quoracle\quorum_system.py

'''
Original code available at:  https://github.com/mwhittaker/quoracle/blob/main/quoracle/quorum_system.py#L541
'''

#...

def load(problem: pulp.LpProblem,
         read_fraction: Dict[float, float]) -> pulp.LpAffineExpression:
    return sum(p * fr_load(problem, fr)
               for (fr, p) in read_fraction.items())


def fr_load(problem: pulp.LpProblem, fr: float) -> pulp.LpAffineExpression:
    l = pulp.LpVariable(f'l_{fr}', 0, 1)

    for node in self.nodes():
        x = node.x
        x_load: pulp.LpAffineExpression = 0

        if x in x_to_read_quorum_vars:
            vs = x_to_read_quorum_vars[x]
            x_load += fr * sum(vs) / self.node(x).read_capacity

        if x in x_to_write_quorum_vars:
            vs = x_to_write_quorum_vars[x]
            x_load += (1 - fr) * sum(vs) / self.node(x).write_capacity

        problem += (x_load <= l, f'{x}{fr}')

    return l

# Form the linear program.
problem = pulp.LpProblem("optimal_strategy", pulp.LpMinimize)