Semaphore Class Reference

#include <Semaphore.h>

Inheritance diagram for Semaphore:

Collaboration diagram for Semaphore:

Classes
class	SemaphoreEvent

Public Types
enum	SemaphoreError { TimedOut, Interrupted }
typedef Result< bool, SemaphoreError >	SemaphoreResult

Public Member Functions
	Semaphore (size_t nInitialValue, bool canInterrupt=true)
virtual	~Semaphore ()
SemaphoreResult	acquireWithResult (size_t n=1, size_t timeoutSecs=0, size_t timeoutUsecs=0)
bool	acquire (size_t n=1, size_t timeoutSecs=0, size_t timeoutUsecs=0)
bool	tryAcquire (size_t n=1)
void	release (size_t n=1)
ssize_t	getValue ()

Private Member Functions
	Semaphore (const Semaphore &)
void	operator= (const Semaphore &)
void	removeThread (class Thread *pThread)

Private Attributes
size_t	magic
Atomic< ssize_t >	m_Counter
Spinlock	m_BeingModified
List< class Thread * >	m_Queue
bool	m_bCanInterrupt

Detailed Description

A counting semaphore.

Definition at line 35 of file Semaphore.h.

Constructor & Destructor Documentation

Semaphore::Semaphore	(	size_t	nInitialValue,
		bool	canInterrupt = true
	)

Constructor

Parameters

nInitialValue	The initial value of the semaphore.
canInterrupt	If false, acquire() retries after interrupt rather than returning a failure status.

Definition at line 70 of file Semaphore.cc.

References assert.

Semaphore::~Semaphore ( )

virtual

Destructor

Definition at line 77 of file Semaphore.cc.

References assert, and List< T, nodePoolSize >::clear().

Semaphore::Semaphore ( const Semaphore &  )

private

Private copy constructor

Note

NOT implemented.

Member Function Documentation

bool Semaphore::acquire ( size_t  n = 1, size_t  timeoutSecs = 0, size_t  timeoutUsecs = 0  )

inline

Convenience wrapper for acquire().

Definition at line 62 of file Semaphore.h.

Referenced by RequestQueue::addRequest(), ProducerConsumer::consumerThread(), Pipe::decreaseRefCount(), RequestQueue::destroy(), UsbHub::doSync(), RequestQueue::halt(), CdiIrqHandler::irq(), LockedFile::lock(), LockedFile::LockedFile(), InputManager::mainThread(), LwipSocketSyscalls::netconnCallback(), Nic3C90x::Nic3C90x(), AsidManager::obtainAsid(), PerProcessorScheduler::processorAddThread(), AsidManager::returnAsid(), Nic3C90x::send(), Ne2k::send(), sys_arch_sem_wait(), sys_mutex_lock(), WaitCleanup::terminated(), ConditionVariable::wait(), KernelElf::waitForModulesToLoad(), RequestQueue::work(), and Pipe::~Pipe().

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Semaphore::SemaphoreResult Semaphore::acquireWithResult	(	size_t	n = 1,
		size_t	timeoutSecs = 0,
		size_t	timeoutUsecs = 0
	)

Attempts to acquire n items from the semaphore. This will block until the semaphore is non-zero.

Parameters

n	The number of semaphore items required. Must be non-zero.
timeoutSecs	Timeout value in seconds - if zero, no timeout.

Returns

a Result with a bool value indicating success if no timeout took place, a Result with a SemaphoreError error otherwise.

Definition at line 99 of file Semaphore.cc.

References Spinlock::acquire(), Timer::addAlarm(), Thread::addWakeupWatcher(), assert, Thread::Continue, Machine::getTimer(), Processor::information(), NOTICE, List< T, nodePoolSize >::pushBack(), Spinlock::release(), Timer::removeAlarm(), removeThread(), Thread::removeWakeupWatcher(), Thread::setDebugState(), Thread::setInterrupted(), Processor::setInterrupts(), Thread::setUnwindState(), tryAcquire(), and Thread::wasInterrupted().

ssize_t Semaphore::getValue

(

)

Gets the current value of the semaphore

Definition at line 318 of file Semaphore.cc.

Referenced by RequestQueue::getNextRequest(), ConditionVariable::wait(), and PosixSubsystem::~PosixSubsystem().

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void Semaphore::operator= ( const Semaphore &  )

private

Private operator=

Note

NOT implemented.

void Semaphore::release

(

size_t

n = 1

)

Releases n items from the semaphore.

Parameters

n	The number of semaphore items to release. Must be non-zero.

Definition at line 239 of file Semaphore.cc.

References Spinlock::acquire(), assert, List< T, nodePoolSize >::begin(), List< T, nodePoolSize >::count(), List< T, nodePoolSize >::end(), Thread::getLock(), Thread::getStatus(), Scheduler::instance(), List< T, nodePoolSize >::popFront(), List< T, nodePoolSize >::pushBack(), Spinlock::release(), Thread::setStatus(), and WARNING.

Referenced by RequestQueue::addRequest(), ProducerConsumer::consumerThread(), RequestQueue::destroy(), ConsoleFile::eventComplete(), RequestQueue::halt(), CdiIrqHandler::irq(), Nic3C90x::irq(), Pipe::isFifo(), LwipSocketSyscalls::netconnCallback(), Buffer< T, allowShortOperation >::notifyMonitors(), AsidManager::obtainAsid(), PollEvent::PollEvent(), InputManager::putNotification(), AsidManager::returnAsid(), Ne2k::send(), InputManager::shutdown(), Thread::shutdown(), UsbHub::syncCallback(), sys_mutex_unlock(), sys_sem_signal(), PosixSubsystem::threadRemoved(), LockedFile::unlock(), KernelElf::updateModuleStatus(), ConditionVariable::wait(), RequestQueue::work(), Pipe::~Pipe(), and PosixSubsystem::~PosixSubsystem().

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void Semaphore::removeThread ( class Thread *  pThread )

private

Removes the given pointer from the thread queue.

Note

Assume no other pointers that match

Definition at line 83 of file Semaphore.cc.

References Spinlock::acquire(), List< T, nodePoolSize >::begin(), List< T, nodePoolSize >::end(), List< T, nodePoolSize >::erase(), and Spinlock::release().

Referenced by acquireWithResult().

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bool Semaphore::tryAcquire

(

size_t

n = 1

)

Attempts to acquire n items from the semaphore. This will not block.

Parameters

n	The number of semaphore items required. Must be non-zero.

Returns

True if acquire succeeded, false otherwise.

Definition at line 223 of file Semaphore.cc.

Referenced by acquireWithResult(), LockedFile::lock(), RequestQueue::work(), and PosixSubsystem::~PosixSubsystem().

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

• Semaphore.h
• Semaphore.cc