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Diffstat (limited to 'src/testing/allocs.go')
-rw-r--r-- | src/testing/allocs.go | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/testing/allocs.go b/src/testing/allocs.go new file mode 100644 index 0000000..1eeb2d4 --- /dev/null +++ b/src/testing/allocs.go @@ -0,0 +1,45 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package testing + +import ( + "runtime" +) + +// AllocsPerRun returns the average number of allocations during calls to f. +// Although the return value has type float64, it will always be an integral value. +// +// To compute the number of allocations, the function will first be run once as +// a warm-up. The average number of allocations over the specified number of +// runs will then be measured and returned. +// +// AllocsPerRun sets GOMAXPROCS to 1 during its measurement and will restore +// it before returning. +func AllocsPerRun(runs int, f func()) (avg float64) { + defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1)) + + // Warm up the function + f() + + // Measure the starting statistics + var memstats runtime.MemStats + runtime.ReadMemStats(&memstats) + mallocs := 0 - memstats.Mallocs + + // Run the function the specified number of times + for i := 0; i < runs; i++ { + f() + } + + // Read the final statistics + runtime.ReadMemStats(&memstats) + mallocs += memstats.Mallocs + + // Average the mallocs over the runs (not counting the warm-up). + // We are forced to return a float64 because the API is silly, but do + // the division as integers so we can ask if AllocsPerRun()==1 + // instead of AllocsPerRun()<2. + return float64(mallocs / uint64(runs)) +} |