From 6600a871ef7376b151cb7e4073c4095209f112ca Mon Sep 17 00:00:00 2001 From: sunnymilk Date: Tue, 27 Aug 2024 17:23:10 -0400 Subject: [PATCH] testing: implement testing.B.Loop Initial implementation for testing.B.Loop, right now the calculation of b.N are still done in the old fasion way, as of now b.Loop is merely an alias for the old loop over b.N. For #61515. Change-Id: If211d0acc5f0c33df530096dceafe0b947ab0c8e Reviewed-on: https://go-review.googlesource.com/c/go/+/608798 TryBot-Result: Gopher Robot Reviewed-by: Junyang Shao Run-TryBot: Junyang Shao LUCI-TryBot-Result: Go LUCI Reviewed-by: Michael Pratt --- api/next/61515.txt | 1 + doc/next/6-stdlib/99-minor/testing/61515.md | 1 + src/testing/benchmark.go | 13 +++++++++++++ src/testing/benchmark_test.go | 16 ++++++++++++++++ 4 files changed, 31 insertions(+) create mode 100644 api/next/61515.txt create mode 100644 doc/next/6-stdlib/99-minor/testing/61515.md diff --git a/api/next/61515.txt b/api/next/61515.txt new file mode 100644 index 0000000000..e797156a61 --- /dev/null +++ b/api/next/61515.txt @@ -0,0 +1 @@ +pkg testing, method (*B) Loop() bool #61515 diff --git a/doc/next/6-stdlib/99-minor/testing/61515.md b/doc/next/6-stdlib/99-minor/testing/61515.md new file mode 100644 index 0000000000..f724eb1b90 --- /dev/null +++ b/doc/next/6-stdlib/99-minor/testing/61515.md @@ -0,0 +1 @@ +Benchmarks can use the new [B.Loop] method in `for b.Loop() { ... }` loops to determine if iteration should continue. diff --git a/src/testing/benchmark.go b/src/testing/benchmark.go index 5591cd4e4d..0271308346 100644 --- a/src/testing/benchmark.go +++ b/src/testing/benchmark.go @@ -113,6 +113,8 @@ type B struct { netBytes uint64 // Extra metrics collected by ReportMetric. extra map[string]float64 + // Remaining iterations of Loop() to be executed in benchFunc. + loopN int } // StartTimer starts timing a test. This function is called automatically @@ -187,6 +189,7 @@ func (b *B) runN(n int) { runtime.GC() b.resetRaces() b.N = n + b.loopN = n b.parallelism = 1 b.ResetTimer() b.StartTimer() @@ -349,6 +352,16 @@ func (b *B) ReportMetric(n float64, unit string) { b.extra[unit] = n } +// Loop returns true until b.N calls has been made to it. +// +// A benchmark should either use Loop or contain an explicit loop from 0 to b.N, but not both. +// After the benchmark finishes, b.N will contain the total number of calls to op, so the benchmark +// may use b.N to compute other average metrics. +func (b *B) Loop() bool { + b.loopN-- + return b.loopN >= 0 +} + // BenchmarkResult contains the results of a benchmark run. type BenchmarkResult struct { N int // The number of iterations. diff --git a/src/testing/benchmark_test.go b/src/testing/benchmark_test.go index 66f555d1f1..b5ad213fb3 100644 --- a/src/testing/benchmark_test.go +++ b/src/testing/benchmark_test.go @@ -127,6 +127,22 @@ func TestRunParallelSkipNow(t *testing.T) { }) } +func TestLoopEqualsRangeOverBN(t *testing.T) { + // Verify that b.N and the b.Loop() iteration count match. + var nIterated, nInfered int + testing.Benchmark(func(b *testing.B) { + i := 0 + for b.Loop() { + i++ + } + nIterated = i + nInfered = b.N + }) + if nIterated != nInfered { + t.Fatalf("Iteration of the two different benchmark loop flavor differs, got %d iterations want %d", nIterated, nInfered) + } +} + func ExampleB_RunParallel() { // Parallel benchmark for text/template.Template.Execute on a single object. testing.Benchmark(func(b *testing.B) {