xclox::ntp::Client Class Reference

Client is an asynchronous multi-query NTP client. More...

#include <client.hpp>

Public Types
Aliases
using	Callback = Query::Callback
	Type of query callback.
using	Status = Query::Status
	Type of query status.
using	DefaultTimeout = Query::DefaultTimeout
	Type of query timeout holder.

Public Member Functions
	Client (Callback callable)
	Default constructor. More...
	~Client ()
	Default destructor.
void	query (const std::string &server, const std::chrono::milliseconds &timeout=std::chrono::milliseconds(DefaultTimeout::ms))
	Place a NTP query [thread-safe]. More...
void	setCallback (Callback callable)
	Register a callable for reporting the result of the query back to the caller.
void	cancel ()
	Cancel all current queries [thread-safe].

Detailed Description

Client is an asynchronous multi-query NTP client.

Typically, a Client object is constructed by passing a callable of type Client::Callback to its constructor. User NTP query requests can be placed via query(). Once the query is finished, the registered callable is called back with the following details:

• NTP server name as it was provided by the caller
• IP address if the server name is successfully resolved or an empty string otherwise
• Client::Status flag indicating the final status of the query
• Packet object representing the server's reply on success or a null packet otherwise
• Elapsed time since sending the packet to the server

A default-constructed Client ignores any queries made on it if there is no registered callback. So, before issuing any query requests on such a Client, a callback has to be registered via setCallback().

Client first tries to resolve the server name; if resolving fails, Client::Status::ResolveError is reported. Otherwise, Client starts querying the resolved addresses one at a time until success or all addresses are queried.

Client awaits all pending queries until completion upon destruction. If you need to destruct a Client object as soon as possible, use cancel() to cancel all queries.

By default, each placed query has a total timeout period of 5 seconds to complete. If a query timed out, it is cancelled and reported to the caller with Client::Status::TimeoutError.

See also

The unit tests in client.h for further details.

Constructor & Destructor Documentation

Client()

xclox::ntp::Client::Client ( Callback  callable )

inlineexplicit

Default constructor.

Parameters

callable

is for reporting the result of each placed query back to the caller.

Member Function Documentation

query()

void xclox::ntp::Client::query ( const std::string &  server, const std::chrono::milliseconds &  timeout = std::chrono::milliseconds(DefaultTimeout::ms)  )

inline

Place a NTP query [thread-safe].

Parameters

server	is a domain name or an IP address, optionally along with a custom port number in the form "host[:port]". The default port is "123".
timeout	is the total time after which the query is cancelled if it is not completed.

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

• include/xclox/ntp/client.hpp