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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/vespalib/util/compressionconfig.h>
#include <vespa/vespalib/util/compressor.h>
#include <lz4.h>
#include <vespa/searchlib/common/identifiable.h>
#include <vespa/vespalib/data/databuffer.h>
#include <vespa/vespalib/objects/deserializer.h>
#include <vespa/vespalib/objects/identifiable.h>
#include <vespa/vespalib/objects/serializer.h>
#include <algorithm>
#include <unordered_set>
#include <ostream>
namespace search {
template <int BucketBits, typename HashT> struct NormalSketch;
/**
* Sketch interface.
*/
template <int BucketBits, typename HashT>
struct Sketch {
enum { bucketBits = BucketBits };
using hash_type = HashT;
using SketchType = Sketch<BucketBits, HashT>;
using UP = std::unique_ptr<SketchType>;
static const HashT BUCKET_COUNT = HashT(1) << BucketBits;
static const HashT BUCKET_MASK = BUCKET_COUNT - 1;
virtual ~Sketch() = default;
virtual int aggregate(HashT hash) = 0;
[[nodiscard]] virtual uint32_t getClassId() const = 0;
virtual void serialize(vespalib::Serializer &os) const = 0;
virtual void deserialize(vespalib::Deserializer &is) = 0;
virtual bool operator==(const SketchType &other) const = 0;
virtual void print(std::ostream &out) const = 0;
};
template <int BucketBits, typename HashT>
std::ostream &operator<<(std::ostream &o, const Sketch<BucketBits, HashT> &s) {
o << "[";
s.print(o);
return o << " ]";
}
template <typename T>
uint8_t countPrefixZeros(T t) {
uint8_t count = 0;
const T FIRST_BIT = T(1) << ((sizeof(T) * 8) - 1);
while (!((t << count) & FIRST_BIT)) {
++count;
}
return ++count;
}
/**
* Sketch containing a set of hashes
*/
template <int BucketBits = 10, typename HashT = uint32_t>
struct SparseSketch : Sketch<BucketBits, HashT> {
using typename Sketch<BucketBits, HashT>::SketchType;
enum { classId = IDENTIFIABLE_CLASSID_NS(search, SparseSketch) };
struct IdentityHash {
size_t operator()(HashT hash) const noexcept { return hash; }
};
std::unordered_set<HashT, IdentityHash> hash_set;
~SparseSketch() override;
[[nodiscard]] size_t getSize() const { return hash_set.size(); }
int aggregate(HashT hash) override {
return hash_set.insert(hash).second ? 1 : 0;
}
[[nodiscard]] uint32_t getClassId() const override { return classId; }
void serialize(vespalib::Serializer &os) const override;
void deserialize(vespalib::Deserializer &is) override;
bool operator==(const SketchType &other) const override {
const auto *other_sparse = dynamic_cast<const SparseSketch<BucketBits, HashT> *>(&other);
if (!other_sparse) {
return false;
}
if (hash_set.size() != other_sparse->hash_set.size()) {
return false;
}
for (auto hash : hash_set) {
if (other_sparse->hash_set.count(hash) == 0) {
return false;
}
}
return true;
}
bool operator==(const SparseSketch<BucketBits, HashT>& other) const {
return operator==(static_cast<const SketchType&>(other));
}
void print(std::ostream &out) const override {
out << " (" << hash_set.size() << " elements)";
for (auto hash : hash_set) {
out << " 0x" << std::hex;
out.width(8);
out.fill('0');
out << hash;
}
}
void merge(const SparseSketch<BucketBits, HashT> &other) {
hash_set.insert(other.hash_set.begin(), other.hash_set.end());
}
};
/**
* Sketch containing a fixed number of buckets
*/
template <int BucketBits = 10, typename HashT = uint32_t>
struct NormalSketch : Sketch<BucketBits, HashT> {
using typename Sketch<BucketBits, HashT>::SketchType;
using Sketch<BucketBits, HashT>::BUCKET_COUNT;
using Sketch<BucketBits, HashT>::BUCKET_MASK;
using UP = std::unique_ptr<NormalSketch>;
enum { classId = IDENTIFIABLE_CLASSID_NS(search, NormalSketch) };
uint8_t bucket[BUCKET_COUNT];
NormalSketch() { memset(&bucket[0], 0, BUCKET_COUNT); }
int aggregate(HashT hash) override {
uint8_t existing_value = bucket[hash & BUCKET_MASK];
uint8_t new_value = countPrefixZeros(hash | BUCKET_MASK);
if (new_value > existing_value) {
bucket[hash & BUCKET_MASK] = new_value;
return new_value - existing_value;
