674 lines
20 KiB
Python
674 lines
20 KiB
Python
# standard imports
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import re
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import datetime
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# local imports
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from shep.error import (
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StateExists,
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StateInvalid,
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StateItemExists,
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StateItemNotFound,
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StateTransitionInvalid,
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StateCorruptionError,
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)
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re_name = r'^[a-zA-Z_\.]+$'
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class State:
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"""State is an in-memory bitmasked state store for key-value pairs, or even just keys alone.
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A State is comprised of a number of atomic state bits, and zero or more aliases that represent unique combinations of these bits.
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The State object will enforce that duplicate states cannot exist. It will also enforce that all alias states are composed of valid atomic states.
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:param bits: Number of atomic states that this State object will represent (i.e. number of bits).
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:type bits: int
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:param logger: Standard library logging instance to output to
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:type logger: logging.Logger
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"""
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base_state_name = 'NEW'
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def __init__(self, bits, logger=None, verifier=None, check_alias=True, event_callback=None, default_state=None):
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self.__initial_bits = bits
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self.__bits = bits
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self.__limit = (1 << bits) - 1
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self.__c = 0
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if default_state == None:
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default_state = self.base_state_name
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setattr(self, default_state, 0)
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self.__reverse = {0: getattr(self, default_state)}
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self.__keys = {getattr(self, default_state): []}
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self.__keys_reverse = {}
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if default_state != self.base_state_name:
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self.__keys_reverse[default_state] = 0
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self.__contents = {}
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self.modified_last = {}
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self.verifier = verifier
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self.check_alias = check_alias
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self.event_callback = event_callback
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@classmethod
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def set_default_state(cls, state_name):
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cls.base_state_name = state_name.upper()
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# return true if v is a single-bit state
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def is_pure(self, v):
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if v == 0:
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return True
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c = 1
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for i in range(self.__bits):
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if c & v > 0:
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break
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c <<= 1
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return c == v
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# validates a state name and return its canonical representation
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def __check_name_valid(self, k):
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if not re.match(re_name, k):
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raise ValueError('only alpha and underscore')
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return k.upper()
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# enforces name validity, aswell as name uniqueness
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def __check_name(self, k):
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k = self.__check_name_valid(k)
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try:
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getattr(self, k)
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raise StateExists(k)
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except AttributeError:
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pass
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return k
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# enforces state value validity and uniqueness
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def __check_valid(self, v):
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v = self.__check_value_typ(v)
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if self.__reverse.get(v):
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raise StateExists(v)
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return v
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# enforces state value within bit limit of instantiation
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def __check_limit(self, v, pure=True):
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if pure:
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if self.__initial_bits == 0:
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self.__bits += 1
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self.__limit = (1 << self.__bits) - 1
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if v > self.__limit:
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raise OverflowError(v)
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return v
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# enforces state value validity, uniqueness and value limit
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def __check_value(self, v):
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v = self.__check_valid(v)
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self.__check_limit(v)
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return v
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# enforces state value validity
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def __check_value_typ(self, v):
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return int(v)
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# enforces state value validity within the currently registered states (number of add calls vs number of bits in instantiation).
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def __check_value_cursor(self, v):
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v = self.__check_value_typ(v)
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if v > 1 << self.__c:
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raise StateInvalid(v)
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return v
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# set a bit for state of the given key
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def __set(self, k, v):
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setattr(self, k, v)
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self.__reverse[v] = k
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self.__c += 1
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# check validity of key to register state for
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def __check_key(self, item):
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if self.__keys_reverse.get(item) != None:
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raise StateItemExists(item)
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# adds a new key to the state store
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def __add_state_list(self, state, item):
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if self.__keys.get(state) == None:
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self.__keys[state] = []
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if not self.is_pure(state) or state == 0:
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self.__keys[state].append(item)
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c = 1
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for i in range(self.__bits):
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part = c & state
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if part > 0:
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if self.__keys.get(part) == None:
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self.__keys[part] = []
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self.__keys[part].append(item)
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c <<= 1
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self.__keys_reverse[item] = state
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if self.__reverse.get(state) == None and not self.check_alias:
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s = self.elements(state)
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self.__alias(s, state)
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def __state_list_index(self, item, state_list):
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"""Get index of a key for a given state.
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A key should only ever exist in one state.
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A failed lookup should indicate a mistake on the caller part, (it may also indicate corruption, but probanbly impossible to tell the difference)
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"""
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idx = -1
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try:
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idx = state_list.index(item)
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except ValueError:
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pass
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if idx == -1:
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raise StateCorruptionError() # should have state int here as value
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return idx
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def add(self, k):
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"""Add a state to the store.
