distribution_test.go

Documentation: cloud.google.com/go/pubsub/internal/distribution

     1  // Copyright 2017 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package distribution
    16  
    17  import (
    18  	"sync"
    19  	"testing"
    20  )
    21  
    22  func TestDistribution(t *testing.T) {
    23  	// These tests come from examples in https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method
    24  	tests := []struct {
    25  		// values in distribution
    26  		vals []int
    27  
    28  		// percentiles and expected percentile values
    29  		pp []float64
    30  		vv []int
    31  	}{
    32  		{
    33  			vals: []int{15, 20, 35, 40, 50},
    34  			pp:   []float64{0.05, 0.3, 0.4, 0.5, 1},
    35  			vv:   []int{15, 20, 20, 35, 50},
    36  		},
    37  		{
    38  			vals: []int{3, 6, 7, 8, 8, 10, 13, 15, 16, 20},
    39  			pp:   []float64{0.25, 0.5, 0.75, 1},
    40  			vv:   []int{7, 8, 15, 20},
    41  		},
    42  		{
    43  			vals: []int{3, 6, 7, 8, 8, 9, 10, 13, 15, 16, 20},
    44  			pp:   []float64{0.25, 0.5, 0.75, 1},
    45  			vv:   []int{7, 9, 15, 20},
    46  		},
    47  	}
    48  
    49  	maxVal := 0
    50  	for _, tst := range tests {
    51  		for _, v := range tst.vals {
    52  			if maxVal < v {
    53  				maxVal = v
    54  			}
    55  		}
    56  	}
    57  
    58  	for _, tst := range tests {
    59  		d := New(maxVal + 1)
    60  		for _, v := range tst.vals {
    61  			d.Record(v)
    62  		}
    63  		for i, p := range tst.pp {
    64  			got, want := d.Percentile(p), tst.vv[i]
    65  			if got != want {
    66  				t.Errorf("d=%v, d.Percentile(%f)=%d, want %d", d, p, got, want)
    67  			}
    68  		}
    69  	}
    70  }
    71  
    72  func TestRace(t *testing.T) {
    73  	const N int = 1e3
    74  	const parallel = 2
    75  
    76  	d := New(N)
    77  
    78  	var wg sync.WaitGroup
    79  	wg.Add(parallel)
    80  	for i := 0; i < parallel; i++ {
    81  		go func() {
    82  			for i := 0; i < N; i++ {
    83  				d.Record(i)
    84  			}
    85  			wg.Done()
    86  		}()
    87  	}
    88  
    89  	for i := 0; i < N; i++ {
    90  		if p := d.Percentile(0.5); p > N {
    91  			t.Fatalf("d.Percentile(0.5)=%d, expected to be at most %d", p, N)
    92  		}
    93  	}
    94  }
    95  
    96  func BenchmarkDistribution(b *testing.B) {
    97  	const N int = 1e3
    98  
    99  	d := New(N)
   100  	for i := 0; i < N; i++ {
   101  		d.Record(i)
   102  	}
   103  
   104  	b.ResetTimer()
   105  	b.ReportAllocs()
   106  
   107  	var index int
   108  	for i := 0; i < b.N; i++ {
   109  		if index = d.Percentile(0.5); index < 0 {
   110  			b.Fatalf("Invalid index: %d", index)
   111  		}
   112  	}
   113  	if index == 0 {
   114  		b.Fatal("Benchmark did not run")
   115  	}
   116  }
   117
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