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rocksdb/table/meta_blocks.h

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4.6 KiB

// Copyright (c) 2013, 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
#include <map>
#include <memory>
#include <string>
#include "db/builder.h"
#include "rocksdb/comparator.h"
#include "rocksdb/options.h"
#include "rocksdb/slice.h"
#include "rocksdb/table_properties.h"
#include "table/block_builder.h"
namespace rocksdb {
class BlockBuilder;
class BlockHandle;
class Env;
class Footer;
class Logger;
class RandomAccessFile;
struct TableProperties;
// An STL style comparator that does the bytewise comparator comparasion
// internally.
struct BytewiseLessThan {
bool operator()(const std::string& key1, const std::string& key2) const {
// smaller entries will be placed in front.
return comparator->Compare(key1, key2) <= 0;
}
const Comparator* comparator = BytewiseComparator();
};
// When writing to a block that requires entries to be sorted by
// `BytewiseComparator`, we can buffer the content to `BytewiseSortedMap`
// before writng to store.
typedef std::map<std::string, std::string, BytewiseLessThan> BytewiseSortedMap;
class MetaIndexBuilder {
public:
MetaIndexBuilder(const MetaIndexBuilder&) = delete;
MetaIndexBuilder& operator=(const MetaIndexBuilder&) = delete;
MetaIndexBuilder();
void Add(const std::string& key, const BlockHandle& handle);
// Write all the added key/value pairs to the block and return the contents
// of the block.
Slice Finish();
private:
// store the sorted key/handle of the metablocks.
BytewiseSortedMap meta_block_handles_;
std::unique_ptr<BlockBuilder> meta_index_block_;
};
class PropertyBlockBuilder {
public:
PropertyBlockBuilder(const PropertyBlockBuilder&) = delete;
PropertyBlockBuilder& operator=(const PropertyBlockBuilder&) = delete;
PropertyBlockBuilder();
void AddTableProperty(const TableProperties& props);
void Add(const std::string& key, uint64_t value);
void Add(const std::string& key, const std::string& value);
void Add(const UserCollectedProperties& user_collected_properties);
// Write all the added entries to the block and return the block contents
Slice Finish();
private:
std::unique_ptr<BlockBuilder> properties_block_;
BytewiseSortedMap props_;
};
// Were we encounter any error occurs during user-defined statistics collection,
// we'll write the warning message to info log.
void LogPropertiesCollectionError(
Logger* info_log, const std::string& method, const std::string& name);
// Utility functions help table builder to trigger batch events for user
// defined property collectors.
// Return value indicates if there is any error occurred; if error occurred,
// the warning message will be logged.
// NotifyCollectTableCollectorsOnAdd() triggers the `Add` event for all
// property collectors.
bool NotifyCollectTableCollectorsOnAdd(
const Slice& key,
const Slice& value,
const Options::TablePropertiesCollectors& collectors,
Logger* info_log);
// NotifyCollectTableCollectorsOnAdd() triggers the `Finish` event for all
// property collectors. The collected properties will be added to `builder`.
bool NotifyCollectTableCollectorsOnFinish(
const Options::TablePropertiesCollectors& collectors,
Logger* info_log,
PropertyBlockBuilder* builder);
// Read the properties from the table.
// @returns a status to indicate if the operation succeeded. On success,
// *table_properties will point to a heap-allocated TableProperties
// object, otherwise value of `table_properties` will not be modified.
Status ReadProperties(const Slice &handle_value, RandomAccessFile *file,
const Footer &footer, Env *env, Logger *logger,
TableProperties **table_properties);
// Directly read the properties from the properties block of a plain table.
// @returns a status to indicate if the operation succeeded. On success,
// *table_properties will point to a heap-allocated TableProperties
// object, otherwise value of `table_properties` will not be modified.
Status ReadTableProperties(RandomAccessFile* file, uint64_t file_size,
uint64_t table_magic_number, Env* env,
Logger* info_log, TableProperties** properties);
// Seek to the properties block.
// If it successfully seeks to the properties block, "is_found" will be
// set to true.
extern Status SeekToPropertiesBlock(Iterator* meta_iter, bool* is_found);
} // namespace rocksdb