#error EliasFanoCoding.h requires x86_64
#endif
-#include <algorithm>
#include <cstdlib>
#include <limits>
#include <type_traits>
namespace folly { namespace compression {
struct EliasFanoCompressedList {
- EliasFanoCompressedList()
- : size(0), numLowerBits(0) { }
+ EliasFanoCompressedList() { }
void free() {
::free(const_cast<unsigned char*>(lower.data()));
::free(const_cast<unsigned char*>(forwardPointers.data()));
}
- size_t size;
- uint8_t numLowerBits;
+ size_t size = 0;
+ uint8_t numLowerBits = 0;
// WARNING: EliasFanoCompressedList has no ownership of
// lower, upper, skipPointers and forwardPointers.
return folly::findLastSet(upperBound / size) - 1;
}
+ // Requires: input range (begin, end) is sorted (encoding
+ // crashes if it's not).
// WARNING: encode() mallocates lower, upper, skipPointers
// and forwardPointers. As EliasFanoCompressedList has
// no ownership of them, you need to call free() explicitly.
- static void encode(const ValueType* list, size_t size,
- EliasFanoCompressedList& result) {
- encode(list, list + size, result);
- }
-
- // Range (begin, end) should be sorted.
template <class RandomAccessIterator>
- static void encode(RandomAccessIterator begin,
- RandomAccessIterator end,
- EliasFanoCompressedList& result) {
- CHECK(std::is_sorted(begin, end));
-
- auto list = begin;
- const size_t size = end - begin;
+ static EliasFanoCompressedList encode(RandomAccessIterator begin,
+ RandomAccessIterator end) {
+ if (begin == end) {
+ return EliasFanoCompressedList();
+ }
+ EliasFanoEncoder encoder(end - begin, *(end - 1));
+ for (; begin != end; ++begin) {
+ encoder.add(*begin);
+ }
+ return encoder.finish();
+ }
+ EliasFanoEncoder(size_t size, ValueType upperBound) {
if (size == 0) {
- result = EliasFanoCompressedList();
return;
}
- const ValueType upperBound = list[size - 1];
uint8_t numLowerBits = defaultNumLowerBits(upperBound, size);
// This is detail::writeBits56 limitation.
// *** Lower bits.
const size_t lowerSize = (numLowerBits * size + 7) / 8;
- unsigned char* lower = nullptr;
if (lowerSize > 0) { // numLowerBits != 0
- lower = static_cast<unsigned char*>(calloc(lowerSize + 7, 1));
- const ValueType lowerMask = (ValueType(1) << numLowerBits) - 1;
- for (size_t i = 0; i < size; ++i) {
- const ValueType lowerBits = list[i] & lowerMask;
- writeBits56(lower, i * numLowerBits, numLowerBits, lowerBits);
- }
+ lower_ = static_cast<unsigned char*>(calloc(lowerSize + 7, 1));
}
// *** Upper bits.
(upperBound >> numLowerBits) + // Number of 0-bits to be stored.
size; // 1-bits.
const size_t upperSize = (upperSizeBits + 7) / 8;
- unsigned char* const upper =
- static_cast<unsigned char*>(calloc(upperSize + 7, 1));
- for (size_t i = 0; i < size; ++i) {
- const ValueType upperBits = list[i] >> numLowerBits;
- const size_t pos = upperBits + i; // upperBits 0-bits and (i + 1) 1-bits.
- upper[pos / 8] |= 1U << (pos % 8);
- }
+ upper_ = static_cast<unsigned char*>(calloc(upperSize + 7, 1));
// *** Skip pointers.
// Store (1-indexed) position of every skipQuantum-th
// 0-bit in upper bits sequence.
- SkipValueType* skipPointers = nullptr;
size_t numSkipPointers = 0;
/* static */ if (skipQuantum != 0) {
- // Workaround to avoid 'division by zero' compile-time error.
- constexpr size_t q = skipQuantum ?: 1;
/* static */ if (kVersion > 0) {
CHECK_LT(size, std::numeric_limits<SkipValueType>::max());
} else {
// more serialization-friendly way (upperSizeBits isn't known outside of
// this function, unlike upperSize; thus numSkipPointers could easily be
// deduced from upperSize).
