Enum StorageError 

#[non_exhaustive]
pub enum StorageError {
    Open,
    Read,
    Write,
    Delete,
    Scan,
    Flush,
    Codec,
    Meta,
    Migrate,
    Path,
    Depth,
    CommitFailed,
    Taken,
    Closed,
    Notify,
    Reentrant,
}

What a store operation failed at.

Each variant names the operation that failed. Which engine said what is the frame below this one in the report, and the particulars - which path, which file, which prefix - are attachments put there by whoever knew them. Two engines failing to write are the same kind of failure, told apart by the frames underneath.

non_exhaustive where the sets that carry it are not: this one is the disk’s own list and grows with the engines, and nobody is meant to match it arm by arm. The sets are the opposite - a match over one is meant to be complete, and gaining a way to fail is meant to break it.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Open

Opening or creating the store.

Read

Reading a value.

Write

Writing a value.

Delete

Removing a key or a subtree.

Scan

Listing what is under a prefix.

Flush

Getting what is buffered onto disk.

Codec

Turning a value into the store’s format, or reading it back.

Meta

Reading or writing the schema bookkeeping - versions, snapshots, the migration log, the initialization markers.

Migrate

Bringing stored data up to the schema the code declares.

Path

A name that cannot be a level, so nothing can be stored under it.

Depth

A path or a value that nests deeper than this store reads back.

Told apart from StorageError::Path because the names are all fine: what is wrong is how many of them there are, and the facts say which budget ran out and by how much.

CommitFailed

The flush this commit was waiting on did not complete.

Taken

Two owners want the same place, so one would write over the other.

Closed

The store was closed and has let go of its file.

A close hands the file to whoever asked for it - another process, a backup, a rename - and it stays theirs, so every later read, write, scan and delete answers with this.

Notify

The change was stored, and somebody subscribed to it could not take it.

The write landed: this is about what happened while telling people. A field that cannot read back what was just written to its path answers with this, which is how the writer finds out that what it stored is not what that field holds.

Reentrant

Asked for from inside something the store is already doing, where doing it would mean waiting for the caller to finish.

Closing from on_persist_failure is the one that reaches here: that callback runs on the thread a close has to wait for.

Trait Implementations

impl Clone for StorageError

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for StorageError

impl Debug for StorageError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for StorageError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for StorageError

impl Error for StorageError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for StorageError

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StorageError