_type.block_concurrent(node_os, node_os_version))
found = False
for blocked_types in chain_groups:
for blocked_type in block_concurrent:
if blocked_type in blocked_types:
blocked_types.update(block_concurrent)
found = True
break
if found:
break
if not found:
chain_groups.append(block_concurrent)
# daisy-chain all items of the chain group while respecting existing
# dependencies between them
for blocked_types in chain_groups:
blocked_types = set(blocked_types)
type_items = set(filter(
lambda item: item.ITEM_TYPE_NAME in blocked_types,
items,
))
processed_items = set()
for item in type_items:
# disregard deps to items of other types and to canned
# actions
item.__deps = set(filter(
lambda dep: (
dep.split(":", 1)[0] in blocked_types and
dep.count(":") == 1
),
item._flattened_deps,
))
previous_item = None
while len(processed_items) < len(type_items):
# find the first item without same-type deps we haven't
# processed yet
try:
item = list(filter(
lambda item: not item.__deps and item not in processed_items,
type_items,
))[0]
except IndexError:
# this can happen if the flattened deps of all items of
# this type already contain a dependency on another
# item of this type
break
if previous_item is not None: # unless we're at the first item
# add dep to previous item -- unless it's already in there
if previous_item not in item._deps:
item._deps.add(previous_item)
item._deps_concurrency.add(previous_item)
item._flattened_deps.add(previous_item.id)
previous_item = item
processed_items.add(item)
# Now remove all deps on the processed item. This frees up
# items depending *only* on the processed item to be
# eligible for the next iteration of this loop.
for other_item in type_items:
with suppress(KeyError):
other_item.__deps.remove(item.id)
def _inject_reverse_dependencies(items):
"""
Looks for 'before' and 'needed_by' deps and creates standard
dependencies accordingly.
"""
for item in items:
for dep_type in ('before', 'needed_by'):
setattr(item, '_deps_' + dep_type, set())
for item in items:
for dep_type in ('before', 'needed_by'):
for depending_item_id in set(getattr(item, dep_type)):
try:
dependent_items = resolve_selector(
depending_item_id,
items,
originating_item_id=item.id,
)
except NoSuchItem:
raise ItemDependencyError(_(
"'{item}' in bundle '{bundle}' has a reverse dependency ({dep_type}) "
"on '{dep}', which doesn't exist"
).format(
item=item.id,
bundle=item.bundle.name,
dep=depending_item_id,
dep_type=dep_type,
))
for dependent_item in dependent_items:
dependent_item._deps.add(item)
getattr(dependent_item, '_deps_' + dep_type).add(item)
def _inject_reverse_triggers(items):
"""
Looks for 'triggered_by' and 'precedes' attributes and turns them
into standard triggers (defined on the opposing end).
"""
for item in items:
for triggering_item_selector in item.triggered_by:
try:
triggering_items = resolve_selector(
triggering_item_selector,
items,
originating_item_id=item.id,
)
except NoSuchItem:
raise ItemDependencyError(_(
"'{item}' in bundle '{bundle}' has a reverse trigger (triggered_by) "
"on '{dep}', which doesn't exist"
).format(
item=item.id,
bundle=item.bundle.name,
dep=triggering_item_selector,
))
for triggering_item in triggering_items:
triggering_item.triggers.add(item.id)
for preceded_item_selector in item.precedes:
try:
preceded_items = resolve_selector(
preceded_item_selector,
items,
originating_item_id=item.id,
)
except NoSuchItem:
raise ItemDependencyError(_(
"'{item}' in bundle '{bundle}' has a reverse trigger (precedes) "
"on '{dep}', which doesn't exist"
).format(
item=item.id,
bundle=item.bundle.name,
dep=preceded_item_selector,
))
for preceded_item in preceded_items:
preceded_item.preceded_by.add(item.id)
def _inject_trigger_dependencies(items):
"""
Injects dependencies from all triggered items to their triggering
items.
"""
for item in items:
item._deps_triggers = set()
for item in items:
for triggered_item_selector in item.triggers:
try:
triggered_items = resolve_selector(
triggered_item_selector,
items,
originating_item_id=item.id,
)
except KeyError:
raise BundleError(_(
"unable to find definition of '{item1}' triggered "
"by '{item2}' in bundle '{bundle}'"
).format(
bundle=item.bundle.name,
item1=triggered_item_selector,
item2=item.id,
))
for triggered_item in triggered_items:
if triggered_item.triggered:
triggered_item._deps.add(item)
triggered_item._deps_triggers.add(item)
else:
raise BundleError(_(
"'{item1}' in bundle '{bundle1}' triggered "
"by '{item2}' in bundle '{bundle2}', "
"but missing 'triggered' attribute"
).format(
item1=triggered_item.id,
bundle1=triggered_item.bundle.name,
item2=item.id,
bundle2=item.bundle.name,
))
def _inject_preceded_by_dependencies(items):
"""
Injects dependencies from all triggering items to their
preceded_by items and attaches triggering items to preceding items.
