root / snf-cyclades-app / synnefo / db / pools / __init__.py @ 4445f97a
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from bitarray import bitarray |
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from base64 import b64encode, b64decode |
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import ipaddr |
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AVAILABLE = True
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UNAVAILABLE = False
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class PoolManager(object): |
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"""PoolManager for DB PoolTable models.
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This class implements a persistent Pool mechanism based on rows of
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PoolTable objects. Values that are pooled by this class, are mapped to an
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index on a bitarray, which is the one that is stored on the DB.
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The object that will be used in order to initialize this pool, must have
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two string attributes (available_map and reserved_map) and the size of the
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pool.
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Subclasses of PoolManager must implement value_to_index and index_to_value
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method's in order to denote how the value will be mapped to the index in
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the bitarray.
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Important!!: Updates on a PoolManager object are not reflected to the DB,
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until save() method is called.
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"""
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def __init__(self, pool_table): |
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self.pool_table = pool_table
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self.pool_size = pool_table.size
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if pool_table.available_map:
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self.available = _bitarray_from_string(pool_table.available_map)
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self.reserved = _bitarray_from_string(pool_table.reserved_map)
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else:
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self.available = self._create_empty_pool(self.pool_size) |
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self.reserved = self._create_empty_pool(self.pool_size) |
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self.add_padding(self.pool_size) |
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def _create_empty_pool(self, size): |
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ba = bitarray(size) |
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ba.setall(AVAILABLE) |
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return ba
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def add_padding(self, pool_size): |
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bits = find_padding(pool_size) |
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self.available.extend([UNAVAILABLE] * bits)
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self.reserved.extend([UNAVAILABLE] * bits)
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def cut_padding(self, pool_size): |
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bits = find_padding(pool_size) |
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self.available = self.available[:-bits] |
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self.reserved = self.reserved[:-bits] |
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@property
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def pool(self): |
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return (self.available & self.reserved) |
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def get(self, value=None): |
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"""Get a value from the pool."""
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if self.empty(): |
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raise EmptyPool
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if value is None: |
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# Get the first available index
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index = int(self.pool.index(AVAILABLE)) |
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assert(index < self.pool_size) |
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self._reserve(index)
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return self.index_to_value(index) |
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else:
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if not self.contains(value): |
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raise InvalidValue("Value %s does not belong to pool." % value) |
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if self.is_available(value): |
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self.reserve(value)
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return value
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else:
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raise ValueNotAvailable("Value %s is not available" % value) |
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def put(self, value, external=False): |
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"""Return a value to the pool."""
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if value is None: |
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raise ValueError |
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index = self.value_to_index(value)
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self._release(index, external)
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def reserve(self, value, external=False): |
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"""Reserve a value."""
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index = self.value_to_index(value)
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self._reserve(index, external)
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return True |
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def save(self, db=True): |
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"""Save changes to the DB."""
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self.pool_table.available_map = _bitarray_to_string(self.available) |
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self.pool_table.reserved_map = _bitarray_to_string(self.reserved) |
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if db:
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self.pool_table.save()
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def empty(self): |
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"""Return True when pool is empty."""
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return not self.pool.any() |
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def size(self): |
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"""Return the size of the bitarray(original size + padding)."""
