benchmark_test.go

     1  // Copyright 2018 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  // This file provides a simple framework to add benchmarks
     6  // based on generated input (source) files.
     7  
     8  package format_test
     9  
    10  import (
    11  	"bytes"
    12  	"flag"
    13  	"fmt"
    14  	"go/format"
    15  	"os"
    16  	"testing"
    17  )
    18  
    19  var debug = flag.Bool("debug", false, "write .src files containing formatting input; for debugging")
    20  
    21  // array1 generates an array literal with n elements of the form:
    22  //
    23  // var _ = [...]byte{
    24  //
    25  //	// 0
    26  //	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    27  //	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    28  //	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
    29  //	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
    30  //	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
    31  //	// 40
    32  //	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
    33  //	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
    34  //	...
    35  func array1(buf *bytes.Buffer, n int) {
    36  	buf.WriteString("var _ = [...]byte{\n")
    37  	for i := 0; i < n; {
    38  		if i%10 == 0 {
    39  			fmt.Fprintf(buf, "\t// %d\n", i)
    40  		}
    41  		buf.WriteByte('\t')
    42  		for j := 0; j < 8; j++ {
    43  			fmt.Fprintf(buf, "0x%02x, ", byte(i))
    44  			i++
    45  		}
    46  		buf.WriteString("\n")
    47  	}
    48  	buf.WriteString("}\n")
    49  }
    50  
    51  var tests = []struct {
    52  	name string
    53  	gen  func(*bytes.Buffer, int)
    54  	n    int
    55  }{
    56  	{"array1", array1, 10000},
    57  	// add new test cases here as needed
    58  }
    59  
    60  func BenchmarkFormat(b *testing.B) {
    61  	var src bytes.Buffer
    62  	for _, t := range tests {
    63  		src.Reset()
    64  		src.WriteString("package p\n")
    65  		t.gen(&src, t.n)
    66  		data := src.Bytes()
    67  
    68  		if *debug {
    69  			filename := t.name + ".src"
    70  			err := os.WriteFile(filename, data, 0660)
    71  			if err != nil {
    72  				b.Fatalf("couldn't write %s: %v", filename, err)
    73  			}
    74  		}
    75  
    76  		b.Run(fmt.Sprintf("%s-%d", t.name, t.n), func(b *testing.B) {
    77  			b.SetBytes(int64(len(data)))
    78  			b.ReportAllocs()
    79  			b.ResetTimer()
    80  			for i := 0; i < b.N; i++ {
    81  				var err error
    82  				sink, err = format.Source(data)
    83  				if err != nil {
    84  					b.Fatal(err)
    85  				}
    86  			}
    87  		})
    88  	}
    89  }
    90  
    91  var sink []byte
    92
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