Hans Dockter wrote:
On Jul 21, 2009, at 6:27 AM, Adam Murdoch wrote:
Steve Appling wrote:
I have been trying to make use of the new onlyIf method to optimize
our large build. OnlyIf seemed liked a very useful approach in the
abstract, but is proving to be more of a challenge in a real
project. It was useful for a few tasks (like jar.onlyIf {
compile.didWork || processResources.didWork }), but not for some of
the more expensive ones. The Test task, in particular, has been
frustrating.
I tried the somewhat too simple:
test.onlyIf { compile.didWork || testCompile.didWork ||
processTestResources.didWork }
This does exactly what it says, it only runs the tests if new code
was compiled or the test resources changed and this seemed great at
first glance. When I tried this on our real project, however, I was
disappointed. What this will do is to cause the test task for a
module to be run only once. If it fails and the developer does not
correct it, then the next time the build is run the test will be
skipped. This gives the false impression that everything is correct
when it is not. To be useful, I think this also needs some type of
state information about whether the tests passed last time, but this
is getting more complicated than I originally envisioned.
A general solution to this problem is going to have to remember
whether a task has completed or failed to execute. It is also going
to have to consider the output artifacts of the task (and do a better
job with the input artifacts). I think it is reasonable for Gradle to
maintain this state, provided we do so in a general-purpose way.
For example, this is something that the OptimisationHelper could
expose, that the onlyIf clause can make use of if it cares:
test.onlyIf { compile.didWork || ... || !completedSuccessfully }
Why not provide the completedSuccessfully (possibly with a different
name) as a task property? As a first implementation we could have a
file (somewhere in .gradle) for each task being executed. This file
just contains true/false at the moment. False is returned if the file
contains false or the file does not exists.
Thinking about this a bit more, we would have to be able to answer the
question: has task A completed successfully since it's dependencies last
did work?
For example:
1. run gradle test, it completes successfully.
2. change some source.
3. run gradle compile
4. run gradle test
The tests should be run in step 4. However, if we stored true/false,
they would not run. Perhaps timestamps would be a better option.
Adam
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