fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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399 lines
14 KiB
399 lines
14 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#ifndef ROCKSDB_LITE
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#include "table/cuckoo_table_reader.h"
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#include <algorithm>
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#include <limits>
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#include <string>
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#include <utility>
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#include <vector>
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#include "rocksdb/iterator.h"
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#include "rocksdb/table.h"
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#include "table/internal_iterator.h"
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#include "table/meta_blocks.h"
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#include "table/cuckoo_table_factory.h"
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#include "table/get_context.h"
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#include "util/arena.h"
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#include "util/coding.h"
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namespace rocksdb {
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namespace {
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const uint64_t CACHE_LINE_MASK = ~((uint64_t)CACHE_LINE_SIZE - 1);
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const uint32_t kInvalidIndex = std::numeric_limits<uint32_t>::max();
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}
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extern const uint64_t kCuckooTableMagicNumber;
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CuckooTableReader::CuckooTableReader(
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const ImmutableCFOptions& ioptions,
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std::unique_ptr<RandomAccessFileReader>&& file, uint64_t file_size,
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const Comparator* comparator,
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uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t))
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: file_(std::move(file)),
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is_last_level_(false),
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identity_as_first_hash_(false),
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use_module_hash_(false),
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num_hash_func_(0),
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unused_key_(""),
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key_length_(0),
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user_key_length_(0),
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value_length_(0),
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bucket_length_(0),
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cuckoo_block_size_(0),
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cuckoo_block_bytes_minus_one_(0),
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table_size_(0),
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ucomp_(comparator),
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get_slice_hash_(get_slice_hash) {
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if (!ioptions.allow_mmap_reads) {
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status_ = Status::InvalidArgument("File is not mmaped");
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}
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TableProperties* props = nullptr;
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status_ = ReadTableProperties(file_.get(), file_size, kCuckooTableMagicNumber,
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ioptions, &props);
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if (!status_.ok()) {
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return;
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}
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table_props_.reset(props);
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auto& user_props = props->user_collected_properties;
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auto hash_funs = user_props.find(CuckooTablePropertyNames::kNumHashFunc);
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if (hash_funs == user_props.end()) {
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status_ = Status::Corruption("Number of hash functions not found");
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return;
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}
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num_hash_func_ = *reinterpret_cast<const uint32_t*>(hash_funs->second.data());
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auto unused_key = user_props.find(CuckooTablePropertyNames::kEmptyKey);
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if (unused_key == user_props.end()) {
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status_ = Status::Corruption("Empty bucket value not found");
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return;
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}
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unused_key_ = unused_key->second;
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key_length_ = static_cast<uint32_t>(props->fixed_key_len);
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auto user_key_len = user_props.find(CuckooTablePropertyNames::kUserKeyLength);
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if (user_key_len == user_props.end()) {
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status_ = Status::Corruption("User key length not found");
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return;
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}
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user_key_length_ = *reinterpret_cast<const uint32_t*>(
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user_key_len->second.data());
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auto value_length = user_props.find(CuckooTablePropertyNames::kValueLength);
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if (value_length == user_props.end()) {
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status_ = Status::Corruption("Value length not found");
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return;
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}
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value_length_ = *reinterpret_cast<const uint32_t*>(
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value_length->second.data());
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bucket_length_ = key_length_ + value_length_;
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auto hash_table_size = user_props.find(
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CuckooTablePropertyNames::kHashTableSize);
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if (hash_table_size == user_props.end()) {
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status_ = Status::Corruption("Hash table size not found");
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return;
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}
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table_size_ = *reinterpret_cast<const uint64_t*>(
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hash_table_size->second.data());
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auto is_last_level = user_props.find(CuckooTablePropertyNames::kIsLastLevel);
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if (is_last_level == user_props.end()) {
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status_ = Status::Corruption("Is last level not found");
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return;
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}
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is_last_level_ = *reinterpret_cast<const bool*>(is_last_level->second.data());
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auto identity_as_first_hash = user_props.find(
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CuckooTablePropertyNames::kIdentityAsFirstHash);
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if (identity_as_first_hash == user_props.end()) {
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status_ = Status::Corruption("identity as first hash not found");
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return;
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}
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identity_as_first_hash_ = *reinterpret_cast<const bool*>(
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identity_as_first_hash->second.data());
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auto use_module_hash = user_props.find(
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CuckooTablePropertyNames::kUseModuleHash);
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if (use_module_hash == user_props.end()) {
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status_ = Status::Corruption("hash type is not found");
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return;
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}
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use_module_hash_ = *reinterpret_cast<const bool*>(
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use_module_hash->second.data());
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auto cuckoo_block_size = user_props.find(
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CuckooTablePropertyNames::kCuckooBlockSize);
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if (cuckoo_block_size == user_props.end()) {
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status_ = Status::Corruption("Cuckoo block size not found");
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return;
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}
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cuckoo_block_size_ = *reinterpret_cast<const uint32_t*>(
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cuckoo_block_size->second.data());
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cuckoo_block_bytes_minus_one_ = cuckoo_block_size_ * bucket_length_ - 1;
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status_ = file_->Read(0, file_size, &file_data_, nullptr);
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}
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Status CuckooTableReader::Get(const ReadOptions& /*readOptions*/,
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const Slice& key, GetContext* get_context,
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bool /*skip_filters*/) {
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assert(key.size() == key_length_ + (is_last_level_ ? 8 : 0));
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Slice user_key = ExtractUserKey(key);
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for (uint32_t hash_cnt = 0; hash_cnt < num_hash_func_; ++hash_cnt) {
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uint64_t offset = bucket_length_ * CuckooHash(
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user_key, hash_cnt, use_module_hash_, table_size_,
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identity_as_first_hash_, get_slice_hash_);
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const char* bucket = &file_data_.data()[offset];
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for (uint32_t block_idx = 0; block_idx < cuckoo_block_size_;
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++block_idx, bucket += bucket_length_) {
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if (ucomp_->Equal(Slice(unused_key_.data(), user_key.size()),
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Slice(bucket, user_key.size()))) {
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return Status::OK();
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}
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// Here, we compare only the user key part as we support only one entry
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// per user key and we don't support snapshot.
