github.com/petermattis/pebble@v0.0.0-20190905164901-ab51a2166067/internal/randvar/skewed_latest_test.go (about)

     1  // Copyright 2018 The Cockroach Authors.
     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
    12  // implied. See the License for the specific language governing
    13  // permissions and limitations under the License. See the AUTHORS file
    14  // for names of contributors.
    15  
    16  package randvar
    17  
    18  import (
    19  	"fmt"
    20  	"sort"
    21  	"testing"
    22  )
    23  
    24  func dumpSamples(x []int) {
    25  	sort.Ints(x)
    26  
    27  	max := x[len(x)-1]
    28  	step := max / 20
    29  	if step == 0 {
    30  		step = 1
    31  	}
    32  	index := 0
    33  	count := 0
    34  	for i := 0; i <= max; i += step {
    35  		count = 0
    36  		for index < len(x) {
    37  			if x[index] >= i+step {
    38  				break
    39  			}
    40  			index++
    41  			count++
    42  		}
    43  		fmt.Printf("[%3d-%3d) ", i, i+step)
    44  		for j := 0; j < count; j++ {
    45  			if j%50 == 0 {
    46  				fmt.Printf("%c", '∎')
    47  			}
    48  		}
    49  		fmt.Println()
    50  	}
    51  }
    52  
    53  func TestSkewedLatest(t *testing.T) {
    54  	z, err := NewSkewedLatest(nil, 0, 99, 0.99)
    55  	if err != nil {
    56  		t.Fatal(err)
    57  	}
    58  
    59  	x := make([]int, 10000)
    60  	for i := range x {
    61  		x[i] = int(z.Uint64())
    62  	}
    63  
    64  	if testing.Verbose() {
    65  		dumpSamples(x)
    66  	}
    67  }