Semaphore

Semaphore. More...

Collaboration diagram for Semaphore:

Typedefs
typedef struct __tag_semaphore	GF_Semaphore
	abstracted semaphore object

Functions
GF_Semaphore *	gf_sema_new (u32 MaxCount, u32 InitCount)
	semaphore constructor More...
void	gf_sema_del (GF_Semaphore *sm)
	semaphore destructor More...
Bool	gf_sema_notify (GF_Semaphore *sm, u32 nb_rel)
	semaphore notification. More...
Bool	gf_sema_wait (GF_Semaphore *sm)
	semaphore wait More...
Bool	gf_sema_wait_for (GF_Semaphore *sm, u32 time_out)
	semaphore time wait More...

Detailed Description

The semaphore object allows controlling how portions of the code (typically access to variables) are executed by two threads (or a thread and the main process) at the same time. The best image for a semaphore is a limited set of money coins (always easy to understand hmm?). If no money is in the set, nobody can buy anything until a coin is put back in the set. When the set is full, the money is wasted (call it "the bank"...).

Function Documentation

gf_sema_new()

GF_Semaphore* gf_sema_new	(	u32	MaxCount,
		u32	InitCount
	)

Constructs a new semaphore object

Parameters

MaxCount	the maximum notification count of this semaphore
InitCount	the initial notification count of this semaphore upon construction

Returns

the semaphore object

gf_sema_del()

void gf_sema_del

(

GF_Semaphore *

sm

)

Destructs the semaphore object. This will wait for the semaphore to be released if needed.

Parameters

sm	the semaphore object

gf_sema_notify()

Bool gf_sema_notify	(	GF_Semaphore *	sm,
		u32	nb_rel
	)

Notifies the semaphore of a certain amount of releases.

Parameters

sm	the semaphore object
nb_rel	sm the number of release to notify

Returns

GF_TRUE if success, GF_FALSE otherwise

gf_sema_wait()

Bool gf_sema_wait

(

GF_Semaphore *

sm

)

Waits for the semaphore to be accessible (eg, may wait an infinite time).

Parameters

sm	the semaphore object

Returns

GF_TRUE if successful wait, GF_FALSE if wait failed

gf_sema_wait_for()

Bool gf_sema_wait_for	(	GF_Semaphore *	sm,
		u32	time_out
	)

Waits for a certain for the semaphore to be accessible, and returns when semaphore is accessible or wait time has passed.

Parameters

sm	the semaphore object
time_out	the amount of time to wait for the release in milliseconds

Returns

returns 1 if the semaphore was released before the timeout, 0 if the semaphore is still not released after the timeout.