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rocksdb/include/rocksdb/table_properties.h

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// 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 <string>
#include <unordered_map>
#include "rocksdb/status.h"
namespace rocksdb {
// TableProperties contains a bunch of read-only properties of its associated
// table.
struct TableProperties {
public:
// Other than basic table properties, each table may also have the user
// collected properties.
// The value of the user-collected properties are encoded as raw bytes --
// users have to interprete these values by themselves.
typedef
std::unordered_map<std::string, std::string>
UserCollectedProperties;
// the total size of all data blocks.
uint64_t data_size = 0;
// the size of index block.
uint64_t index_size = 0;
// the size of filter block.
uint64_t filter_size = 0;
// total raw key size
uint64_t raw_key_size = 0;
// total raw value size
uint64_t raw_value_size = 0;
// the number of blocks in this table
uint64_t num_data_blocks = 0;
// the number of entries in this table
uint64_t num_entries = 0;
// The name of the filter policy used in this table.
// If no filter policy is used, `filter_policy_name` will be an empty string.
std::string filter_policy_name;
// user collected properties
UserCollectedProperties user_collected_properties;
// convert this object to a human readable form
// @prop_delim: delimiter for each property.
std::string ToString(
const std::string& prop_delim = "; ",
const std::string& kv_delim = "=") const;
};
// `TablePropertiesCollector` provides the mechanism for users to collect
// their own interested properties. This class is essentially a collection
// of callback functions that will be invoked during table building.
class TablePropertiesCollector {
public:
virtual ~TablePropertiesCollector() { }
// Add() will be called when a new key/value pair is inserted into the table.
// @params key the original key that is inserted into the table.
// @params value the original value that is inserted into the table.
virtual Status Add(const Slice& key, const Slice& value) = 0;
// Finish() will be called when a table has already been built and is ready
// for writing the properties block.
// @params properties User will add their collected statistics to
// `properties`.
virtual Status Finish(
TableProperties::UserCollectedProperties* properties) = 0;
// The name of the properties collector can be used for debugging purpose.
virtual const char* Name() const = 0;
// Return the human-readable properties, where the key is property name and
// the value is the human-readable form of value.
virtual TableProperties::UserCollectedProperties
GetReadableProperties() const = 0;
};
// Extra properties
// Below is a list of non-basic properties that are collected by database
// itself. Especially some properties regarding to the internal keys (which
// is unknown to `table`).
extern uint64_t GetDeletedKeys(
const TableProperties::UserCollectedProperties& props);
} // namespace rocksdb