Class RDBMSConsistentReadTransaction

java.lang.Object

com.kingsrook.qqq.backend.core.actions.QBackendTransaction

com.kingsrook.qqq.backend.module.rdbms.actions.RDBMSTransaction

com.kingsrook.qqq.backend.module.rdbms.actions.RDBMSConsistentReadTransaction

All Implemented Interfaces:

AutoCloseable

public class RDBMSConsistentReadTransaction
extends RDBMSTransaction

RDBMS transaction opened by RDBMSBackendModule.openConsistentReadTransaction: a (read-only, by default) transaction on one connection, started such that every table read through it sees one snapshot. Pass it as the transaction on query, count, etc. inputs. The connection's isolation level and read-only flag are put back when this transaction is closed (as the connection may come from a pool). Closing without commit rolls back - which, for a read-only transaction, is the same thing, and releases the snapshot.

Constructor Summary

Constructors

Constructor	Description
RDBMSConsistentReadTransaction(Connection connection, RDBMSActionStrategyInterface strategy, ConsistentReadInput input)	Constructor - takes the snapshot (using the strategy for the database vendor), or closes the connection and throws if that fails.

Method Summary

Modifier and Type	Method	Description
void	close()	Close any resources associated with the transaction.
ConsistencyGuarantee	getConsistencyGuarantee()	What a transaction from openConsistentReadTransaction guarantees.
Optional<String>	getExportedSnapshotId()	For a transaction from openConsistentReadTransaction, the id of a snapshot that other transactions can attach to (via ConsistentReadInput .importSnapshotId) - for backends that support sharing one (e.g., postgres).

Methods inherited from class com.kingsrook.qqq.backend.module.rdbms.actions.RDBMSTransaction

commit, getConnection, rollback

Methods inherited from class com.kingsrook.qqq.backend.core.actions.QBackendTransaction

addAfterCommitCallback, discardAfterCommitCallbacks, openConsistentReadFor, openFor, runAfterCommitCallbacks

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

RDBMSConsistentReadTransaction

public RDBMSConsistentReadTransaction(Connection connection,
 RDBMSActionStrategyInterface strategy,
 ConsistentReadInput input)
                               throws SQLException

Constructor - takes the snapshot (using the strategy for the database vendor), or closes the connection and throws if that fails.

Throws:

SQLException

Method Details

getExportedSnapshotId

public Optional<String> getExportedSnapshotId()

Description copied from class: QBackendTransaction

For a transaction from openConsistentReadTransaction, the id of a snapshot that other transactions can attach to (via ConsistentReadInput .importSnapshotId) - for backends that support sharing one (e.g., postgres). Empty otherwise.

Overrides:

getExportedSnapshotId in class QBackendTransaction

getConsistencyGuarantee

public ConsistencyGuarantee getConsistencyGuarantee()

Description copied from class: QBackendTransaction

What a transaction from openConsistentReadTransaction guarantees. Callers should record this, rather than assume ONE_INSTANT.

Overrides:

getConsistencyGuarantee in class QBackendTransaction

close

public void close()

Description copied from class: QBackendTransaction

Close any resources associated with the transaction. In theory, should only be called after a commit or rollback was done.

Specified by:

close in interface AutoCloseable

Overrides:

close in class RDBMSTransaction