Interface LockingSupport

@Incubating(since="7.1",
            group="dialect-locking")
@SPI({USE,IMPLEMENT,SUPPLY})
public interface LockingSupport

Cohesive Dialect profile for pessimistic-locking capabilities and operations.

A provider supplies one profile from Dialect.getLockingSupport() or a supported family-specific supply point such as AbstractSybaseDialect.getLockingSupport(). Its metadata and strategies must describe the same behavior: for example, a TABLE_HINT style must provide a table-hint renderer, and an already-rendered SQL rewriter must return UNSUPPORTED when the available structure cannot place those hints safely.

Hibernate may retain and reuse the profile and its returned components for the lifetime of the Dialect. Implementations should therefore be immutable or thread-safe and must not retain request-specific state. Per-translation target collection belongs to LockingClauseStrategy, not this profile.

Since:

8.0

See Also:

• Dialect.getLockingSupport()
• AbstractSybaseDialect.getLockingSupport()

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	LockingSupport.Metadata	Immutable description of the locking syntax and timeout capabilities of a Dialect.

Method Summary

Modifier and Type	Method	Description
ConnectionLockTimeoutStrategy	getConnectionLockTimeoutStrategy()	The strategy for applying lock timeouts through the JDBC connection, generally by executing a database command.
default FollowOnLockingPolicy	getFollowOnLockingPolicy()	The policy for deciding whether completed SQL requires follow-on locking.
LockingClauseRenderer	getLockingClauseRenderer()	The renderer for a complete statement-level locking clause.
default LockingSqlRewriter	getLockingSqlRewriter()	The strategy for applying locking to already-rendered native or legacy SQL.
LockingSupport.Metadata	getMetadata()	Immutable capability metadata consistent with this profile's renderers and strategies.
default TableLockHintRenderer	getTableLockHintRenderer()	The renderer for table-level locking hints.
default TransactionConcurrencyResolver	getTransactionConcurrencyResolver()	Resolves environment-specific concurrency facts without retaining or modifying a connection.
default String	renderCurrentReadClause(TransactionConcurrency concurrency)	Renders the clause, if any, which, appended to a simple single-table select, makes it a current read, as described for renderCurrentReadTableHint(String, TransactionConcurrency).
default String	renderCurrentReadTableHint(String tableExpression, TransactionConcurrency concurrency)	Renders the table hint, if any, which makes a simple single-table select a current read: a read which returns the latest committed state of the selected rows, waiting for the outcome of any concurrent uncommitted write to them, instead of returning state from a snapshot.

Method Details

getTransactionConcurrencyResolver

default TransactionConcurrencyResolver getTransactionConcurrencyResolver()

Resolves environment-specific concurrency facts without retaining or modifying a connection. The resolved descriptor belongs to JdbcEnvironment, not to this potentially shared dialect profile.

renderCurrentReadTableHint

@SPI({USE,IMPLEMENT})
default String renderCurrentReadTableHint(String tableExpression,
 TransactionConcurrency concurrency)

Renders the table hint, if any, which makes a simple single-table select a current read: a read which returns the latest committed state of the selected rows, waiting for the outcome of any concurrent uncommitted write to them, instead of returning state from a snapshot. A conflicting write may instead cause the read to fail. A successful current read does not itself guarantee that the state remains unchanged until transaction completion. Hibernate performs a current read for the version check it executes just before commit for an entity locked in LockMode.OPTIMISTIC mode.

The caller uses the resolved TransactionConcurrency to decide whether an ordinary Operation.READ already provides ReadGuarantees.isCurrentRead(). If so, the caller omits explicit current-read rendering. Otherwise, the caller must establish that Operation.CURRENT_READ is supported and provides that guarantee before invoking this method. This method renders the explicit strategy; it does not repeat that decision.

By default, a PessimisticLockStyle.TABLE_HINT profile renders its share-lock hint, and other profiles render nothing. A profile may override this to render a cheaper form which waits for the outcome of concurrent writes but retains no lock.

Parameters:

tableExpression - The table reference the hint will follow

concurrency - The resolved transaction concurrency descriptor

Returns:

The table hint, or an empty string if this profile uses no table hint

See Also:

• renderCurrentReadClause(TransactionConcurrency)
• TransactionConcurrency.getReadGuarantees(Operation)

renderCurrentReadClause

@SPI({USE,IMPLEMENT})
default String renderCurrentReadClause(TransactionConcurrency concurrency)

Renders the clause, if any, which, appended to a simple single-table select, makes it a current read, as described for renderCurrentReadTableHint(String, TransactionConcurrency).

The caller consults the resolved TransactionConcurrency and omits explicit current-read rendering when an ordinary Operation.READ is already current. Otherwise, the caller must establish that Operation.CURRENT_READ is supported and provides ReadGuarantees.isCurrentRead() before invoking this method.

By default, a PessimisticLockStyle.CLAUSE profile renders its share-lock clause, and other profiles render nothing. A profile may override this to render a cheaper form which waits for the outcome of concurrent writes but retains no lock.

Parameters:

concurrency - The resolved transaction concurrency descriptor

Returns:

The clause, or an empty string if this profile uses no locking clause

See Also:

• renderCurrentReadTableHint(String, TransactionConcurrency)
• TransactionConcurrency.getReadGuarantees(Operation)

getLockingClauseRenderer

@SPI(SUPPLY)
LockingClauseRenderer getLockingClauseRenderer()

The renderer for a complete statement-level locking clause. Return LockingClauseRenderer.NO_OP when this profile does not use one.

Since:

8.0

See Also:

• LockingClauseRenderer

getTableLockHintRenderer

@SPI(SUPPLY)
default TableLockHintRenderer getTableLockHintRenderer()

The renderer for table-level locking hints. The default reports that this profile does not use table hints.

Since:

8.0

See Also:

• TableLockHintRenderer

getLockingSqlRewriter

@SPI(SUPPLY)
default LockingSqlRewriter getLockingSqlRewriter()

The strategy for applying locking to already-rendered native or legacy SQL. The default derives safe placement from this profile's locking style.

Since:

8.0

See Also:

• LockingSqlRewriter

getFollowOnLockingPolicy

@SPI(SUPPLY)
default FollowOnLockingPolicy getFollowOnLockingPolicy()

The policy for deciding whether completed SQL requires follow-on locking. The default never requests it.

Since:

8.0

See Also:

• FollowOnLockingPolicy

getMetadata

@SPI(SUPPLY)
LockingSupport.Metadata getMetadata()

Immutable capability metadata consistent with this profile's renderers and strategies.

See Also:

• LockingSupport.Metadata

getConnectionLockTimeoutStrategy

@SPI(SUPPLY)
ConnectionLockTimeoutStrategy getConnectionLockTimeoutStrategy()

The strategy for applying lock timeouts through the JDBC connection, generally by executing a database command. Return ConnectionLockTimeoutStrategy.NONE when unsupported.

See Also:

• ConnectionLockTimeoutStrategy