Semaphore Class Reference
[Synchronization Primitives]

A counting semaphore -- a synchronization primitive that allows multiple processes to coordinate access to a shared resource. A Semaphore has an initial value, which represents the quantity of some shared resource. When a process acquires the semaphore, this value is decremented, and when it releases the semaphore, the value is incremented. More...

#include <Semaphore.h>

Inheritance diagram for Semaphore:

List of all members.

Public Member Functions
	Semaphore (const String &name, uint32 value=1, const Permissions &perm=Permissions::USER_READ_WRITE)
	~Semaphore ()
void	Lock ()
bool	TryWait ()
void	Unlock ()
int	GetValue () const
const String &	GetName () const
virtual void	ValidateMem () const
virtual void	CheckMem () const

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Detailed Description

A counting semaphore -- a synchronization primitive that allows multiple processes to coordinate access to a shared resource. A Semaphore has an initial value, which represents the quantity of some shared resource. When a process acquires the semaphore, this value is decremented, and when it releases the semaphore, the value is incremented.

Author:

Mark Lindner

Definition at line 62 of file Semaphore.h.

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Constructor & Destructor Documentation

Semaphore::Semaphore	(	const String &	name,
		uint32	value = 1,
		const Permissions &	perm = Permissions::USER_READ_WRITE
	)

Construct a new Semaphore with the given name, initial value, and permissions. If the underlying semaphore object did not yet exist, it is created.

Parameters:

	name	The name of the semaphore. On POSIX systems, the name must consist of at most 14 alphanumeric characters and may not contain slashes.
	value	The initial value of the semaphore. Must be at least 1.
	perm	The permissions with which to create the semaphore, if it does not yet exist.

Definition at line 45 of file Semaphore.cpp.

Semaphore::~Semaphore

(

)

Destructor. Destroys the underlying semaphore object, if no other processes have a reference to it.

Definition at line 99 of file Semaphore.cpp.

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Member Function Documentation

const String& Semaphore::GetName

(

)

const [inline]

Get the name of the semaphore.

Definition at line 127 of file Semaphore.h.

int Semaphore::GetValue

(

)

const

Get the current value of the semaphore.

Definition at line 170 of file Semaphore.cpp.

void Semaphore::Lock

(

)

Wait on the semaphore. If the semaphore's value is greater than 0, it's value is decremented and the method returns. Otherwise, the method blocks until the value becomes greater than 0.

Returns:

true if the semaphore was acquired, false if an error occurred.

Definition at line 119 of file Semaphore.cpp.

bool Semaphore::TryWait

(

)

Try to wait on the semaphore, returning immediately if it couldn't be acquired.

Returns:

true if the semaphore was acquired, false otherwise.

Definition at line 138 of file Semaphore.cpp.

void Semaphore::Unlock

(

)

Signal the semaphore. Increments the semaphore's value by 1. The semaphore must have previously been acquired.

Returns:

true if the semaphore was released, false otherwise.

Definition at line 151 of file Semaphore.cpp.

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

• spl/threading/Semaphore.h
• src/Semaphore.cpp