Represents a configuration which should be run by server instance. More...

#include <zk/server/configuration.hpp>

Public Types
using	duration_type = std::chrono::milliseconds

Public Member Functions
const optional< std::string > &	source_file () const
	Get the source file. This will only have a value if this was created by from_file. More...

bool	is_minimal () const
	Check if this is a "minimal" configuration – meaning it only has a `data_directory` and `client_port` set. More...

std::map< server_id, std::string >	servers () const
	Get the servers which are part of the ZooKeeper ensemble. More...

configuration &	add_server (server_id id, std::string hostname, std::uint16_t peer_port=default_peer_port, std::uint16_t leader_port=default_leader_port)
	Add a new server to the configuration. More...

std::map< std::string, std::string >	unknown_settings () const
	Get settings that were in the configuration file (or manually added with add_setting) but unknown to this library. More...

configuration &	add_setting (std::string key, std::string value)
	Add an arbitrary setting with the key and value. More...

void	save (std::ostream &stream) const
	Write this configuration to the provided stream. More...

void	save_file (std::string filename)
	Save this configuration to filename. More...


std::uint16_t	client_port () const

configuration &	client_port (optional< std::uint16_t > port)


const optional< std::string > &	data_directory () const

configuration &	data_directory (optional< std::string > path)


duration_type	tick_time () const

configuration &	tick_time (optional< duration_type > time)


std::size_t	init_limit () const

configuration &	init_limit (optional< std::size_t > limit)


std::size_t	sync_limit () const

configuration &	sync_limit (optional< std::size_t > limit)


bool	leader_serves () const

configuration &	leader_serves (optional< bool > serve)


const std::set< std::string > &	four_letter_word_whitelist () const

configuration &	four_letter_word_whitelist (optional< std::set< std::string >> words)

Static Public Member Functions
static configuration	make_minimal (std::string data_directory, std::uint16_t client_port=default_client_port)
	Creates a minimal configuration, setting the four needed values. More...

static configuration	from_file (std::string filename)
	Load the configuration from a file. More...

static configuration	from_stream (std::istream &stream)
	Load configuration from the provided stream. More...

static configuration	from_lines (std::vector< std::string > lines)
	Load configuration from the provided lines. More...

static configuration	from_string (string_view value)
	Load configuration directly from the in-memory value. More...

Static Public Attributes
static const std::uint16_t	default_client_port = std::uint16_t(2181)
	The default value for client_port. More...

static const std::uint16_t	default_peer_port = std::uint16_t(2888)
	The default value for peer_port. More...

static const std::uint16_t	default_leader_port = std::uint16_t(3888)
	The default value for leader_port. More...

static const duration_type	default_tick_time = std::chrono::milliseconds(2000)
	The default value for tick_time. More...

static const std::size_t	default_init_limit = 10U
	The default value for init_limit. More...

static const std::size_t	default_sync_limit = 5U
	The default value for sync_limit. More...

static const std::set < std::string >	default_four_letter_word_whitelist = { "srvr" }
	The default value for four_letter_word_whitelist. More...

static const std::set < std::string >	all_four_letter_word_whitelist = { "*" }
	A value for four_letter_word_whitelist that enables all commands. More...

static const std::set < std::string >	known_four_letter_word_whitelist
	All known values allowed in four_letter_word_whitelist. More...

Friends

bool	operator== (const configuration &lhs, const configuration &rhs)

bool	operator!= (const configuration &lhs, const configuration &rhs)

Detailed Description

Represents a configuration which should be run by server instance.

This can also be used to modify an existing ZooKeeper server configuration file in a safer manner than the unfortunate operating practice of sed, awk, and perl.

This can be used to quickly create a quorum peer, ready to connect to 3 servers.

auto config = server::configuration::make_minimal("zk-data", 2181)
              .add_server(1, "192.168.1.101")
              .add_server(2, "192.168.1.102")
              .add_server(3, "192.168.1.103");
config.save_file("settings.cfg");
{
    std::ofstream of("zk-data/myid");
    // Assuming this is server 1
    of << 1 << std::endl;
}
server::server svr(config);

See also: server For where this is used.; server_group An example of quickly creating multiple ZooKeeper servers on a single machine (for testing).

Definition at line 71 of file configuration.hpp.

Member Function Documentation

configuration & zk::server::configuration::add_server	(	server_id	id,
		std::string	hostname,
		std::uint16_t	peer_port = `default_peer_port`,
		std::uint16_t	leader_port = `default_leader_port`
	)

Add a new server to the configuration.

Parameters

id	The cluster unique ID of this server.
hostname	The address of the server to connect to.
peer_port	The port used to move ZooKeeper data on.
leader_port	The port used for leader election.

Exceptions

std::out_of_range	if the id is not in the valid range of IDs (see server_id).
std::runtime_error	if there is already a server with the given id.

Definition at line 368 of file configuration.cpp.

configuration & zk::server::configuration::add_setting	(	std::string	key,
		std::string	value
	)

Add an arbitrary setting with the key and value.

Note: You should not use this frequently – prefer the named settings.

Definition at line 398 of file configuration.cpp.

std::uint16_t zk::server::configuration::client_port ( ) const

The port a client should use to connect to this server.

Definition at line 259 of file configuration.cpp.

const optional< std::string > & zk::server::configuration::data_directory ( ) const

The directory for "myid" file and "version-2" directory (containing the log, snapshot, and epoch files).

Definition at line 270 of file configuration.cpp.

const std::set< std::string > & zk::server::configuration::four_letter_word_whitelist ( ) const

A list of comma separated four letter words commands that user wants to use. A valid four letter words command must be put in this list or the ZooKeeper server will not enable the command. If unspecified, the whitelist only contains "srvr" command (default_four_letter_word_whitelist).

