rsc.io/go@v0.0.0-20150416155037-e040fd465409/src/runtime/append_test.go (about)

     1  // Copyright 2011 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  package runtime_test
     5  
     6  import "testing"
     7  
     8  const N = 20
     9  
    10  func BenchmarkAppend(b *testing.B) {
    11  	b.StopTimer()
    12  	x := make([]int, 0, N)
    13  	b.StartTimer()
    14  	for i := 0; i < b.N; i++ {
    15  		x = x[0:0]
    16  		for j := 0; j < N; j++ {
    17  			x = append(x, j)
    18  		}
    19  	}
    20  }
    21  
    22  func BenchmarkAppendGrowByte(b *testing.B) {
    23  	for i := 0; i < b.N; i++ {
    24  		var x []byte
    25  		for j := 0; j < 1<<20; j++ {
    26  			x = append(x, byte(j))
    27  		}
    28  	}
    29  }
    30  
    31  func BenchmarkAppendGrowString(b *testing.B) {
    32  	var s string
    33  	for i := 0; i < b.N; i++ {
    34  		var x []string
    35  		for j := 0; j < 1<<20; j++ {
    36  			x = append(x, s)
    37  		}
    38  	}
    39  }
    40  
    41  func benchmarkAppendBytes(b *testing.B, length int) {
    42  	b.StopTimer()
    43  	x := make([]byte, 0, N)
    44  	y := make([]byte, length)
    45  	b.StartTimer()
    46  	for i := 0; i < b.N; i++ {
    47  		x = x[0:0]
    48  		x = append(x, y...)
    49  	}
    50  }
    51  
    52  func BenchmarkAppend1Byte(b *testing.B) {
    53  	benchmarkAppendBytes(b, 1)
    54  }
    55  
    56  func BenchmarkAppend4Bytes(b *testing.B) {
    57  	benchmarkAppendBytes(b, 4)
    58  }
    59  
    60  func BenchmarkAppend7Bytes(b *testing.B) {
    61  	benchmarkAppendBytes(b, 7)
    62  }
    63  
    64  func BenchmarkAppend8Bytes(b *testing.B) {
    65  	benchmarkAppendBytes(b, 8)
    66  }
    67  
    68  func BenchmarkAppend15Bytes(b *testing.B) {
    69  	benchmarkAppendBytes(b, 15)
    70  }
    71  
    72  func BenchmarkAppend16Bytes(b *testing.B) {
    73  	benchmarkAppendBytes(b, 16)
    74  }
    75  
    76  func BenchmarkAppend32Bytes(b *testing.B) {
    77  	benchmarkAppendBytes(b, 32)
    78  }
    79  
    80  func benchmarkAppendStr(b *testing.B, str string) {
    81  	b.StopTimer()
    82  	x := make([]byte, 0, N)
    83  	b.StartTimer()
    84  	for i := 0; i < b.N; i++ {
    85  		x = x[0:0]
    86  		x = append(x, str...)
