On 26/05/2011, at 9:24 PM, <[email protected]>
<[email protected]> wrote:
> Hi,
>
> I have written a simple task that performs a clean if the main version
> changes. This is not something that happens very often (4 times a year), but
> it can be a timeconsuming hassle if a developer forgets to do it locally. In
> addition, we have many different bamboo plans that are affected (x2, since
> they’re running on 2 different servers), which today needs to be manually
> cleaned.
>
> The task currently looks like this:
>
> task cleanWhenMainVersionChange {
> inputs.properties(["mainVersion": mainVersion])
> outputs.files file("$buildDir/cleanWhenMainVersionChange.txt")
> doLast {
> clean.execute()
> }
> }
>
> To work properly, this code needs to be used in 4 different multiprojects,
> with a varying number of tasks being performed for each sub-project. We want
> to ensure that this task is the first to run.
>
> The only way I am aware of to do this, is by setting dependencies. However,
> since there are several different tasks that have the potential to be first,
> we have to set dependencies from all of them to the
> “cleanWhenMainVersionChange” task.
>
> Is there a simpler way to do this, preferably one where we don’t need to know
> about all the tasks that have the potential to be executed first?
Not yet. These sorts of things (run some task before any other task, run some
task after all other tasks) we want to make easy to declare through the DSL.
One option to the moment is to have all tasks depend on your clean task:
tasks.matching { it != cleanWhenMainVersionChanges }.all {
dependsOn cleanWhenMainVersionChanges
}
Another option is to use the task graph whenReady() hook:
gradle.taskGraph.whenReady {
cleanWhenMainVersionChanges.execute()
}
However, this uses an internal API which might go away. We don't recommend
executing tasks by calling execute().
>
>
> Finally; a question regarding outputs:
> If I don’t declare any outputs, the task is executed every time. Running with
> the debug flag reveals that gradle considers any task with no outputs
> declared to never be up-to-date.
>
> However, as you can see, I don’t need to actually create the file – only the
> output declaration. It seems to work as intended if I don’t create the file;
> i.e. it is only performed if the mainVersion property is changed.
>
> Is this intended? If so, why do we need to specify the outputs declaration
> here?
The incremental build feature is currently intended for tasks that create
things, not tasks that destroy things. If you don't declare something about the
outputs, Gradle assumes that the task either doesn't build anything or will
take care of incremental-ness on it's own.
You can tell Gradle that a task doesn't produce any output like this:
task cleanWhenMainVersionChanges {
outputs.upToDateWhen { true }
}
--
Adam Murdoch
Gradle Co-founder
http://www.gradle.org
VP of Engineering, Gradleware Inc. - Gradle Training, Support, Consulting
http://www.gradleware.com