"""
for item in items:
if item.preceded_by and item.triggered:
raise BundleError(_(
"triggered item '{item}' in bundle '{bundle}' must not use "
"'preceded_by' (use chained triggers instead)".format(
bundle=item.bundle.name,
item=item.id,
),
))
for triggered_item_selector in item.preceded_by:
try:
triggered_items = resolve_selector(
triggered_item_selector,
items,
originating_item_id=item.id,
)
except KeyError:
raise BundleError(_(
"unable to find definition of '{item1}' preceding "
"'{item2}' in bundle '{bundle}'"
).format(
bundle=item.bundle.name,
item1=triggered_item_selector,
item2=item.id,
))
for triggered_item in triggered_items:
if triggered_item.triggered:
triggered_item._precedes_items.add(item)
item._deps.add(triggered_item)
else:
raise BundleError(_(
"'{item1}' in bundle '{bundle1}' precedes "
"'{item2}' in bundle '{bundle2}', "
"but missing 'triggered' attribute"
).format(
item1=triggered_item.id,
bundle1=triggered_item.bundle.name,
item2=item.id,
bundle2=item.bundle.name,
))
def _inject_tag_attrs(items, bundles):
"""
Applies the tag-level attributes from bundle.py to all matching
items.
"""
for bundle in bundles:
for tag, attrs in bundle.bundle_attrs.get('tags', {}).items():
for item in resolve_selector(f"tag:{tag}", items, originating_tag=tag):
for attr in (
"after",
"before",
"needs",
"needed_by",
"precedes",
"preceded_by",
"triggers",
"triggered_by",
):
getattr(item, attr).update(attrs.get(attr, set()))
def _add_inherited_tags(items, bundles):
"""
This will apply tags to items based on the tags in bundle.py.
tags = {
"foo": {
"tags": {"bar"}, # will cause all items with tag:foo
# to also have tag:bar
},
}
"""
tags_added = True
while tags_added:
tags_added = False
for bundle in bundles:
for tag, attrs in bundle.bundle_attrs.get('tags', {}).items():
inherited_tags = attrs.get('tags', set())
if not inherited_tags:
# just an optimization to avoid needlessly calling resolve_selector()
continue
for item in resolve_selector(f"tag:{tag}", items):
len_before = len(item.tags)
item.tags.update(inherited_tags)
if len_before < len(item.tags):
tags_added = True
@io.job_wrapper(_("{} processing dependencies").format(bold("{0.name}")))
def prepare_dependencies(node):
"""
Performs all dependency preprocessing on a list of items.
"""
for item in node.items:
item._check_loopback_dependency()
items = set(node.items) # might be a tuple from cached_property
_inject_canned_actions(items)
_inject_tag_filler_items(items, node.bundles)
_add_inherited_tags(items, node.bundles)
_inject_tag_attrs(items, node.bundles)
_prepare_auto_attrs(items)
_prepare_deps(items)
_inject_reverse_triggers(items)
_inject_reverse_dependencies(items)
_inject_trigger_dependencies(items)
_inject_preceded_by_dependencies(items)
_flatten_dependencies(items)
_add_incoming_needs(items)
_inject_concurrency_blockers(items, node.os, node.os_version)
return items
def remove_dep_from_items(items, dep):
"""
Removes the given item id (dep) from the temporary list of
dependencies of all items in the given list.
"""
for item in items:
with suppress(KeyError):
item._deps.remove(dep)
return items
def remove_item_dependents(items, dep_item):
"""
Removes the items depending on the given item from the list of items.
"""
removed_items = set()
for item in items:
if dep_item in item._deps_needs | item._deps_needed_by:
removed_items.add(item)
with suppress(KeyError):
item._deps.remove(dep_item)
for item in removed_items:
items.remove(item)
if removed_items:
io.debug(
"skipped these items because they depend on {item}, which was "
"skipped previously: {skipped}".format(
item=dep_item.id,
skipped=", ".join([item.id for item in removed_items]),
)
)
all_recursively_removed_items = set()
for removed_item in removed_items:
if removed_item.cascade_skip:
items, recursively_removed_items = \
remove_item_dependents(items, removed_item)
all_recursively_removed_items.update(recursively_removed_items)
else:
items = remove_dep_from_items(items, removed_item)
return (items, removed_items | all_recursively_removed_items)
def split_items_without_deps(items):
"""
Takes a list of items and extracts the ones that don't have any
dependencies. The extracted deps are returned as a list.
"""
remaining_items = set()
removed_items = set()
for item in items:
if item._deps:
remaining_items.add(item)
else:
removed_items.add(item)
return (remaining_items, removed_items)