Note: It is planned that the ZooKeeper server will deprecate this whitelist in preference of using a JSON REST API for health checks. It is unlikely to be deprecated any time in the near future and will likely remain in the product for a very long time.

Parameters

words is the list of four letter words to allow or nullopt to clear the setting. If specified as an empty set, this explicitly disables all words, which is different than setting this value to nullopt.

Exceptions

std::invalid_argument if words contains the all value ("*") but it is not the only value in the set.

default_four_letter_word_whitelist all_four_letter_word_whitelist known_four_letter_word_whitelist

Definition at line 325 of file configuration.cpp.

configuration zk::server::configuration::from_file ( std::string filename )

static

Load the configuration from a file.

Definition at line 201 of file configuration.cpp.

configuration zk::server::configuration::from_lines ( std::vector< std::string > lines )

static

Load configuration from the provided lines.

Definition at line 118 of file configuration.cpp.

configuration zk::server::configuration::from_stream ( std::istream & stream )

static

Load configuration from the provided stream.

Definition at line 185 of file configuration.cpp.

configuration zk::server::configuration::from_string ( string_view value )

static

Load configuration directly from the in-memory value.

Definition at line 209 of file configuration.cpp.

std::size_t zk::server::configuration::init_limit ( ) const

The number of ticks that the initial synchronization phase can take. This limits the length of time the ZooKeeper servers in quorum have to connect to a leader.

Definition at line 292 of file configuration.cpp.

bool zk::server::configuration::is_minimal ( ) const

Check if this is a "minimal" configuration – meaning it only has a data_directory and client_port set.

Configurations which are minimal can be started directly from the command line.

Definition at line 216 of file configuration.cpp.

bool zk::server::configuration::leader_serves ( ) const

Should an elected leader accepts client connections? For higher update throughput at the slight expense of read latency, the leader can be configured to not accept clients and focus on coordination. The default to this value is true, which means that a leader will accept client connections.

Definition at line 314 of file configuration.cpp.

configuration zk::server::configuration::make_minimal	(	std::string	data_directory,
		std::uint16_t	client_port = `default_client_port`
	)

static

Creates a minimal configuration, setting the four needed values.

The resulting configuration can be run through a file with save or it can run directly from the command line.

Definition at line 77 of file configuration.cpp.

void zk::server::configuration::save ( std::ostream & stream ) const

Write this configuration to the provided stream.

See also: save_file

Definition at line 413 of file configuration.cpp.

void zk::server::configuration::save_file ( std::string filename )

Save this configuration to filename.

On successful save, source_file will but updated to reflect the new file.

Definition at line 421 of file configuration.cpp.

std::map< server_id, std::string > zk::server::configuration::servers ( ) const

Get the servers which are part of the ZooKeeper ensemble.

Definition at line 359 of file configuration.cpp.

const optional<std::string>& zk::server::configuration::source_file ( ) const

inline

Get the source file. This will only have a value if this was created by from_file.

Definition at line 126 of file configuration.hpp.

std::size_t zk::server::configuration::sync_limit ( ) const

Limits how far out of date a server can be from a leader.

Definition at line 303 of file configuration.cpp.

configuration::duration_type zk::server::configuration::tick_time ( ) const

The time between server "ticks." This value is used to translate init_limit and sync_limit into clock times.

Definition at line 281 of file configuration.cpp.

std::map< std::string, std::string > zk::server::configuration::unknown_settings ( ) const

Get settings that were in the configuration file (or manually added with add_setting) but unknown to this library.

Definition at line 389 of file configuration.cpp.

Friends And Related Function Documentation

bool operator==	(	const configuration &	lhs,
		const configuration &	rhs
	)

friend

Check for equality of configuration. This does not check the specification in lines, but the values of the settings. In other words, two configurations with tick_time set to 1 second are equal, even if the source files are different and "tickTime=1000" was set on different lines.

Definition at line 431 of file configuration.cpp.

Member Data Documentation

const std::set< std::string > zk::server::configuration::all_four_letter_word_whitelist = { "*" }

static

A value for four_letter_word_whitelist that enables all commands.

Note that this is not a list of all allowed words, but simply the string "*".

Definition at line 100 of file configuration.hpp.

const std::uint16_t zk::server::configuration::default_client_port = std::uint16_t(2181)

static

The default value for client_port.

Definition at line 78 of file configuration.hpp.

const std::set< std::string > zk::server::configuration::default_four_letter_word_whitelist = { "srvr" }

static

The default value for four_letter_word_whitelist.

Definition at line 96 of file configuration.hpp.

const std::size_t zk::server::configuration::default_init_limit = 10U

static

The default value for init_limit.

Definition at line 90 of file configuration.hpp.

const std::uint16_t zk::server::configuration::default_leader_port = std::uint16_t(3888)

static

The default value for leader_port.

Definition at line 84 of file configuration.hpp.

const std::uint16_t zk::server::configuration::default_peer_port = std::uint16_t(2888)

static

The default value for peer_port.

Definition at line 81 of file configuration.hpp.

const std::size_t zk::server::configuration::default_sync_limit = 5U

static

The default value for sync_limit.

Definition at line 93 of file configuration.hpp.

const configuration::duration_type zk::server::configuration::default_tick_time = std::chrono::milliseconds(2000)

static

The default value for tick_time.

Definition at line 87 of file configuration.hpp.

const std::set<std::string> zk::server::configuration::known_four_letter_word_whitelist

static

All known values allowed in four_letter_word_whitelist.

This set comes from what ZooKeeper server 3.5.3 supported, so it is possible the version of ZooKeeper you are running supports a different set.

Definition at line 104 of file configuration.hpp.

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

zk/server/configuration.hpp
zk/server/configuration.cpp

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Friends

Detailed Description

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation