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// Copyright (c) 2017-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).
/**
* The encoding of Cassandra Row Value.
*
* A Cassandra Row Value could either be a row tombstone,
* or contains multiple columns, it has following fields:
*
* struct row_value {
* int32_t local_deletion_time; // Time in second when the row is deleted,
* // only used for Cassandra tombstone gc.
* int64_t marked_for_delete_at; // Ms that marked this row is deleted.
* struct column_base columns[]; // For non tombstone row, all columns
* // are stored here.
* }
*
* If the local_deletion_time and marked_for_delete_at is set, then this is
* a tombstone, otherwise it contains multiple columns.
*
* There are three type of Columns: Normal Column, Expiring Column and Column
* Tombstone, which have following fields:
*
* // Identify the type of the column.
* enum mask {
* DELETION_MASK = 0x01,
* EXPIRATION_MASK = 0x02,
* };
*
* struct column {
* int8_t mask = 0;
* int8_t index;
* int64_t timestamp;
* int32_t value_length;
* char value[value_length];
* }
*
* struct expiring_column {
* int8_t mask = mask.EXPIRATION_MASK;
* int8_t index;
* int64_t timestamp;
* int32_t value_length;
* char value[value_length];
* int32_t ttl;
* }
*
* struct tombstone_column {
* int8_t mask = mask.DELETION_MASK;
* int8_t index;
* int32_t local_deletion_time; // Similar to row_value's field.
* int64_t marked_for_delete_at;
* }
*/
#pragma once
#include <chrono>
#include <memory>
#include <vector>
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
namespace ROCKSDB_NAMESPACE {
namespace cassandra {
// Identify the type of the column.
enum ColumnTypeMask {
DELETION_MASK = 0x01,
EXPIRATION_MASK = 0x02,
};
class ColumnBase {
public:
ColumnBase(int8_t mask, int8_t index);
virtual ~ColumnBase() = default;
virtual int64_t Timestamp() const = 0;
virtual int8_t Mask() const;
virtual int8_t Index() const;
virtual std::size_t Size() const;
virtual void Serialize(std::string* dest) const;
static std::shared_ptr<ColumnBase> Deserialize(const char* src,
std::size_t offset);
private:
int8_t mask_;
int8_t index_;
};
class Column : public ColumnBase {
public:
Column(int8_t mask, int8_t index, int64_t timestamp, int32_t value_size,
const char* value);
virtual int64_t Timestamp() const override;
virtual std::size_t Size() const override;
virtual void Serialize(std::string* dest) const override;
static std::shared_ptr<Column> Deserialize(const char* src,
std::size_t offset);
private:
int64_t timestamp_;
int32_t value_size_;
const char* value_;
};
class Tombstone : public ColumnBase {
public:
Tombstone(int8_t mask, int8_t index, int32_t local_deletion_time,
int64_t marked_for_delete_at);
virtual int64_t Timestamp() const override;
virtual std::size_t Size() const override;
virtual void Serialize(std::string* dest) const override;
bool Collectable(int32_t gc_grace_period) const;
static std::shared_ptr<Tombstone> Deserialize(const char* src,
std::size_t offset);
private:
int32_t local_deletion_time_;
int64_t marked_for_delete_at_;
};
class ExpiringColumn : public Column {
public:
ExpiringColumn(int8_t mask, int8_t index, int64_t timestamp,
int32_t value_size, const char* value, int32_t ttl);
virtual std::size_t Size() const override;
virtual void Serialize(std::string* dest) const override;
bool Expired() const;
std::shared_ptr<Tombstone> ToTombstone() const;
static std::shared_ptr<ExpiringColumn> Deserialize(const char* src,
std::size_t offset);
private:
int32_t ttl_;
std::chrono::time_point<std::chrono::system_clock> TimePoint() const;
std::chrono::seconds Ttl() const;
};
using Columns = std::vector<std::shared_ptr<ColumnBase>>;
class RowValue {
public:
// Create a Row Tombstone.
RowValue(int32_t local_deletion_time, int64_t marked_for_delete_at);
// Create a Row containing columns.
RowValue(Columns columns, int64_t last_modified_time);
RowValue(const RowValue& /*that*/) = delete;
RowValue(RowValue&& /*that*/) noexcept = default;
RowValue& operator=(const RowValue& /*that*/) = delete;
RowValue& operator=(RowValue&& /*that*/) = default;
std::size_t Size() const;
bool IsTombstone() const;
// For Tombstone this returns the marked_for_delete_at_,
// otherwise it returns the max timestamp of containing columns.
int64_t LastModifiedTime() const;
void Serialize(std::string* dest) const;
RowValue RemoveExpiredColumns(bool* changed) const;
RowValue ConvertExpiredColumnsToTombstones(bool* changed) const;
RowValue RemoveTombstones(int32_t gc_grace_period) const;
bool Empty() const;
static RowValue Deserialize(const char* src, std::size_t size);
// Merge multiple rows according to their timestamp.
static RowValue Merge(std::vector<RowValue>&& values);
const Columns& get_columns() { return columns_; }
private:
int32_t local_deletion_time_;
int64_t marked_for_delete_at_;
Columns columns_;
int64_t last_modified_time_;
};
} // namespace cassandra
} // namespace ROCKSDB_NAMESPACE
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