- numSkipPointers = (8 * upperSize - size) / q;
- skipPointers = static_cast<SkipValueType*>(
+ numSkipPointers = (8 * upperSize - size) / (skipQuantum ?: 1);
+ skipPointers_ = static_cast<SkipValueType*>(
numSkipPointers == 0
? nullptr
: calloc(numSkipPointers, sizeof(SkipValueType)));
-
- for (size_t i = 0, pos = 0; i < size; ++i) {
- const ValueType upperBits = list[i] >> numLowerBits;
- for (; (pos + 1) * q <= upperBits; ++pos) {
- /* static */ if (kVersion > 0) {
- // Since version 1, just the number of preceding 1-bits is stored.
- skipPointers[pos] = i;
- } else {
- skipPointers[pos] = i + (pos + 1) * q;
- }
- }
- }
}
// *** Forward pointers.
// Store (1-indexed) position of every forwardQuantum-th
// 1-bit in upper bits sequence.
- SkipValueType* forwardPointers = nullptr;
size_t numForwardPointers = 0;
/* static */ if (forwardQuantum != 0) {
- // Workaround to avoid 'division by zero' compile-time error.
- constexpr size_t q = forwardQuantum ?: 1;
/* static */ if (kVersion > 0) {
CHECK_LT(upperBound >> numLowerBits,
std::numeric_limits<SkipValueType>::max());
CHECK_LT(upperSizeBits, std::numeric_limits<SkipValueType>::max());
}
- numForwardPointers = size / q;
- forwardPointers = static_cast<SkipValueType*>(
+ // '?: 1' is a workaround for false 'division by zero' compile-time error.
+ numForwardPointers = size / (forwardQuantum ?: 1);
+ forwardPointers_ = static_cast<SkipValueType*>(
numForwardPointers == 0
? nullptr
: malloc(numForwardPointers * sizeof(SkipValueType)));
+ }
+
+ // *** Result.
+ result_.size = size;
+ result_.numLowerBits = numLowerBits;
+ result_.lower.reset(lower_, lowerSize);
+ result_.upper.reset(upper_, upperSize);
+ result_.skipPointers.reset(
+ reinterpret_cast<unsigned char*>(skipPointers_),
+ numSkipPointers * sizeof(SkipValueType));
+ result_.forwardPointers.reset(
+ reinterpret_cast<unsigned char*>(forwardPointers_),
+ numForwardPointers * sizeof(SkipValueType));
+ }
+
+ void add(ValueType value) {
+ CHECK_GE(value, lastValue_);
- for (size_t i = q - 1, pos = 0; i < size; i += q, ++pos) {
- const ValueType upperBits = list[i] >> numLowerBits;
+ const auto numLowerBits = result_.numLowerBits;
+ const ValueType upperBits = value >> numLowerBits;
+
+ // Upper sequence consists of upperBits 0-bits and (size_ + 1) 1-bits.
+ const size_t pos = upperBits + size_;
+ upper_[pos / 8] |= 1U << (pos % 8);
+ // Append numLowerBits bits to lower sequence.
+ if (numLowerBits != 0) {
+ const ValueType lowerBits = value & ((ValueType(1) << numLowerBits) - 1);
+ writeBits56(lower_, size_ * numLowerBits, numLowerBits, lowerBits);
+ }
+
+ /* static */ if (skipQuantum != 0) {
+ while ((skipPointersSize_ + 1) * skipQuantum <= upperBits) {
+ /* static */ if (kVersion > 0) {
+ // Since version 1, just the number of preceding 1-bits is stored.
+ skipPointers_[skipPointersSize_] = size_;
+ } else {
+ skipPointers_[skipPointersSize_] =
+ size_ + (skipPointersSize_ + 1) * skipQuantum;
+ }
+ ++skipPointersSize_;
+ }
+ }
+
+ /* static */ if (forwardQuantum != 0) {
+ if ((size_ + 1) % forwardQuantum == 0) {
+ const auto pos = size_ / forwardQuantum;
/* static */ if (kVersion > 0) {
// Since version 1, just the number of preceding 0-bits is stored.
