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588 lines
20 KiB
588 lines
20 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
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import collections
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import dns.exception
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import dns.name
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import dns.rdataclass
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import dns.rdataset
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import dns.rdatatype
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import dns.rrset
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import dns.serial
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import dns.ttl
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class TransactionManager:
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def reader(self):
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"""Begin a read-only transaction."""
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raise NotImplementedError # pragma: no cover
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def writer(self, replacement=False):
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"""Begin a writable transaction.
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*replacement*, a ``bool``. If `True`, the content of the
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transaction completely replaces any prior content. If False,
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the default, then the content of the transaction updates the
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existing content.
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"""
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raise NotImplementedError # pragma: no cover
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def origin_information(self):
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"""Returns a tuple
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(absolute_origin, relativize, effective_origin)
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giving the absolute name of the default origin for any
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relative domain names, the "effective origin", and whether
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names should be relativized. The "effective origin" is the
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absolute origin if relativize is False, and the empty name if
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relativize is true. (The effective origin is provided even
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though it can be computed from the absolute_origin and
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relativize setting because it avoids a lot of code
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duplication.)
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If the returned names are `None`, then no origin information is
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available.
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This information is used by code working with transactions to
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allow it to coordinate relativization. The transaction code
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itself takes what it gets (i.e. does not change name
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relativity).
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"""
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raise NotImplementedError # pragma: no cover
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def get_class(self):
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"""The class of the transaction manager.
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"""
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raise NotImplementedError # pragma: no cover
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def from_wire_origin(self):
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"""Origin to use in from_wire() calls.
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"""
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(absolute_origin, relativize, _) = self.origin_information()
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if relativize:
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return absolute_origin
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else:
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return None
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class DeleteNotExact(dns.exception.DNSException):
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"""Existing data did not match data specified by an exact delete."""
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class ReadOnly(dns.exception.DNSException):
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"""Tried to write to a read-only transaction."""
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class AlreadyEnded(dns.exception.DNSException):
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"""Tried to use an already-ended transaction."""
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def _ensure_immutable_rdataset(rdataset):
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if rdataset is None or isinstance(rdataset, dns.rdataset.ImmutableRdataset):
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return rdataset
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return dns.rdataset.ImmutableRdataset(rdataset)
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def _ensure_immutable_node(node):
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if node is None or node.is_immutable():
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return node
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return dns.node.ImmutableNode(node)
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class Transaction:
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def __init__(self, manager, replacement=False, read_only=False):
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self.manager = manager
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self.replacement = replacement
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self.read_only = read_only
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self._ended = False
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self._check_put_rdataset = []
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self._check_delete_rdataset = []
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self._check_delete_name = []
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#
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# This is the high level API
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#
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def get(self, name, rdtype, covers=dns.rdatatype.NONE):
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"""Return the rdataset associated with *name*, *rdtype*, and *covers*,
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or `None` if not found.
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Note that the returned rdataset is immutable.
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"""
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self._check_ended()
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if isinstance(name, str):
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name = dns.name.from_text(name, None)
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rdtype = dns.rdatatype.RdataType.make(rdtype)
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rdataset = self._get_rdataset(name, rdtype, covers)
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return _ensure_immutable_rdataset(rdataset)
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def get_node(self, name):
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"""Return the node at *name*, if any.
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Returns an immutable node or ``None``.
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"""
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return _ensure_immutable_node(self._get_node(name))
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def _check_read_only(self):
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if self.read_only:
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raise ReadOnly
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def add(self, *args):
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"""Add records.
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The arguments may be:
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- rrset
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- name, rdataset...
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- name, ttl, rdata...
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"""
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self._check_ended()
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self._check_read_only()
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return self._add(False, args)
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def replace(self, *args):
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"""Replace the existing rdataset at the name with the specified
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rdataset, or add the specified rdataset if there was no existing
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rdataset.
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The arguments may be:
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- rrset
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- name, rdataset...
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- name, ttl, rdata...
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Note that if you want to replace the entire node, you should do
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a delete of the name followed by one or more calls to add() or
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replace().
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"""
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self._check_ended()
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self._check_read_only()
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return self._add(True, args)
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def delete(self, *args):
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"""Delete records.
