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error.rs
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error.rs
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//! HTTP error types
use std::error::Error as StdError;
use std::fmt::{self, Debug, Display};
use crate::StatusCode;
use std::convert::TryInto;
/// A specialized `Result` type for HTTP operations.
///
/// This type is broadly used across `http_types` for any operation which may
/// produce an error.
pub type Result<T> = std::result::Result<T, Error>;
/// The error type for HTTP operations.
pub struct Error {
error: anyhow::Error,
status: crate::StatusCode,
type_name: Option<&'static str>,
}
impl Error {
/// Create a new error object from any error type.
///
/// The error type must be threadsafe and 'static, so that the Error will be
/// as well. If the error type does not provide a backtrace, a backtrace will
/// be created here to ensure that a backtrace exists.
pub fn new<S, E>(status: S, error: E) -> Self
where
S: TryInto<StatusCode>,
S::Error: Debug,
E: Into<anyhow::Error>,
{
Self {
status: status
.try_into()
.expect("Could not convert into a valid `StatusCode`"),
error: error.into(),
type_name: Some(std::any::type_name::<E>()),
}
}
/// Create a new error object from static string.
pub fn from_str<S, M>(status: S, msg: M) -> Self
where
S: TryInto<StatusCode>,
S::Error: Debug,
M: Display + Debug + Send + Sync + 'static,
{
Self {
status: status
.try_into()
.expect("Could not convert into a valid `StatusCode`"),
error: anyhow::Error::msg(msg),
type_name: None,
}
}
/// Create a new error from a message.
pub(crate) fn new_adhoc<M>(message: M) -> Error
where
M: Display + Debug + Send + Sync + 'static,
{
Self::from_str(StatusCode::InternalServerError, message)
}
/// Get the status code associated with this error.
pub fn status(&self) -> StatusCode {
self.status
}
/// Set the status code associated with this error.
pub fn set_status<S>(&mut self, status: S)
where
S: TryInto<StatusCode>,
S::Error: Debug,
{
self.status = status
.try_into()
.expect("Could not convert into a valid `StatusCode`");
}
/// Get the backtrace for this Error.
///
/// Backtraces are only available on the nightly channel. Tracking issue:
/// [rust-lang/rust#53487][tracking].
///
/// In order for the backtrace to be meaningful, the environment variable
/// `RUST_LIB_BACKTRACE=1` must be defined. Backtraces are somewhat
/// expensive to capture in Rust, so we don't necessarily want to be
/// capturing them all over the place all the time.
///
/// [tracking]: https://github.com/rust-lang/rust/issues/53487
///
/// Note: This function can be called whether or not backtraces
/// are enabled and available. It will return a `None` variant if
/// compiled on a toolchain that does not support backtraces, or
/// if executed without backtraces enabled with
/// `RUST_LIB_BACKTRACE=1`.
#[cfg(backtrace)]
pub fn backtrace(&self) -> Option<&std::backtrace::Backtrace> {
let backtrace = self.error.backtrace();
if let std::backtrace::BacktraceStatus::Captured = backtrace.status() {
Some(backtrace)
} else {
None
}
}
#[cfg(not(backtrace))]
#[allow(missing_docs)]
pub fn backtrace(&self) -> Option<()> {
None
}
/// Attempt to downcast the error object to a concrete type.
pub fn downcast<E>(self) -> std::result::Result<E, Self>
where
E: Display + Debug + Send + Sync + 'static,
{
if self.error.downcast_ref::<E>().is_some() {
Ok(self.error.downcast().unwrap())
} else {
Err(self)
}
}
/// Downcast this error object by reference.
pub fn downcast_ref<E>(&self) -> Option<&E>
where
E: Display + Debug + Send + Sync + 'static,
{
self.error.downcast_ref::<E>()
}
/// Downcast this error object by mutable reference.
pub fn downcast_mut<E>(&mut self) -> Option<&mut E>
where
E: Display + Debug + Send + Sync + 'static,
{
self.error.downcast_mut::<E>()
}
/// Retrieves a reference to the type name of the error, if available.
pub fn type_name(&self) -> Option<&str> {
self.type_name.as_deref()
}
}
impl Display for Error {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
Display::fmt(&self.error, formatter)
}
}
impl Debug for Error {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
Debug::fmt(&self.error, formatter)
}
}
impl<E: Into<anyhow::Error>> From<E> for Error {
fn from(error: E) -> Self {
Self::new(StatusCode::InternalServerError, error)
}
}
impl AsRef<dyn StdError + Send + Sync> for Error {
fn as_ref(&self) -> &(dyn StdError + Send + Sync + 'static) {
self.error.as_ref()
}
}
impl AsRef<StatusCode> for Error {
fn as_ref(&self) -> &StatusCode {
&self.status
}
}
impl AsMut<StatusCode> for Error {
fn as_mut(&mut self) -> &mut StatusCode {
&mut self.status
}
}
impl AsRef<dyn StdError> for Error {
fn as_ref(&self) -> &(dyn StdError + 'static) {
self.error.as_ref()
}
}
impl From<Error> for Box<dyn StdError + Send + Sync + 'static> {
fn from(error: Error) -> Self {
error.error.into()
}
}
impl From<Error> for Box<dyn StdError + 'static> {
fn from(error: Error) -> Self {
Box::<dyn StdError + Send + Sync>::from(error.error)
}
}