ACE_Semaphore Class Reference

Wrapper for Dijkstra style general semaphores. More...

#include <Semaphore.h>

Inheritance diagram for ACE_Semaphore:

Public Member Functions
	ACE_Semaphore (unsigned int count=1, int type=USYNC_THREAD, const ACE_TCHAR *name=0, void *=0, int max=0x7fffffff)
	Initialize the semaphore, with initial value of "count". More...
	~ACE_Semaphore (void)
	Implicitly destroy the semaphore. More...
int	remove (void)
int	acquire (void)
int	acquire (ACE_Time_Value &tv)
int	acquire (ACE_Time_Value *tv)
int	tryacquire (void)
int	release (void)
int	release (unsigned int release_count)
int	acquire_read (void)
int	acquire_write (void)
int	tryacquire_read (void)
int	tryacquire_write (void)
int	tryacquire_write_upgrade (void)
void	dump (void) const
	Dump the state of an object. More...
const ACE_sema_t &	lock (void) const
	Return the underlying lock. More...

Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks. More...

Protected Attributes
ACE_sema_t	semaphore_
bool	removed_

Private Member Functions
void	operator= (const ACE_Semaphore &)
	ACE_Semaphore (const ACE_Semaphore &)

Detailed Description

Wrapper for Dijkstra style general semaphores.

Constructor & Destructor Documentation

ACE_Semaphore::ACE_Semaphore	(	unsigned int	count = 1,
		int	type = USYNC_THREAD,
		const ACE_TCHAR *	name = 0,
		void *	arg = 0,
		int	max = 0x7fffffff
	)

Initialize the semaphore, with initial value of "count".

ACE_Semaphore::~ACE_Semaphore

(

void

)

Implicitly destroy the semaphore.

ACE_Semaphore::ACE_Semaphore ( const ACE_Semaphore &  )

private

Member Function Documentation

int ACE_Semaphore::acquire ( void  )

inline

Block the thread until the semaphore count becomes greater than 0, then decrement it.

int ACE_Semaphore::acquire ( ACE_Time_Value &  tv )

inline

Block the thread until the semaphore count becomes greater than 0 (at which point it is decremented) or until tv times out (in which case -1 is returned and errno == ETIME). Note that tv is assumed to be in "absolute" rather than "relative" time. The value of tv is updated upon return to show the actual (absolute) acquisition time.

Note

Solaris threads do not support timed semaphores. Therefore, if you're running on Solaris you might want to consider using the ACE POSIX pthreads implementation instead, which can be enabled by compiling ACE with -DACE_HAS_PTHREADS, rather than -DACE_HAS_STHREADS or -DACE_HAS_POSIX_SEM.

int ACE_Semaphore::acquire ( ACE_Time_Value *  tv )

inline

If tv == 0 then call <acquire()> directly. Otherwise, Block the thread until the semaphore count becomes greater than 0 (at which point it is decremented) or until tv times out (in which case -1 is returned and errno == ETIME). Note that <*tv> is assumed to be in "absolute" rather than "relative" time. The value of <*tv> is updated upon return to show the actual (absolute) acquisition time.

Note

Solaris threads do not support timed semaphores. Therefore, if you're running on Solaris you might want to consider using the ACE POSIX pthreads implementation instead, which can be enabled by compiling ACE with -DACE_HAS_PTHREADS, rather than -DACE_HAS_STHREADS or -DACE_HAS_POSIX_SEM.

int ACE_Semaphore::acquire_read ( void  )

inline

Acquire semaphore ownership. This calls <acquire> and is only here to make the ACE_Semaphore interface consistent with the other synchronization APIs.

int ACE_Semaphore::acquire_write ( void  )

inline

Acquire semaphore ownership. This calls <acquire> and is only here to make the ACE_Semaphore interface consistent with the other synchronization APIs.

void ACE_Semaphore::dump

(

void

)

const

Dump the state of an object.

const ACE_sema_t & ACE_Semaphore::lock ( void  ) const

inline

Return the underlying lock.

void ACE_Semaphore::operator= ( const ACE_Semaphore &  )

private

int ACE_Semaphore::release ( void  )

inline

Increment the semaphore by 1, potentially unblocking a waiting thread.

int ACE_Semaphore::release ( unsigned int  release_count )

inline

Increment the semaphore by release_count, potentially unblocking waiting threads.

int ACE_Semaphore::remove ( void  )

inline

Explicitly destroy the semaphore. Note that only one thread should call this method since it doesn't protect against race conditions.

int ACE_Semaphore::tryacquire ( void  )

inline

Conditionally decrement the semaphore if count is greater than 0 (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_Semaphore::tryacquire_read ( void  )

inline

Conditionally acquire semaphore (i.e., won't block). This calls <tryacquire> and is only here to make the ACE_Semaphore interface consistent with the other synchronization APIs. Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_Semaphore::tryacquire_write ( void  )

inline

Conditionally acquire semaphore (i.e., won't block). This calls <tryacquire> and is only here to make the ACE_Semaphore interface consistent with the other synchronization APIs. Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_Semaphore::tryacquire_write_upgrade ( void  )

inline

This is only here to make the ACE_Semaphore interface consistent with the other synchronization APIs. Assumes the caller has already acquired the semaphore using one of the above calls, and returns 0 (success) always.

Member Data Documentation

ACE_Semaphore::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

bool ACE_Semaphore::removed_

protected

Keeps track of whether remove() has been called yet to avoid multiple remove() calls, e.g., explicitly and implicitly in the destructor. This flag isn't protected by a lock, so make sure that you don't have multiple threads simultaneously calling remove () on the same object, which is a bad idea anyway...

ACE_sema_t ACE_Semaphore::semaphore_

protected

---

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

• Semaphore.h
• Semaphore.cpp
• Semaphore.inl