Semaphore Class Reference

This class implements a standard semaphore. More...

#include <tsemaphore.h>

Collaboration diagram for Semaphore:

[legend]List of all members.

Public Member Functions
	Semaphore (int initial_value=0)
	Set up a semaphore with passed initial value defaulting to 0:.
	~Semaphore ()
int	value ()
	Get the current value of the semaphore:.
void	post ()
	Increase the semaphore counter:.
void	wait ()
bool	test ()
Private Attributes
ConditionMutex	m
WaitCondition	c
volatile int	v
	volatile needed?

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Detailed Description

This class implements a standard semaphore.

Author:

Wolfgang Wieser ] wwieser (a) gmx <*> de [

Semaphores are counters for resources shared between threads. The basic operations on semaphores are: increment the counter atomically, and wait until the counter is non-null and decrement it atomically.

Definition at line 51 of file tsemaphore.h.

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Constructor & Destructor Documentation

Semaphore::Semaphore (  int  initial_value = 0  )  [inline]

Set up a semaphore with passed initial value defaulting to 0:. Definition at line 64 of file tsemaphore.h. References USE_PRIVATE__POSIX_SEMAPHORES.

Semaphore::~Semaphore (   )  [inline]

Destroy a semaphore. Make sure no thread is waiting for it before destroying a semaphore. Definition at line 73 of file tsemaphore.h. References USE_PRIVATE__POSIX_SEMAPHORES.

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Member Function Documentation

void Semaphore::post (   )

Increase the semaphore counter:. Definition at line 21 of file tsemaphore.cc. References WaitCondition::broadcast(), c, ConditionMutex::lock(), m, ConditionMutex::unlock(), and v.

bool Semaphore::test (   )

Non-blocking version. If the value of the semaphore is >0, decrease it and return 0. Otherwise return 1 instead of waiting. Definition at line 52 of file tsemaphore.cc. References ConditionMutex::lock(), m, ConditionMutex::unlock(), and v.

int Semaphore::value (   )  [inline]

Get the current value of the semaphore:. Definition at line 81 of file tsemaphore.h. References USE_PRIVATE__POSIX_SEMAPHORES.

void Semaphore::wait (   )

Wait for semaphore to become non-zero, then atomically decrease the semaphore count. Definition at line 32 of file tsemaphore.cc. References c, ConditionMutex::lock(), m, ConditionMutex::unlock(), v, and WaitCondition::wait().

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Member Data Documentation

WaitCondition Semaphore::c [private]

Definition at line 58 of file tsemaphore.h. Referenced by post(), and wait().

ConditionMutex Semaphore::m [private]

Definition at line 57 of file tsemaphore.h. Referenced by post(), test(), and wait().

volatile int Semaphore::v [private]

volatile needed? Definition at line 59 of file tsemaphore.h. Referenced by post(), test(), and wait().

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

• /ray/src/lib/threads/tsemaphore.h
• /ray/src/lib/threads/tsemaphore.cc

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