Dv::Thread::Pool Class Reference

A pool of worker threads. More...

#include <pool.h>

Inheritance diagram for Dv::Thread::Pool:

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Collaboration diagram for Dv::Thread::Pool:

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List of all members.

Classes
class	Thread
	Base class for threads that can be kept in a Dv::Thread::Pool. More...
Public Types
enum	Status { NONE = 0, INITIALIZED = 1, FINALIZED = 2 }
	Pool status. More...
Public Member Functions
bool	delegate (time_t msecs=0)
	Delegate some work to an available worker thread.
size_t	slack () const
Status	status () const
size_t	size () const
Private Member Functions
	Pool (size_t max_threads, Factory &factory, const std::string &name)
	Constructor.
	~Pool ()
	Destructor.
const std::string &	name () const
bool	initialize (time_t millisecs)
	Initialize a Dv::Thread::Pool.
bool	finalize (time_t millisecs)
	Finalize a Dv::Thread::Pool by killing all its threads (and joining them).
void	add_live (int n)
	Called at the beginning and the end of a thread's main function.
void	add_free (Thread *t)
	Pool (const Pool &)
Pool &	operator= (const Pool &)
	No assignment operator.
Private Attributes
Factory &	factory_
	Factory to which the pool belongs.
std::vector< Thread * >	all_
	Vector of all threads in the pool.
std::list< Thread * >	free_
	List of threads waiting for work.
Monitor	free_monitor_
	Monitor to use for controlling access to free_.
std::string	name_
	Name of the pool.
size_t	live_threads_
	Number of threads that have started their main function and not yet finished it.
Status	status_
Friends
class	Factory
class	Thread

Detailed Description

A pool of worker threads.

Normally, a pool is owned by a Dv::Thread::Pool::Factory.

See also:: Dv::Thread::Pool::Factor

Member Enumeration Documentation

enum Dv::Thread::Pool::Status

Pool status.

Enumerator:

NONE
INITIALIZED
FINALIZED

Constructor & Destructor Documentation

Dv::Thread::Pool::Pool	(	size_t	max_threads,
		Factory &	factory,
		const std::string &	name
	)			`[private]`

Constructor.

Note that the actual initialisation of the threads in the pool is done by Dv::Thread::Pool::initialize, which is not called by this constructor. It should be called by the constructor of the user's class derived from Dv::Thread::Factory.

Parameters:

	max_threads	number of threads that will be kept in the pool.
	factory	object that is capable of creating a new thread
	name	for the pool's monitor.

See also:: Dv::Thread::Factory::initialize; Dv::Thread::Factory::finalize

Dv::Thread::Pool::~Pool ( ) [private]

Destructor.

Note that the actual finalisation of the threads in the pool is done by Dv::Thread::Pool::finalize, which is not called by this destructor. It should have been called by the destructor of the user's class derived from Dv::Thread::Factory.

See also:: Dv::Thread::Factory::finalize; Dv::Thread::Factory::initialize

Dv::Thread::Pool::Pool ( const Pool & ) [private]

Member Function Documentation

bool Dv::Thread::Pool::delegate ( time_t msecs = 0 )

Delegate some work to an available worker thread.

If a thread is available, this function will among other call its Dv::Thread::Pool::Thread::setup function to supply it with input and then signal it.

Parameters:

msecs

we are prepared to wait until a thread is ready for work (so 0 means immediately return false if there is no thread waiting for work). If negative, we will wait indefinitely until a worker thread becomes available.

Returns:: true iff the delegation was succesful.; false iff no worker threads are available

See also:: Dv::Thread::Pool::Thread::setup; Dv::Thread::Pool::Thread::signal

size_t Dv::Thread::Pool::slack ( ) const [inline]

Returns:: the number of threads that are waiting for work.

References free_.

Referenced by Dv::Thread::Factory::slack().

Status Dv::Thread::Pool::status ( ) const [inline]

Returns:: status of pool

References status_.

size_t Dv::Thread::Pool::size ( ) const [inline]

Returns:: the number of threads in the pool.

References all_.

Referenced by Dv::Thread::Factory::size().

const std::string& Dv::Thread::Pool::name ( ) const [inline, private]

Returns:: name of this pool (used as name for its monitor and also as the basis for the names of the threads' monitor).

Reimplemented from Dv::Thread::Monitor.

References name_.

bool Dv::Thread::Pool::initialize ( time_t millisecs ) [private]

Initialize a Dv::Thread::Pool.

This is separate from the constructor because the function creates and starts a number of threads using the pool's Dv::Thread::Factory::create pure virtual function which only becomes available in the constructor of the Dv::Thread::Factory-derived user class.

Parameters:

millisecs

timeout after which it is assumed that the initialization failed.

Returns:: true iff the initialization succeeded

See also:: Dv::Thread::Factory::init

Referenced by Dv::Thread::Factory::initialize().

bool Dv::Thread::Pool::finalize ( time_t millisecs ) [private]

Finalize a Dv::Thread::Pool by killing all its threads (and joining them).

This is separate from the destructor because the function kills a number of threads which involves the pool's Dv::Thread::Factory::finalize pure virtual function which only remains available in the destructor of the Dv::Thread::Factory-derived user class.

Parameters:

millisecs

timeout after which it is assumed that the initialization failed.

Returns:: true iff the finalization succeeded

See also:: Dv::Thread::Factory::finit

Referenced by Dv::Thread::Factory::finalize().

void Dv::Thread::Pool::add_live ( int n ) [private]

Called at the beginning and the end of a thread's main function.

If the total number of live threads becomes 0, the DEAD condition of the Pool's monitor will be signaled. Conversely, if the total number of live threads becomes equal to the capacity of the pool, the LIVE condition will be signaled.

Parameters:

n

whether a thread started (+1) or finished (-1)