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:param k: State name
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:type k: str
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:raises shep.error.StateExists: State name is already registered
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"""
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v = 1 << self.__c
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k = self.__check_name(k)
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v = self.__check_value(v)
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self.__set(k, v)
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def to_name(self, k):
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if k == None:
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k = 0
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return self.name(k)
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def __alias(self, k, *args):
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v = 0
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for a in args:
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a = self.__check_value_cursor(a)
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v = self.__check_limit(v | a, pure=False)
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if self.is_pure(v):
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raise ValueError('use add to add pure values')
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return self.__set(k, v)
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def alias(self, k, *args):
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"""Add an alias for a combination of states in the store.
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State aggregates may be provided as comma separated values or as a single (or'd) integer value.
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:param k: Alias name
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:type k: str
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:param *args: One or more states to aggregate for this alias.
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:type *args: int or list of ints
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:raises StateInvalid: Attempt to create alias for one or more atomic states that do not exist.
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:raises ValueError: Attempt to use bit value as alias
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"""
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k = self.__check_name(k)
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return self.__alias(k, *args)
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def all(self, pure=False, numeric=False):
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"""Return list of all unique atomic and alias state strings.
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:rtype: list of ints
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:return: states
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"""
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l = []
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for k in dir(self):
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state = None
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if k[0] == '_':
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continue
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if k.upper() != k:
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continue
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if pure:
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state = self.from_name(k)
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if not self.is_pure(state):
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continue
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if numeric:
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if state == None:
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state = self.from_name(k)
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l.append(state)
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else:
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l.append(k)
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l.sort()
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return l
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def elements(self, v, numeric=False, as_string=True):
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r = []
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if v == None or v == 0:
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return self.base_state_name
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c = 1
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for i in range(self.__bits):
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if v & c > 0:
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if numeric:
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r.append(c)
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else:
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r.append(self.name(c))
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c <<= 1
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if numeric or not as_string:
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return r
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return '_' + '.'.join(r)
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def from_elements(self, k):
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r = 0
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if k[0] != '_':
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raise ValueError('elements string must start with underscore (_), got {}'.format(k))
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for v in k[1:].split('.'):
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r |= self.from_name(v)
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return r
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def name(self, v):
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"""Retrieve that string representation of the state attribute represented by the given state integer value.
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:param v: State integer
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:type v: int
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:raises StateInvalid: State corresponding to given integer not found
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:rtype: str
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:return: State name
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"""
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k = self.__reverse.get(v)
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if k == None:
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if self.check_alias:
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raise StateInvalid(v)
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else:
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k = self.elements(v)
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elif v == None or v == 0:
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return self.base_state_name
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return k
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def from_name(self, k):
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"""Retrieve the real state integer value corresponding to an attribute name.
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:param k: Attribute name
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:type k: str
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:raises ValueError: Invalid attribute name
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:raises AttributeError: Attribute not found
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:rtype: int
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:return: Numeric state value
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"""
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k = self.__check_name_valid(k)
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return getattr(self, k)
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def match(self, v, pure=False):
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"""Match against all stored states.
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If pure is set, only match against the single atomic state will be returned.
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:param v: Integer state to match
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:type v: int
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:param pure: Match only pure states
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:type pure: bool
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:raises KeyError: Unknown state
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:rtype: tuple
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:return: 0: Alias that input resolves to, 1: list of atomic states that matches the state
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"""
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alias = None
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if not pure:
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alias = self.__reverse.get(v)
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r = []
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c = 1
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for i in range(self.__bits):
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if v & c > 0:
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try:
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k = self.__reverse[c]
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r.append(k)
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except KeyError:
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pass
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c <<= 1
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return (alias, r,)
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def put(self, key, state=None, contents=None):
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"""Add a key to an existing state.
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If no state it specified, the default state attribute State.base_state_name will be used.
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Contents may be supplied as value to pair with the given key. Contents may be changed later by calling the `replace` method.
