vlink::ThreadPool Class Reference

Fixed-size thread pool for parallel task execution. More...

#include <thread_pool.h>

Collaboration diagram for vlink::ThreadPool:

Public Types
enum	Type : uint8_t { kNormalType = 0 , kLockfreeType = 1 }
	Queue implementation type. More...
enum	Strategy : uint8_t { kOptimizationStrategy = 0 , kPopStrategy = 1 , kBlockStrategy = 2 }
	Idle strategy controlling CPU and wake-up latency trade-offs. More...
using	Callback = std::function<void()>
	Callback type for tasks submitted to the pool.

Public Member Functions
	ThreadPool (size_t thread_count=4U)
	Constructs a ThreadPool with thread_count worker threads and kNormalType queue.
	ThreadPool (size_t thread_count, Type type)
	Constructs a ThreadPool with the specified thread count and queue type.
virtual	~ThreadPool ()
	Destructor. Calls shutdown() and joins all worker threads.
void	set_name (const std::string &name)
	Sets a human-readable name for the pool (and its worker threads).
const std::string &	get_name () const
	Returns the name set via set_name().
Type	get_type () const
	Returns the queue type this pool was constructed with.
Strategy	get_strategy () const
	Returns the current idle strategy.
void	set_strategy (Strategy strategy)
	Changes the idle strategy.
bool	shutdown ()
	Signals all workers to finish current tasks and exit.
bool	post_task (Callback &&callback)
	Posts a task to the queue for execution by a worker thread.
size_t	get_task_count () const
	Returns the number of tasks currently in the queue.
bool	is_in_work_thread () const
	Returns true if the calling thread is a worker thread of this pool.
virtual size_t	get_max_task_count () const
	Returns the maximum queue depth.
template<class FunctionT, class... ArgsT, typename ResultT = std::invoke_result_t<FunctionT, ArgsT...>>
std::future< ResultT >	invoke_task (FunctionT &&function, ArgsT &&... args)
	Dispatches a callable to a worker thread and returns a std::future for the result.

Detailed Description

Fixed-size thread pool for parallel task execution.

Worker threads are created on construction and destroyed on shutdown() or destruction.

Member Typedef Documentation

Callback

using vlink::ThreadPool::Callback = std::function<void()>

Callback type for tasks submitted to the pool.

Member Enumeration Documentation

Strategy

enum vlink::ThreadPool::Strategy : uint8_t

Idle strategy controlling CPU and wake-up latency trade-offs.

Enumerator
kOptimizationStrategy	Balance latency and CPU via yield.
kPopStrategy	Busy-poll (lowest latency, highest CPU).
kBlockStrategy	Block on condition variable (lowest CPU).

Type

enum vlink::ThreadPool::Type : uint8_t

Queue implementation type.

Enumerator
kNormalType	Mutex-protected FIFO queue (default).
kLockfreeType	Lock-free MPMC queue.

Constructor & Destructor Documentation

ThreadPool() [1/2]

vlink::ThreadPool::ThreadPool ( size_t thread_count = 4U )

explicit

Constructs a ThreadPool with thread_count worker threads and kNormalType queue.

Parameters

thread_count

Number of worker threads. Default: 4.

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ThreadPool() [2/2]

vlink::ThreadPool::ThreadPool ( size_t thread_count, Type type )

explicit

Constructs a ThreadPool with the specified thread count and queue type.

Parameters

thread_count	Number of worker threads.
type	Queue implementation type.

~ThreadPool()

virtual vlink::ThreadPool::~ThreadPool ( )

virtual

Destructor. Calls shutdown() and joins all worker threads.

Member Function Documentation

get_max_task_count()

virtual size_t vlink::ThreadPool::get_max_task_count ( ) const

nodiscardvirtual

Returns the maximum queue depth.

Returns

Maximum number of tasks that can be queued simultaneously.

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get_name()

const std::string & vlink::ThreadPool::get_name ( ) const

nodiscard

Returns the name set via set_name().

Returns

Reference to the name string.

get_strategy()

Strategy vlink::ThreadPool::get_strategy ( ) const

nodiscard

Returns the current idle strategy.

Returns

Current strategy.

get_task_count()

size_t vlink::ThreadPool::get_task_count ( ) const

nodiscard

Returns the number of tasks currently in the queue.

Returns

Pending task count.

get_type()

Type vlink::ThreadPool::get_type ( ) const

nodiscard

Returns the queue type this pool was constructed with.

Returns

Queue type.

invoke_task()

template<class FunctionT, class... ArgsT, typename ResultT>

std::future< ResultT > vlink::ThreadPool::invoke_task ( FunctionT && function, ArgsT &&... args )

inlinenodiscard

Dispatches a callable to a worker thread and returns a std::future for the result.

Details.

Thread-safe. The future becomes ready after the callable is executed by a worker.

Warning

Do not block on the future from a pool worker thread if all workers are busy; this will deadlock.

Template Parameters

FunctionT	Callable type.
ArgsT	Argument types.
ResultT	Return type (deduced).

Parameters

function	Callable to dispatch.
args	Arguments forwarded to the callable.

Returns

std::future<ResultT> that becomes ready when the task completes.

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is_in_work_thread()

bool vlink::ThreadPool::is_in_work_thread ( ) const

nodiscard

Returns true if the calling thread is a worker thread of this pool.

Returns

true if called from a pool worker.

post_task()

bool vlink::ThreadPool::post_task

(

Callback &&

callback

)

Posts a task to the queue for execution by a worker thread.

Thread-safe. Returns false if the pool is shutting down or the queue is full (get_max_task_count()).

Parameters

callback

Task to execute.

Returns

true if enqueued successfully.

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set_name()

void vlink::ThreadPool::set_name

(

const std::string &

name

)

Sets a human-readable name for the pool (and its worker threads).

Parameters

name	Name string.

set_strategy()

void vlink::ThreadPool::set_strategy

(

Strategy

strategy

)

Changes the idle strategy.

Parameters

strategy

New strategy.

shutdown()

bool vlink::ThreadPool::shutdown

(

)

Signals all workers to finish current tasks and exit.

Waits for all worker threads to join before returning. After shutdown(), the pool can no longer accept tasks.

Returns

true on success.

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

• include/vlink/base/thread_pool.h