- forwardPointers[pos] = upperBits;
+ forwardPointers_[pos] = upperBits;
} else {
- forwardPointers[pos] = upperBits + i + 1;
+ forwardPointers_[pos] = upperBits + size_ + 1;
}
}
}
- // *** Result.
- result.size = size;
- result.numLowerBits = numLowerBits;
- result.lower.reset(lower, lowerSize);
- result.upper.reset(upper, upperSize);
- result.skipPointers.reset(
- reinterpret_cast<unsigned char*>(skipPointers),
- numSkipPointers * sizeof(SkipValueType));
- result.forwardPointers.reset(
- reinterpret_cast<unsigned char*>(forwardPointers),
- numForwardPointers * sizeof(SkipValueType));
+ lastValue_ = value;
+ ++size_;
+ }
+
+ const EliasFanoCompressedList& finish() const {
+ CHECK_EQ(size_, result_.size);
+ return result_;
}
private:
ptrv |= value << (pos % 8);
folly::storeUnaligned<uint64_t>(ptr, ptrv);
}
+
+ unsigned char* lower_ = nullptr;
+ unsigned char* upper_ = nullptr;
+ SkipValueType* skipPointers_ = nullptr;
+ SkipValueType* forwardPointers_ = nullptr;
+
+ ValueType lastValue_ = 0;
+ size_t size_ = 0;
+ size_t skipPointersSize_ = 0;
+
+ EliasFanoCompressedList result_;
};
// NOTE: It's recommended to compile EF coding with -msse4.2, starting
std::vector<uint32_t> data;
std::vector<size_t> order;
+std::vector<uint32_t> encodeSmallData;
+std::vector<uint32_t> encodeLargeData;
+
typename Encoder::CompressedList list;
void init() {
data = generateRandomList(100 * 1000, 10 * 1000 * 1000, gen);
//data = loadList("/home/philipp/pl_test_dump.txt");
- Encoder::encode(data.data(), data.size(), bm::list);
+ list = Encoder::encode(data.begin(), data.end());
order.clear();
order.reserve(data.size());
order.push_back(i);
}
std::shuffle(order.begin(), order.end(), gen);
+
+ encodeSmallData = generateRandomList(10, 100 * 1000, gen);
+ encodeLargeData = generateRandomList(1000 * 1000, 100 * 1000 * 1000, gen);
}
void free() {
bmSkipTo<bm::Reader>(bm::list, bm::data, 1, bm::k1M);
}
+BENCHMARK_DRAW_LINE();
+
BENCHMARK(SkipTo10_SkipQ128_1M) {
bmSkipTo<bm::Reader>(bm::list, bm::data, 10, bm::k1M);
}
bmSkipTo<bm::Reader>(bm::list, bm::data, 1000, bm::k1M);
}
+BENCHMARK_DRAW_LINE();
+
+BENCHMARK(Encode_10) {
+ auto list = bm::Encoder::encode(bm::encodeSmallData.begin(),
+ bm::encodeSmallData.end());
+ list.free();
+}
+
+BENCHMARK(Encode_1M) {
+ auto list = bm::Encoder::encode(bm::encodeLargeData.begin(),
+ bm::encodeLargeData.end());
+ list.free();
+}
+
#if 0
-Intel Xeon CPU E5-2660 @ 2.7GHz (turbo on), using instructions::Fast.
+Intel(R) Xeon(R) CPU E5-2660 @ 2.7GHz (turbo on), using instructions::Fast.
============================================================================
folly/experimental/test/EliasFanoCodingTest.cpp relative time/iter iters/s
Skip100_ForwardQ128_1M 26.76ms 37.37
Skip1000_ForwardQ128_1M 20.66ms 48.40
GoTo_ForwardQ128_1M 43.75ms 22.86
+----------------------------------------------------------------------------
SkipTo1_SkipQ128_1M 9.74ms 102.70
SkipTo10_SkipQ128_1M 30.62ms 32.66
SkipTo100_SkipQ128_1M 37.70ms 26.53
SkipTo1000_SkipQ128_1M 31.14ms 32.11
+----------------------------------------------------------------------------
+Encode_10 208.16ns 4.80M
+Encode_1M 8.90ms 112.37
============================================================================
#endif
projects / folly.git / commitdiff