    87  	}
    88  }
    89  
    90  func BenchmarkAppendStr1Byte(b *testing.B) {
    91  	benchmarkAppendStr(b, "1")
    92  }
    93  
    94  func BenchmarkAppendStr4Bytes(b *testing.B) {
    95  	benchmarkAppendStr(b, "1234")
    96  }
    97  
    98  func BenchmarkAppendStr8Bytes(b *testing.B) {
    99  	benchmarkAppendStr(b, "12345678")
   100  }
   101  
   102  func BenchmarkAppendStr16Bytes(b *testing.B) {
   103  	benchmarkAppendStr(b, "1234567890123456")
   104  }
   105  
   106  func BenchmarkAppendStr32Bytes(b *testing.B) {
   107  	benchmarkAppendStr(b, "12345678901234567890123456789012")
   108  }
   109  
   110  func BenchmarkAppendSpecialCase(b *testing.B) {
   111  	b.StopTimer()
   112  	x := make([]int, 0, N)
   113  	b.StartTimer()
   114  	for i := 0; i < b.N; i++ {
   115  		x = x[0:0]
   116  		for j := 0; j < N; j++ {
   117  			if len(x) < cap(x) {
   118  				x = x[:len(x)+1]
   119  				x[len(x)-1] = j
   120  			} else {
   121  				x = append(x, j)
   122  			}
   123  		}
   124  	}
   125  }
   126  
   127  var x []int
   128  
   129  func f() int {
   130  	x[:1][0] = 3
   131  	return 2
   132  }
   133  
   134  func TestSideEffectOrder(t *testing.T) {
   135  	x = make([]int, 0, 10)
   136  	x = append(x, 1, f())
   137  	if x[0] != 1 || x[1] != 2 {
   138  		t.Error("append failed: ", x[0], x[1])
   139  	}
   140  }
   141  
   142  func TestAppendOverlap(t *testing.T) {
   143  	x := []byte("1234")
   144  	x = append(x[1:], x...) // p > q in runtime·appendslice.
   145  	got := string(x)
   146  	want := "2341234"
   147  	if got != want {
   148  		t.Errorf("overlap failed: got %q want %q", got, want)
   149  	}
   150  }
   151  
   152  func benchmarkCopySlice(b *testing.B, l int) {
   153  	s := make([]byte, l)
   154  	buf := make([]byte, 4096)
   155  	var n int
   156  	for i := 0; i < b.N; i++ {
   157  		n = copy(buf, s)
   158  	}
   159  	b.SetBytes(int64(n))
   160  }
   161  
   162  func benchmarkCopyStr(b *testing.B, l int) {
   163  	s := string(make([]byte, l))
   164  	buf := make([]byte, 4096)
   165  	var n int
   166  	for i := 0; i < b.N; i++ {
   167  		n = copy(buf, s)
   168  	}
   169  	b.SetBytes(int64(n))
   170  }
   171  
   172  func BenchmarkCopy1Byte(b *testing.B)    { benchmarkCopySlice(b, 1) }
   173  func BenchmarkCopy2Byte(b *testing.B)    { benchmarkCopySlice(b, 2) }
   174  func BenchmarkCopy4Byte(b *testing.B)    { benchmarkCopySlice(b, 4) }
   175  func BenchmarkCopy8Byte(b *testing.B)    { benchmarkCopySlice(b, 8) }
   176  func BenchmarkCopy12Byte(b *testing.B)   { benchmarkCopySlice(b, 12) }
   177  func BenchmarkCopy16Byte(b *testing.B)   { benchmarkCopySlice(b, 16) }
   178  func BenchmarkCopy32Byte(b *testing.B)   { benchmarkCopySlice(b, 32) }
   179  func BenchmarkCopy128Byte(b *testing.B)  { benchmarkCopySlice(b, 128) }
   180  func BenchmarkCopy1024Byte(b *testing.B) { benchmarkCopySlice(b, 1024) }
   181  
   182  func BenchmarkCopy1String(b *testing.B)    { benchmarkCopyStr(b, 1) }
   183  func BenchmarkCopy2String(b *testing.B)    { benchmarkCopyStr(b, 2) }
   184  func BenchmarkCopy4String(b *testing.B)    { benchmarkCopyStr(b, 4) }
   185  func BenchmarkCopy8String(b *testing.B)    { benchmarkCopyStr(b, 8) }
   186  func BenchmarkCopy12String(b *testing.B)   { benchmarkCopyStr(b, 12) }
   187  func BenchmarkCopy16String(b *testing.B)   { benchmarkCopyStr(b, 16) }
   188  func BenchmarkCopy32String(b *testing.B)   { benchmarkCopyStr(b, 32) }
   189  func BenchmarkCopy128String(b *testing.B)  { benchmarkCopyStr(b, 128) }
   190  func BenchmarkCopy1024String(b *testing.B) { benchmarkCopyStr(b, 1024) }