1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <vespa/searchlib/index/field_length_calculator.h>
#include <vespa/vespalib/gtest/gtest.h>
using search::index::FieldLengthCalculator;
namespace search::index {
namespace {
// Arithmetic average of arithmetic sequence 1, 2, ... , samples
double arith_avg(uint32_t samples) {
return static_cast<double>(samples + 1) / 2;
}
}
TEST(FieldLengthCalculatorTest, empty_is_zero)
{
FieldLengthCalculator calc;
EXPECT_EQ(0.0, calc.get_average_field_length());
EXPECT_EQ(0, calc.get_num_samples());
}
TEST(FieldLengthCalculatorTest, startup_is_average)
{
FieldLengthCalculator calc;
calc.add_field_length(3);
EXPECT_DOUBLE_EQ(3.0, calc.get_average_field_length());
EXPECT_EQ(1, calc.get_num_samples());
calc.add_field_length(4);
EXPECT_DOUBLE_EQ(3.5, calc.get_average_field_length());
EXPECT_EQ(2, calc.get_num_samples());
calc.add_field_length(7);
EXPECT_DOUBLE_EQ((3 + 4 + 7)/3.0, calc.get_average_field_length());
EXPECT_EQ(3, calc.get_num_samples());
calc.add_field_length(9);
EXPECT_DOUBLE_EQ((3 + 4 + 7 + 9)/4.0, calc.get_average_field_length());
EXPECT_EQ(4, calc.get_num_samples());
}
TEST(FieldLengthCalculatorTest, average_until_max_num_samples)
{
const uint32_t max_num_samples = 5;
FieldLengthCalculator calc(0.0, 0, max_num_samples);
static constexpr double epsilon = 0.000000001; // Allowed difference
for (uint32_t i = 0; i + 1 < max_num_samples; ++i) {
calc.add_field_length(i + 1);
}
// Arithmetic average
EXPECT_NEAR(arith_avg(max_num_samples - 1), calc.get_average_field_length(), epsilon);
EXPECT_EQ(max_num_samples - 1, calc.get_num_samples());
calc.add_field_length(max_num_samples);
// Arithmetic average
EXPECT_NEAR(arith_avg(max_num_samples), calc.get_average_field_length(), epsilon);
EXPECT_EQ(max_num_samples, calc.get_num_samples());
calc.add_field_length(max_num_samples + 1);
// No longer arithmetic average
EXPECT_LT(arith_avg(max_num_samples + 1), calc.get_average_field_length());
// Switched to exponential decay
EXPECT_NEAR((arith_avg(max_num_samples) * (max_num_samples - 1) + max_num_samples + 1) / max_num_samples, calc.get_average_field_length(), epsilon);
EXPECT_EQ(max_num_samples, calc.get_num_samples());
}
TEST(FieldLengthCalculatorTest, calculator_can_return_info_object)
{
FieldLengthCalculator calc(3, 5);
auto info = calc.get_info();
EXPECT_EQ(3, info.get_average_field_length());
EXPECT_EQ(5, info.get_num_samples());
}
}
GTEST_MAIN_RUN_ALL_TESTS()
|
