This isolates the undo handling in the new transaction object and in doop_source, which currently generates the undo items. This commit will be a stepping stone to rewriting the undo handling. Signed-off-by: Niels Thykier <niels@thykier.net>ubuntu/rebased
Niels Thykier
6 years ago
parent
68fd0ba4b2
commit
5d49a41204
@ -0,0 +1,131 @@
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import contextlib
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@contextlib.contextmanager
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def start_transaction(suite_info, all_binaries, parent_transaction=None):
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tmts = MigrationTransactionState(suite_info, all_binaries, parent_transaction)
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try:
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yield tmts
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except Exception:
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if not tmts.is_committed and not tmts.is_rolled_back:
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tmts.rollback()
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raise
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assert tmts.is_rolled_back or tmts.is_committed
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class MigrationTransactionState(object):
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def __init__(self, suite_info, all_binaries, parent=None):
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self._suite_info = suite_info
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self._all_binaries = all_binaries
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self.parent_transaction = parent
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self._is_rolled_back = False
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self._is_committed = False
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self._undo_items = []
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def add_undo_item(self, undo, item):
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self._assert_open_transaction()
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self._undo_items.append((undo, item))
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def _assert_open_transaction(self):
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assert not self._is_rolled_back and not self._is_committed
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p = self.parent_transaction
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if p:
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p._assert_open_transaction()
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@property
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def undo_items(self):
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"""Only needed by a doop_source for the "hint"-hint case"""
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yield from self._undo_items
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def commit(self):
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"""Commit the transaction
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After this call, it is not possible to roll these changes
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back (except if there is a parent transaction, which can
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still be rolled back).
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"""
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self._assert_open_transaction()
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self._is_committed = True
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if self.parent_transaction:
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for undo_item in self._undo_items:
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self.parent_transaction.add_undo_item(*undo_item)
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def rollback(self):
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"""Rollback all recorded changes by this transaction
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The parent transaction (if any) will remain unchanged
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"""
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self._assert_open_transaction()
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self._is_rolled_back = True
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lundo = self._undo_items
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lundo.reverse()
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# We do the undo process in "4 steps" and each step must be
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# fully completed for each undo-item before starting on the
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# next.
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#
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# see commit:ef71f0e33a7c3d8ef223ec9ad5e9843777e68133 and
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# #624716 for the issues we had when we did not do this.
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all_binary_packages = self._all_binaries
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target_suite = self._suite_info.target_suite
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sources_t = target_suite.sources
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binaries_t = target_suite.binaries
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provides_t = target_suite.provides_table
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# STEP 1
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# undo all the changes for sources
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for (undo, item) in lundo:
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for k in undo['sources']:
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if k[0] == '-':
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del sources_t[k[1:]]
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else:
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sources_t[k] = undo['sources'][k]
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# STEP 2
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# undo all new binaries (consequence of the above)
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for (undo, item) in lundo:
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if not item.is_removal and item.package in item.suite.sources:
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source_data = item.suite.sources[item.package]
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for pkg_id in source_data.binaries:
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binary, _, arch = pkg_id
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if item.architecture in ['source', arch]:
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try:
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del binaries_t[arch][binary]
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except KeyError:
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# If this happens, pkg_id must be a cruft item that
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# was *not* migrated.
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assert source_data.version != all_binary_packages[pkg_id].version
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assert not target_suite.is_pkg_in_the_suite(pkg_id)
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target_suite.remove_binary(pkg_id)
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# STEP 3
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# undo all other binary package changes (except virtual packages)
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for (undo, item) in lundo:
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for p in undo['binaries']:
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binary, arch = p
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binaries_t_a = binaries_t[arch]
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assert binary not in binaries_t_a
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pkgdata = all_binary_packages[undo['binaries'][p]]
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binaries_t_a[binary] = pkgdata
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target_suite.add_binary(pkgdata.pkg_id)
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# STEP 4
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# undo all changes to virtual packages
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for (undo, item) in lundo:
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for provided_pkg, arch in undo['nvirtual']:
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del provides_t[arch][provided_pkg]
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for p in undo['virtual']:
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provided_pkg, arch = p
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provides_t[arch][provided_pkg] = undo['virtual'][p]
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@property
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def is_rolled_back(self):
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return self._is_rolled_back
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@property
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def is_committed(self):
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return self._is_committed
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