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It is not an error if some of the records are not in the existing
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set.
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The arguments may be:
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- rrset
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- name
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- name, rdataclass, rdatatype, [covers]
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- name, rdataset...
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- name, rdata...
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"""
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self._check_ended()
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self._check_read_only()
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return self._delete(False, args)
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def delete_exact(self, *args):
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"""Delete records.
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The arguments may be:
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- rrset
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- name
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- name, rdataclass, rdatatype, [covers]
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- name, rdataset...
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- name, rdata...
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Raises dns.transaction.DeleteNotExact if some of the records
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are not in the existing set.
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"""
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self._check_ended()
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self._check_read_only()
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return self._delete(True, args)
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def name_exists(self, name):
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"""Does the specified name exist?"""
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self._check_ended()
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if isinstance(name, str):
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name = dns.name.from_text(name, None)
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return self._name_exists(name)
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def update_serial(self, value=1, relative=True, name=dns.name.empty):
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"""Update the serial number.
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*value*, an `int`, is an increment if *relative* is `True`, or the
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actual value to set if *relative* is `False`.
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Raises `KeyError` if there is no SOA rdataset at *name*.
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Raises `ValueError` if *value* is negative or if the increment is
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so large that it would cause the new serial to be less than the
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prior value.
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"""
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self._check_ended()
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if value < 0:
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raise ValueError('negative update_serial() value')
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if isinstance(name, str):
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name = dns.name.from_text(name, None)
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rdataset = self._get_rdataset(name, dns.rdatatype.SOA,
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dns.rdatatype.NONE)
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if rdataset is None or len(rdataset) == 0:
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raise KeyError
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if relative:
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serial = dns.serial.Serial(rdataset[0].serial) + value
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else:
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serial = dns.serial.Serial(value)
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serial = serial.value # convert back to int
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if serial == 0:
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serial = 1
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rdata = rdataset[0].replace(serial=serial)
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new_rdataset = dns.rdataset.from_rdata(rdataset.ttl, rdata)
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self.replace(name, new_rdataset)
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def __iter__(self):
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self._check_ended()
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return self._iterate_rdatasets()
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def changed(self):
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"""Has this transaction changed anything?
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For read-only transactions, the result is always `False`.
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For writable transactions, the result is `True` if at some time
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during the life of the transaction, the content was changed.
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"""
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self._check_ended()
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return self._changed()
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def commit(self):
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"""Commit the transaction.
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Normally transactions are used as context managers and commit
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or rollback automatically, but it may be done explicitly if needed.
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A ``dns.transaction.Ended`` exception will be raised if you try
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to use a transaction after it has been committed or rolled back.
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Raises an exception if the commit fails (in which case the transaction
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is also rolled back.
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"""
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self._end(True)
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def rollback(self):
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"""Rollback the transaction.
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Normally transactions are used as context managers and commit
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or rollback automatically, but it may be done explicitly if needed.
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A ``dns.transaction.AlreadyEnded`` exception will be raised if you try
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to use a transaction after it has been committed or rolled back.
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Rollback cannot otherwise fail.
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"""
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self._end(False)
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def check_put_rdataset(self, check):
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"""Call *check* before putting (storing) an rdataset.
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The function is called with the transaction, the name, and the rdataset.
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The check function may safely make non-mutating transaction method
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calls, but behavior is undefined if mutating transaction methods are
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called. The check function should raise an exception if it objects to
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the put, and otherwise should return ``None``.
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"""
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self._check_put_rdataset.append(check)
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def check_delete_rdataset(self, check):
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"""Call *check* before deleting an rdataset.
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The function is called with the transaction, the name, the rdatatype,
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and the covered rdatatype.
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The check function may safely make non-mutating transaction method
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calls, but behavior is undefined if mutating transaction methods are
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called. The check function should raise an exception if it objects to
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the put, and otherwise should return ``None``.
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"""
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self._check_delete_rdataset.append(check)
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def check_delete_name(self, check):
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"""Call *check* before putting (storing) an rdataset.
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The function is called with the transaction and the name.
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The check function may safely make non-mutating transaction method
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calls, but behavior is undefined if mutating transaction methods are
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called. The check function should raise an exception if it objects to
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the put, and otherwise should return ``None``.
