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https://issues.apache.org/jira/browse/HBASE-3260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12972328#action_12972328
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HBase Review Board commented on HBASE-3260:
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Message from: "Andrew Purtell" <[email protected]>

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Ship it!



src/main/java/org/apache/hadoop/hbase/coprocessor/BaseEndpointCoprocessor.java
<http://review.cloudera.org/r/1306/#comment6557>

    What are these arguments about?



src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorHost.java
<http://review.cloudera.org/r/1306/#comment6558>

    Should be a WARN?



src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorHost.java
<http://review.cloudera.org/r/1306/#comment6559>

    Should be a WARN?



src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorHost.java
<http://review.cloudera.org/r/1306/#comment6560>

    Since you are committing a change set in this area, Ryan suggested no need 
for AtomicBoolean here, could just be plain volatile boolean. I think that's 
right.


- Andrew





> Coprocessors: Lifecycle management
> ----------------------------------
>
>                 Key: HBASE-3260
>                 URL: https://issues.apache.org/jira/browse/HBASE-3260
>             Project: HBase
>          Issue Type: Sub-task
>            Reporter: Andrew Purtell
>             Fix For: 0.92.0
>
>         Attachments: statechart.png
>
>
> Considering extending CPs to the master, we have no equivalent to 
> pre/postOpen and pre/postClose as on the regionserver. We also should 
> consider how to resolve dependencies and initialization ordering if loading 
> coprocessors that depend on others. 
> OSGi (http://en.wikipedia.org/wiki/OSGi) has a lifecycle API and is familiar 
> to many Java programmers, so we propose to borrow its terminology and state 
> machine.
> A lifecycle layer manages coprocessors as they are dynamically installed, 
> started, stopped, updated and uninstalled. Coprocessors rely on the framework 
> for dependency resolution and class loading. In turn, the framework calls up 
> to lifecycle management methods in the coprocessor as needed.
> A coprocessor transitions between the below states over its lifetime:
> ||State||Description||
> |UNINSTALLED|The coprocessor implementation is not installed. This is the 
> default implicit state.|
> |INSTALLED|The coprocessor implementation has been successfully installed|
> |STARTING|A coprocessor instance is being started.|
> |ACTIVE|The coprocessor instance has been successfully activated and is 
> running.|
> |STOPPING|A coprocessor instance is being stopped.|
> See attached state diagram. Transitions to STOPPING will only happen as the 
> region is being closed. If a coprocessor throws an unhandled exception, this 
> will cause the RegionServer to close the region, stopping all coprocessor 
> instances on it. 
> Transitions from INSTALLED->STARTING and ACTIVE->STOPPING would go through 
> upcall methods into the coprocessor via the CoprocessorLifecycle interface:
> {code:java}
> public interface CoprocessorLifecycle {
>   void start(CoprocessorEnvironment env) throws IOException; 
>   void stop(CoprocessorEnvironment env) throws IOException;
> }
> {code}

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