[Xamarin.Android.Build.Tasks] _CopyIntermediateAssemblies uses CopyIfChanged #2128
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…Changed Context: dotnet#2088 970da9e was a good step towards "correctness" in building incrementally in the following scenario: - File | New Xamarin.Forms project | NetStandard library - Build - Change XAML - Build In this scenario, there is now a new target rising to the surface we can improve: 276 ms _CopyIntermediateAssemblies 1 calls Looking at the target, it seems we could use the `CopyIfChanged` task here more effectively. This task will automaticaly set the timestamps of files that have been copied, and so we don't need any subsequent `<ItemGroup />` or `<Touch />` elements. It was also touching *all* files instead of just the ones that were changed. After this change: 33 ms _CopyIntermediateAssemblies 1 calls The overall build went from 7.058s to 6.652s, so there must be some other targets that benefit from the timestamps not changing on *all* of these files.
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Build logs here: CopyIntermediateAssemblies.zip |
dellis1972
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Sep 3, 2018
jonathanpeppers
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Oct 16, 2018
Context: dotnet#2247 Context: dotnet#2128 The `_CopyIntermediateAssemblies` target has a bug for incremental builds, reproduced by the following: - Build a Xamarin.Android app project - `touch` the project's assembly in `$(IntermediateOutputPath)` - Build a second time. `_CopyIntermediateAssemblies` will run as expected. - Build a third time. `_CopyIntermediateAssemblies` will still run! When in this state, `_CopyIntermediateAssemblies` will always run. This is bad because it triggers other expensive targets like `_UpdateAndroidResgen` _every time_. I believe I introduced this in dotnet#2128, which was when I saw `_CopyIntermediateAssemblies` taking more time than it used to. It was a good tradeoff though, since it prevented `_UpdateAndroidResgen` from running too often. 15.9 does not have dotnet#2128. To fix this problem properly, I introduced a new `_copyintermediate.stamp` file to be used as the `Outputs` of the target. In addition to fixing our incremental build here, there should be performance gains in only verifying the timestamp of one file in `Outputs`. The `Inputs` of the `_CopyIntermediateAssemblies` were also incorrect, as it was not using the "satellite" assembly files as an input. This does not fully complete dotnet#2247, as there are two other targets listed I need to investigate further. These are likely unrelated to the changes in dotnet#2128.
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Context: #2088
970da9e was a good step towards "correctness" in building
incrementally in the following scenario:
In this scenario, there is now a new target rising to the surface we
can improve:
Looking at the target, it seems we could use the
CopyIfChangedtaskhere more effectively. This task will automaticaly set the timestamps
of files that have been copied, and so we don't need any subsequent
<ItemGroup />or<Touch />elements. It was also touching allfiles instead of just the ones that were changed.
After this change:
The overall build went from 7.058s to 6.652s, so there must be some
other targets that benefit from the timestamps not changing on all
of these files.