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https://issues.apache.org/jira/browse/WHIRR-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13198535#comment-13198535
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David Alves commented on WHIRR-221:
-----------------------------------
Hi
I'm working on this, I started from scratch a while ago and I just now got the
time to start to put things together.
Andrei: I would prefer not to use annotations since dependencies might depend
on configuration.
So the idea is:
add a getDependedOnRole() method to ClusterActionController. This method
returns the set of roles this role needs before it can start. This might be
fixes (e.g. hard-coded into the ClusterActionController class) or it might be
configurable through the properties file.
In each phase (configure, bootstrap start etc) the a Action calls dependency
analyzer that returns a set of stages. Each stage has a set of roles that can
be started in parallel and must finish before the next stage.
The dependency graph is build based on calls to getDependedOnRole(). The roots
are services that depend on no one, the next stage is composed of the root's
children, etc.
Still too early for a patch as I'm still finishing things up, but if you guys
would wan't to take a look at the dependency analyzer and the new
clusteractionhandler here are the github links:
https://github.com/dralves/whirr/blob/whirr-221/core/src/main/java/org/apache/whirr/service/DependencyAnalyzer.java
https://github.com/dralves/whirr/blob/whirr-221/core/src/main/java/org/apache/whirr/service/ClusterActionHandlerSupport.java
https://github.com/dralves/whirr/blob/whirr-221/core/src/test/java/org/apache/whirr/service/DependencyAnalyzerTest.java
> Optionally control the order of starting services
> -------------------------------------------------
>
> Key: WHIRR-221
> URL: https://issues.apache.org/jira/browse/WHIRR-221
> Project: Whirr
> Issue Type: New Feature
> Components: core, documentation
> Reporter: Andrei Savu
> Assignee: Andrei Savu
> Priority: Critical
> Fix For: 0.8.0
>
> Attachments: WHIRR-221-v1.patch, WHIRR-221-v3.patch, WHIRR-221.patch
>
>
> As Lars sugested in WHIRR-170:
> The user should "be able to optionally control the order (services start).
> This could be role based and specified like so
> {code}
> whirr.role-order=zk,nn+jt,dn+tt,hbase-master,hbase-regionserver
> {code}
> If not specified the system should make any effort to start the services as
> quickly as possible, for example in multiple threads. In other words, when
> the role-order is not given no guarantee about order can be given."
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