LogCabin::Server::RaftConsensusInternal::ConfigurationManager Class Reference

Ensures the current configuration reflects the latest state of the log and snapshot. More...

#include <RaftConsensus.h>

List of all members.

Public Member Functions
	ConfigurationManager (Configuration &configuration)
	Constructor.
	~ConfigurationManager ()
	Destructor.
void	add (uint64_t index, const Protocol::Raft::Configuration &description)
	Called when a new configuration is added to the log.
void	truncatePrefix (uint64_t firstIndexKept)
	Called when a log prefix is truncated (after saving a snapshot that covers this prefix).
void	truncateSuffix (uint64_t lastIndexKept)
	Called when a log suffix is truncated (when the leader doesn't agree with this server's log).
void	setSnapshot (uint64_t index, const Protocol::Raft::Configuration &description)
	Called when a new snapshot is saved.
std::pair< uint64_t, Protocol::Raft::Configuration >	getLatestConfigurationAsOf (uint64_t lastIncludedIndex) const
	Return the configuration as of a particular log index.
Private Member Functions
void	restoreInvariants ()
	Helper function called after changing this object's state.
Private Attributes
Configuration &	configuration
	Defines the servers that are part of the cluster.
std::map< uint64_t, Protocol::Raft::Configuration >	descriptions
	This contains all the cluster configurations found in the log, plus one additional configuration from the latest snapshot.
std::pair< uint64_t, Protocol::Raft::Configuration >	snapshot
	This reflects the configuration found in this server's latest snapshot, or {0, {}} if this server has no snapshot.
Friends
class	Invariants

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Detailed Description

Ensures the current configuration reflects the latest state of the log and snapshot.

Definition at line 709 of file RaftConsensus.h.

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Constructor & Destructor Documentation

LogCabin::Server::RaftConsensusInternal::ConfigurationManager::ConfigurationManager

(

Configuration &

configuration

)

[explicit]

Constructor.

Parameters:

configuration

The configuration that this object is in charge of setting.

Definition at line 743 of file RaftConsensus.cc.

LogCabin::Server::RaftConsensusInternal::ConfigurationManager::~ConfigurationManager

(

)

Destructor.

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Member Function Documentation

void LogCabin::Server::RaftConsensusInternal::ConfigurationManager::add	(	uint64_t	index,
		const Protocol::Raft::Configuration &	description
	)

Called when a new configuration is added to the log.

Parameters:

index	The log index of this configuration (equivalently, its ID).
description	The serializable representation of the configuration.

void LogCabin::Server::RaftConsensusInternal::ConfigurationManager::truncatePrefix

(

uint64_t

firstIndexKept

)

Called when a log prefix is truncated (after saving a snapshot that covers this prefix).

Parameters:

firstIndexKept

The log entries in range [1, firstIndexKept) are being discarded.

void LogCabin::Server::RaftConsensusInternal::ConfigurationManager::truncateSuffix

(

uint64_t

lastIndexKept

)

Called when a log suffix is truncated (when the leader doesn't agree with this server's log).

Parameters:

lastIndexKept

The log entries in range (lastIndexKept, infinity) are being discarded.

void LogCabin::Server::RaftConsensusInternal::ConfigurationManager::setSnapshot	(	uint64_t	index,
		const Protocol::Raft::Configuration &	description
	)

Called when a new snapshot is saved.

Only the latest such configuration is kept.

Parameters:

index	The log index of this configuration (equivalently, its ID).
description	The serializable representation of the configuration.

Protocol::Raft::Configuration LogCabin::Server::RaftConsensusInternal::ConfigurationManager::getLatestConfigurationAsOf

(

uint64_t

lastIncludedIndex

)

const

Return the configuration as of a particular log index.

This is useful when taking snapshots.

Parameters:

lastIncludedIndex

Configurations greater than this index will be ignored.

Returns:

The index and description of the configuration with the largest index in the range [1, lastIncludedIndex].

Definition at line 790 of file RaftConsensus.cc.

void LogCabin::Server::RaftConsensusInternal::ConfigurationManager::restoreInvariants

(

)

[private]

Helper function called after changing this object's state.

• Make sure the snapshot configuration is in the descriptions map.
• Set configuration to the configuration with the largest index in the descriptions map, or reset it the map is empty.

Definition at line 806 of file RaftConsensus.cc.

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Friends And Related Function Documentation

friend class Invariants [friend]

Definition at line 806 of file RaftConsensus.h.

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Member Data Documentation

Configuration& LogCabin::Server::RaftConsensusInternal::ConfigurationManager::configuration [private]

Defines the servers that are part of the cluster.

See Configuration.

Definition at line 783 of file RaftConsensus.h.

std::map<uint64_t, Protocol::Raft::Configuration> LogCabin::Server::RaftConsensusInternal::ConfigurationManager::descriptions [private]

This contains all the cluster configurations found in the log, plus one additional configuration from the latest snapshot.

It is used to find the right configuration when taking a snapshot and truncating the end of the log. It must be kept consistent with the log when it is loaded, as the log grows, as it gets truncated from the beginning for snapshots, and as it gets truncated from the end upon conflicts with the leader.

The key is the entry ID where the configuration belongs in the log; the value is the serializable form of the configuration.

Definition at line 798 of file RaftConsensus.h.

std::pair<uint64_t, Protocol::Raft::Configuration> LogCabin::Server::RaftConsensusInternal::ConfigurationManager::snapshot [private]

This reflects the configuration found in this server's latest snapshot, or {0, {}} if this server has no snapshot.

Definition at line 804 of file RaftConsensus.h.

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The documentation for this class was generated from the following files:

• Server/RaftConsensus.h
• Server/RaftConsensus.cc