CurrentTransaction (Oracle - Berkeley DB Java API)
Date: 2018-05-29

com.sleepycat.collections

## Class CurrentTransaction

- java.lang.Object
- - com.sleepycat.collections.CurrentTransaction

-     public class CurrentTransaction
      extends java.lang.Object

  Provides access to the current transaction for the current thread within the context of a Berkeley DB environment. This class provides explicit transaction control beyond that provided by the `TransactionRunner` class. However, both methods of transaction control manage per-thread transactions.

- - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Transaction` | `abortTransaction()` Aborts the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
    `Transaction` | `beginTransaction(TransactionConfig config)` Begins a new transaction for this environment and associates it with the current thread.
    `Transaction` | `commitTransaction()` Commits the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
    `Environment` | `getEnvironment()` Returns the underlying Berkeley DB environment.
    `static CurrentTransaction` | `getInstance(Environment env)` Gets the CurrentTransaction accessor for a specified Berkeley DB environment.
    `Transaction` | `getTransaction()` Returns the transaction associated with the current thread for this environment, or null if no transaction is active.

    - ### Methods inherited from class java.lang.Object

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

- - ### Method Detail

    - #### getInstance

          public static CurrentTransaction getInstance(Environment env)

      Gets the CurrentTransaction accessor for a specified Berkeley DB environment. This method always returns the same reference when called more than once with the same environment parameter.
      Parameters:
        `env` - is an open Berkeley DB environment.
      Returns:
        the CurrentTransaction accessor for the given environment, or null if the environment is not transactional.

    - #### getEnvironment

          public final Environment getEnvironment()

      Returns the underlying Berkeley DB environment.
      Returns:
        the Environment.

    - #### getTransaction

          public final Transaction getTransaction()

      Returns the transaction associated with the current thread for this environment, or null if no transaction is active.
      Returns:
        the Transaction.

    - #### beginTransaction

          public final Transaction beginTransaction(TransactionConfig config)
                                             throws DatabaseException

      Begins a new transaction for this environment and associates it with the current thread. If a transaction is already active for this environment and thread, a nested transaction will be created.
      Parameters:
        `config` - the transaction configuration used for calling `Environment.beginTransaction(com.sleepycat.db.Transaction, com.sleepycat.db.TransactionConfig)`, or null to use the default configuration.
      Returns:
        the new transaction.
      Throws:
        `DatabaseException` - if the transaction cannot be started, in which case any existing transaction is not affected.
        `java.lang.IllegalStateException` - if a transaction is already active and nested transactions are not supported by the environment.

    - #### commitTransaction

          public final Transaction commitTransaction()
                                              throws DatabaseException,
                                                     java.lang.IllegalStateException

      Commits the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
      Returns:
        the parent transaction or null if the committed transaction was not nested.
      Throws:
        `DatabaseException` - if an error occurs committing the transaction. The transaction will still be closed and the parent transaction will become the current transaction.
        `java.lang.IllegalStateException` - if no transaction is active for the current thread for this environment.

    - #### abortTransaction

          public final Transaction abortTransaction()
                                             throws DatabaseException,
                                                    java.lang.IllegalStateException

      Aborts the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
      Returns:
        the parent transaction or null if the aborted transaction was not nested.
      Throws:
        `DatabaseException` - if an error occurs aborting the transaction. The transaction will still be closed and the parent transaction will become the current transaction.
        `java.lang.IllegalStateException` - if no transaction is active for the current thread for this environment.

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