You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
britney2-ubuntu/britney2/transaction.py

129 lines
4.6 KiB

class MigrationTransactionState(object):
def __init__(self, suite_info, all_binaries, parent=None):
self._suite_info = suite_info
self._all_binaries = all_binaries
self.parent_transaction = parent
self._is_rolled_back = False
self._is_committed = False
self._undo_items = []
self._pending_child = False
if self.parent_transaction:
# Transactions can only support one child transaction at a time
assert not self.parent_transaction._pending_child
self.parent_transaction._pending_child = True
def add_undo_item(self, undo, updated_binaries):
# We do not accept any changes to this transaction while it has a child transaction
# (the undo code does not handle that case correctly)
assert not self._pending_child
self._assert_open_transaction()
self._undo_items.append((undo, updated_binaries))
def _assert_open_transaction(self):
assert not self._is_rolled_back and not self._is_committed
p = self.parent_transaction
if p:
p._assert_open_transaction()
@property
def undo_items(self):
"""Only needed by a doop_source for the "hint"-hint case"""
yield from self._undo_items
def commit(self):
"""Commit the transaction
After this call, it is not possible to roll these changes
back (except if there is a parent transaction, which can
still be rolled back).
"""
self._assert_open_transaction()
self._is_committed = True
if self.parent_transaction:
self.parent_transaction._pending_child = False
for undo_item in self._undo_items:
self.parent_transaction.add_undo_item(*undo_item)
def rollback(self):
"""Rollback all recorded changes by this transaction
The parent transaction (if any) will remain unchanged
"""
self._assert_open_transaction()
self._is_rolled_back = True
lundo = self._undo_items
lundo.reverse()
all_binary_packages = self._all_binaries
target_suite = self._suite_info.target_suite
sources_t = target_suite.sources
binaries_t = target_suite.binaries
provides_t = target_suite.provides_table
# Historically, we have done the undo process in "4 steps"
# with the rule that each step must be fully completed for
# each undo-item before starting on the next.
#
# see commit:ef71f0e33a7c3d8ef223ec9ad5e9843777e68133 and
# #624716 for the issues we had when we did not do this.
#
# Today, only STEP 2 and STEP 3 are known to potentially
# clash. If there is a point in merging the loops/steps,
# then it is now feasible.
# STEP 1
# undo all the changes for sources
for (undo, updated_binaries) in lundo:
for (k, v) in undo['sources'].items():
if v is None:
del sources_t[k]
else:
sources_t[k] = v
# STEP 2
# undo all new/updated binaries
# Note this must be completed fully before starting STEP 3
# as it potentially breaks STEP 3 if the two are interleaved.
for (_, updated_binaries) in lundo:
for pkg_id in updated_binaries:
pkg_name, _, pkg_arch = pkg_id
try:
del binaries_t[pkg_arch][pkg_name]
except KeyError:
continue
target_suite.remove_binary(pkg_id)
# STEP 3
# undo all other binary package changes (except virtual packages)
for (undo, updated_binaries) in lundo:
for p in undo['binaries']:
binary, arch = p
binaries_t_a = binaries_t[arch]
pkgdata = all_binary_packages[undo['binaries'][p]]
binaries_t_a[binary] = pkgdata
target_suite.add_binary(pkgdata.pkg_id)
# STEP 4
# undo all changes to virtual packages
for (undo, _) in lundo:
for p, value in undo['virtual'].items():
provided_pkg, arch = p
if value is None:
del provides_t[arch][provided_pkg]
else:
provides_t[arch][provided_pkg] = undo['virtual'][p]
if self.parent_transaction:
self.parent_transaction._pending_child = False
@property
def is_rolled_back(self):
return self._is_rolled_back
@property
def is_committed(self):
return self._is_committed