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Better estimations in tests
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also removed commented out code
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@Enmk
Enmk committed Feb 28, 2024
1 parent 12f0399 commit a72ad04
Showing 1 changed file with 14 additions and 79 deletions.
93 changes: 14 additions & 79 deletions ut/ColumnString_ut.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,12 @@ size_t EstimateColumnStringMemoryUsage(
) {
static const size_t COLUMN_STRING_DEFAULT_BLOCK_SIZE = 4096;
static const size_t COLUMN_STRING_MAX_EXPECTED_MEMORY_OVERHEAD = 4096;
const float max_estimation_error_factor = item_estimated_size == ColumnString::NO_PREALLOCATE ? 2.5 : 2;

// space wasted in block since not all items can be fit perfectly, and there is some unused space at the end of the block.
const auto estimate_lost_space_in_block = (static_cast<size_t>(item_estimated_size) != 0
? COLUMN_STRING_DEFAULT_BLOCK_SIZE % static_cast<size_t>(static_cast<size_t>(item_estimated_size) * std::max(1.0f, value_to_estimation_average_size_ratio))
: COLUMN_STRING_DEFAULT_BLOCK_SIZE / 10);

// if no estimation provided, use factual total size of all items
if (item_estimated_size == ColumnString::EstimatedValueSize{0} && total_items_size && number_of_items)
Expand All @@ -42,13 +48,6 @@ size_t EstimateColumnStringMemoryUsage(
const size_t estimated_total_item_size = number_of_items * static_cast<size_t>(item_estimated_size) * value_to_estimation_average_size_ratio;
const auto estimated_number_of_blocks = std::max<size_t>(1, estimated_total_item_size ? COLUMN_STRING_DEFAULT_BLOCK_SIZE / estimated_total_item_size : 1);

// space wasted in block since not all items can be fit perfectly, and there is some unused space at the end of the block.
const auto estimate_lost_space_in_block = (static_cast<size_t>(item_estimated_size) != 0
? COLUMN_STRING_DEFAULT_BLOCK_SIZE % static_cast<size_t>(static_cast<size_t>(item_estimated_size) * value_to_estimation_average_size_ratio)
: COLUMN_STRING_DEFAULT_BLOCK_SIZE / 10);

const auto max_estimation_error_factor = item_estimated_size == ColumnString::NO_PREALLOCATE ? 2 : 1.2;

return (number_of_items * sizeof(std::string_view)
+ estimated_total_item_size
+ estimate_lost_space_in_block * estimated_number_of_blocks
Expand Down Expand Up @@ -213,49 +212,6 @@ TEST(ColumnString, InvalidSizeEstimation) {
EXPECT_THROW(col.SetEstimatedValueSize(ColumnString::EstimatedValueSize(std::numeric_limits<size_t>::max())), ValidationError);
}

TEST(ColumnString, WithSizeEstimation) {
const ColumnString::EstimatedValueSize value_size_estimations[] = {
ColumnString::EstimatedValueSize::TINY,
ColumnString::EstimatedValueSize::SMALL,
ColumnString::EstimatedValueSize::MEDIUM,
ColumnString::EstimatedValueSize::LARGE,

// ColumnString::EstimatedValueSize(0),
ColumnString::EstimatedValueSize(1),
ColumnString::EstimatedValueSize(300),
ColumnString::EstimatedValueSize(10'000),
};

auto values = MakeStrings();
std::cerr << "Number of values: " << values.size() << std::endl;

for (ColumnString::EstimatedValueSize estimation : value_size_estimations) {
SCOPED_TRACE(::testing::Message("with estimation: ") << estimation);
std::cerr << "\nEstimation " << estimation << std::endl;

auto col = std::make_shared<ColumnString>(estimation);

dumpMemoryUsage("After constructing with estimation", col);

col->Reserve(values.size());
dumpMemoryUsage("After Reserve()", col);

size_t i = 0;
for (const auto & v : values) {
col->Append(v);

EXPECT_EQ(i + 1, col->Size());
EXPECT_EQ(v, col->At(i));

++i;
}

dumpMemoryUsage("After appending all values", col);
}
}



struct SizeRatio {
std::vector<float> ratios;
float average;
Expand All @@ -276,19 +232,6 @@ std::ostream & operator<<(std::ostream& ostr, const SizeRatio & r) {
return ostr << "SizeRatio{ average: " << std::fixed << r.average << " } ";
}

