Conditional Class Reference

A conditional variable synchcronization object for one to one and one to many signal and control events between processes. More...

#include <thread.h>

Inheritance diagram for Conditional:

Collaboration diagram for Conditional:

Public Member Functions
	Conditional (const char *id=NULL)
	Create an instance of a conditional. More...
virtual	~Conditional ()
	Destroy the conditional. More...
void	signal (bool broadcast)
	Signal a conditional object and a waiting threads. More...
bool	wait (timeout_t timer=0, bool locked=false)
	Wait to be signaled from another thread. More...
void	enterMutex (void)
	Locks the conditional's mutex for this thread. More...
void	lock (void)
	In the future we will use lock in place of enterMutex since the conditional composite is not a recursive mutex, and hence using enterMutex may cause confusion in expectation with the behavior of the Mutex class. More...
bool	tryEnterMutex (void)
	Tries to lock the conditional for the current thread. More...
bool	test (void)
void	leaveMutex (void)
	Leaving a mutex frees that mutex for use by another thread. More...
void	unlock (void)

Private Attributes
pthread_cond_t	_cond
pthread_mutex_t	_mutex

Detailed Description

A conditional variable synchcronization object for one to one and one to many signal and control events between processes.

Conditional variables may wait for and receive signals to notify when to resume or perform operations. Multiple waiting threads may be woken with a broadcast signal.

Warning

While this class inherits from Mutex, the methods of the class Conditional just handle the system conditional variable, so the user is responsible for calling enterMutex and leaveMutex so as to avoid race conditions. Another thing to note is that if you have several threads waiting on one condition, not uncommon in thread pools, each thread must take care to manually unlock the mutex if cancellation occurs. Otherwise the first thread cancelled will deadlock the rest of the thread.

Author

David Sugar conditional.

Todo:

implement in win32

Definition at line 636 of file thread.h.

Constructor & Destructor Documentation

Conditional::Conditional

(

const char *

id = NULL

)

Create an instance of a conditional.

Parameters

id	name of conditional, optional for deadlock testing.

virtual Conditional::~Conditional ( )

virtual

Destroy the conditional.

Member Function Documentation

void Conditional::enterMutex

(

void

)

Locks the conditional's mutex for this thread.

Remember that Conditional's mutex is NOT a recursive mutex!

See Also

leaveMutex

void Conditional::leaveMutex

(

void

)

Leaving a mutex frees that mutex for use by another thread.

See Also

enterMutex

void Conditional::lock ( void  )

inline

In the future we will use lock in place of enterMutex since the conditional composite is not a recursive mutex, and hence using enterMutex may cause confusion in expectation with the behavior of the Mutex class.

See Also

enterMutex

Definition at line 686 of file thread.h.

void Conditional::signal

(

bool

broadcast

)

Signal a conditional object and a waiting threads.

Parameters

broadcast

this signal to all waiting threads if true.

bool Conditional::test ( void  )

inline

Definition at line 701 of file thread.h.

bool Conditional::tryEnterMutex

(

void

)

Tries to lock the conditional for the current thread.

Behaves like enterMutex , except that it doesn't block the calling thread.

Returns

true if locking the mutex was succesful otherwise false

See Also

enterMutex

leaveMutex

void Conditional::unlock ( void  )

inline

Definition at line 711 of file thread.h.

bool Conditional::wait	(	timeout_t	timer = 0,
		bool	locked = false
	)

Wait to be signaled from another thread.

Parameters

timer	time period to wait.
locked	flag if already locked the mutex.

Field Documentation

pthread_cond_t Conditional::_cond

private

Definition at line 639 of file thread.h.

pthread_mutex_t Conditional::_mutex

private

Definition at line 640 of file thread.h.

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

• thread.h