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/*-
*
* This file is part of Oracle NoSQL Database
* Copyright (C) 2011, 2016 Oracle and/or its affiliates. All rights reserved.
*
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*
* Oracle NoSQL Database server software is free software: you can
* redistribute it and/or modify it under the terms of the GNU Affero
* General Public License as published by the Free Software Foundation,
* version 3.
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* If you have received this file as part of Oracle NoSQL Database Client or
* distributed separately the following applies:
*
* Oracle NoSQL Database client software is free software: you can
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* as published by the Apache Software Foundation, version 2.0.
*
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* Database client or server distribution. If not, see
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*
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package oracle.kv;
import java.util.Set;
/**
* Thrown when write operations cannot be initiated because a quorum of
* Replicas as determined by the {@link 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 {@code
* ReplicaAckPolicy}. The {@code ReplicaAckPolicy} for the default durability
* policy (specified by {@link KVStoreConfig#getDurability}) is {@link
* Durability.ReplicaAckPolicy#SIMPLE_MAJORITY}. With {@code 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 {@link
* 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 {@link
* 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.
*
*
*/
public class DurabilityException extends FaultException {
private static final long serialVersionUID = 1L;
private final Durability.ReplicaAckPolicy ackPolicy;
private final int requiredNodeCount;
private final Set availableReplicas;
/**
* For internal use only.
* @hidden
*/
public DurabilityException(Throwable cause,
Durability.ReplicaAckPolicy ackPolicy,
int requiredNodeCount,
Set availableReplicas) {
super(cause, true /*isRemote*/);
this.ackPolicy = ackPolicy;
this.requiredNodeCount = requiredNodeCount;
this.availableReplicas = availableReplicas;
}
/**
* Returns the Replica ack policy that was in effect for the operation.
*/
public Durability.ReplicaAckPolicy getCommitPolicy() {
return ackPolicy;
}
/**
* Returns the number of nodes that were required to be active in order to
* satisfy the Replica ack policy associated with the operation.
*/
public int getRequiredNodeCount() {
return requiredNodeCount;
}
/**
* Returns the set of Replicas that were available at the time of the
* operation.
*/
public Set getAvailableReplicas() {
return availableReplicas;
}
}