kcas/
err.rs

1use crate::types::{Stage, ThreadId, WordNum};
2use displaydoc::Display;
3
4/// Any error which can occur during a k-CAS operation.
5#[derive(Debug, Display, Eq, PartialEq)]
6pub enum Error {
7    /// An unrecoverable error occurred and in-flight changes may not have been cleaned up: {0}
8    Fatal(FatalError),
9    /// The value at one of the target addresses was not equal to the expected value.
10    ValueWasNotExpectedValue,
11}
12
13impl From<FatalError> for Error {
14    fn from(fatal_error: FatalError) -> Self {
15        Error::Fatal(fatal_error)
16    }
17}
18
19/// An unrecoverable error.
20#[derive(Debug, Display, Eq, PartialEq)]
21pub enum FatalError {
22    /// Tried to deserialize a number as a stage, but it does not correlate to a valid stage: {0}
23    StageOutOfBounds(usize),
24
25    /// Stage changed from {original_stage} to {actual_stage}, which should not be possible.
26    IllegalStageChange {
27        original_stage: Stage,
28        actual_stage: Stage,
29    },
30
31    /// While helping a thread, that thread's stage changed to {0}, which should not be possible.
32    IllegalHelpeeStage(Stage),
33
34    /// The target address {target_address} at word number {word_num} was not a valid pointer
35    TargetAddressWasNotValidPointer {
36        word_num: WordNum,
37        target_address: usize,
38    },
39
40    /** The sequence number of the current KCAS operation was changed by a thread other than
41        the originating thread {originating_thread_id}, which should not be possible.
42    */
43    SequenceNumChangedByNonOriginatingThread { originating_thread_id: ThreadId },
44
45    /** While setting the target address {target_address} at word number {word_num} to the desired
46        value, a CAS failure indicated the current value at the address was not a claim marker, but
47        instead {actual_value}, which should not be possible.
48    */
49    TriedToSetValueWhichWasNotClaimMarker {
50        word_num: WordNum,
51        target_address: usize,
52        actual_value: usize,
53    },
54    /** The top {num_reserved_bits} bits of value {value} at target address {target_address} with
55        word number {word_num} were not expected. These bits are reserved for kcas internal thread
56        identifiers and should not be used for real information: the only allowed values are either
57        all 0s or all 1s.
58    */
59    TopBitsOfValueWereIllegal {
60        word_num: WordNum,
61        target_address: usize,
62        value: usize,
63        /// the most significant bits
64        num_reserved_bits: usize,
65    },
66    ///
67    SharedStateWasNotValidPointer,
68}
69
70impl From<StageOutOfBoundsError> for FatalError {
71    fn from(stage_out_of_bounds_error: StageOutOfBoundsError) -> Self {
72        FatalError::StageOutOfBounds(stage_out_of_bounds_error.0)
73    }
74}
75
76/// Attempted to convert a usize into a Stage but it was out of bounds: {0}
77#[derive(Debug, Display, Eq, PartialEq)]
78pub struct StageOutOfBoundsError(pub(crate) usize);
kcas/err.rs

kcas/
err.rs
