Adam Murdoch wrote:
Steve Appling wrote:
Tom Eyckmans wrote:
2009/5/6 Adam Murdoch <[email protected]
<mailto:[email protected]>>
<clip>
I'm curious, how we will make this available to tasks?
You'd implement a ChangeProcessor that gets notified of what has
changed, depending how the task works you can just keep a list of the
files / directories that have changed and execute the function of the
task on the list or execute the function of the task in the
ChangeProcessor methods.
Currently the change detection always scans for all files /
directories that have changed, this is not always needed so I'll add
mulitple old / new state comparison strategies. So you can have only
one event if the directory has changed in some way or for every file
/ directory that has changed.
When I was experimenting with Tom's change detection, I added a
dependsOnDir method to Task that used his ChangeProcessor. If nothing
in the dir changed, it would throw a StopExecutionException. This
seemed to work well for customizing some simple user defined tasks.
This is a good idea - it's simple, but is probably sufficient for 90% of
custom tasks.
I'm not sure about the method name - do we want to reuse 'dependsOn' or
use a different term?
Adam
That is a good point, Adam. This is very different from the other dependencies,
in some ways this is the opposite (stopping tasks instead of adding more to the
DAG). I think there may be a range of these user specified optimizations. How
about this instead:
Task gets a new method, onlyIf that takes a closure. The closure is run before
any actions and is expected to return a boolean. If the boolean is true, then
the task continues executing normally, if it returns false, the task is stops
execution, but logs an appropriate lifecycle message "skipped (optimized)".
The onlyIf closure runs with a delegate of a new class, an OptimizationHelper,
that has some of the helper methods for various checks like Tom's change
detection. This could look like:
myTask.onlyIf {
dirChanged(file 'src/main/java')
}
or
myTask.onlyIf { !file('build/someresult').exists() }
This seems very simple. If anyone likes this, I can make a git branch that
would support this.
--
Steve Appling
Automated Logic Research Team
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