#error EliasFanoCoding.h requires GCC
#endif
-#if !defined(__x86_64__)
+#if !FOLLY_X64
#error EliasFanoCoding.h requires x86_64
#endif
-#include <algorithm>
#include <cstdlib>
#include <limits>
#include <type_traits>
#include <boost/noncopyable.hpp>
#include <glog/logging.h>
-#include "folly/Bits.h"
-#include "folly/CpuId.h"
-#include "folly/Likely.h"
-#include "folly/Range.h"
+#include <folly/Bits.h>
+#include <folly/CpuId.h>
+#include <folly/Likely.h>
+#include <folly/Range.h>
#if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__
#error EliasFanoCoding.h requires little endianness
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_);
+
+ 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);
+ }
- for (size_t i = q - 1, pos = 0; i < size; i += q, ++pos) {
- const ValueType upperBits = list[i] >> numLowerBits;
+ /* 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
explicit UpperBitsReader(const EliasFanoCompressedList& list)
: forwardPointers_(list.forwardPointers.data()),
skipPointers_(list.skipPointers.data()),
- start_(list.upper.data()),
- block_(start_ != nullptr ? folly::loadUnaligned<block_t>(start_) : 0),
- outer_(0), // outer offset: number of consumed bytes in upper.
- inner_(-1), // inner offset: (bit) position in current block.
- position_(-1), // index of current value (= #reads - 1).
- value_(0) { }
+ start_(list.upper.data()) {
+ reset();
+ }
+
+ void reset() {
+ block_ = start_ != nullptr ? folly::loadUnaligned<block_t>(start_) : 0;
+ outer_ = 0;
+ inner_ = -1;
+ position_ = -1;
+ value_ = 0;
+ }
size_t position() const { return position_; }
ValueType value() const { return value_; }
return value_;
}
+ ValueType jump(size_t n) {
+ if (Encoder::forwardQuantum == 0 || n <= Encoder::forwardQuantum) {
+ reset();
+ } else {
+ position_ = -1; // Avoid reading the head, skip() will reposition.
+ }
+ return skip(n);
+ }
+
+ ValueType jumpToNext(ValueType v) {
+ if (Encoder::skipQuantum == 0 || v < Encoder::skipQuantum) {
+ reset();
+ } else {
+ value_ = 0; // Avoid reading the head, skipToNext() will reposition.
+ }
+ return skipToNext(v);
+ }
+
private:
ValueType setValue() {
value_ = static_cast<ValueType>(8 * outer_ + inner_ - position_);
const unsigned char* const skipPointers_;
const unsigned char* const start_;
block_t block_;
- size_t outer_;
- size_t inner_;
- size_t position_;
+ size_t outer_; // Outer offset: number of consumed bytes in upper.
+ size_t inner_; // Inner offset: (bit) position in current block.
+ size_t position_; // Index of current value (= #reads - 1).
ValueType value_;
};
class Instructions = instructions::Default>
class EliasFanoReader : private boost::noncopyable {
public:
+ typedef Encoder EncoderType;
typedef typename Encoder::ValueType ValueType;
explicit EliasFanoReader(const EliasFanoCompressedList& list)
: list_(list),
lowerMask_((ValueType(1) << list_.numLowerBits) - 1),
- upper_(list),
- progress_(0),
- value_(0) {
+ upper_(list_) {
DCHECK(Instructions::supported());
// To avoid extra branching during skipTo() while reading
// upper sequence we need to know the last element.
(lastUpperValue << list_.numLowerBits);
}
- size_t size() const { return list_.size; }
-
- size_t position() const { return progress_ - 1; }
- ValueType value() const { return value_; }
+ void reset() {
+ upper_.reset();
+ progress_ = 0;
+ value_ = 0;
+ }
bool next() {
if (UNLIKELY(progress_ == list_.size)) {
bool skip(size_t n) {
CHECK_GT(n, 0);
- progress_ += n - 1;
- if (LIKELY(progress_ < list_.size)) {
- value_ = readLowerPart(progress_) |
+ progress_ += n;
+ if (LIKELY(progress_ <= list_.size)) {
+ value_ = readLowerPart(progress_ - 1) |
(upper_.skip(n) << list_.numLowerBits);
- ++progress_;
return true;
}
DCHECK_GE(value, value_);
if (value <= value_) {
return true;
- }
- if (value > lastValue_) {
+ } else if (value > lastValue_) {
progress_ = list_.size;
value_ = std::numeric_limits<ValueType>::max();
return false;
}
upper_.skipToNext(value >> list_.numLowerBits);
- progress_ = upper_.position();
- value_ = readLowerPart(progress_) |
- (upper_.value() << list_.numLowerBits);
- ++progress_;
- while (value_ < value) {
- value_ = readLowerPart(progress_) |
- (upper_.next() << list_.numLowerBits);
- ++progress_;
+ iterateTo(value);
+ return true;
+ }
+
+ bool jump(size_t n) {
+ if (LIKELY(n - 1 < list_.size)) { // n > 0 && n <= list_.size
+ progress_ = n;
+ value_ = readLowerPart(n - 1) | (upper_.jump(n) << list_.numLowerBits);
+ return true;
+ } else if (n == 0) {
+ reset();
+ return true;
+ }
+ progress_ = list_.size;
+ value_ = std::numeric_limits<ValueType>::max();
+ return false;
+ }
+
+ ValueType jumpTo(ValueType value) {
+ if (value <= 0) {
+ reset();
+ return true;
+ } else if (value > lastValue_) {
+ progress_ = list_.size;
+ value_ = std::numeric_limits<ValueType>::max();
+ return false;
}
+ upper_.jumpToNext(value >> list_.numLowerBits);
+ iterateTo(value);
return true;
}
+ size_t size() const { return list_.size; }
+
+ size_t position() const { return progress_ - 1; }
+ ValueType value() const { return value_; }
+
private:
ValueType readLowerPart(size_t i) const {
+ DCHECK_LT(i, list_.size);
const size_t pos = i * list_.numLowerBits;
const unsigned char* ptr = list_.lower.data() + (pos / 8);
const uint64_t ptrv = folly::loadUnaligned<uint64_t>(ptr);
return lowerMask_ & (ptrv >> (pos % 8));
}
+ void iterateTo(ValueType value) {
+ progress_ = upper_.position();
+ value_ = readLowerPart(progress_) | (upper_.value() << list_.numLowerBits);
+ ++progress_;
+ while (value_ < value) {
+ value_ = readLowerPart(progress_) | (upper_.next() << list_.numLowerBits);
+ ++progress_;
+ }
+ }
+
const EliasFanoCompressedList list_;
const ValueType lowerMask_;
detail::UpperBitsReader<Encoder, Instructions> upper_;
- size_t progress_;
- ValueType value_;
+ size_t progress_ = 0;
+ ValueType value_ = 0;
ValueType lastValue_;
};
projects / folly.git / blobdiff