dist_lock::DistLockedWorker Class Reference

#include <userver/dist_lock/dist_locked_worker.hpp>

Detailed Description

A high-level primitive that perpetually tries to acquire a distributed lock and runs user callback in a separate task while the lock is held. Cancels the task when the lock is lost.

Definition at line 27 of file dist_locked_worker.hpp.

Public Types
using	WorkerFunc = std::function<void()>

Public Member Functions
	DistLockedWorker (std::string name, WorkerFunc worker_func, std::shared_ptr< DistLockStrategyBase > strategy, const DistLockSettings &settings={}, engine::TaskProcessor *task_processor=nullptr)
const std::string &	Name () const
	Name of the worker.
DistLockSettings	GetSettings () const
	Retrieves settings in a thread-safe way.
void	UpdateSettings (const DistLockSettings &)
	Update settings in a thread-safe way.
void	Start ()
void	Stop ()
void	RunOnce ()
bool	IsRunning () const
std::optional< std::chrono::steady_clock::duration >	GetLockedDuration () const
const Statistics &	GetStatistics () const
	Returns lock acquisition statistics.

Member Typedef Documentation

WorkerFunc

using dist_lock::DistLockedWorker::WorkerFunc = std::function<void()>

Definition at line 29 of file dist_locked_worker.hpp.

Constructor & Destructor Documentation

DistLockedWorker()

dist_lock::DistLockedWorker::DistLockedWorker	(	std::string	name,
		WorkerFunc	worker_func,
		std::shared_ptr< DistLockStrategyBase >	strategy,
		const DistLockSettings &	settings = {},
		engine::TaskProcessor *	task_processor = nullptr )

Creates a DistLockedWorker.

Parameters

name	name of the worker
worker_func	a callback that's started each time we acquire the lock and is cancelled when the lock is lost.
settings	distributed lock settings
strategy	distributed locking strategy
task_processor	TaskProcessor for running worker_func, using current TaskProcessor if nullptr

Note

worker_func must honour task cancellation and stop ASAP when it is cancelled, otherwise brain split is possible (IOW, two different users do work assuming both of them hold the lock, which is not true).

Member Function Documentation

GetLockedDuration()

std::optional< std::chrono::steady_clock::duration > dist_lock::DistLockedWorker::GetLockedDuration

(

)

const

Returns for how long the lock is held (if held at all). Returned value may be less than the real duration.

IsRunning()

bool dist_lock::DistLockedWorker::IsRunning

(

)

const

Returns

whether the DistLockedTask is started.

RunOnce()

void dist_lock::DistLockedWorker::RunOnce

(

)

Run task once acquiring the lock.

Exceptions

std::exception

rethrows exception from worker_func.

Start()

void dist_lock::DistLockedWorker::Start

(

)

Starts acquiring the lock. Please note that it's possible that the lock is acquired and the WorkerFunc is entered before Start() returns.

See also

DistLockedTask::DistLockedTask

Stop()

void dist_lock::DistLockedWorker::Stop

(

)

Stops acquiring the lock. It is guaranteed that the lock is not held after Stop() return and WorkerFunc is stopped (if was started).

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

• userver/dist_lock/dist_locked_worker.hpp