#include <userver/dist_lock/dist_locked_worker.hpp>

Detailed Description

Perpetually acquires a distributed lock and runs a callback while it is held and runs user callback in a separate task while the lock is held. Cancels the task when the lock is lost.

Definition at line 31 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, logging::Level locker_log_level=logging::Level::kInfo)
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
bool	OwnsLock () const noexcept
std::optional< std::chrono::steady_clock::duration >	GetLockedDuration () const
const Statistics &	GetStatistics () const
	Returns lock acquisition statistics.
bool	IsCancelAdvised () const
	Returns true when it is advised to cancel the task.

Member Typedef Documentation

◆ WorkerFunc

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

Definition at line 33 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,
		logging::Level	locker_log_level = logging::Level::kInfo )

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
locker_log_level	Log level for Locker (default is info)

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.

◆ OwnsLock()

bool dist_lock::DistLockedWorker::OwnsLock ( ) const

noexcept

Returns: is current worker owns the lock

◆ 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).

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

userver/dist_lock/dist_locked_worker.hpp