oracle.kv
Class DurabilityException

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              oracle.kv.FaultException
                  oracle.kv.DurabilityException

All Implemented Interfaces:

Serializable

public class DurabilityException
extends FaultException

Thrown when write operations cannot be initiated because a quorum of Replicas as determined by the Durability.ReplicaAckPolicy was not available.

The likelihood of this exception being thrown depends on the number of nodes per replication group, the rate of node failures and how quickly a failed node is restored to operation, and the specified ReplicaAckPolicy. The ReplicaAckPolicy for the default durability policy (specified by KVStoreConfig.getDurability()) is Durability.ReplicaAckPolicy.SIMPLE_MAJORITY. With SIMPLE_MAJORITY, this exception is thrown only when the majority of nodes in a replication group are unavailable, and in a well-maintained KVStore system with at least three nodes per replication group this exception should rarely be thrown.

If the client overrides the default and specifies Durability.ReplicaAckPolicy.ALL, then this exception will be thrown when any node in a replication group is unavailable; in other words, it is much more likely to be thrown. If the client specifies Durability.ReplicaAckPolicy.NONE, then this exception will never be thrown.

When this exception is thrown the KVStore service will perform administrative notifications so that actions can be taken to correct the problem. Depending on the nature of the application, the client may wish to

• retry the write operation immediately,
• fall back to a read-only mode and resume write operations at a later time, or
• give up and report an error at a higher level.

See Also:

Serialized Form

Method Summary

Set<String>	getAvailableReplicas() Returns the set of Replicas that were available at the time of the operation.
Durability.ReplicaAckPolicy	getCommitPolicy() Returns the Replica ack policy that was in effect for the operation.
int	getRequiredNodeCount() Returns the number of nodes that were required to be active in order to satisfy the Replica ack policy associated with the operation.

Methods inherited from class oracle.kv.FaultException

getFaultClassName, getRemoteStackTrace, toString, wasLoggedRemotely

Methods inherited from class java.lang.Throwable

fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace

Methods inherited from class java.lang.Object

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

Method Detail

getCommitPolicy

public Durability.ReplicaAckPolicy getCommitPolicy()

Returns the Replica ack policy that was in effect for the operation.

getRequiredNodeCount

public int getRequiredNodeCount()

Returns the number of nodes that were required to be active in order to satisfy the Replica ack policy associated with the operation.

getAvailableReplicas

public Set<String> getAvailableReplicas()

Returns the set of Replicas that were available at the time of the operation.