Enum TransactionPrecondition 

pub enum TransactionPrecondition {
    CollectionVersion {
        collection: String,
        version: u64,
    },
    StateVersion {
        version: u64,
    },
    ApplicationRevision {
        revision_id: String,
    },
    CausalCursor {
        cursor: BTreeMap<String, u64>,
    },
    Record {
        collection: String,
        id: String,
        require_absent: bool,
        expected_version: Option<u64>,
        expected_version_token: Option<String>,
        expected_epoch: Option<u64>,
        expected_lease_id: Option<String>,
    },
}

Variants

CollectionVersion

Fields

collection: String

version: u64

StateVersion

Fields

version: u64

ApplicationRevision

Fields

revision_id: String

CausalCursor

Fields

cursor: BTreeMap<String, u64>

Record

What must be true of one record for the transaction to commit.

Distinct from every variant above, and evaluated in a different place for a reason: those compare counters that can be read before the commit lock is taken, while this one compares the fields a caller reads back — the document’s __version, its authority epoch, its lease — and must therefore be evaluated inside the same lock as the writes. Checking it against the pre-commit snapshot would be a client-side check wearing the authority’s name: between the read and the write, another writer commits.

It is also what makes putIfAbsent and updateIfVersion mean the same thing against a managed authority as against the file runtime. Mapping a caller’s expectedVersion onto if_version would not: that fences the row’s internal storage sequence, which is a different number that happens to share a name.

Fields

collection: String

id: String

require_absent: bool

expected_version: Option<u64>

expected_version_token: Option<String>

expected_version as a version token; see TransactionOperation::if_version_token.

expected_epoch: Option<u64>

expected_lease_id: Option<String>

Trait Implementations

impl Clone for TransactionPrecondition

fn clone(&self) -> TransactionPrecondition

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TransactionPrecondition

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for TransactionPrecondition

fn deserialize<__D>( __deserializer: __D, ) -> Result<TransactionPrecondition, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for TransactionPrecondition

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.