Re: Review Request 57626: HIVE-16164: Provide mechanism for passing HMS notification ID between transactional and non-transactional listeners.

[Mohit Sabharwal <mo...@cloudera.com>]

> On March 30, 2017, 1:54 p.m., Mohit Sabharwal wrote:
> > metastore/src/java/org/apache/hadoop/hive/metastore/events/ListenerEvent.java
> > Lines 51-52 (patched)
> > <https://reviews.apache.org/r/57626/diff/6/?file=1677663#file1677663line51>
> >
> >     What's the point of have duplicate parameter map ? What is the use case ?
> >     
> >     If you need unmodifiable paramters, why can't you add a new method called getunmodifiableParameters() which simply return Collections.unmodifiableMap(parameters) ?
> >     
> >     Do you really need to call updateUnmodifiableParameters() everytime ? Looks like you're only updating 'parameters' variable, but then creating a new updateUnmodifiableParameters every time a new items is added. 
> >     
> >     As I said, you can simply add a new method called getunmodifiableParameters() which returns Collections.unmodifiableMap(parameters) without the need for this copy.
> 
> Sergio Pena wrote:
>     We want to avoid that an external listener gets a reference to the mutable map object and override any key/value already set by other listeners. Part of the contract on the ListenerEvent.putParameter() is that you cannot override an existing key/value. Because we don't control the external listeners, we prefered to return an inmutable map whenever getParameters() was called.
>     
>     Does it make sense?

That makes complete sense. But why do you need two explicit references to the same map stored as class members ? You could just have one reference called 'parameters' and add a getter (called, say, getunmodifiableParameters) that returns Collections.unmodifiableMap(parameters).


- Mohit


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On March 28, 2017, 3:17 p.m., Sergio Pena wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/57626/
> -----------------------------------------------------------
> 
> (Updated March 28, 2017, 3:17 p.m.)
> 
> 
> Review request for hive.
> 
> 
> Bugs: HIVE-16164
>     https://issues.apache.org/jira/browse/HIVE-16164
> 
> 
> Repository: hive-git
> 
> 
> Description
> -------
> 
> This fix updates the EnvironmentContext with a DB_NOTIFICATION_EVENT_ID property from withing the DbNotificationListener class. It then passes the EnvironmentContext from transactional listeners to non-transactional listeners so that the eventId is shared between them.
> 
> The patch provides the following changes:
> - DbNotificationListener       Changes to pass the EnvironmentContext from transactional to non-transactional listeners.
> - HiveAlterHandler             Changes to pass the EnvironmentContext from transactional to non-transactional listeners.
> - MetaStoreListenerNotifier    New helper class that wraps the notification call to the listeners.
> - TestObjectStore              Verifies that the addNotificationEvent() method saves the eventId on the NotificationEvent object.
> - TestDbNotificationListener   Verifies that any HMS call is passing the DB_NOTIFICATION_EVENT_ID to non-transactional listeners.
> 
> 
> Diffs
> -----
> 
>   hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/listener/DbNotificationListener.java ea6cb790bc03fc38be07a3be7be34aa9c5d293ba 
>   hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/listener/MetaStoreEventListenerConstants.java PRE-CREATION 
>   itests/hcatalog-unit/src/test/java/org/apache/hive/hcatalog/listener/TestDbNotificationListener.java 1cf47c36cb490ce0b17ffe312cd2e9fc4bb7cd9a 
>   metastore/src/java/org/apache/hadoop/hive/metastore/HiveAlterHandler.java 4ce6a659c94265d83abbaedb9c52d7e15bf8dde6 
>   metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 80b1e98b9efbf068f0cd32303499a3a9b5bbd67b 
>   metastore/src/java/org/apache/hadoop/hive/metastore/MetaStoreListenerNotifier.java PRE-CREATION 
>   metastore/src/java/org/apache/hadoop/hive/metastore/events/ListenerEvent.java 62aeb8cc343fc4aab72e76da890e36ac3a16b7bf 
>   metastore/src/test/org/apache/hadoop/hive/metastore/TestObjectStore.java 1f87eeb18f6edf7351b3c8da6a6826c08656e48c 
> 
> 
> Diff: https://reviews.apache.org/r/57626/diff/6/
> 
> 
> Testing
> -------
> 
> HiveQA showed only one test failure. it is fixed, and waiting for HiveQA to complete 100% tests.
> 
> 
> Thanks,
> 
> Sergio Pena
> 
>