...
Run Format

Source file src/testing/allocs.go

     1	// Copyright 2013 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package testing
     6	
     7	import (
     8		"runtime"
     9	)
    10	
    11	// AllocsPerRun returns the average number of allocations during calls to f.
    12	// Although the return value has type float64, it will always be an integral value.
    13	//
    14	// To compute the number of allocations, the function will first be run once as
    15	// a warm-up. The average number of allocations over the specified number of
    16	// runs will then be measured and returned.
    17	//
    18	// AllocsPerRun sets GOMAXPROCS to 1 during its measurement and will restore
    19	// it before returning.
    20	func AllocsPerRun(runs int, f func()) (avg float64) {
    21		defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
    22	
    23		// Warm up the function
    24		f()
    25	
    26		// Measure the starting statistics
    27		var memstats runtime.MemStats
    28		runtime.ReadMemStats(&memstats)
    29		mallocs := 0 - memstats.Mallocs
    30	
    31		// Run the function the specified number of times
    32		for i := 0; i < runs; i++ {
    33			f()
    34		}
    35	
    36		// Read the final statistics
    37		runtime.ReadMemStats(&memstats)
    38		mallocs += memstats.Mallocs
    39	
    40		// Average the mallocs over the runs (not counting the warm-up).
    41		// We are forced to return a float64 because the API is silly, but do
    42		// the division as integers so we can ask if AllocsPerRun()==1
    43		// instead of AllocsPerRun()<2.
    44		return float64(mallocs / uint64(runs))
    45	}
    46	

View as plain text