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use crate::{Error, Result, StdError};
use std::any::TypeId;
pub trait Wrapper<T, E> {
fn wrap(self, msg: &str) -> Result<T>;
fn err_is<U>(&self) -> bool
where
U: StdError + 'static;
fn retry<F>(self, max: usize, f: F) -> Result<T, E>
where
F: Fn(usize) -> Result<T, E>;
fn retry_on<F>(self, max: usize, id: TypeId, f: F) -> Result<T, E>
where
F: Fn(usize) -> Result<T, E>;
}
impl<T, E> Wrapper<T, E> for Result<T, E>
where
E: StdError + Send + Sync + 'static,
{
fn wrap(self, msg: &str) -> Result<T> {
match self {
Err(err) => Error::wrap(err, msg),
Ok(val) => Ok(val),
}
}
fn err_is<U>(&self) -> bool
where
U: StdError + 'static,
{
match self {
Ok(_) => false,
Err(e) => (e as &(dyn StdError + 'static)).is::<U>(),
}
}
fn retry<F>(self, max: usize, f: F) -> Result<T, E>
where
F: Fn(usize) -> Result<T, E>,
{
let mut retries = 0;
let mut result = self;
while retries < max && result.is_err() {
retries += 1;
result = f(retries);
}
result
}
fn retry_on<F>(self, max: usize, id: TypeId, f: F) -> Result<T, E>
where
F: Fn(usize) -> Result<T, E>,
{
let mut retries = 0;
let mut result = self;
while retries < max
&& match result {
Ok(_) => false,
Err(_) => TypeId::of::<E>() == id,
}
{
retries += 1;
result = f(retries);
}
result
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::sync::Once;
static INIT: Once = Once::new();
pub fn initialize() {
INIT.call_once(|| {
std::env::set_var(crate::WITCHER_COLOR, "0");
std::env::set_var("RUST_BACKTRACE", "0");
});
}
fn retry() -> Result<()> {
do_external_thing().retry(3, |_| do_external_thing()).wrap("Failed while attacking beast")
}
fn retry_on_concreate_error_type_using_err_is() -> Result<()> {
let mut retries = 0;
let mut result = do_external_thing();
while retries < 3 && result.err_is::<std::io::Error>() {
retries += 1;
result = do_external_thing();
}
result.wrap(&format!("Failed while attacking beast: {}", retries))
}
fn retry_on_concreate_error_type() -> Result<()> {
do_external_thing().retry_on(3, TypeId::of::<std::io::Error>(), |_| do_external_thing()).wrap("Failed while attacking beast")
}
fn do_external_thing() -> std::io::Result<()> {
Err(std::io::Error::new(std::io::ErrorKind::Other, "Oh no, we missed!"))
}
#[test]
fn test_retry_on() {
initialize();
assert_eq!("Failed while attacking beast", retry().unwrap_err().to_string());
assert_eq!("Failed while attacking beast", retry_on_concreate_error_type().unwrap_err().to_string());
assert_eq!("Failed while attacking beast: 3", retry_on_concreate_error_type_using_err_is().unwrap_err().to_string());
}
}