Enum Class Operation

java.lang.Object
java.lang.Enum<Operation>
org.hibernate.dialect.lock.spi.Operation
All Implemented Interfaces:
Serializable, Comparable<Operation>, Constable
public enum Operation extends Enum<Operation>

A kind of database operation on an existing row, used to ask a TransactionConcurrency descriptor about read guarantees and conflicts between transactions.

These values identify the operation performed, independently of the Hibernate or Jakarta Persistence lock mode that motivated it. They are not isolation levels or an ordering of lock strength. Two values may have the same behavior in a particular database configuration while remaining distinct operations.

In particular, CURRENT_READ identifies a strategy chosen for read freshness, while SHARED_LOCK_READ and UPDATE_LOCK_READ identify strategies chosen to acquire a particular kind of row lock. A current read may use one of those locks, but need not retain protection after the read completes. An ordinary READ may itself acquire locks or provide current-read semantics because of the configured isolation.

Consult TransactionConcurrency.supports(Operation) before asking about an operation, and use TransactionConcurrency.getReadGuarantees(Operation) and TransactionConcurrency.getBlockingDuration(Operation, Operation) for its resolved behavior. The operation name alone does not establish lock duration or compatibility with other operations.

Since:
8.0

  • Enum Constant Details

    • READ

      public static final Operation READ

      An ordinary read using the connection's configured isolation, without an explicit locking clause or current-read hint.

      This may read a snapshot, wait for uncommitted writes, or acquire row locks, depending on the resolved configuration. "Ordinary" does not imply that the database performs the read without locks.

    • CURRENT_READ

      public static final Operation CURRENT_READ

      A read using the dialect's explicit strategy for observing current committed row state. A conflicting uncommitted write must be resolved before the read succeeds, rather than bypassed by returning an older snapshot; the conflict may instead cause the read to fail.

      The strategy may use a specialized hint, a shared lock, or a lock for update. Its purpose is freshness at the read, not necessarily protection against changes after the read. Use the resolved ReadGuarantees to determine whether it also retains a lock or prevents modification until transaction completion.

      An ordinary read that already provides these freshness guarantees is still described by READ; this value describes the explicit strategy.

    • SHARED_LOCK_READ

      public static final Operation SHARED_LOCK_READ

      A read explicitly acquiring an actual shared row lock. Shared locks permit other shared-lock readers while excluding conflicting writes.

      This value describes the database lock actually acquired, not a request for LockMode.PESSIMISTIC_READ. If a dialect implements that request by acquiring a lock for update, the resulting operation is UPDATE_LOCK_READ. Such substitution does not establish support for this operation.

    • UPDATE_LOCK_READ

      public static final Operation UPDATE_LOCK_READ

      A read explicitly acquiring the dialect's row lock for subsequent update. The read reserves the row against competing operations seeking to update it, but does not itself modify the row.

      The database may implement this using an update lock or an exclusive lock. Compatibility with shared-lock readers and ordinary readers is database-specific and must be obtained from TransactionConcurrency. Unlike WRITE, this operation remains a read and has ReadGuarantees.

    • WRITE

      public static final Operation WRITE

      An operation that actually updates or deletes an existing row, rather than merely locking it for a possible later modification.

      Inserts and their effects on predicates or ranges are outside the scope of this contract. This operation participates in blocking questions but has no ReadGuarantees.

  • Method Details

    • values

      public static Operation[] values()
      Returns an array containing the constants of this enum class, in the order they are declared.
      Returns:
      an array containing the constants of this enum class, in the order they are declared

    • valueOf

      public static Operation valueOf(String name)
      Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)
      Parameters:
      name - the name of the enum constant to be returned.
      Returns:
      the enum constant with the specified name
      Throws:
      IllegalArgumentException - if this enum class has no constant with the specified name
      NullPointerException - if the argument is null