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Description
Family::get_or_create forces to clone labels data for the lookup of a counter. Example:
#[derive(Clone, Eq, Hash, PartialEq, EncodeLabelSet)]
struct RequestLabels {
host: String,
api: String,
}
fn test() {
let family = Family::<RequestLabels, Counter>::default();
fn call(host: &str, api: &str, family: &Family<RequestLabels, Counter>) {
let labels = RequestLabels {
host: host.to_string(),
api: api.to_string(),
};
let counter = family.get_or_create(&labels);
counter.inc();
}
}I must create RequestLabels with cloning host and api values instead of getting counter by data references. The Family struct uses the std::collections::HashMap inside, which doesn't allow any other way to look up.
It would be great to have the ability to write something like this:
#[derive(Clone, Eq, Hash, PartialEq, EncodeLabelSet)]
struct RequestLabels {
host: String,
api: String,
}
struct RequestLabelsQ<'a> {
host: &'a str,
api: &'a str,
}
impl Equivalent<RequestLabels> for RequestLabelsQ<'_> {
fn equivalent(&self, key: &RequestLabels) -> bool {
self.host == key.host && self.api == key.api
}
}
fn test() {
let family = Family::<RequestLabels, Counter>::default();
fn call(host: &str, api: &str, family: &Family<RequestLabels, Counter>) {
let labels = RequestLabelsQ {
host, api,
};
let counter = family.get_or_create(&labels);
counter.inc();
}
}This will require using hashbrown instead of std::collections::HashMap (but actually std map is wrapper on hashbrown).
Equivalent
HashMap::get
Also, it will affect the definition of Family::get_or_create but the behavior should be the same.
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