Pool of NTP servers: rate-limited multi-server offset estimation. More...

#include <ntp_client_pool.hpp>

Classes
struct	ServerState
	Runtime state for a configured server. More...

Public Member Functions
	NtpClientPoolT (NtpPoolConfig cfg={})
	Construct pool with configuration.

	NtpClientPoolT (const NtpClientPoolT &)=delete

NtpClientPoolT &	operator= (const NtpClientPoolT &)=delete

	NtpClientPoolT (NtpClientPoolT &&other) noexcept
	Move-construct pool state.

NtpClientPoolT &	operator= (NtpClientPoolT &&other) noexcept
	Move-assign pool state.

void	set_servers (std::vector< NtpServerConfig > servers)
	Replace server list (keeps pool config).

void	add_server (NtpServerConfig server_cfg)
	Add one server.

void	set_default_servers ()
	Replace server list with a conservative default set.

void	clear_servers ()
	Clear server list.

bool	measure ()
	Perform measurement using current config (queries up to sample_servers).

bool	measure_n (std::size_t servers_to_sample)
	Perform measurement using a custom number of servers.

int64_t	offset_us () const noexcept
	Last estimated pool offset (µs).

int64_t	utc_time_us () const noexcept
	Current UTC time in microseconds based on pool offset.

int64_t	utc_time_ms () const noexcept
	Current UTC time in milliseconds based on pool offset.

int64_t	utc_time_sec () const noexcept
	Current UTC time in seconds based on pool offset.

std::vector< NtpSample >	last_samples () const
	Returns last measurement samples (copy).

bool	apply_samples (const std::vector< NtpSample > &samples)
	Apply pre-collected samples (testing/offline).

NtpPoolConfig	config () const
	Access config.

void	set_config (NtpPoolConfig cfg)
	Replace pool configuration.

Static Public Member Functions
static std::vector< NtpServerConfig >	build_default_servers ()
	Build a conservative default server list.

static int64_t	median (std::vector< int64_t > &values)
	Returns median of values.

static int64_t	median_mad_trim (std::vector< int64_t > &offsets)
	Median with MAD trimming.

static int64_t	best_delay_offset (const std::vector< NtpSample > &samples)
	Offset from best (lowest) delay sample.

Public Attributes
NtpPoolConfig	m_cfg

std::mutex	m_mtx

std::vector< ServerState >	m_servers

std::vector< NtpSample >	m_last_samples

std::atomic< int64_t >	m_offset_us

std::mt19937_64	m_rng

Private Member Functions
std::vector< std::size_t >	pick_servers_locked (std::size_t servers_to_sample)

NtpSample	query_one (std::size_t server_index)

void	update_server_state_after_query (std::size_t index, const NtpSample &sample)

bool	update_from_samples (const std::vector< NtpSample > &samples, const NtpPoolConfig &cfg)

Static Private Member Functions
static std::uint64_t	init_seed (std::uint64_t seed)

Detailed Description

template<class ClientT>
class time_shield::NtpClientPoolT< ClientT >

Pool of NTP servers: rate-limited multi-server offset estimation.

Template Parameters

ClientT NTP client type with interface: ClientT(const std::string& host, int port); bool query(); // may throw int last_error_code() const; int64_t offset_us() const; int64_t delay_us() const; int stratum() const;

Definition at line 78 of file ntp_client_pool.hpp.

Constructor & Destructor Documentation

◆ NtpClientPoolT() [1/3]

template<class ClientT>

time_shield::NtpClientPoolT< ClientT >::NtpClientPoolT ( NtpPoolConfig cfg = {} )

inlineexplicit

Construct pool with configuration.

Parameters

cfg	Pool configuration.

Definition at line 82 of file ntp_client_pool.hpp.

◆ NtpClientPoolT() [2/3]

template<class ClientT>

time_shield::NtpClientPoolT< ClientT >::NtpClientPoolT ( const NtpClientPoolT< ClientT > & )

delete

◆ NtpClientPoolT() [3/3]

template<class ClientT>

time_shield::NtpClientPoolT< ClientT >::NtpClientPoolT ( NtpClientPoolT< ClientT > && other )

inlinenoexcept

Move-construct pool state.

Definition at line 91 of file ntp_client_pool.hpp.

Member Function Documentation

◆ add_server()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::add_server ( NtpServerConfig server_cfg )

inline

Add one server.

Parameters

server_cfg Server configuration to add.

Definition at line 135 of file ntp_client_pool.hpp.

