Added some more skeleton around strategies.
This commit is contained in:
Michael Whittaker
parent
56992f1c8d
commit
efbeb8dc44
1 changed files with 94 additions and 19 deletions
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@ -1,5 +1,8 @@
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from typing import Iterator, Generic, List, Optional, Set, TypeVar
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from typing import (Dict, Iterator, Generic, List, Optional, Set, Tuple,
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TypeVar, Union)
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import itertools
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import numpy as np
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import pulp
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T = TypeVar('T')
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@ -139,15 +142,53 @@ def _or(lhs: Expr[T], rhs: Expr[T]) -> 'Or[T]':
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return Or([lhs, rhs])
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def choose(k: int, es: List[Expr[T]]) -> Choose[T]:
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return Choose(k, es)
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def choose(k: int, es: List[Expr[T]]) -> Expr[T]:
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if k == 1:
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return Or(es)
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elif k == len(es):
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return And(es)
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else:
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return Choose(k, es)
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def majority(es: List[Expr[T]]) -> Choose[T]:
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return Choose(len(es) // 2 + 1, es)
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def majority(es: List[Expr[T]]) -> Expr[T]:
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return choose(len(es) // 2 + 1, es)
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class QuorumSystem:
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Distribution = Union[int, float, Dict[float, float], List[Tuple[float, float]]]
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def _canonicalize_distribution(d: Distribution) -> Dict[float, float]:
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if isinstance(d, int):
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if d < 0 or d > 1:
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raise ValueError('distribution must be in the range [0, 1]')
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return {float(d): 1.}
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elif isinstance(d, float):
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if d < 0 or d > 1:
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raise ValueError('distribution must be in the range [0, 1]')
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return {d: 1.}
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elif isinstance(d, dict):
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if len(d) == 0:
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raise ValueError('distribution cannot empty')
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if any(weight < 0 for weight in d.values()):
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raise ValueError('distribution cannot have negative weights')
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total_weight = sum(d.values())
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if total_weight == 0:
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raise ValueError('distribution cannot have zero weight')
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return {float(f): weight / total_weight
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for (f, weight) in d.items()
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if weight > 0}
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elif isinstance(d, list):
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return _canonicalize_distribution({f: weight for (f, weight) in d})
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else:
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raise ValueError('distribution must be an int, a float, a Dict[float, '
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'float] or a List[Tuple[float, float]]')
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class QuorumSystem(Generic[T]):
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def __init__(self, reads: Optional[Expr[T]] = None,
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writes: Optional[Expr[T]] = None) -> None:
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if reads is not None and writes is not None:
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@ -170,17 +211,55 @@ class QuorumSystem:
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def __repr__(self) -> str:
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return f'QuorumSystem(reads={self.reads}, writes={self.writes})'
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def strategy(self, read_fraction: Distribution) -> 'Strategy[T]':
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# TODO(mwhittaker): Implement.
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reads = list(self.read_quorums())
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writes = list(self.write_quorums())
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return ExplicitStrategy(reads, [1 / len(reads)] * len(reads),
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writes, [1 / len(writes)] * len(writes))
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def is_read_quorum(self, xs: Set[T]) -> bool:
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return self.reads.is_quorum(xs)
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def read_quorums(self) -> Iterator[Set[T]]:
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return self.reads.quorums()
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def write_quorums(self) -> Iterator[Set[T]]:
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return self.writes.quorums()
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def is_read_quorum(self, xs: Set[T]) -> bool:
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return self.reads.is_quorum(xs)
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def is_write_quorum(self, xs: Set[T]) -> bool:
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return self.writes.is_quorum(xs)
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class Strategy(Generic[T]):
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def load(self, read_fraction: Distribution) -> int:
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raise NotImplementedError
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def get_read_quorum(self) -> Set[T]:
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raise NotImplementedError
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def get_write_quorum(self) -> Set[T]:
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raise NotImplementedError
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class ExplicitStrategy(Strategy[T]):
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def __init__(self,
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reads: List[Set[T]],
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read_weights: List[float],
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writes: List[Set[T]],
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write_weights: List[float]) -> None:
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self.reads = reads
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self.read_weights = read_weights
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self.writes = writes
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self.write_weights = write_weights
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# TODO(mwhittaker): Implement __str__ and __repr__.
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def load(self, read_fraction: Distribution) -> int:
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raise NotImplementedError
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def get_read_quorum(self) -> Set[T]:
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return np.random.choice(self.reads, p=self.read_weights)
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def get_write_quorum(self) -> Set[T]:
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return np.random.choice(self.writes, p=self.write_weights)
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a = Node('a')
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@ -188,18 +267,14 @@ b = Node('b')
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c = Node('c')
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d = Node('d')
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e = Node('e')
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f = Node('g')
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f = Node('f')
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g = Node('g')
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h = Node('h')
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i = Node('i')
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disjunction = a + b + c
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conjunction = disjunction * disjunction * disjunction
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print(conjunction)
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print(conjunction.dual())
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print(conjunction.dual().dual())
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print(QuorumSystem(reads=conjunction))
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grid = QuorumSystem(reads=a*b*c + d*e*f + g*h*i)
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sigma = grid.strategy(0.1)
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for _ in range(10):
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print(sigma.get_write_quorum())
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# - num_quorums
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# - has dups?
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