rocksdb/table/block_based_table_builder.h
Shobhit Dayal b45b1cde3e Feature for sampling and reporting compressibility (#4842)
Summary:
This is a feature to sample data-block compressibility and and report them as stats. 1 in N (tunable) blocks is sampled for compressibility using two algorithms:
1. lz4 or snappy for fast compression
2. zstd or zlib for slow but higher compression.

The stats are reported to the caller as raw-bytes and compressed-bytes. The block continues to be compressed for storage using the specified CompressionType.

The db_bench_tool how has a command line option for specifying the sampling rate. It's default value is 0 (no sampling). To test the overhead for a certain value, users can compare the performance of db_bench_tool, varying the sampling rate. It is unlikely to have a noticeable impact for high values like 20.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4842

Differential Revision: D13629011

Pulled By: shobhitdayal

fbshipit-source-id: 14ca668bcab6499b2a1734edf848eb62a4f4fafa
2019-03-18 12:15:34 -07:00

146 lines
5.7 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <stdint.h>
#include <limits>
#include <string>
#include <utility>
#include <vector>
#include "rocksdb/flush_block_policy.h"
#include "rocksdb/listener.h"
#include "rocksdb/options.h"
#include "rocksdb/status.h"
#include "table/meta_blocks.h"
#include "table/table_builder.h"
#include "util/compression.h"
namespace rocksdb {
class BlockBuilder;
class BlockHandle;
class WritableFile;
struct BlockBasedTableOptions;
extern const uint64_t kBlockBasedTableMagicNumber;
extern const uint64_t kLegacyBlockBasedTableMagicNumber;
class BlockBasedTableBuilder : public TableBuilder {
public:
// Create a builder that will store the contents of the table it is
// building in *file. Does not close the file. It is up to the
// caller to close the file after calling Finish().
BlockBasedTableBuilder(
const ImmutableCFOptions& ioptions, const MutableCFOptions& moptions,
const BlockBasedTableOptions& table_options,
const InternalKeyComparator& internal_comparator,
const std::vector<std::unique_ptr<IntTblPropCollectorFactory>>*
int_tbl_prop_collector_factories,
uint32_t column_family_id, WritableFileWriter* file,
const CompressionType compression_type,
const uint64_t sample_for_compression,
const CompressionOptions& compression_opts, const bool skip_filters,
const std::string& column_family_name, const uint64_t creation_time = 0,
const uint64_t oldest_key_time = 0, const uint64_t target_file_size = 0);
// REQUIRES: Either Finish() or Abandon() has been called.
~BlockBasedTableBuilder();
// No copying allowed
BlockBasedTableBuilder(const BlockBasedTableBuilder&) = delete;
BlockBasedTableBuilder& operator=(const BlockBasedTableBuilder&) = delete;
// 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;
// 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;
bool NeedCompact() const override;
// Get table properties
TableProperties GetTableProperties() const override;
private:
bool ok() const { return status().ok(); }
// Transition state from buffered to unbuffered. See `Rep::State` API comment
// for details of the states.
// REQUIRES: `rep_->state == kBuffered`
void EnterUnbuffered();
// Call block's Finish() method
// and then write the compressed block contents to file.
void WriteBlock(BlockBuilder* block, BlockHandle* handle, bool is_data_block);
// Compress and write block content to the file.
void WriteBlock(const Slice& block_contents, BlockHandle* handle,
bool is_data_block);
// Directly write data to the file.
void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle,
bool is_data_block = false);
Status InsertBlockInCache(const Slice& block_contents,
const CompressionType type,
const BlockHandle* handle);
void WriteFilterBlock(MetaIndexBuilder* meta_index_builder);
void WriteIndexBlock(MetaIndexBuilder* meta_index_builder,
BlockHandle* index_block_handle);
void WritePropertiesBlock(MetaIndexBuilder* meta_index_builder);
void WriteCompressionDictBlock(MetaIndexBuilder* meta_index_builder);
void WriteRangeDelBlock(MetaIndexBuilder* meta_index_builder);
void WriteFooter(BlockHandle& metaindex_block_handle,
BlockHandle& index_block_handle);
struct Rep;
class BlockBasedTablePropertiesCollectorFactory;
class BlockBasedTablePropertiesCollector;
Rep* rep_;
// Advanced operation: flush any buffered key/value pairs to file.
// Can be used to ensure that two adjacent entries never live in
// the same data block. Most clients should not need to use this method.
// REQUIRES: Finish(), Abandon() have not been called
void Flush();
// Some compression libraries fail when the raw size is bigger than int. If
// uncompressed size is bigger than kCompressionSizeLimit, don't compress it
const uint64_t kCompressionSizeLimit = std::numeric_limits<int>::max();
};
Slice CompressBlock(const Slice& raw, const CompressionInfo& info,
CompressionType* type, uint32_t format_version,
bool do_sample, std::string* compressed_output,
std::string* sampled_output_fast,
std::string* sampled_output_slow);
} // namespace rocksdb