EventHandler (Oracle - Berkeley DB Java API)
Date: 2010-04-12

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## com.sleepycat.db
Interface EventHandler

All Known Implementing Classes:
  EventHandlerAdapter

    public interface EventHandler

An interface classs with prototype definitions of all event functions that can be called via the Berkeley DB event callback mechanism.

A user can choose to implement the EventHandler class, and implement handlers for all of the event types. Alternatively it is possible to extend the EventHandlerAdapter class, and implement only those events relevant to the specific application.

The `EnvironmentConfig.setEventHandler` is used to provide a mechanism for reporting event messages from the Berkeley DB library to the application.

Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined.

Method Summary
`void` | `handlePanicEvent()` A callback function to be called when a panic event is sent from the Berkeley DB library.
`void` | `handleRepClientEvent()` A callback function to be called when a Replication Client event is sent from the Berkeley DB library.
`void` | `handleRepElectedEvent()` A callback function to be called when an event is sent from the Berkeley DB library.
`void` | `handleRepMasterEvent()` A callback function to be called when an event is sent from the Berkeley DB library.
`void` | `handleRepNewMasterEvent(int envId)` A callback function to be called when an event is sent from the Berkeley DB library.
`void` | `handleRepPermFailedEvent()` A callback function to be called when an event is sent from the Berkeley DB library.
`void` | `handleRepStartupDoneEvent()` A callback function to be called when an event is sent from the Berkeley DB library.
`void` | `handleWriteFailedEvent(int errorCode)` A callback function to be called when an event is sent from the Berkeley DB library.

Method Detail

### handlePanicEvent

    void handlePanicEvent()

  A callback function to be called when a panic event is sent from the Berkeley DB library.

  This event callback is received when an error occurs in the Berkeley DB library where the only solution is to shut down the application and run recovery. In such cases, the Berkeley DB methods will throw `RunRecoveryException` exceptions. It is often easier to simply exit the application when such errors occur, rather than gracefully return up the stack.

  When this callback is received the database environment has failed. All threads of control in the database environment should exit the environment and recovery should be run.

### handleRepClientEvent

    void handleRepClientEvent()

  A callback function to be called when a Replication Client event is sent from the Berkeley DB library.

  This event callback is received when this member of a replication group is now a client site.

### handleRepElectedEvent

    void handleRepElectedEvent()

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when this site has just won an election. An Application using the Base replication API should arrange for a call to the `Environment.startReplication` method after receiving this event to, reconfigure the local environment as a replication master.

  Replication Manager applications may safely igore this event. The Replication Manager calls `Environment.startReplication` automatically on behalf of the application when appropriate (resulting in firing of the `EventHandler.handleRepMasterEvent` event).

### handleRepMasterEvent

    void handleRepMasterEvent()

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when this site is now the master site of its replication group. It is the application's responsibility to begin acting as the master environment.

### handleRepNewMasterEvent

    void handleRepNewMasterEvent(int envId)

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when the replication group of which this site is a member has just established a new master; the local site is not the new master.

  Parameters:
    `envId` - The environment ID of the new master site.

### handleRepPermFailedEvent

    void handleRepPermFailedEvent()

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when the replication manager did not receive enough acknowledgements (based on the acknowledgement policy configured with `EnvironmentConfig.setReplicationManagerAckPolicy`) to ensure a transaction's durability within the replication group. The transaction will be flushed to the master's local disk storage for durability.

### handleRepStartupDoneEvent

    void handleRepStartupDoneEvent()

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when the client has completed startup synchronization and is now processing live log records received from the master.

### handleWriteFailedEvent

    void handleWriteFailedEvent(int errorCode)

  A callback function to be called when an event is sent from the Berkeley DB library.

  This event callback is received when a Berkeley DB write to stable storage failed.

  Parameters:
    `errorCode` - If an operating system specific error code is available for the failure it will be passed in the errorCode parameter.

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