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use std::{
cmp::PartialEq,
error::Error as StdError,
fmt::{self, Display},
io,
};
use super::*;
/// The top-level result type for dealing with
/// the `PageCache`.
pub type Result<T> = std::result::Result<T, Error>;
/// A compare and swap result. If the CAS is successful,
/// the new `PagePtr` will be returned as `Ok`. Otherwise,
/// the `Err` will contain a tuple of the current `PagePtr`
/// and the old value that could not be set atomically.
pub type CasResult<'a, P, R> =
std::result::Result<PagePtr<'a, P>, Option<(PagePtr<'a, P>, R)>>;
/// An Error type encapsulating various issues that may come up
/// in both the expected and unexpected operation of a `PageCache`.
#[derive(Debug)]
pub enum Error {
/// The underlying collection no longer exists.
CollectionNotFound(Vec<u8>),
/// The system has been used in an unsupported way.
Unsupported(String),
/// An unexpected bug has happened. Please open an issue on github!
ReportableBug(String),
/// A read or write error has happened when interacting with the file
/// system.
Io(io::Error),
/// Corruption has been detected in the storage file.
Corruption {
/// The file location that corrupted data was found at.
at: DiskPtr,
},
// a failpoint has been triggered for testing purposes
#[doc(hidden)]
#[cfg(feature = "failpoints")]
FailPoint,
}
impl Clone for Error {
fn clone(&self) -> Self {
use self::Error::*;
match self {
Io(ioe) => {
Io(std::io::Error::new(ioe.kind(), format!("{:?}", ioe)))
}
CollectionNotFound(name) => CollectionNotFound(name.clone()),
Unsupported(why) => Unsupported(why.clone()),
ReportableBug(what) => ReportableBug(what.clone()),
Corruption { at } => Corruption { at: *at },
#[cfg(feature = "failpoints")]
FailPoint => FailPoint,
}
}
}
impl Eq for Error {}
impl PartialEq for Error {
fn eq(&self, other: &Self) -> bool {
use self::Error::*;
match *self {
CollectionNotFound(ref l) => {
if let CollectionNotFound(ref r) = *other {
l == r
} else {
false
}
}
Unsupported(ref l) => {
if let Unsupported(ref r) = *other {
l == r
} else {
false
}
}
ReportableBug(ref l) => {
if let ReportableBug(ref r) = *other {
l == r
} else {
false
}
}
#[cfg(feature = "failpoints")]
FailPoint => {
if let FailPoint = *other {
true
} else {
false
}
}
Corruption { at: l } => {
if let Corruption { at: r } = *other {
l == r
} else {
false
}
}
Io(_) => false,
}
}
}
impl From<io::Error> for Error {
#[inline]
fn from(io_error: io::Error) -> Self {
Error::Io(io_error)
}
}
impl StdError for Error {
fn description(&self) -> &str {
use self::Error::*;
match *self {
CollectionNotFound(_) => "Collection does not exist.",
Unsupported(ref e) | ReportableBug(ref e) => &*e,
#[cfg(feature = "failpoints")]
FailPoint => "Fail point has been triggered.",
Io(ref e) => e.description(),
Corruption { .. } => "Read corrupted data.",
}
}
}
impl Display for Error {
fn fmt(
&self,
f: &mut fmt::Formatter<'_>,
) -> std::result::Result<(), fmt::Error> {
use self::Error::*;
match *self {
CollectionNotFound(ref name) => {
write!(f, "Collection {:?} does not exist", name,)
}
Unsupported(ref e) => write!(f, "Unsupported: {}", e),
ReportableBug(ref e) => write!(
f,
"Unexpected bug has happened: {}. \
PLEASE REPORT THIS BUG!",
e
),
#[cfg(feature = "failpoints")]
FailPoint => write!(f, "Fail point has been triggered."),
Io(ref e) => write!(f, "IO error: {}", e),
Corruption { at } => {
write!(f, "Read corrupted data at file offset {}", at)
}
}
}
}