}
return 0;
}
uint32_t compress_buckets_into(char *buffer, uint32_t size) const;
void decompress_buckets_from(char *buffer, uint32_t size);
[[nodiscard]] uint32_t getClassId() const override { return classId; }
void serialize(vespalib::Serializer &os) const override;
void deserialize(vespalib::Deserializer &is) override;
bool operator==(const SketchType &other) const override {
const auto *other_normal = dynamic_cast<const NormalSketch<BucketBits, HashT> *>(&other);
if (!other_normal) {
return false;
}
for (size_t i = 0; i < BUCKET_COUNT; ++i) {
if (other_normal->bucket[i] != bucket[i]) {
return false;
}
}
return true;
}
bool operator==(const NormalSketch<BucketBits, HashT>& other) const {
return operator==(static_cast<const SketchType&>(other));
}
void print(std::ostream &out) const override {
for (size_t i = 0; i < BUCKET_COUNT; ++i) {
out << " " << int(bucket[i]);
}
}
void merge(const NormalSketch<BucketBits, HashT> &other) {
std::transform(bucket, bucket + BUCKET_COUNT, other.bucket, bucket,
[](uint8_t a, uint8_t b) { return std::max(a, b); });
}
void merge(const SparseSketch<BucketBits, HashT> &other) {
for (auto hash : other.hash_set) {
aggregate(hash);
}
}
};
template <int BucketBits, typename HashT>
SparseSketch<BucketBits, HashT>::~SparseSketch() = default;
template <int BucketBits, typename HashT>
void SparseSketch<BucketBits, HashT>::
serialize(vespalib::Serializer &os) const {
uint32_t size = hash_set.size();
os << size;
for (HashT hash : hash_set) {
os << hash;
}
}
template <int BucketBits, typename HashT>
void SparseSketch<BucketBits, HashT>::
deserialize(vespalib::Deserializer &is) {
uint32_t size;
is >> size;
for (uint32_t i = 0; i < size; ++i) {
uint32_t hash;
is >> hash;
aggregate(hash);
}
}
template <int BucketBits, typename HashT>
uint32_t NormalSketch<BucketBits, HashT>::
compress_buckets_into(char *buffer, uint32_t size) const {
vespalib::compression::CompressionConfig config(vespalib::compression::CompressionConfig::LZ4, 9, 9);
vespalib::ConstBufferRef org(&bucket[0], BUCKET_COUNT);
vespalib::DataBuffer compress_buffer(buffer, size);
vespalib::compression::CompressionConfig::Type r =
vespalib::compression::compress(config, org, compress_buffer, false);
assert(compress_buffer.getDead() == buffer);
if (r == vespalib::compression::CompressionConfig::LZ4) {
assert(compress_buffer.getDataLen() < BUCKET_COUNT);
return compress_buffer.getDataLen();
} else {
assert(BUCKET_COUNT <= size);
memcpy(buffer, bucket, BUCKET_COUNT);
return BUCKET_COUNT;
}
}
template <int BucketBits, typename HashT>
void NormalSketch<BucketBits, HashT>::
decompress_buckets_from(char *buffer, uint32_t size) {
if (size == BUCKET_COUNT) { // not compressed
memcpy(bucket, buffer, BUCKET_COUNT);
} else {
vespalib::ConstBufferRef compressed(buffer, size);
vespalib::DataBuffer uncompressed(reinterpret_cast<char *>(&bucket[0]), BUCKET_COUNT);
vespalib::compression::decompress(vespalib::compression::CompressionConfig::LZ4, BUCKET_COUNT,
compressed, uncompressed, false);
}
}
template <int BucketBits, typename HashT>
void NormalSketch<BucketBits, HashT>::
serialize(vespalib::Serializer &os) const {
vespalib::alloc::Alloc backing(vespalib::alloc::Alloc::alloc(LZ4_compressBound(BUCKET_COUNT)));
char * compress_array(static_cast<char *>(backing.get()));
uint32_t size = compress_buckets_into(compress_array, backing.size());
os << BUCKET_COUNT << size;
for (size_t i = 0; i < size; ++i) {
os << static_cast<uint8_t>(compress_array[i]);
}
}
template <int BucketBits, typename HashT>
void NormalSketch<BucketBits, HashT>::
deserialize(vespalib::Deserializer &is) {
uint32_t bucket_count, size;
is >> bucket_count >> size;
assert(bucket_count == BUCKET_COUNT);
uint8_t compressed_array[BUCKET_COUNT];
for (size_t i = 0; i < size; ++i) {
is >> compressed_array[i];
}
decompress_buckets_from(reinterpret_cast<char *>(compressed_array), size);
}
} // namespace search
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