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return self.pool.length() |
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def _reserve(self, index, external=False): |
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if external:
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self.reserved[index] = UNAVAILABLE
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else:
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self.available[index] = UNAVAILABLE
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def _release(self, index, external=False): |
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if external:
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self.reserved[index] = AVAILABLE
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else:
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self.available[index] = AVAILABLE
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def contains(self, value): |
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index = self.value_to_index(value)
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return index >= 0 and index < self.pool_size |
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def count_available(self): |
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return self.pool.count(AVAILABLE) |
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def count_unavailable(self): |
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return self.pool_size - self.count_available() |
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def count_reserved(self): |
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return self.reserved[:self.pool_size].count(UNAVAILABLE) |
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def count_unreserved(self): |
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return self.pool_size - self.count_reserved() |
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def is_available(self, value, index=False): |
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if not index: |
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idx = self.value_to_index(value)
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else:
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idx = value |
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return self.pool[idx] == AVAILABLE |
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def is_reserved(self, value, index=False): |
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if not index: |
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idx = self.value_to_index(value)
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else:
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idx = value |
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return self.reserved[idx] == UNAVAILABLE |
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def to_01(self): |
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return self.pool[:self.pool_size].to01() |
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def to_map(self): |
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return self.to_01().replace("0", "X").replace("1", ".") |
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def extend(self, bits_num): |
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assert(bits_num >= 0) |
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self.resize(bits_num)
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def shrink(self, bits_num): |
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assert(bits_num >= 0) |
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size = self.pool_size
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tmp = self.available[(size - bits_num): size]
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if tmp.count(UNAVAILABLE):
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raise Exception("Can not shrink. In use") |
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self.resize(-bits_num)
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def resize(self, bits_num): |
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if bits_num == 0: |
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return
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# Cut old padding
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self.cut_padding(self.pool_size) |
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# Do the resize
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if bits_num > 0: |
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self.available.extend([AVAILABLE] * bits_num)
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self.reserved.extend([AVAILABLE] * bits_num)
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else:
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self.available = self.available[:bits_num] |
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self.reserved = self.reserved[:bits_num] |
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# Add new padding
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self.pool_size = self.pool_size + bits_num |
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self.add_padding(self.pool_size) |
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self.pool_table.size = self.pool_size |
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def index_to_value(self, index): |
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raise NotImplementedError |
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def value_to_index(self, value): |
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raise NotImplementedError |
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def __repr__(self): |
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return repr(self.pool_table) |
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class EmptyPool(Exception): |
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pass
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class ValueNotAvailable(Exception): |
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pass
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class InvalidValue(Exception): |
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pass
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def find_padding(size): |
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extra = size % 8
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return extra and (8 - extra) or 0 |
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def bitarray_to_01(bitarray_): |
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return bitarray_.to01()
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def bitarray_to_map(bitarray_): |
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return bitarray_to_01(bitarray_).replace("0", "X").replace("1", ".") |
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def _bitarray_from_string(bitarray_): |
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ba = bitarray() |
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ba.frombytes(b64decode(bitarray_)) |
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return ba
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def _bitarray_to_string(bitarray_): |
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return b64encode(bitarray_.tobytes())
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##
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## Custom pools
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##
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class BridgePool(PoolManager): |
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def index_to_value(self, index): |
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# Bridge indexes should start from 1
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return self.pool_table.base + str(index + 1) |
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def value_to_index(self, value): |
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return int(value.replace(self.pool_table.base, "")) - 1 |
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class MacPrefixPool(PoolManager): |
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def __init__(self, pool_table): |
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do_init = False if pool_table.available_map else True |
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super(MacPrefixPool, self).__init__(pool_table) |
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if do_init:
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for i in xrange(1, self.pool_size): |
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if not self.validate_mac(self.index_to_value(i)): |
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self._reserve(i, external=True) |
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# Reserve the first mac-prefix for public-networks
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self._reserve(0, external=True) |
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def index_to_value(self, index): |
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"""Convert index to mac_prefix"""
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base = self.pool_table.base
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a = hex(int(base.replace(":", ""), 16) + index).replace("0x", '') |
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mac_prefix = ":".join([a[x:x + 2] for x in xrange(0, len(a), 2)]) |
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return mac_prefix
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def value_to_index(self, value): |
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base = self.pool_table.base
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return int(value.replace(":", ""), 16) - int(base.replace(":", ""), 16) |
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@staticmethod
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def validate_mac(value): |
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hex_ = value.replace(":", "") |
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bin_ = bin(int(hex_, 16))[2:].zfill(8) |
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return bin_[6] == '1' and bin_[7] == '0' |
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class IPPool(PoolManager): |
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def __init__(self, pool_table): |
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do_init = False if pool_table.available_map else True |
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subnet = pool_table.subnet |
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self.net = ipaddr.IPNetwork(subnet.cidr)
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super(IPPool, self).__init__(pool_table) |
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if do_init:
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self._reserve(0, external=True) |
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if gateway:
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self.reserve(gateway, external=True) |
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self._reserve(self.pool_size - 1, external=True) |
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def value_to_index(self, value): |
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addr = ipaddr.IPAddress(value) |
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return int(addr) - int(self.net.network) |
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def index_to_value(self, index): |
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return str(self.net[index]) |
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def contains(self, address): |
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addr = ipaddr.IPAddress(address) |
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return addr in self.net |
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def return_start(self): |
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return str(ipaddr.IPAddress(self.base) + self.offset) |
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def return_end(self): |
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return str(ipaddr.IPAddress(self.base) + self.offset + self.size - 1) |