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"""
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self._check_delete_name.append(check)
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#
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# Helper methods
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#
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def _raise_if_not_empty(self, method, args):
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if len(args) != 0:
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raise TypeError(f'extra parameters to {method}')
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def _rdataset_from_args(self, method, deleting, args):
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try:
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arg = args.popleft()
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if isinstance(arg, dns.rrset.RRset):
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rdataset = arg.to_rdataset()
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elif isinstance(arg, dns.rdataset.Rdataset):
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rdataset = arg
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else:
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if deleting:
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ttl = 0
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else:
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if isinstance(arg, int):
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ttl = arg
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if ttl > dns.ttl.MAX_TTL:
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raise ValueError(f'{method}: TTL value too big')
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else:
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raise TypeError(f'{method}: expected a TTL')
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arg = args.popleft()
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if isinstance(arg, dns.rdata.Rdata):
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rdataset = dns.rdataset.from_rdata(ttl, arg)
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else:
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raise TypeError(f'{method}: expected an Rdata')
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return rdataset
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except IndexError:
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if deleting:
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return None
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else:
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# reraise
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raise TypeError(f'{method}: expected more arguments')
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def _add(self, replace, args):
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try:
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args = collections.deque(args)
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if replace:
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method = 'replace()'
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else:
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method = 'add()'
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arg = args.popleft()
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if isinstance(arg, str):
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arg = dns.name.from_text(arg, None)
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if isinstance(arg, dns.name.Name):
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name = arg
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rdataset = self._rdataset_from_args(method, False, args)
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elif isinstance(arg, dns.rrset.RRset):
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rrset = arg
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name = rrset.name
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# rrsets are also rdatasets, but they don't print the
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# same and can't be stored in nodes, so convert.
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rdataset = rrset.to_rdataset()
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else:
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raise TypeError(f'{method} requires a name or RRset ' +
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'as the first argument')
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if rdataset.rdclass != self.manager.get_class():
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raise ValueError(f'{method} has objects of wrong RdataClass')
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if rdataset.rdtype == dns.rdatatype.SOA:
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(_, _, origin) = self.manager.origin_information()
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if name != origin:
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raise ValueError(f'{method} has non-origin SOA')
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self._raise_if_not_empty(method, args)
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if not replace:
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existing = self._get_rdataset(name, rdataset.rdtype,
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rdataset.covers)
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if existing is not None:
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if isinstance(existing, dns.rdataset.ImmutableRdataset):
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trds = dns.rdataset.Rdataset(existing.rdclass,
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existing.rdtype,
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existing.covers)
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trds.update(existing)
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existing = trds
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rdataset = existing.union(rdataset)
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self._checked_put_rdataset(name, rdataset)
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except IndexError:
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raise TypeError(f'not enough parameters to {method}')
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def _delete(self, exact, args):
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try:
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args = collections.deque(args)
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if exact:
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method = 'delete_exact()'
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else:
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method = 'delete()'
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arg = args.popleft()
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if isinstance(arg, str):
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arg = dns.name.from_text(arg, None)
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if isinstance(arg, dns.name.Name):
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name = arg
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if len(args) > 0 and (isinstance(args[0], int) or
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isinstance(args[0], str)):
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# deleting by type and (optionally) covers
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rdtype = dns.rdatatype.RdataType.make(args.popleft())
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if len(args) > 0:
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covers = dns.rdatatype.RdataType.make(args.popleft())
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else:
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covers = dns.rdatatype.NONE
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self._raise_if_not_empty(method, args)
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existing = self._get_rdataset(name, rdtype, covers)
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if existing is None:
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if exact:
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raise DeleteNotExact(f'{method}: missing rdataset')
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else:
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self._delete_rdataset(name, rdtype, covers)
