#include <userver/concurrent/background_task_storage.hpp>

Public Member Functions
	BackgroundTaskStorage ()

	BackgroundTaskStorage (engine::TaskProcessor &task_processor)
	Creates a BTS that launches tasks in the specified engine::TaskProcessor.

	BackgroundTaskStorage (const BackgroundTaskStorage &)=delete

BackgroundTaskStorage &	operator= (const BackgroundTaskStorage &)=delete

void	CancelAndWait () noexcept

template<typename... Args>
void	AsyncDetach (std::string name, Args &&... args)
	Launch a task that will be cancelled and waited for in the BTS destructor.

template<typename... Args>
void	AsyncDetach (engine::TaskProcessor &task_processor, std::string name, Args &&... args)

void	Detach (engine::Task &&task)

std::int64_t	ActiveTasksApprox () const noexcept
	Approximate number of currently active tasks.

Detailed Description

A storage that allows one to start detached tasks; cancels and waits for unfinished tasks completion at the destructor. Provides CancelAndWait to explicitly cancel tasks (recommended).

Usable for detached tasks that capture references to resources with a limited lifetime. You must guarantee that the resources are available while the BackgroundTaskStorage is alive.

Usage synopsis

  std::string x = kString;
  std::string y;
  {
    // You must guarantee that 'x' and 'y' are alive during 'bts' lifetime.
    concurrent::BackgroundTaskStorage bts;
 
    bts.AsyncDetach("task", [&x, &y] {
      engine::InterruptibleSleepFor(20s);
      EXPECT_TRUE(engine::current_task::ShouldCancel());
      y = std::move(x);
    });
 
    DoStuff();
 
    // It is recommended to call CancelAndWait explicitly for the clarity of
    // tasks' lifetime. BTS destructor calls CancelAndWait implicitly as well.
    bts.CancelAndWait();
  }

Definition at line 58 of file background_task_storage.hpp.

Constructor & Destructor Documentation

◆ BackgroundTaskStorage()

concurrent::BackgroundTaskStorage::BackgroundTaskStorage ( )

Creates a BTS that launches tasks in the engine::TaskProcessor used at the BTS creation.

Member Function Documentation

◆ AsyncDetach() [1/2]

template<typename... Args>

void concurrent::BackgroundTaskStorage::AsyncDetach	(	engine::TaskProcessor &	task_processor,
		std::string	name,
		Args &&...	args
	)

inline

Deprecated:: Pass engine::TaskProcessor to BTS constructor instead.

Definition at line 88 of file background_task_storage.hpp.

◆ AsyncDetach() [2/2]

template<typename... Args>

void concurrent::BackgroundTaskStorage::AsyncDetach	(	std::string	name,
		Args &&...	args
	)

inline

Launch a task that will be cancelled and waited for in the BTS destructor.

The task is started as non-Critical, it may be cancelled due to TaskProcessor overload. engine::TaskInheritedVariable instances are not inherited from the caller. See utils::AsyncBackground for details.

Definition at line 81 of file background_task_storage.hpp.