A pool of threads to execute work concurrently. More...

#include <glibmm/threadpool.h>

Public Member Functions
	ThreadPool (int max_threads=-1, bool exclusive=false)
	Constructs a new thread pool. More...

virtual	~ThreadPool () noexcept

void	push (const sigc::slot< void > & slot)
	Inserts slot into the list of tasks to be executed by the pool. More...

void	set_max_threads (int max_threads)
	Sets the maximal allowed number of threads for the pool. More...

int	get_max_threads () const
	Returns the maximal number of threads for the pool. More...

unsigned int	get_num_threads () const
	Returns the number of threads currently running in the pool. More...

unsigned int	unprocessed () const
	Returns the number of tasks still unprocessed in the pool. More...

bool	get_exclusive () const
	Returns whether all threads are exclusive to this pool. More...

void	shutdown (bool immediately=false)
	Frees all resources allocated for the pool. More...

GThreadPool *	gobj ()

const GThreadPool *	gobj () const

Static Public Member Functions
static void	set_max_unused_threads (int max_threads)
	Sets the maximal number of unused threads to max_threads. More...

static int	get_max_unused_threads ()
	Returns the maximal allowed number of unused threads. More...

static unsigned int	get_num_unused_threads ()
	Returns the number of currently unused threads. More...

static void	stop_unused_threads ()
	Stops all currently unused threads. More...

Detailed Description

A pool of threads to execute work concurrently.

Deprecated:: This is deprecated in favor of the standard C++ concurrency API in C++11 and C++14.

Constructor & Destructor Documentation

◆ ThreadPool()

Glib::ThreadPool::ThreadPool	(	int	max_threads = `-1`,
		bool	exclusive = `false`
	)

explicit

Constructs a new thread pool.

Whenever you call ThreadPool::push(), either a new thread is created or an unused one is reused. At most max_threads threads are running concurrently for this thread pool. max_threads = -1 allows unlimited threads to be created for this thread pool.

The parameter exclusive determines, whether the thread pool owns all threads exclusive or whether the threads are shared globally. If exclusive is true, max_threads threads are started immediately and they will run exclusively for this thread pool until it is destroyed by ~ThreadPool(). If exclusive is false, threads are created when needed and shared between all non-exclusive thread pools. This implies that max_threads may not be -1 for exclusive thread pools.

Parameters

max_threads	The maximal number of threads to execute concurrently in the new thread pool, -1 means no limit.
exclusive	Should this thread pool be exclusive?

Exceptions

Glib::ThreadError An error can only occur when exclusive is set to true and not all max_threads threads could be created.

◆ ~ThreadPool()

virtual Glib::ThreadPool::~ThreadPool ( )

virtualnoexcept

Member Function Documentation

◆ get_exclusive()

bool Glib::ThreadPool::get_exclusive ( ) const

Returns whether all threads are exclusive to this pool.

Returns: Whether all threads are exclusive to this pool.

◆ get_max_threads()

int Glib::ThreadPool::get_max_threads ( ) const

Returns the maximal number of threads for the pool.

Returns: The maximal number of threads.

◆ get_max_unused_threads()

static int Glib::ThreadPool::get_max_unused_threads ( )

static

Returns the maximal allowed number of unused threads.

Returns: The maximal number of unused threads.

◆ get_num_threads()

unsigned int Glib::ThreadPool::get_num_threads ( ) const

Returns the number of threads currently running in the pool.

Returns: The number of threads currently running.

◆ get_num_unused_threads()

static unsigned int Glib::ThreadPool::get_num_unused_threads ( )

static

Returns the number of currently unused threads.

Returns: The number of currently unused threads.

◆ gobj() [1/2]

GThreadPool * Glib::ThreadPool::gobj ( )

inline

◆ gobj() [2/2]

const GThreadPool * Glib::ThreadPool::gobj ( ) const

inline

◆ push()

void Glib::ThreadPool::push ( const sigc::slot< void > & slot )

Inserts slot into the list of tasks to be executed by the pool.

When the number of currently running threads is lower than the maximal allowed number of threads, a new thread is started (or reused). Otherwise slot stays in the queue until a thread in this pool finishes its previous task and processes slot.

Because sigc::trackable is not thread-safe, if the slot represents a non-static class method and is created by sigc::mem_fun(), the class concerned should not derive from sigc::trackable. You can use, say, boost::bind() or, in C++11, std::bind() or a C++11 lambda expression instead of sigc::mem_fun().

Parameters

slot	A new task for the thread pool.

Exceptions

Glib::ThreadError An error can only occur when a new thread couldn't be created. In that case slot is simply appended to the queue of work to do.

◆ set_max_threads()

void Glib::ThreadPool::set_max_threads ( int max_threads )

Sets the maximal allowed number of threads for the pool.

A value of -1 means that the maximal number of threads is unlimited. Setting max_threads to 0 means stopping all work for pool. It is effectively frozen until max_threads is set to a non-zero value again.

A thread is never terminated while it is still running. Instead the maximal number of threads only has effect for the allocation of new threads in ThreadPool::push(). A new thread is allocated whenever the number of currently running threads in the pool is smaller than the maximal number.

Parameters

max_threads A new maximal number of threads for the pool.

Exceptions

Glib::ThreadError An error can only occur when a new thread couldn't be created.

◆ set_max_unused_threads()

static void Glib::ThreadPool::set_max_unused_threads ( int max_threads )

static

Sets the maximal number of unused threads to max_threads.

If max_threads is -1, no limit is imposed on the number of unused threads.

Parameters

max_threads Maximal number of unused threads.

◆ shutdown()

void Glib::ThreadPool::shutdown ( bool immediately = false )

Frees all resources allocated for the pool.

If immediately is true, no new task is processed. Otherwise the pool is not freed before the last task is processed. Note however, that no thread of this pool is interrupted while processing a task. Instead at least all still running threads can finish their tasks before the pool is freed.

This method does not return before all tasks to be processed (dependent on immediately, whether all or only the currently running) are ready. After calling shutdown() the pool must not be used anymore.

Parameters

immediately Should the pool shut down immediately?

◆ stop_unused_threads()

static void Glib::ThreadPool::stop_unused_threads ( )

static

Stops all currently unused threads.

This does not change the maximal number of unused threads. This function can be used to regularly stop all unused threads e.g. from Glib::signal_timeout().

◆ unprocessed()

unsigned int Glib::ThreadPool::unprocessed ( ) const

Returns the number of tasks still unprocessed in the pool.

Returns: The number of unprocessed tasks.

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ThreadPool()

◆ ~ThreadPool()

Member Function Documentation

◆ get_exclusive()

◆ get_max_threads()

◆ get_max_unused_threads()

◆ get_num_threads()

◆ get_num_unused_threads()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ push()

◆ set_max_threads()

◆ set_max_unused_threads()

◆ shutdown()

◆ stop_unused_threads()

◆ unprocessed()