◆ apply_samples()

template<class ClientT>

bool time_shield::NtpClientPoolT< ClientT >::apply_samples ( const std::vector< NtpSample > & samples )

inline

Apply pre-collected samples (testing/offline).

Parameters

samples Sample list to apply.

Returns: True when pool offset updated.

Note: Primarily for tests; does not enforce rate limiting or backoff.

Definition at line 452 of file ntp_client_pool.hpp.

◆ best_delay_offset()

template<class ClientT>

static int64_t time_shield::NtpClientPoolT< ClientT >::best_delay_offset ( const std::vector< NtpSample > & samples )

inlinestatic

Offset from best (lowest) delay sample.

Parameters

samples Sample list to scan.

Returns: Offset from the sample with the lowest delay.

Definition at line 511 of file ntp_client_pool.hpp.

◆ build_default_servers()

template<class ClientT>

static std::vector< NtpServerConfig > time_shield::NtpClientPoolT< ClientT >::build_default_servers ( )

inlinestatic

Build a conservative default server list.

Returns: Default server list with conservative timing settings.

Definition at line 144 of file ntp_client_pool.hpp.

◆ clear_servers()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::clear_servers ( )

inline

Clear server list.

Definition at line 384 of file ntp_client_pool.hpp.

◆ config()

template<class ClientT>

NtpPoolConfig time_shield::NtpClientPoolT< ClientT >::config ( ) const

inline

Access config.

Returns: Current pool configuration.

Definition at line 533 of file ntp_client_pool.hpp.

◆ init_seed()

template<class ClientT>

static std::uint64_t time_shield::NtpClientPoolT< ClientT >::init_seed ( std::uint64_t seed )

inlinestaticprivate

Definition at line 570 of file ntp_client_pool.hpp.

◆ last_samples()

template<class ClientT>

std::vector< NtpSample > time_shield::NtpClientPoolT< ClientT >::last_samples ( ) const

inline

Returns last measurement samples (copy).

Returns: Copy of samples from the last measurement.

Definition at line 443 of file ntp_client_pool.hpp.

◆ measure()

template<class ClientT>

bool time_shield::NtpClientPoolT< ClientT >::measure ( )

inline

Perform measurement using current config (queries up to sample_servers).

Returns: True when pool offset updated.

Definition at line 391 of file ntp_client_pool.hpp.

◆ measure_n()

template<class ClientT>

bool time_shield::NtpClientPoolT< ClientT >::measure_n ( std::size_t servers_to_sample )

inline

Perform measurement using a custom number of servers.

Parameters

servers_to_sample Number of servers to query in this measurement.

Returns: True when pool offset updated.

Definition at line 399 of file ntp_client_pool.hpp.

◆ median()

template<class ClientT>

static int64_t time_shield::NtpClientPoolT< ClientT >::median ( std::vector< int64_t > & values )

inlinestatic

Returns median of values.

Parameters

values Values to process in-place.

Returns: Median of the input values.

Definition at line 463 of file ntp_client_pool.hpp.

◆ median_mad_trim()

template<class ClientT>

static int64_t time_shield::NtpClientPoolT< ClientT >::median_mad_trim ( std::vector< int64_t > & offsets )

inlinestatic

Median with MAD trimming.

Parameters

offsets Offset list to process in-place.

Returns: Median after MAD-based trimming.

Definition at line 479 of file ntp_client_pool.hpp.

◆ offset_us()

template<class ClientT>

int64_t time_shield::NtpClientPoolT< ClientT >::offset_us ( ) const

inlinenoexcept

Last estimated pool offset (µs).

Returns: Offset in microseconds (UTC - local realtime).

Definition at line 427 of file ntp_client_pool.hpp.

◆ operator=() [1/2]

template<class ClientT>

NtpClientPoolT & time_shield::NtpClientPoolT< ClientT >::operator= ( const NtpClientPoolT< ClientT > & )

delete

◆ operator=() [2/2]

template<class ClientT>

NtpClientPoolT & time_shield::NtpClientPoolT< ClientT >::operator= ( NtpClientPoolT< ClientT > && other )

inlinenoexcept

Move-assign pool state.

Definition at line 104 of file ntp_client_pool.hpp.

◆ pick_servers_locked()

template<class ClientT>

std::vector< std::size_t > time_shield::NtpClientPoolT< ClientT >::pick_servers_locked ( std::size_t servers_to_sample )

inlineprivate

Definition at line 577 of file ntp_client_pool.hpp.

◆ query_one()

template<class ClientT>

NtpSample time_shield::NtpClientPoolT< ClientT >::query_one ( std::size_t server_index )

inlineprivate

Definition at line 599 of file ntp_client_pool.hpp.