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:param key: Content key to add
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:type key: str
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:param state: Initial state for the put. If not given, initial state will be State.base_state_name
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:type state: int
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:param contents: Contents to associate with key. A valie of None should be recognized as an undefined value as opposed to a zero-length value throughout any backend
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:type contents: str
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:raises StateItemExists: Content key has already been added
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:raises StateInvalid: Given state has not been registered
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:rtype: integer
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:return: Resulting state that key is put under (should match the input state)
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"""
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if state == None:
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state = getattr(self, self.base_state_name)
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elif self.__reverse.get(state) == None and self.check_alias:
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raise StateInvalid(state)
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self.__check_key(key)
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if self.event_callback != None:
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old_state = self.__keys_reverse.get(key)
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self.event_callback(key, None, self.name(state))
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self.__add_state_list(state, key)
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if contents != None:
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self.__contents[key] = contents
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self.register_modify(key)
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return state
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def move(self, key, to_state):
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"""Move a given content key from one state to another.
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:param key: Key to move
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:type key: str
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:param to_state: Numeric state to move to (may be atomic or alias)
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:type to_state: integer
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:raises StateItemNotFound: Given key has not been registered
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:raises StateInvalid: Given state has not been registered
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:rtype: integer
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:return: Resulting state from move (should match the state given as input)
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"""
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current_state = self.__keys_reverse.get(key)
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if current_state == None:
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raise StateItemNotFound(key)
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new_state = self.__reverse.get(to_state)
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if new_state == None and self.check_alias:
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raise StateInvalid(to_state)
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return self.__move(key, current_state, to_state)
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# implementation for state move that ensures integrity of keys and states.
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def __move(self, key, from_state, to_state):
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current_state_list = self.__keys.get(from_state)
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if current_state_list == None:
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raise StateCorruptionError(current_state)
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idx = self.__state_list_index(key, current_state_list)
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new_state_list = self.__keys.get(to_state)
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if current_state_list == None:
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raise StateCorruptionError(to_state)
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if self.verifier != None:
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r = self.verifier(self, from_state, to_state)
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if r != None:
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raise StateTransitionInvalid(r)
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current_state_list.pop(idx)
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if self.event_callback != None:
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old_state = self.__keys_reverse.get(key)
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self.event_callback(key, self.name(old_state), self.name(to_state))
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self.__add_state_list(to_state, key)
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self.register_modify(key)
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return to_state
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def set(self, key, or_state):
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"""Move to an alias state by setting a single bit.
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:param key: Content key to modify state for
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:type key: str
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:param or_state: Atomic stat to add
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:type or_state: int
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:raises ValueError: State is not a single bit state
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:raises StateItemNotFound: Content key is not registered
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:raises StateInvalid: Resulting state after addition of atomic state is unknown
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:rtype: int
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:returns: Resulting state
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"""
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if not self.is_pure(or_state):
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raise ValueError('can only apply using single bit states')
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current_state = self.__keys_reverse.get(key)
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if current_state == None:
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raise StateItemNotFound(key)
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to_state = current_state | or_state
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new_state = self.__reverse.get(to_state)
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if new_state == None and self.check_alias:
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raise StateInvalid('resulting to state is unknown: {}'.format(to_state))
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return self.__move(key, current_state, to_state)
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def unset(self, key, not_state, allow_base=False):
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"""Unset a single bit, moving to a pure or alias state.
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The resulting state cannot be State.base_state_name (0).
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:param key: Content key to modify state for
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:type key: str
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:param or_state: Atomic stat to add
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:type or_state: int
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:raises ValueError: State is not a single bit state, or attempts to revert to State.base_state_name
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:raises StateItemNotFound: Content key is not registered
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:raises StateInvalid: Resulting state after addition of atomic state is unknown
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:rtype: int
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:returns: Resulting state
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"""
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if not self.is_pure(not_state):
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raise ValueError('can only apply using single bit states')
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current_state = self.__keys_reverse.get(key)
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if current_state == None:
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raise StateItemNotFound(key)
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to_state = current_state & (~not_state)
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if to_state == current_state:
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raise ValueError('invalid change for state {}: {}'.format(key, not_state))
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if to_state == getattr(self, self.base_state_name) and not allow_base:
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raise ValueError('State {} for {} cannot be reverted to {}'.format(current_state, key, self.base_state_name))
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new_state = self.__reverse.get(to_state)
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if new_state == None:
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raise StateInvalid('resulting to state is unknown: {}'.format(to_state))
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return self.__move(key, current_state, to_state)
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def change(self, key, sets, unsets):
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current_state = self.__keys_reverse.get(key)
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if current_state == None:
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raise StateItemNotFound(key)
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to_state = current_state | sets
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to_state &= ~unsets & self.__limit
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if sets == 0:
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to_state = current_state & (~unsets)
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if to_state == current_state:
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raise ValueError('invalid change by unsets for state {}: {}'.format(key, unsets))
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if to_state == getattr(self, self.base_state_name):
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raise ValueError('State {} for {} cannot be reverted to {}'.format(current_state, key, self.base_state_name))
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new_state = self.__reverse.get(to_state)
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if new_state == None:
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raise StateInvalid('resulting to state is unknown: {}'.format(to_state))
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return self.__move(key, current_state, to_state)
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def state(self, key):
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"""Return the current numeric state for the given content key.
