use crate::resolver::{Mode, MultiQuery, Resolver, ResolverGroup};
use std::fmt;
use std::ops::Add;
pub trait Estimate {
fn estimate(&self, query: &MultiQuery) -> Estimation;
}
#[derive(Debug, Default)]
pub struct Estimation {
pub min_requests: usize,
pub max_requests: usize,
}
impl Add for Estimation {
type Output = Estimation;
fn add(self, rhs: Self) -> Self::Output {
Estimation {
min_requests: self.min_requests + rhs.min_requests,
max_requests: self.max_requests + rhs.max_requests,
}
}
}
impl fmt::Display for Estimation {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let str = format!("[min={}, max={}]", self.min_requests, self.max_requests);
f.write_str(&str)
}
}
impl Estimate for Resolver {
fn estimate(&self, query: &MultiQuery) -> Estimation {
let min_lookups = query.names.len() * query.record_types.len();
let max_lookups = query.names.len() * query.record_types.len() * (1 + self.opts.retries);
Estimation {
min_requests: min_lookups,
max_requests: max_lookups,
}
}
}
impl Estimate for ResolverGroup {
fn estimate(&self, query: &MultiQuery) -> Estimation {
match self.opts.mode {
Mode::Multi => self
.resolvers
.iter()
.take(self.opts.limit.unwrap_or(self.resolvers.len()))
.map(|x| x.estimate(query))
.fold(Default::default(), |acc, e| acc + e),
Mode::Uni => self.resolvers.first().map(|x| x.estimate(query)).unwrap_or_default(),
}
}
}