A counting semaphore. More...

Public Member Functions
	CountingSemaphore ()
	Construct an initially blocking semaphore (initial count 0) without max count. More...

	CountingSemaphore (unsigned int count)
	Construct a semaphore with the given initial count without max count. More...

	CountingSemaphore (unsigned int count, unsigned int maxCount)
	Construct a semaphore with the given initial count and max count. More...

void	notify ()
	Signal that one waiting thread may continue. More...

void	wait ()
	Wait until a thread may enter. More...

bool	try_wait ()
	Try to enter. More...

Detailed Description

A counting semaphore.

Threads can enter when the internal count is > 0. Notifiying the semaphore increments the count and allows threads to enter. A thread can wait until it may enter. When it enters, it decrements the internal count. An optional max count can limit the value of count (useful e.g. when your buffer has a limited number of items).

A counting semaphore can be used e.g. in Producer-Consumer patterns. The producer signals new jobs/items via notify(), while the consumer waits for new jobs via wait().

Constructor & Destructor Documentation

◆ CountingSemaphore() [1/3]

simox::threads::CountingSemaphore::CountingSemaphore ( )

Construct an initially blocking semaphore (initial count 0) without max count.

◆ CountingSemaphore() [2/3]

simox::threads::CountingSemaphore::CountingSemaphore ( unsigned int count )

Construct a semaphore with the given initial count without max count.

Parameters

count The initial count (0 to block initially).

◆ CountingSemaphore() [3/3]

simox::threads::CountingSemaphore::CountingSemaphore	(	unsigned int	count,
		unsigned int	maxCount
	)

Construct a semaphore with the given initial count and max count.

Parameters

count	The initial count (0 to block initially).
maxCount	An optional count limit (1 for a binary semaphore).

Member Function Documentation

◆ notify()

void simox::threads::CountingSemaphore::notify ( )

Signal that one waiting thread may continue.

Also known as post() or signal(). Increments the count by 1, if it is below the optional max count.

◆ try_wait()

bool simox::threads::CountingSemaphore::try_wait ( )

Try to enter.

If the semaphore is currently blocking, return false. If the semaphore is free (count > 0), decrement the count and return true.

Returns: True if entering was successful, false if semaphore was blocking.

◆ wait()

void simox::threads::CountingSemaphore::wait ( )

Wait until a thread may enter.

Decrements the count when resuming.

Public Member Functions