Improve javadoc around trigger execution Patch by Sam Tunnicliffe; reviewed by brandonwilliams for CASSANDRA-9334
Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/116de2be Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/116de2be Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/116de2be Branch: refs/heads/cassandra-2.1 Commit: 116de2bee5920bc6842300a3f686d88f443b281d Parents: 59b8e17 Author: Sam Tunnicliffe <s...@beobal.com> Authored: Tue May 12 11:49:03 2015 +0100 Committer: Sam Tunnicliffe <s...@beobal.com> Committed: Tue May 19 11:59:44 2015 +0100 ---------------------------------------------------------------------- .../org/apache/cassandra/triggers/ITrigger.java | 4 +-- .../cassandra/triggers/TriggerExecutor.java | 32 ++++++++++++++++++++ 2 files changed, 34 insertions(+), 2 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/cassandra/blob/116de2be/src/java/org/apache/cassandra/triggers/ITrigger.java ---------------------------------------------------------------------- diff --git a/src/java/org/apache/cassandra/triggers/ITrigger.java b/src/java/org/apache/cassandra/triggers/ITrigger.java index 4701b61..21aba05 100644 --- a/src/java/org/apache/cassandra/triggers/ITrigger.java +++ b/src/java/org/apache/cassandra/triggers/ITrigger.java @@ -36,7 +36,7 @@ import org.apache.cassandra.db.Mutation; * 2) ITrigger implementation can be instantiated multiple times during the server life time. * (Depends on the number of times trigger folder is updated.)<br> * 3) ITrigger implementation should be state-less (avoid dependency on instance variables).<br> - * + * * <br><b>The API is still beta and can change.</b> */ public interface ITrigger @@ -46,7 +46,7 @@ public interface ITrigger * * @param partitionKey - partition Key for the update. * @param update - update received for the CF - * @return modifications to be applied, null if no action to be performed. + * @return additional modifications to be applied along with the supplied update */ public Collection<Mutation> augment(ByteBuffer partitionKey, ColumnFamily update); } http://git-wip-us.apache.org/repos/asf/cassandra/blob/116de2be/src/java/org/apache/cassandra/triggers/TriggerExecutor.java ---------------------------------------------------------------------- diff --git a/src/java/org/apache/cassandra/triggers/TriggerExecutor.java b/src/java/org/apache/cassandra/triggers/TriggerExecutor.java index 677daad..bc6f46c 100644 --- a/src/java/org/apache/cassandra/triggers/TriggerExecutor.java +++ b/src/java/org/apache/cassandra/triggers/TriggerExecutor.java @@ -60,6 +60,23 @@ public class TriggerExecutor cachedTriggers.clear(); } + /** + * Augment a partition update by executing triggers to generate an intermediate + * set of mutations, then merging the ColumnFamily from each mutation with those + * supplied. This is called from @{link org.apache.cassandra.service.StorageProxy#cas} + * which is scoped for a single partition. For that reason, any mutations generated + * by triggers are checked to ensure that they are for the same table and partition + * key as the primary update; if not, InvalidRequestException is thrown. If no + * additional mutations are generated, the original updates are returned unmodified. + * + * @param key partition key for the update + * @param updates partition update to be applied, contains the merge of the original + * update and any generated mutations + * @return the final update to be applied, the original update merged with any + * additional mutations generated by configured triggers + * @throws InvalidRequestException if any mutation generated by a trigger does not + * apply to the exact same partition as the initial update + */ public ColumnFamily execute(ByteBuffer key, ColumnFamily updates) throws InvalidRequestException { List<Mutation> intermediate = executeInternal(key, updates); @@ -78,6 +95,21 @@ public class TriggerExecutor return updates; } + /** + * Takes a collection of mutations and possibly augments it by adding extra mutations + * generated by configured triggers. If no additional mutations are created + * this returns null, signalling to the caller that only the initial set of + * mutations should be applied. If additional mutations <i>are</i> generated, + * the total set (i.e. the original plus the additional mutations) are applied + * together in a logged batch. Should this not be possible because the initial + * mutations contain counter updates, InvalidRequestException is thrown. + * + * @param mutations initial collection of mutations + * @return augmented mutations. Either the union of the initial and additional + * mutations or null if no additional mutations were generated + * @throws InvalidRequestException if additional mutations were generated, but + * the initial mutations contains counter updates + */ public Collection<Mutation> execute(Collection<? extends IMutation> mutations) throws InvalidRequestException { boolean hasCounters = false;