e6b3e3b4db
Summary: We'll need the prefix seek support for property aggregation. Test Plan: make all check Reviewers: haobo, sdong, dhruba Reviewed By: haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D15963
113 lines
4.1 KiB
C++
113 lines
4.1 KiB
C++
// 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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#pragma once
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#include <string>
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#include <map>
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#include "rocksdb/status.h"
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namespace rocksdb {
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// -- Table Properties
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// Other than basic table properties, each table may also have the user
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// collected properties.
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// The value of the user-collected properties are encoded as raw bytes --
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// users have to interprete these values by themselves.
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// Note: To do prefix seek/scan in `UserCollectedProperties`, you can do
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// something similar to:
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//
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// UserCollectedProperties props = ...;
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// for (auto pos = props.lower_bound(prefix);
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// pos != props.end() && pos->first.compare(0, prefix.size(), prefix) == 0;
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// ++pos) {
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// ...
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// }
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typedef std::map<std::string, std::string> UserCollectedProperties;
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// TableProperties contains a bunch of read-only properties of its associated
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// table.
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struct TableProperties {
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public:
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// the total size of all data blocks.
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uint64_t data_size = 0;
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// the size of index block.
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uint64_t index_size = 0;
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// the size of filter block.
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uint64_t filter_size = 0;
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// total raw key size
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uint64_t raw_key_size = 0;
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// total raw value size
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uint64_t raw_value_size = 0;
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// the number of blocks in this table
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uint64_t num_data_blocks = 0;
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// the number of entries in this table
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uint64_t num_entries = 0;
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// format version, reserved for backward compatibility
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uint64_t format_version = 0;
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// If 0, key is variable length. Otherwise number of bytes for each key.
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uint64_t fixed_key_len = 0;
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// The name of the filter policy used in this table.
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// If no filter policy is used, `filter_policy_name` will be an empty string.
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std::string filter_policy_name;
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// user collected properties
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UserCollectedProperties user_collected_properties;
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// convert this object to a human readable form
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// @prop_delim: delimiter for each property.
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std::string ToString(const std::string& prop_delim = "; ",
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const std::string& kv_delim = "=") const;
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};
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// table properties' human-readable names in the property block.
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struct TablePropertiesNames {
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static const std::string kDataSize;
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static const std::string kIndexSize;
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static const std::string kFilterSize;
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static const std::string kRawKeySize;
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static const std::string kRawValueSize;
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static const std::string kNumDataBlocks;
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static const std::string kNumEntries;
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static const std::string kFormatVersion;
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static const std::string kFixedKeyLen;
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static const std::string kFilterPolicy;
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};
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extern const std::string kPropertiesBlock;
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// `TablePropertiesCollector` provides the mechanism for users to collect
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// their own interested properties. This class is essentially a collection
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// of callback functions that will be invoked during table building.
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class TablePropertiesCollector {
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public:
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virtual ~TablePropertiesCollector() {}
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// Add() will be called when a new key/value pair is inserted into the table.
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// @params key the original key that is inserted into the table.
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// @params value the original value that is inserted into the table.
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virtual Status Add(const Slice& key, const Slice& value) = 0;
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// Finish() will be called when a table has already been built and is ready
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// for writing the properties block.
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// @params properties User will add their collected statistics to
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// `properties`.
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virtual Status Finish(UserCollectedProperties* properties) = 0;
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// The name of the properties collector can be used for debugging purpose.
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virtual const char* Name() const = 0;
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// Return the human-readable properties, where the key is property name and
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// the value is the human-readable form of value.
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virtual UserCollectedProperties GetReadableProperties() const = 0;
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};
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// Extra properties
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// Below is a list of non-basic properties that are collected by database
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// itself. Especially some properties regarding to the internal keys (which
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// is unknown to `table`).
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extern uint64_t GetDeletedKeys(const UserCollectedProperties& props);
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} // namespace rocksdb
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