rocksdb/table/cuckoo_table_builder.h
Lei Jin 94997eab5e reduce memory usage of cuckoo table builder
Summary:
builder currently buffers all key value pairs as a vector of
pair<string, string>. That is too much due to std::string
overhead. It wasn't able to fit 1B key/values (12bytes total) in 100GB
of ram. Switch to use a plain string to store the key/value sequence and
use only 12GB of ram as a result.

Test Plan: db_bench

Reviewers: igor, sdong, yhchiang

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23763
2014-09-25 16:34:24 -07:00

119 lines
4.0 KiB
C++

// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#ifndef ROCKSDB_LITE
#include <stdint.h>
#include <limits>
#include <string>
#include <utility>
#include <vector>
#include "rocksdb/status.h"
#include "table/table_builder.h"
#include "rocksdb/table.h"
#include "rocksdb/table_properties.h"
#include "util/autovector.h"
namespace rocksdb {
class CuckooTableBuilder: public TableBuilder {
public:
CuckooTableBuilder(
WritableFile* file, double max_hash_table_ratio,
uint32_t max_num_hash_func, uint32_t max_search_depth,
const Comparator* user_comparator, uint32_t cuckoo_block_size,
bool use_module_hash, bool identity_as_first_hash,
uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t));
// REQUIRES: Either Finish() or Abandon() has been called.
~CuckooTableBuilder() {}
// Add key,value to the table being constructed.
// REQUIRES: key is after any previously added key according to comparator.
// REQUIRES: Finish(), Abandon() have not been called
void Add(const Slice& key, const Slice& value) override;
// Return non-ok iff some error has been detected.
Status status() const override { return status_; }
// Finish building the table. Stops using the file passed to the
// constructor after this function returns.
// REQUIRES: Finish(), Abandon() have not been called
Status Finish() override;
// Indicate that the contents of this builder should be abandoned. Stops
// using the file passed to the constructor after this function returns.
// If the caller is not going to call Finish(), it must call Abandon()
// before destroying this builder.
// REQUIRES: Finish(), Abandon() have not been called
void Abandon() override;
// Number of calls to Add() so far.
uint64_t NumEntries() const override;
// Size of the file generated so far. If invoked after a successful
// Finish() call, returns the size of the final generated file.
uint64_t FileSize() const override;
private:
struct CuckooBucket {
CuckooBucket()
: vector_idx(kMaxVectorIdx), make_space_for_key_call_id(0) {}
uint32_t vector_idx;
// This number will not exceed kvs_.size() + max_num_hash_func_.
// We assume number of items is <= 2^32.
uint32_t make_space_for_key_call_id;
};
static const uint32_t kMaxVectorIdx = std::numeric_limits<int32_t>::max();
bool MakeSpaceForKey(
const autovector<uint64_t>& hash_vals,
const uint64_t call_id,
std::vector<CuckooBucket>* buckets,
uint64_t* bucket_id);
Status MakeHashTable(std::vector<CuckooBucket>* buckets);
inline Slice GetKey(uint64_t idx) const;
inline Slice GetUserKey(uint64_t idx) const;
inline Slice GetValue(uint64_t idx) const;
uint32_t num_hash_func_;
WritableFile* file_;
const double max_hash_table_ratio_;
const uint32_t max_num_hash_func_;
const uint32_t max_search_depth_;
const uint32_t cuckoo_block_size_;
uint64_t hash_table_size_;
bool is_last_level_file_;
bool has_seen_first_key_;
uint64_t key_size_;
uint64_t value_size_;
// A list of fixed-size key-value pairs concatenating into a string.
// Use GetKey(), GetUserKey(), and GetValue() to retrieve a specific
// key / value given an index
std::string kvs_;
// Number of key-value pairs stored in kvs_
uint64_t num_entries_;
Status status_;
TableProperties properties_;
const Comparator* ucomp_;
bool use_module_hash_;
bool identity_as_first_hash_;
uint64_t (*get_slice_hash_)(const Slice& s, uint32_t index,
uint64_t max_num_buckets);
std::string largest_user_key_ = "";
std::string smallest_user_key_ = "";
bool closed_; // Either Finish() or Abandon() has been called.
// No copying allowed
CuckooTableBuilder(const CuckooTableBuilder&) = delete;
void operator=(const CuckooTableBuilder&) = delete;
};
} // namespace rocksdb
#endif // ROCKSDB_LITE