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:param key: Key to return content for
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:type key: str
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:raises StateItemNotFound: Content key is unknown
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:rtype: int
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:returns: State
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"""
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state = self.__keys_reverse.get(key)
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if state == None:
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raise StateItemNotFound(key)
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return state
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def get(self, key):
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"""Retrieve the content for a content key.
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:param key: Content key to retrieve content for
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:type key: str
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:rtype: any
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:returns: Content
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"""
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return self.__contents.get(key)
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def list(self, state):
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"""List all content keys matching a state.
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:param state: State to match
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:type state: int
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:rtype: list of str
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:returns: Matching content keys
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"""
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try:
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return self.__keys[state]
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except KeyError:
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return []
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def sync(self, state=None):
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"""Noop method for interface implementation providing sync to backend.
|
||
|
||
:param state: State to sync.
|
||
:type state:
|
||
:todo: (for higher level implementer) if sync state is none, sync all
|
||
"""
|
||
pass
|
||
|
||
|
||
def path(self, state, key=None):
|
||
"""In the memory-only class no persisted state is used, and this will return None.
|
||
|
||
See shep.persist.PersistedState.path for more information.
|
||
"""
|
||
return None
|
||
|
||
|
||
def peek(self, key):
|
||
"""Return the next pure state.
|
||
|
||
Will return the same result as the method next, but without advancing to the new state.
|
||
|
||
:param key: Content key to inspect state for
|
||
:type key: str
|
||
:raises StateItemNotFound: Unknown content key
|
||
:raises StateInvalid: Attempt to advance from an alias state, OR beyond the last known pure state.
|
||
:rtype: int
|
||
:returns: Next state
|
||
"""
|
||
state = self.__keys_reverse.get(key)
|
||
if state == None:
|
||
raise StateItemNotFound(key)
|
||
if not self.is_pure(state):
|
||
raise StateInvalid('cannot run next on an alias state')
|
||
|
||
if state == 0:
|
||
state = 1
|
||
else:
|
||
state <<= 1
|
||
if state > self.__limit:
|
||
raise StateInvalid('unknown state {}'.format(state))
|
||
|
||
return state
|
||
|
||
|
||
def next(self, key):
|
||
"""Advance to the next pure state.
|
||
|
||
:param key: Content key to inspect state for
|
||
:type key: str
|
||
:raises StateItemNotFound: Unknown content key
|
||
:raises StateInvalid: Attempt to advance from an alias state, OR beyond the last known pure state.
|
||
:rtype: int
|
||
:returns: Next state
|
||
"""
|
||
from_state = self.state(key)
|
||
new_state = self.peek(key)
|
||
return self.__move(key, from_state, new_state)
|
||
|
||
|
||
def replace(self, key, contents):
|
||
"""Replace contents associated by content key.
|
||
|
||
:param key: Content key to replace for
|
||
:type key: str
|
||
:param contents: New contents
|
||
:type contents: any
|
||
:raises KeyError: Unknown content key
|
||
"""
|
||
self.state(key)
|
||
self.__contents[key] = contents
|
||
|
||
|
||
def modified(self, key):
|
||
return self.modified_last[key]
|
||
|
||
|
||
def register_modify(self, key):
|
||
self.modified_last[key] = datetime.datetime.utcnow().timestamp()
|
||
|
||
|
||
def mask(self, key, states=0):
|
||
statemask = self.__limit + 1
|
||
statemask |= states
|
||
statemask = ~statemask
|
||
statemask &= self.__limit
|
||
return statemask
|
||
|
||
|
||
def purge(self, key):
|
||
state = self.state(key)
|
||
state_name = self.name(state)
|
||
|
||
v = self.__keys.get(state)
|
||
v.remove(key)
|
||
|
||
del self.__keys_reverse[key]
|
||
|
||
try:
|
||
del self.__contents[key]
|
||
except KeyError:
|
||
pass
|
||
|
||
try:
|
||
del self.modified_last[key]
|
||
except KeyError:
|
||
pass
|
||
|
||
|
||
def count(self):
|
||
return self.__c
|