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Uncurried versions of 'bracket' and 'bracketExit' #617

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Merged
merged 2 commits into from
Mar 18, 2019
Merged

Uncurried versions of 'bracket' and 'bracketExit' #617

merged 2 commits into from
Mar 18, 2019

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@LGLO
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@LGLO LGLO commented Mar 9, 2019

I open this to have version of bracket suitable for hot-path in performance sensitive applications.

@LGLO LGLO requested a review from jdegoes March 9, 2019 17:27
jdegoes
jdegoes previously approved these changes Mar 10, 2019
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Looks great to me! You preserved all the code from the old versions, right? Just moved them over?

Also, would be nice to have a little code that shows the uncurried ones infer (somewhat).

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jdegoes commented Mar 10, 2019

@LGLO Thanks a lot for doing this! Let's merge after the build is passing.

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LGLO commented Mar 10, 2019

👍 I'll try to retain scaladoc link, although it's tricky.
When I do scaladoc fix, then I'll also add specs for inference (to see that besides compilation there are no cast exceptions).

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jdegoes commented Mar 13, 2019

@LGLO Would love to get this in as soon as the build passes!

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LGLO commented Mar 15, 2019

@jdegoes I've run this benchmark:

  @Benchmark
  def curriedBracket: UIO[Unit] = {
      ZIO.bracket(ZIO.unit)(_ => ZIO.unit)(_ => ZIO.unit)
  }
  @Benchmark
  def tupledBracket: UIO[Unit] = {
    ZIO.bracket(ZIO.unit, (_: Unit) => ZIO.unit, (_: Unit) => ZIO.unit)
  }

5 iterations, 30 seconds each (to let GC work) and observed no difference:

[info] Benchmark                                                                        Mode  Cnt     Score     Error   Units
[info] BracketBenchmark.curriedBracket                                                  avgt    5    28.820 ±   3.596   ns/op
[info] BracketBenchmark.curriedBracket:·gc.alloc.rate                                   avgt    5  4429.676 ± 552.787  MB/sec
[info] BracketBenchmark.curriedBracket:·gc.alloc.rate.norm                              avgt    5   136.002 ±   0.014    B/op
[info] BracketBenchmark.curriedBracket:·gc.churn.CodeHeap_'non-profiled_nmethods'       avgt    5     0.008 ±   0.003  MB/sec
[info] BracketBenchmark.curriedBracket:·gc.churn.CodeHeap_'non-profiled_nmethods'.norm  avgt    5    ≈ 10⁻⁴              B/op
[info] BracketBenchmark.curriedBracket:·gc.churn.G1_Old_Gen                             avgt    5  4437.325 ± 550.946  MB/sec
[info] BracketBenchmark.curriedBracket:·gc.churn.G1_Old_Gen.norm                        avgt    5   136.237 ±   0.566    B/op
[info] BracketBenchmark.curriedBracket:·gc.count                                        avgt    5  1434.000            counts
[info] BracketBenchmark.curriedBracket:·gc.time                                         avgt    5  1306.000                ms
[info] BracketBenchmark.tupledBracket                                                   avgt    5    28.790 ±   3.233   ns/op
[info] BracketBenchmark.tupledBracket:·gc.alloc.rate                                    avgt    5  4433.757 ± 496.258  MB/sec
[info] BracketBenchmark.tupledBracket:·gc.alloc.rate.norm                               avgt    5   136.000 ±   0.001    B/op
[info] BracketBenchmark.tupledBracket:·gc.churn.CodeHeap_'non-profiled_nmethods'        avgt    5     0.009 ±   0.003  MB/sec
[info] BracketBenchmark.tupledBracket:·gc.churn.CodeHeap_'non-profiled_nmethods'.norm   avgt    5    ≈ 10⁻⁴              B/op
[info] BracketBenchmark.tupledBracket:·gc.churn.G1_Old_Gen                              avgt    5  4443.315 ± 493.961  MB/sec
[info] BracketBenchmark.tupledBracket:·gc.churn.G1_Old_Gen.norm                         avgt    5   136.294 ±   0.773    B/op
[info] BracketBenchmark.tupledBracket:·gc.count                                         avgt    5  1558.000            counts
[info] BracketBenchmark.tupledBracket:·gc.time                                          avgt    5  1356.000                ms

I cannot prove this PR helps in anything.
I guess it should be closed.

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jdegoes commented Mar 16, 2019

@LGLO I am ok merging, actually, because in the best case the JIT can eliminate short-lived allocations, but that depends a lot on the code being run, version of JRE, etc. At least with these versions, we have a guarantee of minimal allocation. What do you think?

@LGLO LGLO force-pushed the bracket-uncurried-for-performance branch from 27ba045 to 4c0342a Compare March 17, 2019 22:25
LGLO
LGLO commented Mar 17, 2019
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core/jvm/src/test/scala/scalaz/zio/IOSpec.scala
} yield (result must_=== 0L) and (released must_=== true)
}

object UncurriedBracketCompilesRegardlessOrderOfEAndRTypes {
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I don't really know where to place these if-compiles-works tests.

LGLO
LGLO commented Mar 17, 2019
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core/shared/src/main/scala/scalaz/zio/ZIO.scala
* Finalizers offer very powerful guarantees, but they are low-level, and
* should generally not be used for releasing resources. For higher-level
* logic built on `ensuring`, see [[ZIO#bracket]].
* logic built on `ensuring`, see `ZIO#bracket`.
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I'm sorry for this one, but scaladoc finds two bracket methods now and I cannot find method when signature contains type bounded by type LowerR declared inside ZIO.

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LGLO commented Mar 17, 2019

Okey!
I've fixed doc and added test.

jdegoes
jdegoes approved these changes Mar 18, 2019
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Looks great!

@jdegoes jdegoes merged commit 10a63c1 into zio:master Mar 18, 2019
@LGLO LGLO deleted the bracket-uncurried-for-performance branch May 3, 2019 19:37
ghostdogpr pushed a commit to ghostdogpr/scalaz-zio that referenced this pull request May 5, 2019
@LGLO @ghostdogpr
Uncurried versions of 'bracket' and 'bracketExit' (zio#617)
6f7396e 
* Uncurried versions of 'bracket' and 'bracketExit'

* Fixed doc and added specs
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