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return
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else:
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rdataset = self._rdataset_from_args(method, True, args)
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elif isinstance(arg, dns.rrset.RRset):
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rdataset = arg # rrsets are also rdatasets
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name = rdataset.name
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else:
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raise TypeError(f'{method} requires a name or RRset ' +
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'as the first argument')
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self._raise_if_not_empty(method, args)
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if rdataset:
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if rdataset.rdclass != self.manager.get_class():
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raise ValueError(f'{method} has objects of wrong '
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'RdataClass')
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existing = self._get_rdataset(name, rdataset.rdtype,
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rdataset.covers)
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if existing is not None:
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if exact:
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intersection = existing.intersection(rdataset)
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if intersection != rdataset:
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raise DeleteNotExact(f'{method}: missing rdatas')
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rdataset = existing.difference(rdataset)
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if len(rdataset) == 0:
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self._checked_delete_rdataset(name, rdataset.rdtype,
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rdataset.covers)
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else:
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self._checked_put_rdataset(name, rdataset)
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elif exact:
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raise DeleteNotExact(f'{method}: missing rdataset')
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else:
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if exact and not self._name_exists(name):
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raise DeleteNotExact(f'{method}: name not known')
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self._checked_delete_name(name)
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except IndexError:
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raise TypeError(f'not enough parameters to {method}')
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def _check_ended(self):
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if self._ended:
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raise AlreadyEnded
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def _end(self, commit):
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self._check_ended()
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if self._ended:
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raise AlreadyEnded
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try:
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self._end_transaction(commit)
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finally:
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self._ended = True
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def _checked_put_rdataset(self, name, rdataset):
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for check in self._check_put_rdataset:
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check(self, name, rdataset)
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self._put_rdataset(name, rdataset)
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def _checked_delete_rdataset(self, name, rdtype, covers):
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for check in self._check_delete_rdataset:
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check(self, name, rdtype, covers)
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self._delete_rdataset(name, rdtype, covers)
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def _checked_delete_name(self, name):
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for check in self._check_delete_name:
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check(self, name)
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self._delete_name(name)
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#
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# Transactions are context managers.
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#
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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if not self._ended:
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if exc_type is None:
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self.commit()
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else:
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self.rollback()
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return False
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#
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# This is the low level API, which must be implemented by subclasses
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# of Transaction.
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#
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def _get_rdataset(self, name, rdtype, covers):
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"""Return the rdataset associated with *name*, *rdtype*, and *covers*,
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or `None` if not found.
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"""
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raise NotImplementedError # pragma: no cover
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def _put_rdataset(self, name, rdataset):
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"""Store the rdataset."""
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raise NotImplementedError # pragma: no cover
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def _delete_name(self, name):
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"""Delete all data associated with *name*.
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It is not an error if the name does not exist.
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"""
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raise NotImplementedError # pragma: no cover
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def _delete_rdataset(self, name, rdtype, covers):
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"""Delete all data associated with *name*, *rdtype*, and *covers*.
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It is not an error if the rdataset does not exist.
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"""
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raise NotImplementedError # pragma: no cover
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|
|
def _name_exists(self, name):
|
|
"""Does name exist?
|
|
|
|
Returns a bool.
|
|
"""
|
|
raise NotImplementedError # pragma: no cover
|
|
|
|
def _changed(self):
|
|
"""Has this transaction changed anything?"""
|
|
raise NotImplementedError # pragma: no cover
|
|
|
|
def _end_transaction(self, commit):
|
|
"""End the transaction.
|
|
|
|
*commit*, a bool. If ``True``, commit the transaction, otherwise
|
|
roll it back.
|
|
|
|
If committing adn the commit fails, then roll back and raise an
|
|
exception.
|
|
"""
|
|
raise NotImplementedError # pragma: no cover
|
|
|
|
def _set_origin(self, origin):
|
|
"""Set the origin.
|
|
|
|
This method is called when reading a possibly relativized
|
|
source, and an origin setting operation occurs (e.g. $ORIGIN
|
|
in a zone file).
|
|
"""
|
|
raise NotImplementedError # pragma: no cover
|
|
|
|
def _iterate_rdatasets(self):
|
|
"""Return an iterator that yields (name, rdataset) tuples.
|
|
"""
|
|
raise NotImplementedError # pragma: no cover
|
|
|
|
def _get_node(self, name):
|
|
"""Return the node at *name*, if any.
|
|
|
|
Returns a node or ``None``.
|
|
"""
|
|
raise NotImplementedError # pragma: no cover
|