Struct persist::indexed::encoding::BlobMeta

pub struct BlobMeta {
    pub seqno: SeqNo,
    pub id_mapping: Vec<StreamRegistration>,
    pub graveyard: Vec<StreamRegistration>,
    pub arrangements: Vec<ArrangementMeta>,
}

The structure serialized and stored as a value in crate::storage::Blob storage for metadata keys.

Invariants:

• All strings in id_mapping are unique.
• All ids in id_mapping are unique.
• All strings in graveyard are unique.
• All ids in graveyard are unique.
• None of the strings in graveyard are present in any of the (string, id) tuples in id_mapping.
• None of the ids in graveyard are present in any of the (string, id) tuples in id_mapping.
• The same set of ids are present in id_mapping, unsealeds, and traces.
• For each id, the ts_lower in the unsealed is <= the ts_upper in the corresponding trace. (This is less than equals and not strictly equals because truncating the unnecessary elements out of unsealed is fallible, and is allowed to lag behind the migration of new data into trace)
• id_mapping.len() + graveyard.len() is == next_stream_id.
• All of the keys for trace and unsealed batches are unique across all persisted streams.

Fields

seqno: SeqNo

Which mutations are included in the represented state.

Persist is a state machine, with all mutating requests modeled as input state changes sequenced into a log. Periodically those state changes are applied and the resulting state is written out to blob storage. This field indicates which prefix of the log (0..=self.seqno) has been included in the state represented by this BlobMeta. SeqNo(0) represents the initial empty state, the first mutation is SeqNo(1).

Invariant: For each UnsealedMeta in unsealeds, this is >= the last batch’s upper. If they are not equal, there is logically an empty batch between [last batch’s upper, self.seqno).

id_mapping: Vec<StreamRegistration>

Internal stream id indexed by external stream name.

Invariant: Each stream name and stream id are in here at most once.

graveyard: Vec<StreamRegistration>

Set of deleted streams, indexed by external stream name.

arrangements: Vec<ArrangementMeta>

Arrangements indexed by stream id.

Invariant: Each stream id is in here at most once.

Implementations

impl BlobMeta

pub fn validate(&self) -> Result<(), Error>

Asserts Self’s documented invariants, returning an error if any are violated.

pub fn next_stream_id(&self) -> Id

The next Id to issue for a stream being added to id_mapping.

Trait Implementations

impl Clone for BlobMeta

fn clone(&self) -> BlobMeta

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for BlobMeta

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

Formats the value using the given formatter.

impl Default for BlobMeta

fn default() -> Self

Returns the “default value” for a type.

impl From<ProtoMeta> for BlobMeta

fn from(x: ProtoMeta) -> Self

Performs the conversion.

impl PartialEq<BlobMeta> for BlobMeta

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl Eq for BlobMeta

impl StructuralEq for BlobMeta

impl StructuralPartialEq for BlobMeta