ITrigger (apache-cassandra API)
Date: 2014-10-21

org.apache.cassandra.triggers

## Interface ITrigger

-     public interface ITrigger

  Trigger interface, For every Mutation received by the coordinator `augment(ByteBuffer, ColumnFamily)` is called.

  Contract:
  1) Implementation of this interface should only have a constructor without parameters
  2) ITrigger implementation can be instantiated multiple times during the server life time. (Depends on the number of times trigger folder is updated.)
  3) ITrigger implementation should be state-less (avoid dependency on instance variables).
  The API is still beta and can change.

- - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `java.util.Collection<Mutation>` | `augment(java.nio.ByteBuffer partitionKey, ColumnFamily update)` Called exactly once per CF update, returned mutations are atomically updated.

- - ### Method Detail

    - #### augment

          java.util.Collection<Mutation> augment(java.nio.ByteBuffer partitionKey,
                                               ColumnFamily update)

      Called exactly once per CF update, returned mutations are atomically updated.
      Parameters:
        `partitionKey` - - partition Key for the update.
        `update` - - update received for the CF
      Returns:
        modifications to be applied, null if no action to be performed.

Copyright © 2014 The Apache Software Foundation