//std::vector<SizeRatio> ratios{
// // estimation is about right
// SizeRatio({0.9, 0.95, 1.0, 1.05, 1.1}),
// // estimation is a bit high, real values are about 0.8 of estimated size
// SizeRatio({0.75, 0.8, 0.85}),
// // estimation is a bit low, real values are about 1.2 of estimated size
// SizeRatio({1.25, 1.2, 1.25}),
// // estimation is to high, real values are about 2.0 of estimated size
// SizeRatio({1.9, 2, 2.1}),
// // estimation is to low, real values are about 0.5 of estimated size
// SizeRatio({0.4, 0.5, 0.6}),
// };

/** Make sure that setting value size estimates with ColumnString::EstimatedValueSize either via contructor or via SetEstimatedValueSize
* doesn't break ColumnString functionality and well-behaves with Reserve() and Append().
* I.e. values are appended properly, nothing crashes and memory usage is not crazy-high if estimation is incorrect.
Expand Down Expand Up @@ -340,7 +283,10 @@ struct ColumnStringEstimatedValueSizeTest : public ::testing::TestWithParam<std:

size_t EstimateMemoryUsage(size_t total_values_size, float expected_number_of_items_multiplier = 1.0) {
const auto & [single_value_size_estimation, size_ratio] = GetParam();
return EstimateColumnStringMemoryUsage(expected_number_of_items * expected_number_of_items_multiplier, single_value_size_estimation, size_ratio.average, total_values_size);
return EstimateColumnStringMemoryUsage(expected_number_of_items * expected_number_of_items_multiplier,
single_value_size_estimation,
size_ratio.average,
total_values_size);
}
};

Expand Down Expand Up @@ -383,10 +329,8 @@ TEST_P(ColumnStringEstimatedValueSizeTest, AppendNoReserve)

EXPECT_NO_FATAL_FAILURE(AppendStrings(col, total_values_size));

const auto max_estimation_error_factor = single_value_size_estimation == ColumnString::NO_PREALLOCATE ? 2.5 : 2;

// since there was no Reserve call prior, there could be more some overallocations, hence some estimation error
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size) * max_estimation_error_factor);
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size));
}

TEST_P(ColumnStringEstimatedValueSizeTest, ReserveExactAndAppend)
Expand All @@ -399,10 +343,7 @@ TEST_P(ColumnStringEstimatedValueSizeTest, ReserveExactAndAppend)
EXPECT_NO_THROW(col.Reserve(expected_number_of_items));
EXPECT_NO_FATAL_FAILURE(AppendStrings(col, total_values_size));

const auto max_estimation_error_factor = single_value_size_estimation == ColumnString::NO_PREALLOCATE ? 2.5 : 2;

// Allow minor overallocations, hence * 1.2
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size) * max_estimation_error_factor);
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size));
}

TEST_P(ColumnStringEstimatedValueSizeTest, ReserveLessAndAppend)
Expand All @@ -415,10 +356,7 @@ TEST_P(ColumnStringEstimatedValueSizeTest, ReserveLessAndAppend)
EXPECT_NO_THROW(col.Reserve(expected_number_of_items * .8));
EXPECT_NO_FATAL_FAILURE(AppendStrings(col, total_values_size));

const auto max_estimation_error_factor = single_value_size_estimation == ColumnString::NO_PREALLOCATE ? 2.5 : 2;

// Allow minor overallocations, hence * 1.2
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size) * max_estimation_error_factor);
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size));
}

TEST_P(ColumnStringEstimatedValueSizeTest, ReserveMoreAndAppend)
Expand All @@ -431,10 +369,7 @@ TEST_P(ColumnStringEstimatedValueSizeTest, ReserveMoreAndAppend)
EXPECT_NO_THROW(col.Reserve(expected_number_of_items * 1.2));
EXPECT_NO_FATAL_FAILURE(AppendStrings(col, total_values_size));

const auto max_estimation_error_factor = single_value_size_estimation == ColumnString::NO_PREALLOCATE ? 2.5 : 2;

// Allow minor overallocations, hence * 1.2
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size, 1.2) * max_estimation_error_factor);
EXPECT_LT(col.MemoryUsage(), EstimateMemoryUsage(total_values_size, 1.2));
}

/** TODO more tests
Expand Down

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