For the details about this PR, please see the blog post https://eed3si9n.com/sbt-remote-cache/.
* Add cache basics
* Refactor Attributed to use StringAttributeMap, which is Map[StringAttributeKey, String]
* Implement disk cache
* Rename Package to Pkg
* Virtualize packageBin
* Use HashedVirtualFileRef for packageBin
* Virtualize compile task
In https://github.com/sbt/sbt/pull/5981 I tried to work around the spruious post-macro "a pure expression does nothing" warning (https://github.com/scala/bug/issues/12112) by trying to remove some pure-looking expressions out of the tree.
This quickly backfired when it was reported that sbt 1.4.3 was not evaluating some code. This backs out the macro-level manipulation, and instead try to silence the warning at the reporter level. This feels safer, and it seems to work just as well.
Ref https://github.com/scala/bug/issues/12112
Current app transformation macro creates a tree that looks like:
```scala
FullInstance.app[[T0[x]](T0[Int], T0[Int]), Unit](scala.Tuple2(task2, task1), (($p$macro$3: (Int, Int)) => {
<synthetic> val $q$macro$2: Int = $p$macro$3._1;
<synthetic> val $q$macro$1: Int = $p$macro$3._2;
{
($q$macro$1: Int);
($q$macro$2: Int);
()
}
}))(AList.tuple2[Int, Int])
```
Starting Scala 2.12.12 the compiler's "pure expression does nothing" has become more enthusiastic/accurate in its reach, and it started warning about the naked reference to `$q$macro$1` that appears to do nothing, even though in reality it would trigger the tasks and do something in the context of sbt. It's just _that_ particular line ends up macroed away into a pure expression.
A somewhat bizarre workaround is to make a fake call to a method just to satisfy this warning. I've chosen `scala.Predef.identity` here so it can be composed together with the existing expression nesting when they exist.
Using the scala reflect library always introduces significant
classloading overhead. We can eliminate the classloading overhead by
generating StringTypeTags at compile time instead.
This sped up average project loading time by a few hundred milliseconds
on my computer. The ManagedLoggedReporter in zinc is still using the
type tag based apis but after the next sbt release, we can upgrade the
zinc apis. We also could consider breaking binary compatibility.
To demonstrate [-Yno-lub](http://eed3si9n.com/stricter-scala-with-ynolub), this shows the code changes that removes lubing (Not all subprojects are done).
After I made the changes, I switched the Scala back to normal 2.12.10.
In my recent changes to watch, I have been moving towards a world in
which sbt manages the file inputs and outputs at the task level. The
main idea is that we want to enable a user to specify the inputs and
outputs of a task and have sbt able to track those inputs across
multiple task evaluations. Sbt should be able to automatically trigger a
build when the inputs change and it also should be able to avoid task
evaluation if non of the inputs have changed.
The former case of having sbt automatically watch the file inputs of a
task has been present since watch was refactored. In this commit, I
make it possible for the user to retrieve the lists of new, modified and
deleted files. The user can then avoid task evaluation if none of the
inputs have changed.
To implement this, I inject a number of new settings during project
load if the fileInputs setting is defined for a task. The injected
settings are:
allPathsAndAttributes -- this retrieves all of the paths described by
the fileInputs for the task along with their attributes
fileStamps -- this retrieves all of the file stamps for the files
returned by allPathsAndAttributes
Using these two injected tasks, I also inject a number of derived tasks,
such as allFiles, which returns all of the regular files returned by
allPathsAndAttributes and changedFiles, which returns all of the regular
files that have been modified since the last run.
Using these injected settings, the user is able to write tasks that
avoid evaluation if the inputs haven't changed.
foo / fileInputs += baseDirectory.value.toGlob / ** / "*.scala"
foo := {
foo.previous match {
case Some(p) if (foo / changedFiles).value.isEmpty => p
case _ => fooImpl((foo / allFiles).value
}
}
To make this whole mechanism work, I add a private task key:
val fileAttributeMap = taskKey[java.util.HashMap[Path, Stamp]]("...")
This keeps track of the stamps for all of the files that are managed by
sbt. The fileStamps task will first look for the stamp in the attribute
map and, only if it is not present, it will update the cache. This
allows us to ensure that a given file will only be stamped once per task
evaluation run no matter how the file inputs are specified. Moreover, in
a continuous build, I'm able to reuse the attribute map which can
significantly reduce latency because the default file stamping
implementation used by zinc is fairly expensive (it can take anywhere
between 300-1500ms to stamp 5000 8kb source files on my mac).
I also renamed some of the watch related keys to be a bit more clear.
The newest version of io repackages a number of classes into the
sbt.nio.* packages. It also changes some of the semantics of glob
related apis. This commit updates all of the usages of the updated apis
within sbt but should have no functional difference.
Prior to this commit, it was necessary to add breadcrumbs for every
input that is used within a dynamic task. In this commit, I rework the
watch setup so that we can track the dynamic inputs that are used. To
simplify the discussion, I'm going to ignore aggregation and
multi-commands, but they are both supported. To implement this change, I
update the GlobLister.all method to take a second implicit argument:
DynamicInputs. This is effectively a mutable Set of Globs that is
updated every time a task looks up files from a glob. The repository.get
method should already register the glob with the repository. The set of
globs are necessary because the repository may not do any file filtering
so the file event monitor needs to check the input globs to ensure that
the file event is for a file that actually requested by a task during
evaluation.
* Long term, I plan to add support for lifting tasks into a dynamic task
in a way that records _all_ of the possible dependencies for the task
through each of the dynamic code paths. We should revisit this change to
determine if its still necessary after that change.
Right now, the sbt.internal.io.Source is something of a second class
citizen within sbt. Since sbt 0.13, there have been extension classes
defined that can convert a file to a PathFinder but no analog has been
introduced for sbt.internal.io.Source.
Given that sbt.internal.io.Source was not really intended to be part of
the public api (just look at its package), I think it makes sense to
just replace it with Glob. In this commit, I add extension
methods to Glob and Seq[Glob] that make it possible to easily
retrieve all of the files for a particular Glob within a task. The
upshot is that where previously, we'd have had to write something like:
watchSources += Source(baseDirectory.value / "src" / "main" / "proto", "*.proto", NothingFilter)
now we can write
watchGlobs += baseDirectory.value / "src" / "main" / "proto" * "*.proto"
Moreover, within a task, we can now do something like:
foo := {
val allWatchGlobs: Seq[File] = watchGlobs.value.all
println(allWatchSources.mkString("all watch source files:\n", "\n", ""))
}
Before we would have had to manually retrieve the files.
The implementation of the dsl uses the new GlobExtractor class which
proxies file look ups through a FileTree.Repository. This makes it so
that, by default, all file i/o using Sources will use the default
FileTree.Repository. The default is a macro that returns
`sbt.Keys.fileTreeRepository.value: @sbtUnchecked`. By doing it this
way, the default repository can only be used within a task definition
(since it delegates to `fileTreeRepository.value`). It does not,
however, prevent the user from explicitly providing a
FileTree.Repository instance which the user is free to instantiate
however they wish.
Bonus: optimize imports in Def.scala and Defaults.scala
Adrien Piquerez
Eugene Yokota
Julien Richard-Foy
Ethan Atkins
Dale Wijnand
xuwei-k
Ethan Atkins