Enum ProtocolStateError 

#[non_exhaustive]
pub enum ProtocolStateError {
    NotFound(String),
    Corrupted(String),
    StoreFailed(String),
    LoadFailed(String),
    DeleteFailed(String),
}

Failure of a protocol-state storage operation.

Deliberately defined here rather than reusing offline_protocol_mls::StorageError: the whole point of this trait is that install-scoped delivery state does not share a contract — or a crate — with cryptographic storage. Implementations map their platform errors onto these variants.

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.

NotFound(String)

The requested entry does not exist.

Ok(None) from ProtocolStateStorage::load is the preferred way to report absence; this variant exists for implementations whose platform API cannot express it any other way. The SDK reads the two identically — a load that fails with NotFound is absence, not a lost record — so an implementation that reports absence this way does not cause spurious message_failed settlements on restore.

Corrupted(String)

The entry exists but can never be decoded by the backing store.

This is the variant for a permanent loss the implementation detected itself — a truncated or tampered record, a framing header that does not parse, an entry over MAX_PROTOCOL_STATE_RECORD_TRANSFER_BYTES. The SDK reads it as exactly that: the record is dropped and, for categories the application holds message ids for, settled with a terminal message_failed (or a pending_state_lost diagnostic) so the id cannot hang forever.

Report it only when the record can never be read. Every other error variant means “this read failed”, which the SDK treats as recoverable: the record is left in place for a later launch and nothing is settled. Reporting a transient failure here would tell the application a message failed terminally and then deliver it on the next launch.

Returning Ok(None) for a record the implementation destroyed is accepted — the built-in providers did that before this variant carried meaning — but it costs the settlement: the SDK cannot distinguish it from a record that was never written, so the application is told nothing at all.

StoreFailed(String)

The entry could not be written.

LoadFailed(String)

The entry could not be read.

DeleteFailed(String)

The entry could not be removed.

Trait Implementations

impl Clone for ProtocolStateError

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProtocolStateError

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

Formats the value using the given formatter.

impl Display for ProtocolStateError

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

Formats the value using the given formatter.

impl Eq for ProtocolStateError

impl Error for ProtocolStateError

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 ProtocolStateError

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ProtocolStateError