◆ set_config()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::set_config ( NtpPoolConfig cfg )

inline

Replace pool configuration.

Parameters

cfg	New pool configuration.

Definition at line 539 of file ntp_client_pool.hpp.

◆ set_default_servers()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::set_default_servers ( )

inline

Replace server list with a conservative default set.

Definition at line 379 of file ntp_client_pool.hpp.

◆ set_servers()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::set_servers ( std::vector< NtpServerConfig > servers )

inline

Replace server list (keeps pool config).

Parameters

servers Server configurations to use.

Definition at line 122 of file ntp_client_pool.hpp.

◆ update_from_samples()

template<class ClientT>

bool time_shield::NtpClientPoolT< ClientT >::update_from_samples	(	const std::vector< NtpSample > &	samples,
		const NtpPoolConfig &	cfg )

inlineprivate

Definition at line 666 of file ntp_client_pool.hpp.

◆ update_server_state_after_query()

template<class ClientT>

void time_shield::NtpClientPoolT< ClientT >::update_server_state_after_query	(	std::size_t	index,
		const NtpSample &	sample )

inlineprivate

Definition at line 638 of file ntp_client_pool.hpp.

◆ utc_time_ms()

template<class ClientT>

int64_t time_shield::NtpClientPoolT< ClientT >::utc_time_ms ( ) const

inlinenoexcept

Current UTC time in milliseconds based on pool offset.

Returns: UTC time in milliseconds using pool offset.

Definition at line 435 of file ntp_client_pool.hpp.

◆ utc_time_sec()

template<class ClientT>

int64_t time_shield::NtpClientPoolT< ClientT >::utc_time_sec ( ) const

inlinenoexcept

Current UTC time in seconds based on pool offset.

Returns: UTC time in seconds using pool offset.

Definition at line 439 of file ntp_client_pool.hpp.

◆ utc_time_us()

template<class ClientT>

int64_t time_shield::NtpClientPoolT< ClientT >::utc_time_us ( ) const

inlinenoexcept

Current UTC time in microseconds based on pool offset.

Returns: UTC time in microseconds using pool offset.

Definition at line 431 of file ntp_client_pool.hpp.

Member Data Documentation

◆ m_cfg

template<class ClientT>

NtpPoolConfig time_shield::NtpClientPoolT< ClientT >::m_cfg

Definition at line 559 of file ntp_client_pool.hpp.

◆ m_last_samples

template<class ClientT>

std::vector<NtpSample> time_shield::NtpClientPoolT< ClientT >::m_last_samples

Definition at line 563 of file ntp_client_pool.hpp.

◆ m_mtx

template<class ClientT>

std::mutex time_shield::NtpClientPoolT< ClientT >::m_mtx

mutable

Definition at line 561 of file ntp_client_pool.hpp.

◆ m_offset_us

template<class ClientT>

std::atomic<int64_t> time_shield::NtpClientPoolT< ClientT >::m_offset_us

Definition at line 565 of file ntp_client_pool.hpp.

◆ m_rng

template<class ClientT>

std::mt19937_64 time_shield::NtpClientPoolT< ClientT >::m_rng

Definition at line 567 of file ntp_client_pool.hpp.

◆ m_servers

template<class ClientT>

std::vector<ServerState> time_shield::NtpClientPoolT< ClientT >::m_servers

Definition at line 562 of file ntp_client_pool.hpp.

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

include/time_shield/ntp_client_pool.hpp

Classes

Public Member Functions

Static Public Member Functions

Public Attributes

Private Member Functions

Static Private Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ NtpClientPoolT() [1/3]

◆ NtpClientPoolT() [2/3]

◆ NtpClientPoolT() [3/3]

Member Function Documentation

◆ add_server()

◆ apply_samples()

◆ best_delay_offset()

◆ build_default_servers()

◆ clear_servers()

◆ config()

◆ init_seed()

◆ last_samples()

◆ measure()

◆ measure_n()

◆ median()

◆ median_mad_trim()

◆ offset_us()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ pick_servers_locked()

◆ query_one()

◆ set_config()

◆ set_default_servers()

◆ set_servers()

◆ update_from_samples()

◆ update_server_state_after_query()

◆ utc_time_ms()

◆ utc_time_sec()

◆ utc_time_us()

Member Data Documentation

◆ m_cfg

◆ m_last_samples

◆ m_mtx

◆ m_offset_us

◆ m_rng

◆ m_servers