df-consul/src/with_index.rs

110 lines
2.7 KiB
Rust

use std::fmt::{Debug, Display, Write};
use anyhow::{bail, Result};
use log::*;
use reqwest::Response;
use serde::Deserialize;
use crate::Consul;
impl Consul {
pub(crate) async fn get_with_index<T: for<'de> Deserialize<'de>>(
&self,
mut url: String,
last_index: Option<usize>,
) -> Result<WithIndex<T>> {
if let Some(i) = last_index {
if url.contains('?') {
write!(&mut url, "&index={}", i).unwrap();
} else {
write!(&mut url, "?index={}", i).unwrap();
}
}
debug!("GET {} as {}", url, std::any::type_name::<T>());
let http = self.client.get(&url).send().await?;
Ok(WithIndex::<T>::index_from(&http)?.value(http.json().await?))
}
}
/// Wraps the returned value of an [API call with blocking
/// possibility](https://developer.hashicorp.com/consul/api-docs/features/blocking) with the
/// returned Consul index
pub struct WithIndex<T> {
pub(crate) value: T,
pub(crate) index: usize,
}
impl<T> WithIndex<T> {
/// (for internal use, mostly)
pub fn index_from(resp: &Response) -> Result<WithIndexBuilder<T>> {
let index = match resp.headers().get("X-Consul-Index") {
Some(v) => v.to_str()?.parse::<usize>()?,
None => bail!("X-Consul-Index header not found"),
};
Ok(WithIndexBuilder {
index,
_phantom: Default::default(),
})
}
/// Returns the inner value, discarding the index
pub fn into_inner(self) -> T {
self.value
}
/// Returns the Consul index, to be used in future calls to the same API endpoint to make them
/// blocking
pub fn index(&self) -> usize {
self.index
}
}
impl<T> std::convert::AsRef<T> for WithIndex<T> {
fn as_ref(&self) -> &T {
&self.value
}
}
impl<T> std::borrow::Borrow<T> for WithIndex<T> {
fn borrow(&self) -> &T {
&self.value
}
}
impl<T> std::ops::Deref for WithIndex<T> {
type Target = T;
fn deref(&self) -> &T {
&self.value
}
}
impl<T: Debug> Debug for WithIndex<T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
<T as Debug>::fmt(self, f)
}
}
impl<T: Display> Display for WithIndex<T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
<T as Display>::fmt(self, f)
}
}
/// (for internal use, mostly)
pub struct WithIndexBuilder<T> {
_phantom: std::marker::PhantomData<T>,
index: usize,
}
impl<T> WithIndexBuilder<T> {
/// (for internal use, mostly)
pub fn value(self, value: T) -> WithIndex<T> {
WithIndex {
value,
index: self.index,
}
}
}