Struct TransactionManager 

pub struct TransactionManager { /* private fields */ }

Manages transactions and MVCC versioning.

Implementations

impl TransactionManager

pub fn new() -> Self

Creates a new transaction manager.

pub fn begin(&self) -> TxId

Begins a new transaction.

pub fn record_write( &self, tx_id: TxId, entity: impl Into<EntityId>, ) -> Result<()>

Records a write operation for the transaction.

Errors

Returns an error if the transaction is not active.

pub fn record_read( &self, tx_id: TxId, entity: impl Into<EntityId>, ) -> Result<()>

Records a read operation for the transaction (for serializable isolation).

Errors

Returns an error if the transaction is not active.

pub fn commit(&self, tx_id: TxId) -> Result<EpochId>

Commits a transaction with conflict detection.

Errors

Returns an error if:

• The transaction is not active
• There’s a write-write conflict with another committed transaction

pub fn abort(&self, tx_id: TxId) -> Result<()>

Aborts a transaction.

Errors

Returns an error if the transaction is not active.

pub fn get_write_set(&self, tx_id: TxId) -> Result<HashSet<EntityId>>

Returns the write set of a transaction.

This returns a copy of the entities written by this transaction, used for rollback to discard uncommitted versions.

pub fn abort_all_active(&self)

Aborts all active transactions.

Used during database shutdown.

pub fn state(&self, tx_id: TxId) -> Option<TxState>

Returns the state of a transaction.

pub fn start_epoch(&self, tx_id: TxId) -> Option<EpochId>

Returns the start epoch of a transaction.

pub fn current_epoch(&self) -> EpochId

Returns the current epoch.

pub fn min_active_epoch(&self) -> EpochId

Returns the minimum epoch that must be preserved for active transactions.

This is used for garbage collection - versions visible at this epoch must be preserved.

pub fn active_count(&self) -> usize

Returns the number of active transactions.

pub fn gc(&self) -> usize

Cleans up completed transactions that are no longer needed for conflict detection.

A committed transaction’s write set must be preserved until all transactions that started before its commit have completed. This ensures write-write conflict detection works correctly.

Returns the number of transactions cleaned up.

pub fn mark_committed(&self, tx_id: TxId, epoch: EpochId)

Marks a transaction as committed at a specific epoch.

Used during recovery to restore transaction state.

pub fn last_assigned_tx_id(&self) -> Option<TxId>

Returns the last assigned transaction ID.

Returns None if no transactions have been started yet.

Trait Implementations

impl Default for TransactionManager

fn default() -> Self

Returns the “default value” for a type.