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use crate::api::{Key, Value};
use std::fmt;
use std::sync::atomic::{AtomicUsize, Ordering};
static ENCODER_ID_COUNTER: AtomicUsize = AtomicUsize::new(0);
pub trait Encoder: fmt::Debug {
fn encode(&self, labels: &mut dyn Iterator<Item = (&Key, &Value)>) -> String;
fn id(&self) -> EncoderId;
}
#[derive(Debug)]
pub struct EncoderId(usize);
impl EncoderId {
pub fn is_valid(&self) -> bool {
self.0 != 0
}
}
#[derive(Debug)]
pub struct DefaultLabelEncoder;
impl Encoder for DefaultLabelEncoder {
fn encode(&self, labels: &mut dyn Iterator<Item = (&Key, &Value)>) -> String {
labels
.enumerate()
.fold(String::new(), |mut acc, (idx, (key, value))| {
if idx > 0 {
acc.push_str(",")
}
acc.push_str(key.as_str());
acc.push_str("=");
acc.push_str(String::from(value).as_str());
acc
})
}
fn id(&self) -> EncoderId {
new_encoder_id()
}
}
pub fn default_encoder() -> Box<dyn Encoder + Send + Sync> {
Box::new(DefaultLabelEncoder)
}
pub fn new_encoder_id() -> EncoderId {
let old_encoder_id = ENCODER_ID_COUNTER.fetch_add(1, Ordering::AcqRel);
EncoderId(old_encoder_id + 1)
}