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if (ucomp_->Equal(user_key, Slice(bucket, user_key.size()))) {
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Slice value(bucket + key_length_, value_length_);
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if (is_last_level_) {
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// Sequence number is not stored at the last level, so we will use
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// kMaxSequenceNumber since it is unknown. This could cause some
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// transactions to fail to lock a key due to known sequence number.
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// However, it is expected for anyone to use a CuckooTable in a
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// TransactionDB.
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get_context->SaveValue(value, kMaxSequenceNumber);
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} else {
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Slice full_key(bucket, key_length_);
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ParsedInternalKey found_ikey;
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ParseInternalKey(full_key, &found_ikey);
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bool dont_care __attribute__((__unused__));
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get_context->SaveValue(found_ikey, value, &dont_care);
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}
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// We don't support merge operations. So, we return here.
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return Status::OK();
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}
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}
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}
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return Status::OK();
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}
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void CuckooTableReader::Prepare(const Slice& key) {
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// Prefetch the first Cuckoo Block.
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Slice user_key = ExtractUserKey(key);
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uint64_t addr = reinterpret_cast<uint64_t>(file_data_.data()) +
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bucket_length_ * CuckooHash(user_key, 0, use_module_hash_, table_size_,
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identity_as_first_hash_, nullptr);
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uint64_t end_addr = addr + cuckoo_block_bytes_minus_one_;
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for (addr &= CACHE_LINE_MASK; addr < end_addr; addr += CACHE_LINE_SIZE) {
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PREFETCH(reinterpret_cast<const char*>(addr), 0, 3);
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}
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}
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class CuckooTableIterator : public InternalIterator {
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public:
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explicit CuckooTableIterator(CuckooTableReader* reader);
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~CuckooTableIterator() {}
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bool Valid() const override;
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void SeekToFirst() override;
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void SeekToLast() override;
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void Seek(const Slice& target) override;
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void SeekForPrev(const Slice& target) override;
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void Next() override;
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void Prev() override;
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Slice key() const override;
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Slice value() const override;
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Status status() const override { return status_; }
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void InitIfNeeded();
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private:
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struct BucketComparator {
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BucketComparator(const Slice& file_data, const Comparator* ucomp,
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uint32_t bucket_len, uint32_t user_key_len,
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const Slice& target = Slice())
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: file_data_(file_data),
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ucomp_(ucomp),
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bucket_len_(bucket_len),
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user_key_len_(user_key_len),
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target_(target) {}
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bool operator()(const uint32_t first, const uint32_t second) const {
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const char* first_bucket =
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(first == kInvalidIndex) ? target_.data() :
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&file_data_.data()[first * bucket_len_];
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const char* second_bucket =
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(second == kInvalidIndex) ? target_.data() :
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&file_data_.data()[second * bucket_len_];
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return ucomp_->Compare(Slice(first_bucket, user_key_len_),
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Slice(second_bucket, user_key_len_)) < 0;
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}
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private:
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const Slice file_data_;
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const Comparator* ucomp_;
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const uint32_t bucket_len_;
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const uint32_t user_key_len_;
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const Slice target_;
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};
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const BucketComparator bucket_comparator_;
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void PrepareKVAtCurrIdx();
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CuckooTableReader* reader_;
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bool initialized_;
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Status status_;
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// Contains a map of keys to bucket_id sorted in key order.
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std::vector<uint32_t> sorted_bucket_ids_;
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// We assume that the number of items can be stored in uint32 (4 Billion).
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uint32_t curr_key_idx_;
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Slice curr_value_;
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IterKey curr_key_;
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// No copying allowed
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CuckooTableIterator(const CuckooTableIterator&) = delete;
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void operator=(const Iterator&) = delete;
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};
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CuckooTableIterator::CuckooTableIterator(CuckooTableReader* reader)
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: bucket_comparator_(reader->file_data_, reader->ucomp_,
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reader->bucket_length_, reader->user_key_length_),
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reader_(reader),
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initialized_(false),
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curr_key_idx_(kInvalidIndex) {
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sorted_bucket_ids_.clear();
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curr_value_.clear();
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curr_key_.Clear();
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}
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void CuckooTableIterator::InitIfNeeded() {
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if (initialized_) {
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return;
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}
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sorted_bucket_ids_.reserve(reader_->GetTableProperties()->num_entries);
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uint64_t num_buckets = reader_->table_size_ + reader_->cuckoo_block_size_ - 1;
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assert(num_buckets < kInvalidIndex);
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const char* bucket = reader_->file_data_.data();
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for (uint32_t bucket_id = 0; bucket_id < num_buckets; ++bucket_id) {
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if (Slice(bucket, reader_->key_length_) != Slice(reader_->unused_key_)) {
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sorted_bucket_ids_.push_back(bucket_id);
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}
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bucket += reader_->bucket_length_;
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}
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assert(sorted_bucket_ids_.size() ==
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reader_->GetTableProperties()->num_entries);
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std::sort(sorted_bucket_ids_.begin(), sorted_bucket_ids_.end(),
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bucket_comparator_);
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curr_key_idx_ = kInvalidIndex;
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initialized_ = true;
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}
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void CuckooTableIterator::SeekToFirst() {
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InitIfNeeded();
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curr_key_idx_ = 0;
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PrepareKVAtCurrIdx();
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}
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void CuckooTableIterator::SeekToLast() {
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InitIfNeeded();
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curr_key_idx_ = static_cast<uint32_t>(sorted_bucket_ids_.size()) - 1;
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PrepareKVAtCurrIdx();
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}
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void CuckooTableIterator::Seek(const Slice& target) {
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InitIfNeeded();
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const BucketComparator seek_comparator(
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reader_->file_data_, reader_->ucomp_,
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reader_->bucket_length_, reader_->user_key_length_,
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ExtractUserKey(target));
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auto seek_it = std::lower_bound(sorted_bucket_ids_.begin(),
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sorted_bucket_ids_.end(),
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kInvalidIndex,
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seek_comparator);
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curr_key_idx_ =
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static_cast<uint32_t>(std::distance(sorted_bucket_ids_.begin(), seek_it));
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PrepareKVAtCurrIdx();
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}
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void CuckooTableIterator::SeekForPrev(const Slice& /*target*/) {
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// Not supported
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assert(false);
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}
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bool CuckooTableIterator::Valid() const {
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return curr_key_idx_ < sorted_bucket_ids_.size();
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}
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void CuckooTableIterator::PrepareKVAtCurrIdx() {
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if (!Valid()) {
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curr_value_.clear();
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curr_key_.Clear();
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return;
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}
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uint32_t id = sorted_bucket_ids_[curr_key_idx_];
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const char* offset = reader_->file_data_.data() +
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id * reader_->bucket_length_;
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if (reader_->is_last_level_) {
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// Always return internal key.
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curr_key_.SetInternalKey(Slice(offset, reader_->user_key_length_),
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0, kTypeValue);
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} else {
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curr_key_.SetInternalKey(Slice(offset, reader_->key_length_));
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}
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curr_value_ = Slice(offset + reader_->key_length_, reader_->value_length_);
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}
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void CuckooTableIterator::Next() {
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if (!Valid()) {
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curr_value_.clear();
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curr_key_.Clear();
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return;
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}
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++curr_key_idx_;
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PrepareKVAtCurrIdx();
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}
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void CuckooTableIterator::Prev() {
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if (curr_key_idx_ == 0) {
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curr_key_idx_ = static_cast<uint32_t>(sorted_bucket_ids_.size());
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}
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if (!Valid()) {
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curr_value_.clear();
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curr_key_.Clear();
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return;
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}
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--curr_key_idx_;
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PrepareKVAtCurrIdx();
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}
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Slice CuckooTableIterator::key() const {
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assert(Valid());
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return curr_key_.GetInternalKey();
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}
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Slice CuckooTableIterator::value() const {
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assert(Valid());
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return curr_value_;
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}
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extern InternalIterator* NewErrorInternalIterator(const Status& status,
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Arena* arena);
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InternalIterator* CuckooTableReader::NewIterator(
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const ReadOptions& /*read_options*/, Arena* arena, bool /*skip_filters*/) {
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if (!status().ok()) {
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return NewErrorInternalIterator(
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Status::Corruption("CuckooTableReader status is not okay."), arena);
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}
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CuckooTableIterator* iter;
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if (arena == nullptr) {
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iter = new CuckooTableIterator(this);
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} else {
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auto iter_mem = arena->AllocateAligned(sizeof(CuckooTableIterator));
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iter = new (iter_mem) CuckooTableIterator(this);
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}
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return iter;
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}
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size_t CuckooTableReader::ApproximateMemoryUsage() const { return 0; }
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} // namespace rocksdb
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#endif
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